Polymers in Aerospace Applications docx

Most bres used in aerospace applications serve as reinforcements in composite materials; other uses are found for these fibres in cabin furnishing, parachutes, and other specialised app

Expert overviews covering the science and technology of rubber and plastics

Volume 16, Number 12

Joel R Fried

Polymers in Aerospace Applications

16

–

12

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ether-of dynamic storage and loss moduli ether-of specimens with time observed during isothermal annealing Analysis of FTIR spectra indicated that variations in hydrogen bonding with time during isothermal annealing very much resembled variations of dynamic storage modulus with time during isothermal annealing Isochronal dynamic temp sweep experiments indicated that the thermoplastic PUs exhibited a hysteresis effect in the heating and cooling processes It was concluded that the microphase separation transition

or order-disorder transition in thermoplastic PUs could not be determined from the isochronal dynamic temp sweep experiment The plots of log dynamic storage modulus versus log loss modulus varied with temp over the entire range of temps (110-190C) investigated 57 refs

GOODRICH B.F

USA

Accession no.771897

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Volume 1

Report 1 Conductive Polymers, W.J Feast

Report 2 Medical, Surgical and Pharmaceutical Applications of

Polymers, D.F Williams

Report 3 Advanced Composites, D.K Thomas, RAE,

Farnborough.

Report 4 Liquid Crystal Polymers, M.K Cox, ICI, Wilton.

Report 5 CAD/CAM in the Polymer Industry, N.W Sandland and

M.J Sebborn, Cambridge Applied Technology.

Report 8 Engineering Thermoplastics, I.T Barrie, Consultant.

Report 10 Reinforced Reaction Injection Moulding,

P.D Armitage, P.D Coates and A.F Johnson

Report 11 Communications Applications of Polymers,

R Spratling, British Telecom.

Report 12 Process Control in the Plastics Industry,

R.F Evans, Engelmann & Buckham Ancillaries.

Volume 2

Report 13 Injection Moulding of Engineering Thermoplastics,

A.F Whelan, London School of Polymer Technology.

Report 14 Polymers and Their Uses in the Sports and Leisure

Industries, A.L Cox and R.P Brown, Rapra Technology

Ltd.

Report 15 Polyurethane, Materials, Processing and Applications,

G Woods, Consultant.

Report 16 Polyetheretherketone, D.J Kemmish, ICI, Wilton.

Report 17 Extrusion, G.M Gale, Rapra Technology Ltd.

Report 18 Agricultural and Horticultural Applications of

Polymers, J.C Garnaud, International Committee for

Plastics in Agriculture.

Report 19 Recycling and Disposal of Plastics Packaging,

R.C Fox, Plas/Tech Ltd.

Report 20 Pultrusion, L Hollaway, University of Surrey.

Report 21 Materials Handling in the Polymer Industry,

H Hardy, Chronos Richardson Ltd.

Report 22 Electronics Applications of Polymers, M.T.Goosey,

Plessey Research (Caswell) Ltd.

Report 23 Offshore Applications of Polymers, J.W.Brockbank,

Avon Industrial Polymers Ltd.

Report 24 Recent Developments in Materials for Food Packaging,

R.A Roberts, Pira Packaging Division.

Volume 3

Report 25 Foams and Blowing Agents, J.M Methven, Cellcom

Technology Associates.

Report 26 Polymers and Structural Composites in Civil

Engineering, L Hollaway, University of Surrey.

Report 27 Injection Moulding of Rubber, M.A Wheelans,

Consultant.

Report 28 Adhesives for Structural and Engineering Applications,

C O’Reilly, Loctite (Ireland) Ltd.

Report 29 Polymers in Marine Applications, C.F.Britton, Corrosion

Monitoring Consultancy.

Report 30 Non-destructive Testing of Polymers, W.N Reynolds,

National NDT Centre, Harwell.

Report 31 Silicone Rubbers, B.R Trego and H.W.Winnan,

Dow Corning Ltd.

Report 32 Fluoroelastomers - Properties and Applications,

D Cook and M Lynn, 3M United Kingdom Plc and

Report 36 Developments in Additives to Meet Health and

Environmental Concerns, M.J Forrest, Rapra

Technology Ltd.

Volume 4

Report 37 Polymers in Aerospace Applications, W.W Wright,

University of Surrey.

Report 38 Epoxy Resins, K.A Hodd

Report 39 Polymers in Chemically Resistant Applications,

D Cattell, Cattell Consultancy Services.

Report 40 Internal Mixing of Rubber, J.C Lupton

Report 41 Failure of Plastics, S Turner, Queen Mary College.

Report 42 Polycarbonates, R Pakull, U Grigo, D Freitag, Bayer AG.

Report 43 Polymeric Materials from Renewable Resources,

Report 46 Quality Today in Polymer Processing, S.H Coulson,

J.A Cousans, Exxon Chemical International Marketing.

Report 47 Chemical Analysis of Polymers, G Lawson, Leicester

Polytechnic

Report 48 Plastics in Building, C.M.A Johansson

Volume 5

Report 49 Blends and Alloys of Engineering Thermoplastics, H.T

van de Grampel, General Electric Plastics BV.

Report 50 Automotive Applications of Polymers II,

A.N.A Elliott, Consultant.

Report 51 Biomedical Applications of Polymers, C.G Gebelein,

Youngstown State University / Florida Atlantic University Report 52 Polymer Supported Chemical Reactions, P Hodge,

University of Manchester.

Report 53 Weathering of Polymers, S.M Halliwell, Building

Research Establishment.

Report 54 Health and Safety in the Rubber Industry, A.R Nutt,

Arnold Nutt & Co and J Wade.

Report 55 Computer Modelling of Polymer Processing,

E Andreassen, Å Larsen and E.L Hinrichsen, Senter for Industriforskning, Norway.

Report 56 Plastics in High Temperature Applications,

J Maxwell, Consultant.

Report 57 Joining of Plastics, K.W Allen, City University.

Report 58 Physical Testing of Rubber, R.P Brown, Rapra

Technology Ltd.

Report 59 Polyimides - Materials, Processing and Applications,

A.J Kirby, Du Pont (U.K.) Ltd.

Report 60 Physical Testing of Thermoplastics, S.W Hawley, Rapra

Report 66 Reinforced Thermoplastics - Composition, Processing

and Applications, P.G Kelleher, New Jersey Polymer

Extension Center at Stevens Institute of Technology.

Report 67 Plastics in Thermal and Acoustic Building Insulation,

V.L Kefford, MRM Engineering Consultancy.

Report 68 Cure Assessment by Physical and Chemical

Techniques, B.G Willoughby, Rapra Technology Ltd.

Report 69 Toxicity of Plastics and Rubber in Fire, P.J Fardell,

Building Research Establishment, Fire Research Station.

Report 70 Acrylonitrile-Butadiene-Styrene Polymers,

M.E Adams, D.J Buckley, R.E Colborn, W.P England

and D.N Schissel, General Electric Corporate Research

and Development Center.

Report 71 Rotational Moulding, R.J Crawford, The Queen’s

University of Belfast.

Report 72 Advances in Injection Moulding, C.A Maier,

Econology Ltd.

Volume 7

Report 73 Reactive Processing of Polymers, M.W.R Brown,

P.D Coates and A.F Johnson, IRC in Polymer Science

and Technology, University of Bradford.

Report 74 Speciality Rubbers, J.A Brydson.

Report 75 Plastics and the Environment, I Boustead, Boustead

Consulting Ltd.

Report 76 Polymeric Precursors for Ceramic Materials,

R.C.P Cubbon.

Report 77 Advances in Tyre Mechanics, R.A Ridha, M Theves,

Goodyear Technical Center.

Report 78 PVC - Compounds, Processing and Applications,

J.Leadbitter, J.A Day, J.L Ryan, Hydro Polymers Ltd.

Report 79 Rubber Compounding Ingredients - Need, Theory

and Innovation, Part I: Vulcanising Systems,

Antidegradants and Particulate Fillers for General

Purpose Rubbers, C Hepburn, University of Ulster.

Report 80 Anti-Corrosion Polymers: PEEK, PEKK and Other

Polyaryls, G Pritchard, Kingston University.

Report 81 Thermoplastic Elastomers - Properties and

Applications, J.A Brydson.

Report 82 Advances in Blow Moulding Process Optimization,

Andres Garcia-Rejon,Industrial Materials Institute,

National Research Council Canada.

Report 83 Molecular Weight Characterisation of Synthetic

Polymers, S.R Holding and E Meehan, Rapra

Technology Ltd and Polymer Laboratories Ltd.

Report 84 Rheology and its Role in Plastics Processing,

P Prentice, The Nottingham Trent University.

Volume 8

Report 85 Ring Opening Polymerisation, N Spassky, Université

Pierre et Marie Curie.

Report 86 High Performance Engineering Plastics,

Report 89 Polymer Membranes - Materials, Structures and

Separation Performance, T deV Naylor, The Smart

Report 92 Continuous Vulcanisation of Elastomer Profi les,

A Hill, Meteor Gummiwerke.

Report 93 Advances in Thermoforming, J.L Throne, Sherwood

Technologies Inc.

Report 94 Compressive Behaviour of Composites, C Soutis,

Imperial College of Science, Technology and Medicine Report 95 Thermal Analysis of Polymers, M P Sepe, Dickten &

Masch Manufacturing Co.

Report 96 Polymeric Seals and Sealing Technology, J.A Hickman,

St Clair (Polymers) Ltd.

Volume 9

Report 97 Rubber Compounding Ingredients - Need, Theory

and Innovation, Part II: Processing, Bonding, Fire Retardants, C Hepburn, University of Ulster.

Report 98 Advances in Biodegradable Polymers, G.F Moore &

S.M Saunders, Rapra Technology Ltd.

Report 99 Recycling of Rubber, H.J Manuel and W Dierkes,

Vredestein Rubber Recycling B.V.

Report 100 Photoinitiated Polymerisation - Theory and

Applications, J.P Fouassier, Ecole Nationale Supérieure

Report 106 Properties and Applications of Elastomeric

Polysulfi des, T.C.P Lee, Oxford Brookes University.

Report 107 High Performance Polymer Fibres, P.R Lewis,

The Open University.

Report 108 Chemical Characterisation of Polyurethanes,

M.J Forrest, Rapra Technology Ltd.

Volume 10

Report 109 Rubber Injection Moulding - A Practical Guide,

J.A Lindsay.

Report 110 Long-Term and Accelerated Ageing Tests on Rubbers,

R.P Brown, M.J Forrest and G Soulagnet, Rapra Technology Ltd.

Report 111 Polymer Product Failure, P.R Lewis,

The Open University.

Report 112 Polystyrene - Synthesis, Production and Applications,

J.R Wünsch, BASF AG.

Report 113 Rubber-Modifi ed Thermoplastics, H Keskkula,

University of Texas at Austin.

Report 114 Developments in Polyacetylene - Nanopolyacetylene,

V.M Kobryanskii, Russian Academy of Sciences.

Report 115 Metallocene-Catalysed Polymerisation, W Kaminsky,

University of Hamburg.

Report 116 Compounding in Co-rotating Twin-Screw Extruders, Y

Wang, Tunghai University.

Report 117 Rapid Prototyping, Tooling and Manufacturing, R.J.M

J.A Sidwell, Rapra Technology Ltd.

Report 120 Electronics Applications of Polymers II, M.T Goosey,

Shipley Ronal.

Volume 11

Report 121 Polyamides as Engineering Thermoplastic Materials,

I.B Page, BIP Ltd.

Report 122 Flexible Packaging - Adhesives, Coatings and

Processes, T.E Rolando, H.B Fuller Company.

Report 123 Polymer Blends, L.A Utracki, National Research Council

Canada.

Report 124 Sorting of Waste Plastics for Recycling, R.D Pascoe,

University of Exeter.

Report 125 Structural Studies of Polymers by Solution NMR,

H.N Cheng, Hercules Incorporated.

Report 126 Composites for Automotive Applications, C.D Rudd,

University of Nottingham.

Report 127 Polymers in Medical Applications, B.J Lambert and

F.-W Tang, Guidant Corp., and W.J Rogers, Consultant.

Report 128 Solid State NMR of Polymers, P.A Mirau,

Report 132 Stabilisers for Polyolefi ns, C Kröhnke and F Werner,

Clariant Huningue SA.

Volume 12

Report 133 Advances in Automation for Plastics Injection

Moulding, J Mallon, Yushin Inc.

Report 134 Infrared and Raman Spectroscopy of Polymers,

J.L Koenig, Case Western Reserve University.

Report 135 Polymers in Sport and Leisure, R.P Brown.

Report 136 Radiation Curing, R.S Davidson, DavRad Services.

Report 137 Silicone Elastomers, P Jerschow, Wacker-Chemie GmbH.

Report 138 Health and Safety in the Rubber Industry, N Chaiear,

Khon Kaen University.

Report 139 Rubber Analysis - Polymers, Compounds and

Products, M.J Forrest, Rapra Technology Ltd.

Report 140 Tyre Compounding for Improved Performance,

M.S Evans, Kumho European Technical Centre.

Report 141 Particulate Fillers for Polymers, Professor R.N Rothon,

Rothon Consultants and Manchester Metropolitan

University.

Report 142 Blowing Agents for Polyurethane Foams, S.N Singh,

Huntsman Polyurethanes.

Report 143 Adhesion and Bonding to Polyolefi ns, D.M Brewis and

I Mathieson, Institute of Surface Science & Technology,

Loughborough University.

J.C Love, The University of Warwick.

Report 146 In-Mould Decoration of Plastics, J.C Love and

V Goodship, The University of Warwick.

Report 147 Rubber Product Failure, Roger P Brown.

Report 148 Plastics Waste – Feedstock Recycling, Chemical

Recycling and Incineration, A Tukker, TNO.

Report 149 Analysis of Plastics, Martin J Forrest, Rapra Technology

Ltd.

Report 150 Mould Sticking, Fouling and Cleaning, D.E Packham,

Materials Research Centre, University of Bath.

Report 151 Rigid Plastics Packaging - Materials, Processes and

Applications, F Hannay, Nampak Group Research &

Development.

Report 152 Natural and Wood Fibre Reinforcement in Polymers,

A.K Bledzki, V.E Sperber and O Faruk, University of Kassel.

Report 153 Polymers in Telecommunication Devices, G.H Cross,

University of Durham.

Report 154 Polymers in Building and Construction, S.M Halliwell,

BRE.

Report 155 Styrenic Copolymers, Andreas Chrisochoou and

Daniel Dufour, Bayer AG.

Report 156 Life Cycle Assessment and Environmental Impact

of Polymeric Products, T.J O’Neill, Polymeron

Consultancy Network.

Volume 14

Report 157 Developments in Colorants for Plastics,

Ian N Christensen.

Report 158 Geosynthetics, David I Cook.

Report 159 Biopolymers, R.M Johnson, L.Y Mwaikambo and

N Tucker, Warwick Manufacturing Group.

Report 160 Emulsion Polymerisation and Applications of Latex,

Christopher D Anderson and Eric S Daniels, Emulsion Polymers Institute.

Report 161 Emissions from Plastics, C Henneuse-Boxus and

T Pacary, Certech.

Report 162 Analysis of Thermoset Materials, Precursors and

Products, Martin J Forrest, Rapra Technology Ltd.

Report 163 Polymer/Layered Silicate Nanocomposites, Masami

Okamoto, Toyota Technological Institute.

Report 164 Cure Monitoring for Composites and Adhesives, David

Report 168 Plastic Flame Retardants: Technology and Current

Developments, J Innes and A Innes, Flame Retardants

Report 174 Pharmaceutical Applications of Polymers for Drug

Delivery, David Jones, Queen's University, Belfast.

Report 175 Tyre Recycling, Valerie L Shulman, European Tyre

Recycling Association (ETRA).

Report 176 Polymer Processing with Supercritical Fluids,

V Goodship and E.O Ogur.

Report 177 Bonding Elastomers: A Review of Adhesives &

Processes, G Polaski, J Means, B Stull, P Warren, K

Allen, D Mowrey and B Carney.

Report 178 Mixing of Vulcanisable Rubbers and Thermoplastic

Elastomers, P.R Wood.

Report 179 Polymers in Asphalt, H.L Robinson, Tarmac Ltd, UK Report 180 Biocides in Plastics, D Nichols, Thor Overseas Limited.

Volume 16

Report 181 New EU Regulation of Chemicals: REACH,

D.J Knight, SafePharm Laboratories Ltd.

Report 182 Food Contact Rubbers 2 - Products, Migration and

Regulation, M.J Forrest.

Report 183 Adhesion to Fluoropolymers, D.M Brewis and R.H

Dahm, IPTME, Loughborough University.

Report 184 Fluoroplastics, J.G Drobny.

Report 185 Epoxy Composites: Impact Resistance and Flame

Retardancy, Debdatta Ratna.

Report 186 Coatings and Inks for Food Contact Materials,

Martin Forrest, Smithers Rapra.

Report 187 Nucleating Agents, Stuart Fairgrieve, SPF Polymer

Consultants.

Report 188 Silicone Products for Food Contact Applications,

Martin Forrest, Smithers Rapra.

Report 189 Degradation and Stabilisation of Polymers,

Stuart Fairgrieve, SPF Polymer Consultants

Mark Staiger, Univeristy of Canterbury, New Zeland

Report 191 Polyvinylalcohol: Materials, Processing and

ISBN: 978-1-84735-093-0

Applications

Joel R Fried

1 Introduction 3

2 Adhesives 3

3 Coatings 3

4 Fibres 3

4.1 Fibre Types 3

4.1.1 Carbon-Based Fibres 3

4.1.2 Inorganic Fibres 4

4.1.3 Polymeric Fibres 5

4.1.4 Hybrid Fibres 6

4.2 Fibre Forms .6

4.3 Interfacial Properties 6

4.3.1 Coupling Agents 6

4.3.2 Surface Treatment 7

5 Composites 7

5.1 Matrix Polymers 7

5.1.1 Thermosetting Matrices .8

5.1.2 TP Matrices .10

5.2 Fabrication Methods .12

5.3 Non-destructive Testing 12

6 Nanocomposites 13

6.1 Nano-Reinforcements 13

6.2 Processing 15

6.3 Properties of Nanocomposites 15

7 Foams 16

References 16

Abbreviations 16

Abstracts 19

Index 131

The views and opinions expressed by authors in Rapra Review Reports do not necessarily refl ect those

of Smithers Rapra Technology or the editor The series is published on the basis that no responsibility

or liability of any nature shall attach to Smithers Rapra Technology arising out of or in connection with any utilisation in any form of any material contained therein

Author contact details: Joel R Fried

Department of Chemical and Materials Engineering University of Cincinnati

2600 Clifton Avenue, Cincinnati, Ohio 45221USA

1 Introduction

The last RAPRA Report on Polymers in Aerospace

Applications (W.W Wright, Report 37) was published in

1990 The present report strives to provide a contemporary

review of this area with an emphasis on the literature

appearing after 1990 It includes coverage of new materials

and technologies (particularly nanocomposites)

The principal use for polymers in aerospace applications

is as a matrix material and/or reinforcing  bre for

composites Other major applications include use in

adhesives, anti-misting additives, coatings, elastomers,

 bres, and foams

2 Adhesives

Applications for adhesives include metal-to-metal

bonding for aluminium and titanium parts,

composite-to-metal bonding, and the bonding of elastomers to

metal parts Structural adhesives are manufactured in

 lm and paste form (344) These are widely used in the

manufacture, assembly, and repair of interior and exterior

aircraft components Examples include the reinforcement

of honeycomb structures such as luggage lockers and

 oor panels (190) Another use is the damping of engine

and noise vibration (190) For example, epoxy-based

syntactic paste has been used for engine vibration

damping A  ame-retardant epoxy paste has been used

for high-strength reinforcement in honeycomb core parts

as well as in fasteners in overhead baggage lockers (190)

Adhesives with working temperatures in the range 315

°C to 400 °C have been reported for advanced thermal

protection systems bondlines Ultra-high

temperature-resistant epoxy adhesives have been used to join together

polybenzimidazole (PBI) sheets (199) under high-energy

irradiation and low-pressure plasma treatment to provide

service temperatures in the range –260 °C to +370 °C for

potential aerospace and space applications (199)

3 Coatings

Coatings can provide protection against abrasion and

corrosion as well as reduce icing, provide shielding against

electromagnetic interference (EMI) or radio frequency

interference (RFI), and to protect insulation Modi ed

phosphate pigments contained in an epoxy/polyurethane

carrier have been used for primers for metal and plastic

substrates These primers are resistant to hydraulic

 uids Polysul des and silicone resins have been used for anti-icing applications Nylon-6,6 reinforced with nickel-coated carbon  bres (CF) have been used for EMI/RFI shielding Thin  lms of poly(vinylidene  uoride), polyethylene, and polyimides (PI) have been used to cover layers of insulation in aircraft and space vehicles

4 Fibres

The most widely used  bres for aerospace are glass, carbon, aramid, and boron (470) Other  bres used for high-performance composites include ultra-high molecular weight polyethylene (UHMWPE) and

poly(p-phenylene-2,6-benzobisoxazole) (PBO) (217)

A comparison of the modulus and strength of glass,

carbon, and aramid  bres is given in Table 1 Principal

differences between  bre groups include modulus as well as thermal and chemical stability As shown by

representative values in Table 1, the modulus can vary

by more than one order of magnitude Most  bres used

in aerospace applications serve as reinforcements in composite materials; other uses are found for these fibres in cabin furnishing, parachutes, and other specialised applications Properties and applications

of carbon-based, inorganic, and polymeric  bres are reviewed in depth within the following sub-sections

Table 1 Mechanical Properties of Typical

or coal tar) Early CF were produced from the pyrolysis

of Rayon precursors PAN precursors are now more

common because they can be produced without the

high-temperature graphitisation step required for Rayon-based

CF In general, CF is less impact-resistant that aramid or

glass  bre (398) There is a continuing need to produce

lower-cost CF ideally produced at low temperatures

from cheap, abundant precursors such as anthracitic

coal powder Pitch-based CF have low-to-negative

coef cients of thermal expansion that are attractive for

spacecraft applications (253) CF are stronger than glass

or aramid  bres but are less impact-resistant and contact

with metal can result in galvanic corrosion (253) It is

estimated that 30% of CF consumption in 2009 will be

for the aircraft and aerospace sector, with about 54%

of the remaining production targeted for industrial use

and 15% for sporting goods (245) Global demand for

PAN-based CF is expected to grow at >10% per year

(248) This is attributed to a resurgence of the aerospace

market and speci cally to production demands for new

commercial aircraft such as the Boeing B787 and Airbus

A380, as well as increased demand in other market

sectors including use in the manufacture of windmill

blades Global production  gures for carbon  bres

between 1999 and 2009 are shown in Figure 1.

Figure 1 Estimated global production of carbon

 bre (245)

Another carbon-based  bre with interesting properties,

especially for nanocomposite applications (see Section

6.1) is vapour-grown carbon  bre (VGCF) (310) VGCF

has some similarities to multiwall carbon nanotubes

(MWNT) but has larger outer (50–200 nm) and inner

(30–90 nm) diameters, with lengths in the range 50

m to 100 m and aspect ratios between 100 to 500

VGCF has a typical tensile strength of 2.92 GPa and a

tensile modulus of 240 GPa, and has very high thermal

conductivity (e.g., 1950 W/(m·K)) VGCF also has lower cost but defective microstructure can be a concern

4.1.2 Inorganic Fibres

Inorganic  bres include primarily glass  bres but also

 bres fabricated from more specialised material such

as quartz and boron that  nd use in high-performance composite applications

Glass Fibre

Compared with CF, glass  bre has higher density but offers superior impact resistance Glass  bres come in several forms, including E-glass, S-glass, C-glass, and quartz The commonest is E-glass (i.e., electrical grade),

a calcium aluminoborosilicate glass E-glass is a better electrical insulator than other glass  bres and represents 90% of all glass- bre reinforcements (particularly

 berglass) About 50% of the composition of E-glass is silica oxide The remaining composition includes oxides

of aluminium, boron, calcium, and other compounds, including limestone,  uorspar, boric acid, and clay (253) High-strength glass, a magnesium aluminosilicate glass,

is known as S-glass in the USA (R-glass in Europe and T-glass in Japan) Compared with E-glass  bres,  bres made from S-glass have higher silica oxide content and are about 40–70% stronger (253) and 20% stiffer (398) Applications include aircraft panels, helicopter rotor blades, and  lament-wound rocket motor cases (470) Corrosion-resistant glass (C-glass or E-CR glass) provides greater resistance to acid environments than does E-glass (253)

Quartz Fibre

Compared with glass  bre, quartz  bre provides superior performance, including lower density, better mechanical properties (e.g., about twice the elongation-to-break and higher strength and stiffness), higher durability, better electromagnetic properties (favourable for fabrication of aircraft radomes), and a near zero coef cient of thermal expansion (CTE) (309, 398) These superior properties come at a premium in cost The use temperature of quartz

 bre is as high as 1050 °C for continuous exposure and

up to 1250 °C for short exposures (309)

Boron Fibre

Boron  bres were developed in the early 1960s and were the  rst high-performance reinforcements for advanced

composites Boron  bres can be made by the

vapour-deposition of boron vapours on tungsten or carbon

 laments They have very high strength and modulus,

and offer excellent compressive properties and buckling

resistance Although boron  bres are expensive, their

superior mechanical properties have led to applications as

structural components on some high-performance military

aircraft (470) Examples of aerospace applications include

aircraft empennage skins, space shuttle truss members,

and prefabricated aircraft repair patches (253, 309)

4.1.3 Polymeric Fibres

Most polymeric  bres used for composite applications

are highly aromatic, rigid-chain polymers These

include aromatic polyamides, known as aramids

NomexTM and KevlarTM are aramids These have

high use-temperatures and provide high modulus and

excellent ballistic properties Specialty polymeric  bres

include PBO and polybenzothiozole Quite distinct

from these high-performance polymers that have highly

aromatic main chains is UHMWPE UHMWPE is a

highly crystalline aliphatic polymer that is extruded

as a gel under high pressure at low temperatures to

achieve highly extended single chains offering very

high modulus in the tensile direction

O C

Figure 2 Structure of Kevlar

and poly(m-phenylene isophthalamide) (NomexTM)

N

N

Figure 3 Structure of Nomex

Nomex is prepared by the condensation polymerisation of 1,3-phenylene diamine and isophthallic acid (254) The most widely used aramid  bre for high-performance composites

is Kevlar Kevlar is prepared by the polycondensation

of 1,4-phenylene diamine and terephthalic acid Aramid fibres have lower compressive strength than CF or inorganic  bres Other disadvantages include high water absorption and poor matrix adhesion in some cases The

high tensile strength (Table 1) of aramid  bres offers

important opportunities for composite applications such as

 lament-wound rocket motor cases, gas pressure vessels, and lightly loaded structures on aircraft (470) Aramid

 bres provide exceptional impact resistance and tensile strength (253) Typical high-performance aramid  bres have moduli of about 138 GPa and tensile strength in the range of 3,447 MPa The properties of aramid  bres can

be modi ed by surface oxidation or plasma etching that can improve off-axis strength of the composite (254) Bonding of the  bre to the matrix can be improved through chemical modi cation, plasma treatment, or by the use of

a coupling agent (254)

PBO

PBO  bres (Zylon®) [a.1] have higher strength than CF PBO also offers excellent heat and  ame resistance (469) and has about twice the modulus and tensile strength of that of an aramid  bre The decomposition temperature

of PBO is about 100 °C higher than Kevlar (253, 309, 398) Comparison of the properties of aramid and PBO

 bres is made in Table 2.

O O

Figure 4 Structure of PBO

Polybenzothiazole (PBZT)

Another rigid-rod polymer similar in structure to PBO

is PBZT [a.2] Like PBO, PBZT has high modulus, high temperature resistance, and excellent resistance

to organic solvents

N S

Figure 5 Structure of PBZT

The attractive properties of these lightweight  bres

made from UHMWPE include high impact resistance,

extremely high speci c strength, excellent chemical,

ultraviolet (UV), and moisture resistance, outstanding

impact resistance, abrasion resistance, low dielectric

constant, and anti-ballistic properties (253) Conversely,

UHMWPE  bres have low resistance to elongation

under sustained load and a comparatively low

use-temperature (398) with a melting point of 150 °C

UHMWPE fibre is produced by gel spinning of

UHMWPE dissolved in a suitable solvent (254)

Fibre drawing increases strength and modulus (254)

Functional groups can be introduced on the surface of

UHMWPE  bres by means of corona discharge and

plasma treatment (254) The aerospace applications

for UHMWPE  bre composites are limited, but their

antiballistic properties are suitable for applications such

as the bulletproof insert in forti ed cockpit doors in

Boeing single-aisle aircraft (253, 398)

Poly(aryl ether ether ketone) (PEEK)

PEEK, is a semicrystalline engineering thermoplastic (TP)

with a heat distortion temperature (HDT) of 148 °C

O C O

O

Figure 6 Structure of PEEK

PEEK can be spun into high-modulus yarn for aerospace

applications by drawing at 200 °C (1) These yarns can

be used under long-term exposure to 250 °C and

short-term exposure at 500 °C

4.1.4 Hybrid Fibres

CF can be woven with aramid and glass  bres to produce hybrid cloths for composite application Carbon/aramid and carbon/glass  bre hybrids have been used in some aircraft applications such as ribbed aircraft engine thrust reversers (254, 398)

4.2 Fibre Forms

Fibre reinforcements come in various forms, including continuous spools of tow (carbon) or roving (glass), woven fabrics, stitched multaxials, non-woven mats, and chopped  bre Tows are bundles of continuous  bres The number of individual  bres in a tow is designated by

a number followed by ‘K’, indicating a multiplication by

1000 CF tows consist of thousands of  bre Typical sizes

of aerospace-grade tows range 1 K to 12 K (253) Tows may be used directly in  lament winding or pultrusion,

or fabricated in a unidirectional tape

4.3 Interfacial Properties

Good interfacial strength between the  ller and the matrix polymer is critical to achieving high modulus and particularly strength [a.3] This is often achieved

by using a coupling agent that shares the chemical characteristics of the  bre and the matrix, as discussed

in Section 4.3.1 For high-temperature aerospace

applications, special  bre treatments may be used in place of coupling agents that may degrade at elevated temperatures

4.3.1 Coupling Agents

In general, the interfacial strength of composites can

be improved by the use of low-molecular-weight organofunctional silanes or titanates For example, the interfacial strength of a glass  bre-reinforced composite

Table 2 Mechanical Properties of PBO and Aramid Fibres (469)

(g/den)

Elongation at Break (%)

Tensile Modulus (g/den)

den: Denier, a measure of the  bre weight reported in the number of grams per 9000 m

can be improved by the use of silicon-containing

coupling agents: these are the most common Titanate

coupling agents are also used in some cases Examples

of commonly used coupling agents are given in

Table 3 The effect of two different silane coupling agents

(Table 3) on the  exural properties of an unsaturated

polyester composite is illustrated in Table 4 Comparison

shows that vinyl silane and particularly methacrylate

silane improve  exural strength under dry exposure and

at 2-hour exposure in boiling water

4.3.2 Surface Treatment

The interfacial properties of  bres can be improved

without the use of traditional coupling agents For

example, the interfacial adhesion of UHMWPE  bre can

be improved by plasma treatment in pure oxygen The

surface life of  bre-reinforced polyimide composites

in a high-temperature oxidative environment can be

extended by coating a polyimide precursor solution

followed by curing at elevated temperature in a nitrogen

environment (468)

5 Composites

Compared with metals, composites offer high strength and low weight Other attractive properties for aerospace applications include good vibrational damping, low CTE, and good fatigue resistance Conversely, the low thermal and thermo-oxidative stability of some polymeric composites can be a concern for many high-temperature aerospace applications Although carbon fibre-reinforced plastics (CFRP) represent a small portion of the total composite market (i.e., compared with glass-reinforced plastics such as  breglass), the market growth of CFRP is signi cantly greater than for other composite materials

5.1 Matrix Polymers

Polymeric matrices for composites include traditional thermosets (e.g., epoxies) and TP resins (475), including some PI and aromatic ketone polymers (e.g., PEEK and poly(aryl ether ketone ketone) PEKK) TP are semicrystalline or amorphous Some TP polymers such as

Table 3 Common Coupling Agents [a.3]

Epoxy silane

H2C C H CH 2O C H 2C H2C H 2 CH 2 Si( OC H 3) O

Methacrylate

H2C C C O CH2CH2CH2 Si(OCH3)3

Primary amine silane NH2CH2C H2CH2 Si(OCH3)3

Vinyl silane H2C CH Si(OCH3)3

Table 4 Flexural Strength of a Glass-Reinforced Polyester [a.3]

Flexural Strength (GPa)

PI can be crosslinked though the use of end-functioning

low-molecular weight resin In general, thermosetting

resins provide greater resistance to aggressive  uids

such as acetone and hydraulic  uids, but lower-impact

properties and the shelf-life of pre-cure resins is limited

Composites prepared from TP resins can be fabricated by

a wide variety of methods and provide higher toughness

and increased fatigue and wear resistance, but generally

have poor solvent resistance

The ability to withstand high temperatures can be a

critical consideration in many aerospace applications

For example, skin temperatures of Mach 1 aircraft

reach 110 °C, but temperatures can reach 300 °C (327)

for Mach 3 military aircraft Guided weapons, re-entry

vessels, and space shuttle service can require even higher

use-temperature PI prepared from the condensation

polymerisation of an aromatic tetracarboxylic acid

and an aromatic diamine, were developed in the

1960s to provide such high service temperatures PBI,

polybenzoxazoles, and polyquinolines provide even

higher temperature stability but at higher costs

5.1.1 Thermosetting Matrices

The commonest thermosets for advanced composites

include epoxies, phenolics, cyanate esters (CE),

bismaleimides (BMI), and PI Typical properties of

epoxy, phenolic, BMI, and CE resins are compared in

Table 5 Although most properties are similar among

the four thermosets, the highest temperature stability

(based upon thermogravimetric analysis (TGA) data)

is achieved by the BMI and CE resins Other polymers

belonging to this category and reviewed in this section

are benzoxazines and phthalonitrile resins

Benzoxazines are formed from the reaction of phenol

with an aldehyde and aromatic amine (253) Maleimide-

and norbornene-functionalised benzoxazines provide improved thermal properties, including char yields

of >55% and high glass transition temperature (Tg) (250 °C) (277)

Bismalemides

BMI thermosetting resin has similar properties to those

of epoxies but offers better temperature performance, especially hot/wet service temperatures up to 232 °C (462), and high performance-to-cost ratio They have been used for high-temperature structural applications on military aircraft (290) Like epoxies, the brittleness of BMI resins

is high, but toughened versions (see Table 5) are available

(470) Toughening methods include copolymerisation with styrene and hydroxyl methacrylate (254) Crosslinked BMI

thermosets such as 4,4-bismaleimide diphenyl

methane/o-o´-diallyl alcohol of bisphenol A (Matrimid 5292, Ciba Geigy) provide excellent high-temperature performance (464) A study of the effect of storage ageing on BMI prepregs have suggested that ageing for >30 days may reduce the curing rate (16)

Cyanoacrylate Esters

CE provide excellent strength and toughness, low moisture absorption, and superior electrical properties with a hot/wet service temperature around 149 °C (253,

398, 462) CE resins provide low dielectric loss, good adhesive properties, high glass-transition temperature (i.e., 220 °C to 290 °C), high solubility in ketones, and low moisture absorption (198) CE are more easily processed than BMI Brittleness of cured CE resin can be a concern, and CE is often toughened (198)

by including TP polymers or rubber Applications for

CE include ablatives and radomes due to excellent

Table 5 Properties of High-Performance Thermosets (462)

dielectric properties of CE CE also can be blended with

epoxies and BMI (462) Epoxy-modi ed bisphenol-A

dicyanate resin reinforced with high-modulus CF for

potential applications in a space environment has shown

good resistance to thermal cycling, UV-irradiation, and

exposure to boiling water (198) CE can be used for

the formation of interpenetrating networks by blending

with TP and thermosets (462) CE composites are

used in primary and secondary structures in military

aircraft as well as in satellite applications (462) These

can be processed by conventional methods including

pre-preging, resin transfer moulding (RTM),  lament

winding, and sheet moulding techniques (462)

Epoxy

Epoxy resins are the most commonly used matrix material

for composites, but their use in high-performance

applications is limited by low service temperature that

is adversely affected by moisture content, loading, and

by the use of toughening agents For example, an upper

temperature limit of about 177 °C for dry structural use

and only 149 °C for wet exposure has been suggested

(198) Heavy loading of epoxy composites can lower

use temperature to 120 °C In general, the upper use

temperature for advanced epoxies is limited to 150 °C

to 180 °C (462) Epoxy resins provide many attractive

features, including good handling properties, processibility,

and low cost (470) Epoxies are commonly used in

structural applications Disadvantages include brittleness

and moisture absorption that can lower use temperature

as mentioned above Toughened epoxies have found

applications in aircraft structural composites (290) but

toughening can also signi cantly lower use temperature

as indicated Resin  ow characteristics and mechanical

properties of tetraglycidyldiaminodiphenylmethane

(TGDM) based epoxy resins can be modi ed by reactive

blending with an acrylonitrile–butadiene–methacrylic

acid rubber (456)

Oxidative degradation of epoxy resins is also an important

concern The mechanism of oxidative degradation of

an aerospace epoxy resin based upon TGDM and

triglycidylaminophenol and diaminodiphenylsulfone

has been investigated by Fourier transform infrared

analysis (237) Results show that very different

mechanisms are operative at 120 °C (close to actual use

temperatures) compared with 170 °C (representative

of accelerated ageing) where general oxidative

changes occur in all areas of the matrix At the lower

temperature, the major reaction is probably oxidation of

a methylene group adjacent to the nitrogen atom of the

TGDM unit, whereas 170 °C ageing resulted in broader,

general changes throughout the matrix

Phenolic Resins

Phenolics such as phenol–formaldehyde resin are low-cost, flame-resistant, and low-smoke resins Applications include  ame-resistant aircraft interior panels as well as ablative and rocket nozzle applications (398) Phenolics provide good heat and  ame resistance, ablative characteristics, and low cost (462) Major shortcomings include brittleness, poor shelf-life, and the need for high-pressure curing

Phthalonitrile Resins

Oligomeric phthalonitrile resins have several attractive properties for high-performance composite applications, including very low moisture absorption and good thermal stability (2) These resins have been used to prepare void-free composites Phthalonitrile end-capped oligomers are prepared by reacting pyromellitic dianhydride, an aromatic diamine, and 4-(aminophenoxy) phthalonitrile (APPH) Networks can be formed by reacting the end-capped oligomers with 4,4´-diaminodiphenyl sulfone

at elevated temperatures

CN

CN O

by the use a functionally terminated oligomer as in the

case of PMR-15 (in situ polymerisation of monomer

reactants and the designation ‘-15’ in PMR-15 indicated the molecular weight of the first formed oligomer (i.e., 1500)) can lead to high-temperature and void-free

composites PI composite can be fabricated using quartz,

glass, boron, and graphite  bres reinforcement and are

favoured as engineering laminates in supersonic aircraft

(327) The use temperature for PI is typically 200 °C to

280 °C (463), although working temperatures as high as

315 °C have been reported

PI resins can be thermosetting and TP For composite

applications, thermosetting PI are the primary choice

Thermosetting polyimides can provide hot/wet use

temperature 260 °C to 320 °C These PI are formed

by a polycondensation reaction, but the release

of volatiles may cause problems in terms of void

formation during cure Cost is typically high for

these resins

PMR polyimides such as PMR-15 use a two-stage curing

process The  rst-stage consists of solvent evaporation

and an imidisation reaction to form short-chain imide

oligomers with the release of condensation water The

second stage involves a ring-opening addition-type

crosslinking reaction at nadic end groups to form the

 nal crosslinked polyimide matrix The absence of

volatile release in the second stage is an advantage in

forming void-free composites Disadvantages include

the need for a multi-stage cure process and the toxicity of

the monomer 4,4´-methylenedianiline (301, 314) Over

the past 20 years, PMR-15 has been the most widely

used PI in the aerospace industry due to its high Tg (~340

°C) and good thermo-oxidative stability Oxidation of

the neat resin is diffusion-controlled, resulting in the

formation of a surface oxidation layer (11) Ageing of

PMR-15 neat resin in air at 288 °C has shown a small

increase in Tg (330 °C to 336 °C) attributed to an

increase in crosslink density (7) Ageing for 1000 hours

resulted in a visibly damaged surface layer of ~0.16

mm thickness This layer results in a decrease in tensile

strength by acting as a crack initiation site, promoting

premature failure Tandon and co-workers (228)

developed a model for thermo-oxidative ageing with a

diffusion-reaction model whereby temperature, oxygen

concentration, and weight-loss effects are considered

Extensive studies of the effect of ageing on the

nano-indentation strain rate sensitivity have shown that the

average strain rate sensitivity in the oxidised surface

layer is much higher than that of the non-oxidised interior, indicating that the oxidised surface layer has limited ductility and, thereby, is more susceptible to fracture [a.4] A second-generation material is PMR

II (in situ polymerisation) LARC™-ITPI, based upon

the polycondensation of 4,4´-isophthaloyldiphthalic anhydride (IDPA) and 1,3-phenylenediamine, is another high-temperature PI matrix for aerospace applications (473)

5.1.2 TP Matrices

Composites made using a TP matrix represent a small but fast-growing market (253, 255, 290, 475) TP can be amorphous or semicrystalline Some of the most widely used TP for composite applications include PEEK,

polyetherimide (PEI), and poly(p-phenylene sul de)

(PPS) Representative properties are shown in Table

6 Continuous  bre-reinforced TP composites (471)

provide cost-effective manufacturing achieved by a high degree of automation Applications include use in aircraft interiors, wing ribs and panels, buckhead  oor panels, and landing gear doors Compared with thermosets, TP composites provide the advantage of signi cantly higher impact strength On the negative side, use temperatures and resistance to solvents such as methyl ether ketone and hydraulic  uids of TP composites are lower than obtained using thermosetting composites Such  uids act as stress cracking agents that can lead to mechanical failure The properties of non-halogen  re-resistant TP have been reviewed by Lyon and Emrick (40)

Polyarylates

Aromatic polyester carbonates (polyarylates) having the general structure:

OC CO

OCO

CH3 O

C OCO CH3

O

Figure 8 Structure of Polyarylate

Table 6 Representative Properties of Thermoplastic Resins (474)

Temperature (ºC)

Yield Strength (MPa)

Modulus (GPa)

are available in clear/transparent and pigmented

versions that meet heat and smoke requirements for

aircraft interior applications (40)

Poly(ether ether ketone)

PEEK or poly(ether ether ketone) (Victrex®) is used for

the matrix of TP prepregs containing carbon, glass, and

aramid  bres PEEK has been reported to be capable

of withstanding continuous operating temperature

up to 260 °C in low-stress operations and 120 °C in

aerospace structural applications (191) PEEK has

good resistance to hydrolysis, corrosion, chemical, and

radiation exposure It provides high thermal stability,

low coef cient of expansion, good abrasion resistance,

low smoke and toxic gas emission, and excellent

stiffness (191)

O C

Figure 9 Structure of PEEK

Poly(arylether ketone ketone)

Developed in the 1980s, PEKK is a semicrystalline

TP with low  ammability, a Tg of 156 °C, and melting

temperatures in the range 300 °C to 310 °C (378) PEKK

is the preferred TP resin matrix at temperatures >90

°C (378) PEKK composites have been prepared from

short and continuous (i.e., tape and fabric, respectively)

glass and CF composites (378) PEKK has high hot/

wet retentions (up to 130 °C) due to low resin moisture

pick-up (378) All high-temperature glass  bre sizings

are suitable with PEKK and its processing temperature

(335-345 °C) (378) Choice of sizing, however, can

signi cantly affect performance

CH 3

O

Figure 10 Structure of PEI

PEI is an amorphous polymer, developed in the 1980s, that offers high heat resistance, strength, and modulus The mechanical performance of PEI degrades with exposure to aggressive  uids such as Skydrol hydraulic

 uid (255) The effect of moisture on the interlaminar resistance of woven fabric PEI composite has been reported (187) Properties of composite structures formed by reactive heating a phenylethynyl-terminated PEI (Reactive Ultem®) coating on PAN-based CF have been reported (189) A suggested application

is the rigidisation of in atable composite structures

in space

Polyimides

PI composites have been used at temperatures >300

°C for electronics and aerospace applications (466) High-temperature coupling agents for S-glass and quartz fabric-reinforced PI are required at these temperatures to maintain high flexural strength (466) Thermoplastic polyimides (TPI) include LARCTM-TPI based on benzophenone dicarboxylic dianhydride and 3,3´-diamino benzophenone (254), LARCTM-ITPI based upon IDPA and 1,3-phenylenediamine (473), NR-10 B2 prepared

by reacting hexa uoro isopropylidene dianhydride

with a 95/5 molar ratio of p/m-phenylene diamine,

and polyimide 2080 produced by the reaction of benzophenone dicarboxylic acid dianhydride with a mixture of 80/20-toluene diisocyanate and methylene 4,4´-diisocyanate (254)

Figure 11 Structure of LARC-ITPI

Matrimid® is a high Tg (approximately 313 °C) amorphous TPI made from diaminophenylindane and 3,3´-4,4´-benzophenone tetracarboxylic dianhydride (BTDA)

O

O

O C

O

O

Figure 12 Structure of Matrimid

Polyamideimides such as TorlonTM, prepared by reacting

trimellitoyl acid chloride with a mixture of 70/30

4,4´-diamino diphenyl oxide and phenylene diamine, has

some of the properties of polyamides such as toughness

and ductility, and the high heat resistance of PI

Current grades of PPS (e.g., Forton®) exhibit good

resistance to temperatures up to 240 °C (melting point

between 280 °C and 290 °C) and are resistant to oils,

fuels, solvents, anti-icing agents, and to acids/bases

in the pH range 2 to 12 Other attractive properties

include excellent hardness, dimensional stability,

and excellent  re resistance Water absorption is near

0.04%, signi cantly lower than for other TP (including

PEI and PEEK) used in aerospace applications

PPS can be processed by various TP composite

technologies, including pultrusion, compression

moulding, thermoforming, automated tape laying/ bre

placement, and bladder moulding Use of PPS matrix

has been reported for structural applications on the

Airbus A340 and A380 (290)

S

Figure 14 Structure of PPS

Polysulfones

Polysulfones that have been used in aerospace

applications for aircraft interiors, and TP composite

applications include bisphenol A polysulfone (PSF,

UDELTM) and polyphenylsulfone (PPSU, RadelTM)

O

O S

Figure 16 Structure of PPSU

5.2 Fabrication Methods

Fibre reinforcement and matrix resin may be combined

in a single step by various processes such as wet

lay-up,  lament winding, pultrusion, and RTM For some applications, resin-impregnated  bres (prepregs) are used Prepregs can be made by using solvent, holt-melt, or powder impregnation techniques A  bre-to-matrix ratio is typically 60:40 or higher for advanced composite materials (398) Resistive heating has been proposed as a route for the rigidisation of in atable composite structures in space (189) The properties of

a CF-reinforced heat-crosslinkable PEI (Ultem®) have been reported Forming processes for TP composites include thermoforming, press-forming, compression moulding, matched-die moulding, welding, and diaphragm forming (448) Compression moulding

is a high-volume, high-pressure method suitable for complex, high-strength glass-mat reinforced TP

Resin Transfer Moulding

In the RTM process, a resin including high-temperature

PI is injected into a closed cavity mould  lled with  bre reinforcement (314) RTM offers low fabrication cost compared with other alternatives such as autoclaving High-temperature composite parts prepared by RTM have been incorporated in many high-performance military aircraft including the F-22 Raptor (314) where

a RTM-processed bismaleimide prepreg has been used (467) The mould may be evacuated to assist the moulding process (vacuum-assisted RTM) (253)

5.3 Non-destructive Testing

Ultrasound techniques were used to monitor the cure of

 breglass in 1966 Combined with other non-destructive evaluation techniques such as thermography and radiography techniques, composite properties such as density, modulus, and strength can be determined (280)

6 Nanocomposites

Several excellent review articles on the properties and

processing of nanocomposites are available (3, 41,

180, 206, 250, 312, 331, 358, 450 [a.5]) In general,

the distinguishing characteristic of nanocomposites

compared with more traditional composite materials is

the dimensions of the reinforcing  ller Nancomposites

contain inorganic reinforcements with high aspect ratio

and dimensions of 1–100 nm The small size results in

properties often superior to traditional composites Some

of the attractive properties of nanocomposites important

for aerospace application include improved electrical

and mechanical properties, reduced oxygen and water

permeability, increased thermal stability, better  ame

resistance, improved resistance to wear, elevated

heat-distortion temperature, potential for surface and interface

modi cation, and easier processibility Applications

include fire-retardant coatings, rocket propulsion

insulation, rocket nozzle ablative materials, aerospace

structural panels, ultra-light space structures, and space

mirror substrates (310, 298) Other potential aerospace

applications include devices such as light-emitting

diodes, photovoltaic cells, and gas sensors [a.6]

One of the  rst nanocomposites was fabricated from

Nylon-6 by researchers at Toyota in the late 1980s

Typical properties of nylon nanocomposites are given

in Table 7 As shown, tensile modulus and strength

are signi cantly improved without sacri cing impact

strength Particularly noteworthy is the improvement

in heat-distortion temperature due to the reinforcement

The use of nanocomposite material has been increasing

very rapidly since the 1980s The US market for

nanocomposites is expected to reach 11 billion pounds

by the year 2020

Table 7 Representative Properties of a Nylon-6

Nanocomposite [a.3]

Coef cient of thermal

Tensile modulus (GPa) 1.1 2.1

Tensile Strength (MPa) 69 107

Impact strength (kJ/m2) 2.3 2.8

Water absorption (%) 0.87 0.51

Property improvement can be signi cant at small loading

For example, the modulus of polydimethylsiloxane

reinforced by 1% clay can be increased by approximately

100% For a polysulfone organoclay nanocomposite,

modulus and strength reach a maximum at about 3 wt% organoclay content with little sacri ce in elongation at break (461) At higher loading, exfoliation decreases and mechanical properties decline

Nanocomposites have been prepared from nearly all commodity and engineering-grade plastics, including thermosetting resins Examples of TP include polysiloxanes, Nylon 11, poly(vinyl acetate)–acrylic copolymer, poly(ethylene oxide), PEI, PI, and some TP elastomers such as polyamide silicone copolymer (298) Thermosets include phenolic, cyanate ester, and epoxies Nanocomposite can be made using various  llers having

at least one dimension in the nanometer range (95) Fillers include nanoclays, nanotubes, nano bres, or silica and various metal oxides Nano bres are electrospun whiskers with diameters in the range 10–100 nm and length-to-diameter ratios >1000

6.1 Nano-Reinforcements

Fillers used for nanocomposites include modi ed montmorillonite (MMT) nanoclays, nanosilica, carbon nano bre (CNF), carbon nanotubes (CNT), polyhedral oliogomeric silsesquioxane (POSS), and various nanoparticles such as silica and more exotic

organic- llers such indium tin oxide (ITO) (298)

MMT

The commonest form of nano-reinforcement is organoclay, MMT MMT is a naturally occurring 2:1 phylloslicate with the same structure as talc and mica, but a different layer charge Modi cation of the inorganic surface of MMT

by organic treatment is used to increase dispersion in the polymer matrix The crystal structure of MMT consists of

1 nm thin layers with a central octahedral sheet of alumina fused between two external silica tetrahedral sheets These platelets have thicknesses of ~1 nm with aspect ratios (i.e., diameter:thickness) of 10:1 to 1000:1 and are arranged

in stacks that can be separated (or exfoliated) during composite fabrication Isomorphoic substitution within the layers (e.g., replacing Al3+ by Mg2+) can be used to modify the charge exchange capacity The silicate sheets

in MMT are separated by cations, typically sodium, as

illustrated in Figure 17 These cations balance the overall

charge The sodium cation in the gallery can be exchanged with other cations such as lithium, potassium, and calcium

In water-swollen layered silicates, organic cations, such

as an alkyl ammonium cation, can also be used to replace Na+ The speci c alkyl selection can be used

to improve miscibility with the nanocomposite matrix

Some examples include dimethyl distearyl ammonium

chloride and dimethyl stearyl benzyl ammonium chloride

Silicone rubber nanocomposites can be fabricated by

ion-exchanging Na+/MMT with dimethyl ditallow ammonium

bromide or hexadecyltrimethylammonium bromide This

type of organophilic modi cation improves the polymer

miscibility of MMT The ion-exchange process also

increases the gallery height in relation to the molecular

size of the organic cation

Figure 17 Structure of sodium montmorillonite

Reproduced with permission from Southern Clay

Product, Incorporated

Nanosilica

Nanosilicas such as Aerosil® are very pure amorphous

silica produced by high-temperature hydrolysis of

silicon tetrachloride in an oxy-hydrogen gas  ame

to produce particles in the range 7–40 nm (298)

Hydrophilic and hydrophobic grades of nanosilicas are

commercially available Alkoxysilyl functional groups

can improve matrix–silica binding (197)

Polyhedral Oligomeric Silsesquioxanes

Polyhedral oligomeric silsesquioxanes (POSS is a

trademark of Hybrid Plastics (www.hybridplastics.

com)) can serve as multifunctional additives providing

molecular-level reinforcement as well as serving as

processing aids and flame retardants (298) Other

advantages of POSS-filled nanocomposites include

increased service temperature, low density, low thermal

conductivity, thermo-oxidative resistance, and ageing

resistance The chemical composition of POSS (RSiO1.5),

is intermediate between that of silica (SiO2) and silicones

(R2SiO) The commonest POSS has eight silicon atoms,

each carrying an organic group (Figure 18) The typical

dimensions of POSS particles are 1–3 nm

Figure 18 Representation of a typical POSS structure

Possible organic substituents, R, are indicated Reproduced with permission from D.R Paul and L.M

Robeson, Polymer, 2008, 49, 15, 3187

© 2008, Elsevier

Carbon Nano bres

CNF are discontinuous graphic  laments produced in the gas phase by the pyrolysis of hydrocarbons Typical diameters of CNF range 50 nm to 200 nm with lengths

in the range 50 m to 100 m

Carbon Nanotubes

CNT provide attractive combinations of high

 exibility and strength combined with high stiffness and low density Carbon nanotubes can be single-walled (SWNT) or MWNT SWNT have diameters

as small as 0.4 nm compared with MWNT that have diameters in the range 2–25 nm The typical tensile strength of CNT is 100–600 GPa This range is about two orders of magnitude higher than that of typical CF Densities of CNT are about 1.3 g/cm3 compared with 1.8–1.9 g/cm3 for CF (310) Compressive strengths

of CNT are about two orders of magnitude higher than that of any other  bre CNT also have extremely high stiffness, with Young’s modulus in the range 1–5 TPa, compared with 750 GPa for CF CNT can also carry large current densities (>100 MA/cm2 for MWNT) Experimental thermal conductivities are about 200 W/(m·K) A problem with the use of CNT

is the need for chemical modi cation for favourable interaction with polymeric matrices Their use requires high dispersion Techniques used to achieve

good dispersion include in situ polymerisation of

the matrix, shear mixing, the use of surfactants, and solution processing (310)

Graphite Nanoplatelets

An alternative to CNT is the use of graphite nanoplatelets, especially for conducting nanocomposite applications Several forms of nanographite include

expanded graphite, exfoliated graphite, and graphene

Functionalised graphene sheets can be prepared by

controlled thermal expansion of graphite oxide

6.2 Processing

Methods to disperse nanoparticles include high-shear

mixing for liquid resins and three-roll milling for

liquid resins, Brabender-type mixing for high-viscosity

resins, and twin-screw extrusion for solid polymers

(298) The process of exfoliation of surface-treated

nanoclays under high-shear mixing is illustrated in

Figure 19 Exfoliation results in improved mechanical

properties, barrier performance, and application

processing Exchange of natural Na+

counter-ions with long-chain quaternary ammonium catcounter-ions

results in improved dispersion into hydrophobic

polymers (298)

Figure 19 Mechanism of organoclay dispersion

and exfoliation during melt processing Reproduced

with permission from D.R Paul and L.M Robeson,

Polymer, 2008, 49, 15, 3187 © 2008, Elsevier

6.3 Properties of Nanocomposites

One of the most signi cant effects of nano llers on the

properties of the matrix polymer is the signi cant increase

in modulus compared with the neat resin The addition of

nano-sized  llers (especially organoclays) can increase

modulus and tensile strength at signi cantly smaller

 ller content compared with more traditional reinforcing

agents such as glass  bre Modelling of the mechanical

properties of nanocomposite materials has been given

(183, 227, 315, 424) The effect of wt%  ller on relative

modulus (i.e., the ratio of composite modulus to matrix

polymer modulus) is compared for MMT and glass 

bre- lled Nylon 6 in Figure 20 As shown, approximately 20

wt% of glass  bre is necessary to increase the modulus

of Nylon 6 to the same level achieved by addition of 7

wt% of MMT

Figure 20 Comparison of relative modulus (i.e., the

ratio of the modulus of the nancomposite to that of the matrix polymer) at different concentrations of glass

 bre and MMT concentration in Nylon 6 Reproduced with permission from T.D Fornes and D.R Paul,

Polymer, 2003, 44, 17, 4993 © 2003, Elsevier

Advantages of nanocomposites include improved barrier

to fuel and dimensional stability (i.e., lower CTE) (301) Higher oxygen barrier performance can increase thermo-oxidative stability (301) For example, the oxygen permeability coef cients of polyimide nanocomposites have been reported to drop by two-thirds and the thermal expansion coefficient to drop by 20% (301) Water resistivity also can be improved by adding reactive inorganic  llers Nanocomposite  lms of CNT and ITO

in polysiloxane have the capability for thermal control in satellite applications (197) Such nanocomposites provide anti-static properties POSS and CNT can signi cantly reduce the heat release rate and, thereby, improve  ame retardancy (235) Whereas nano llers have small effects

on the Tg, the effect on the HDT is signi cant due to the large reinforcement effect of the nano ller, as illustrated in

Figure 21 As shown, the storage modulus, qualitatively

related to the tensile modulus, is increased in the glassy region as well as the rubbery plateau The result is a signi cant increase in the heat distortion temperature

Figure 21 Dynamic mechanical storage modulus of

Nylon 6 as a function of temperature and wt% MMT content The horizontal line illustrates how HDT at an applied stress of 1.82 MPa changes with MMT loading Reproduced with permission from T.D Fornes and D.R

Paul, Polymer, 2003, 44, 17, 4993 © 2003, Elsevier

The effect of oxydianiline (ODA)-modi ed clay on the

tensile properties of a BTDA-ODA polyimide is illustrated

in Figure 22 Values represent relative modulus, relative

maximum stress at break, and relative elongation at

break (compared with the neat polyimide) As shown,

the modulus is increased by more than threefold at only 7

wt% ODA-modi ed organoclay This increase in stiffness

is accompanied by smaller improvements in stress and

elongation at break A similar improvement in tensile

modulus and stress with a maximum at 3 wt% MMT has

been reported for polysulfone nanocomposites (461)

Figure 22 Relative tensile properties (property of

nanocomposite to that of the matrix polymer) reported

for a polyimide (BTDA–ODA) nanocomposite

prepared using ODA-modi ed organoclay Data taken

from H-L Tyan, K-H Wei and T-E Hsieh, Journal

of Polymer Science Part B: Polymer Physics Edition,

2000, 38, 22, 2873 © 2000, Elsevier

7 Foams

In use since 1971, polymethacrylimide (PMI) has

been fabricated into foam cores offering high strength,

stiffness, and fatigue life Thermoformed PMI foam

has been used in many aerospace applications (252) as

an alternative to Nomex® and aluminium honeycomb

structures Applications include helicopter rotor blades

and structural sandwich cores of fuselage panels, as well

as stringer pro les in pressure bulkheads

References

a.1 V Kholodovych and W.J Welsh in Polymer

Data Handbook, Ed., J.E Mark, Oxford

University Press Inc., New York, NY, USA,

2009, p.386

a.2 V Kholodovych and W.J Welsh in Polymer

Data Handbook, Ed., J.E Mark, 2009, Oxford

University Press Inc., New York, NY, USA,

2009, p.394

a.3 J.R Fried, Polymer Science & Technology, 2nd

Edition, Prentice Hall Upper Saddle River, Prentice Hall, NJ, USA, 2003

a.4 Y.C Lu, G.P Tandon, S Putthanarat and G.A

Schoeppner, Journal of Materials Science, 2009,

CNT Carbon nanotubesCTE Coef cient of thermal expansion EMI Electromagnetic interferenceHDT Heat distortion temperatureIDPA 4,4´-Benzophenone isophthaloyldiphthalic

anhydrideITO Indium tin oxide

POSS Polyhedral oligomeric silsesquioxanes

PPS Poly(p-phenylene sul de)

PPSU Polyphenylsulfone

PSF Polysulfone

RFI Radio frequency interference

RTM Resin transfer moulding

SWNT Single wall carbon nanotubes

Tg Glass transition temperature

TGA Thermogravimetric analysis

TGDM Tetraglycidyldiaminodiphenylmethane

TP Thermoplastic

TPI Thermoplastic polyimides

UHMWPE Ultra-high molecular weight

polyethylene

UV Ultraviolet

VGCF Vapour-grown carbon  bre

Abstracts from the Polymer Library Database

Item 1

Journal of Applied Polymer Science

112, No.4, 15th May 2009, p.2497

PROPERTIES OF HIGH MODULUS PEEK

YARNS FOR AEROSPACE APPLICATIONS

Shekar R I; Kotresh T M; Rao P M D; Kumar K

India, Defence Bioengineering and Electromedical

Laboratory; Bangalore,Central Silk Technological

Research Institute; Kanpur,Defence Materials Stores

Research & Development Establishment

The effects of the interactions between the rheological

properties, spinning process variables and drawing

conditions were investigated in order to obtain high

modulus PEEK yarns that could be tailored for aerospace

applications Wide angle X-ray diffraction results indicated

that drawing carried out above the glass transition

temperature affected unit cell parameters, density

and mechanical properties The degree of orientation,

characterised in terms of sonic velocity, was as high as 3

km/s with a sonic modulus of 105 gpd The crystallinity

increased with increasing draw temperature Useful

properties were observed at an optimum draw temperature

of 200 deg.C (which may be the region of maximum

crystallisation rate) and were primarily attributed to

the maximum crystallisation temperature and the heat

setting effect The thermal stability of PEEK yarn under

dynamic conditions suggested that PEEK could be used

for high temperature applications (up to 250 deg.C) for

long periods of exposure and 500 deg.C for short term

Phthalonitrile terminated oligomers were prepared in two

stages by reacting an excess amount of pyromellitic dianhydride

with aromatic diamines in a N,N-dimethylacetamide/

toluene solvent mixture to form an anhydride terminated

oligomeric intermediate, which was terminated by reaction

with 4-(aminophenoxy)phthalonitrile The oligomers were

converted to network polymers using 4,4’-diaminodiphenyl

sulphone as curing agent at elevated temperatures

Polymerisation of the oligomeric phthalonitrile/diamine

mixtures and prepolymers was followed by DSC and the

complex viscosity of the prepolymers during polymerisation

determined by means of isothermal rheometric analysis The

thermal and thermooxidative properties of the polymers were investigated by TGA, which showed that the polymers possessed better thermal and thermooxidative stability than current commercially available high-temperature thermosetting resins 32 refs (POLYCHAR-16, World Forum on Advanced Materials, Lucknow, India, 17th -21st Feb.2008)

Choudalakis G; Gotsis A D Crete, Technical UniversityThis is a review of the existing studies on the permeability

of gas molecules in nanocomposite materials that consist of inorganic platelet-shaped fi llers in polymeric matrices We describe the dominant mechanisms for the transport of small molecules in polymers and polymer nanocomposites, as well

as the procedures for the measurement of the permeability and the diffusivity The emphasis is given on the various models that have been proposed for the prediction of permeability in polymer-clay nanocomposites The infl uence

of the characteristics of the inorganic particles on the barrier properties of the composite membrane is discussed and tested using the model and the available experimental data Some aspects on the methods of improving the barrier properties of the nanocomposite are examined and a few applications of these materials as gas barriers are presented

67 refs Copyright (c) 2009 Elsevier Ltd

EUROPEAN COMMUNITY; EUROPEAN UNION; GREECE; WESTERN EUROPE

Accession no.1039758

Item 4

SAMPE Fall Technical Conference: Multifunctional Materials: Working Smarter Together Proceedings of

a conference held Memphis, Tn., 8-11 Sept., 2008.

Covina, Ca., SAMPE International Business Offi ce,

2008, Paper 44, pp.8

TAILORING THERMAL PROPERTIES

IN COMPOSITE MATERIALS AND ITS INTERFACES FOR THERMOMECHANICAL APPLICATIONS

Roy A K; Sangwook Sihn; Ganguli S; Varshney VWright-Patterson Air Force Base; Dayton, University, Research Institute; Universal Technology Corp

(SAMPE)

Thermal transport phenomena in aerospace fi bre-reinforced composites, composite joints and the composite material

interface are analysed It is shown through fi nite element

analysis and molecular dynamics simulations that interface

impedance plays an important role in dictating thermal

transport through the interface and that through materials

modelling parameters can be identifi ed to guide processing

for tailoring interface performance 8 refs

USA

Accession no.1036261

Item 5

SAMPE Fall Technical Conference: Multifunctional

Materials: Working Smarter Together Proceedings of a

conference held Memphis, Tn., 8-11 Sept., 2008

Covina, Ca., SAMPE International Business Offi ce

2008, Paper 12, pp.13

LIFE PREDICTION OF CARBON FIBER/PEKK

THERMOPLASTIC COMPOSITE MATERIAL

FOR STRUCTURES DESIGN

Dan-Jumbo E; Keller R; Westerman B; Kuraishi A; Tsai

S W; Wang J

Boeing Co.; Stanford, University

(SAMPE)

The development of a life prediction technique for characterising

the long-term behaviour of composites fabricated from

standard modulus carbon fi bre and polyetherketoneketone

using Miyano’s Accelerated Testing Methodology, which

is based on viscoelastic theory The accelerated testing is

combined with the time temperature superposition principle

to relate long-term deformation and strength to

short-term accelerated tests over a series of elevated operating

temperatures, including repair analysis Creep master curves

are generated from the data for static strength and deformation

predictions applicable to a wide range of temperatures and

times for design and repair applications 3 refs

COMPARISON OF FLUORINATED LIQUID

SILICONE RUBBER AND HEAT CURED

FLUOROSILICONE ELASTOMER

Franssen O; Bosshammer S; Riley G; Toub M

Momentive Performance Materials GmbH

The development by Momentive Performance Materials of

fully fl uorinated liquid silicone rubber(LSR) compounds

with good fuel and oil resistance and processability

equivalent to that of commercial standard LSRs is

described Data on the physical properties, fl uid resistance

and processability of the new LSRs are presented The new

materials are currently available in the 40-70 Shore A range

of durometer and they are expected to play a major role in

providing cost-effective options for demanding applications

in the automotive and aerospace industries 12 refs

EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE

Ruggles-Wrenn M B; Broeckert J LUS,Air Force Institute of TechnologyThe creep behaviour of PMR-15 polyimide thermoset polymer, aged in air and in argon at 299 deg.C for up

to 1000 hours was evaluated Prior isothermal ageing increased the elastic modulus and decreased the capacity

to accumulate creep strain A rise in Tg with ageing time was attributed to an increase in the crosslink density of the polyimide 20 refs

SAMPE FALL TECHNICAL CONFERENCE 2008 PROCEEDINGS

OF A CONFERENCE HELD MEMPHIS, TN., 8-11 SEPT., 2008

MULTIFUNCTIONAL MATERIALS: WORKING SMARTER TOGETHER

(SAMPE)The Fall 2008 SAMPE Technical Conference consisted

of over 150 papers, covering topics which focused on nanocomposites and multifunctional materials Papers were presented under the following topics: aerospace structures and applications; carbon-carbon composites and foams; composite design and analysis; composite fatigue and fracture; composites for the automotive industry; composites from agricultural products; design for multifunctionality; electromagnetic multifunctional materials; environmental considerations; high temperature resins and composites; infrastructure applications; joints in composite structures; manufacturing and processing advances; multifunctional materials with integral NDE; analysis and characterisation of nanocomposites; applications of nanocomposites; CNT/CNF alignment of nanocomposites; electrical and thermal properties

of nanocomposites; fire behaviour of nanocomposites; processing of nanocomposites; nano-industrial applications; nanostructured multifunctional materials; NDE and structural health monitoring; resins and adhesives; sandwich structures; testing of composites; thermomechanical multifunctional materials; and thermoplastic composites

USA

Accession no.1033201

Beier U; Sandler J K W; Altstaedt V; Spanner H;

Weimer C; Roser T; Buchs W

Bayreuth,University; Eurocopter Deutschland GmbH

The results are reported of a study of the use of innovative low

melting temperature polyamide and soluble phenoxy stitching

yarns to manufacture cost-reduced textile preforms for liquid

composite moulding of high-performance composites for

aerospace applications Tests are carried out on stitched

composite panels to assess panel quality, compression

performance, apparent interlaminar shear strength and

compression after impact behaviour The innovative yarns,

which are compared with conventional polyester stitching

yarn, are shown to reduce fi bre undulations in the carbon

fi bre-reinforced epoxy composites, allowing further

pre-stabilisation of the dry preforms by thermobonding and

optimised composite performance 27 refs

EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY;

EVALUATION METHOD OF ADHESIVE

FRACTURE TOUGHNESS BASED ON DOUBLE

CANTILEVER BEAM (DCB) TESTS INCLUDING

RESIDUAL THERMAL STRESSES

Yokozeki T; Ogasawara T

Tokyo,University; Japan,Aerospace Exploration Agency

The energy release rate associated with crack growth in

adhesive double cantilever beam specimens, including

the effects of residual stresses, was formulated using

laminate beam theory, and the calculation of the correction

for temperature effects based on specimen geometry and

thermomechanical properties such as coeffi cient of thermal

expansion, is described The results are compared with

those based on fi nite element analysis, and the residual

stress effects on the evaluation of adhesive fracture

toughness are discussed in terms of aerospace applications

of fi bre-reinforced composite laminates 13 refs

INFLUENCE OF AGING TEMPERATURE, TIME,

AND ENVIRONMENT ON THERMO-OXIDATIVE

BEHAVIOR OF PMR-15: NANOMECHANICAL CHARACTERIZATION

Putthanarat S; Tandon G P; Schoeppner G ADayton,University; US,Air Force Research LaboratoryThe effects of ageing temperature, ageing time, and ageing environment on the thermo-oxidative behaviour

of a commercial high-temperature polyimide resin with applications in the aerospace industry were investigated

by optical microscopy and nanoindentation testing

to characterise localised mechanical properties and the development and growth of the oxidative layer The results are discussed in terms of the chemical changes taking place in the polymer during oxidation

A brief review on existing methods of adhesive bond strength determination is presented with emphasis on aerospace applications The recent development of two new methods for the non-destructive inspection of bond strength, laser shock preened proof testing to determine joint properties in situ, which requires access to two surfaces and expensive instrumentation, and the tape peel test, which is an inexpensive method to determine adhesion potential of a composite surface prior to fi nal bond consolidation, are discussed in terms of their scope

of application and limitations 143 refs

VIBRATION DAMPING IN SANDWICH PANELS

Maheri M R; Adams R D; Hugon JBristol,University; Alcatel; Kerman,UniversityThe inherent damping mechanism in sandwich panels, including those with both aluminium and carbon fi bre-reinforced composite plastic skins with aluminium honeycomb cores was analysed using the basic laminate theory, a fi rst-order shear deformation theory and a discretisation method Implementation of the method using a fi nite-element software package to predict the overall damping value of a sandwich honeycomb panel for each specifi c mode is described, and the results are discussed in comparison with experimental data for typical honeycomb structural panels used in aerospace applications 17 refs

EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE;

IRAN; UK; WESTERN EUROPE

Accession no.1031732

Item 14

Journal of Materials Science

43, No.20, Oct.2008, p.6578-6585

VERY STIFF FIBRES WOVEN INTO

ENGINEERING’S FUTURE: A LONG-TERM

PERSPECTIVE

Kelly A

Cambridge,University

Advances in the design, development and properties of

fi bre-reinforced composite laminates and the growth in

their use since the 1960s are reviewed with emphasis on the

use of glass, carbon and synthetic (such as aramid) fi bres

for reinforcement, especially for aerospace applications

Problems associated with composite design, testing for

fatigue and damage, and environmental concerns such

as recycling of composite structures, are also discussed

CHALLENGES OF SHAPE MEMORY

POLYMERS: A REVIEW OF THE PROGRESS

TOWARD OVERCOMING SMP’S LIMITATIONS

Rousseau I A

General Motors Corp

Many applications ranging from biomedical to aerospace

have been proposed for the use of shape memory polymers

(SMPs) To optimize SMPs properties for appropriately

targeting such wide-spreading application requirements,

it becomes necessary to understand the structure/property

relationships in SMPs The literature was reviewed and the

recent advances made in the development of SMPs were

determined to establish guidelines for composition and

structure considerations for designing SMPs with targeted

chemical, physical, and shape memory (SM) properties It

was concluded that covalently crosslinked glassy thermosets

appear to be better SMP candidates because of their

intrinsically higher modulus, greater thermal and chemical

stability, higher shape fi xity and recovery, and possibly

their longer cycle life However, material design allows for

reaching comparable or better properties for all classes of

SMPs This emphasizes that optimisation of SMPs requires

application-specifi c molecular, structural, and geometrical

design Current techniques for improving stress recovery

and cycle time, which compared to shape memory alloys are

the two main limitations of SMPs, are extensively discussed

Understanding the relationships between the composition

and structure of an SMP and its SM properties as well as

its limitations enables one to better defi ne the development areas for high performance SMPs 74 refs

GUO Z SHANGHAI,UNIVERSITY

The effects of room temperature ageing on the cure kinetics of a bismaleimide (BMI) matrix prepreg have been characterized by different time and storage conditions The study has focused on the stability of BMI matrix carbon

fi bre prepregs, when exposed to controlled environmental conditions before being used in composite manufacturing The effects of ageing on reactivity, glass transition temperature, and process window have been investigated

by differential scanning calorimeter through dynamic and isothermal tests A theoretical kinetic model for epoxy matrix prepregs, developed in previous studies, has been applied to the cure of both aged and virgin BMI matrix The model is able to satisfactorily describe the effect of processing variables such as temperature and degree of cure during the curing of the composite under different conditions (curing temperature and heating rate) The effects

of diffusion-controlled phenomena on the cure kinetics, associated with changes in glass transition temperature as a function of the degree of cure, have been taken into account

in the formulation of an nth-order kinetic model 12 refs

Spelz Uxperion Aerospace GmbHThe serial production of CFRP thermoplastic profi les for aircraft applications, specifi cally the fi xation rails

of the sidewall panels of the Airbus A330/340, by xperion Aerospace GmbH is described The continuous compression moulding process used is outlined, together with the weight reduction resulting from substitution of aluminium, and the material and process chain, involving polyether-imide The manufacture of the individual components of the fi xation rails is discussed and subsequent processing is considered

EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE

Accession no.1031432

Item 18

Journal of Thermoplastic Composite Materials

21, No.6, Nov.2008, p.543-555

IMPACT OF ND-YAG LASER DRILLING ON THE

FATIGUE CHARACTERISTICS OF APC-2A/AS4

THERMOPLASTIC COMPOSITE MATERIAL

Young T M

Limerick,University

The effect of neodymium-doped-yttrium aluminium garnet

laser drilling on the static tensile strength and fatigue life

of quasi-isotropic thermoplastic composites APC-2A/AS4

(PEEK thermoplastic composite material in unidirectional

form) for aerospace applications was investigated The

holes had diameters of about 120 micrometers and were

spaced about 500 micrometers apart The drilled specimens

were inspected using scanning electron microscopy A

maximum stress versus cycles to failure was represented

by a power law function, which was used with a reduced

coefficient of fatigue strength value to describe the

fatigue life characteristics of the laser-drilled specimens

ADVANCED COMPOSITE CENTRE FOR

INNOVATION AND SCIENCE Proceedings of the

Annual Conference, held University of Bristol, 9th July

2008

Bristol, Advanced Composites Centre for Innovation &

Science, 2008, paper 2, pp.5, 30 cm, 012 Downloaded

from : www.bris.ac.uk/composites (Accessed 23/7/08)

AUXETIC MATERIALS AND STRUCTURES

Scarpa F

(UK,Advanced Composites Centre for Innovation and

Science; Bristol,University)

This is a PowerPoint presentation on auxetic materials

and structures It deals with foams, composite laminates

and honeycomb structures Some data on properties are

included and some applications indicated

ALCOHOL/ALUMINUM HYBRID LAYERED

ASSEMBLY FOR HIGH-PERFORMANCE

FIBROUS INSULATION

Wu H; Fan J; Qin X; Mo S; Hinestroza J P

Hong Kong,Polytechnic University; Shanghai,Donghua

University; Cornell University

A hybrid layered assembly based on aluminium-coated

PVAL nanofi bre supported on a PP web was fabricated

by electrospinning and physical vapour deposition Characterisation was carried out using SEM and TEM

IR spectral transmission and water vapour transmission through the materials with or without the nanofi bre of metal coating were determined Potential applications in protective clothing, sleeping bags, building applications and aircraft are mentioned 28 refs

in terms of applications of sensor paints in marine research, high-throughput screening and combinatorial microbiology, medicine, and in the design of aircraft and road vehicles 30 refs

EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE

Accession no.1029181

Item 22

SAMPE ‘08: Material and Process Innovations: Changing our World Volume 53 Proceedings of a conference held Long Beach, Ca., 18-22 May, 2008.Covina, Ca., SAMPE International Business Offi ce,

2008, Paper 194, pp.9

A NEW NON-METALLIC ACOUSTIC CORE WITH A BURIED SEPTUM FOR APPLICATION

IN COMPOSITE ACOUSTIC PANELS

Welch J M; Kitt B R; Gallman JSpirit AeroSystems

(SAMPE)

A new, non-metallic Acousti-Cap honeycomb core with a permeable plastic septum cap for application in composite acoustic panels for nacelle applications is reported and application possibilities associated with the new core are briefl y discussed A typical production method for fabricating the acoustic panel using the new core involving perforated sheet construction and cure, perforated sheet

to acoustic core bonding and machining, is described and non-destructive testing of a large area acoustic repair

to identify any anomalies incurred during bonding is briefl y reported

USA

Accession no.1028788

Item 23

SAMPE ‘08: Material and Process Innovations:

Changing our World Volume 53 Proceedings of a

conference held Long Beach, Ca., 18-22 May, 2008

Covina, Ca., SAMPE International Business Offi ce,

2008, Paper 191, pp.14

PROCESS AND SIMULATION CHAINS

FOR ADVANCED TEXTILE STRUCTURAL

COMPOSITES

Drechsler K

Stuttgart,University

(SAMPE)

Various textile preforms, including braided and stitched

textile structures, for composites are described and

their use in aerospace and automotive applications is

discussed Methods for simulating the manufacturing

process and predicting the mechanical performance of

textile-reinforced composites are also considered and some

application examples are presented 15 refs

EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY;

WESTERN EUROPE

Accession no.1028785

Item 24

SAMPE ‘08: Material and Process Innovations:

Changing our World Volume 53 Proceedings of a

conference held Long Beach, Ca., 18-22 May, 2008

Covina, Ca., SAMPE International Business Offi ce,

2008, Paper 160, pp.13

ATL DESIGN TOOL FOR TOW PATH

OPTIMIZATION

Wyatt J; Haj-Hariri H; Gruber M

Virginia,University; Accudyne Inc

(SAMPE)

An algorithm for automated tape laying is presented

and applied to industrial applications, including pad-up

geometries in aircraft panels and aircraft cowling, to calculate

optimal tow paths, constrained to prevent overlap and to

minimise tow gaps It calculates natural paths, optimises

initial conditions for the natural paths, forces tows off natural

paths to close remaining gaps and quantifi es various design

metrics These metrics include fi bre strain, compression

wrinkle caused by bi-normally bending trajectories and

folding wrinkle created by rapid substrate variations

5 refs

USA

Accession no.1028756

Item 25

SAMPE ‘08: Material and Process Innovations:

Changing our World Volume 53 Proceedings of a

conference held Long Beach, Ca., 18-22 May, 2008

Covina, Ca., SAMPE International Business Offi ce,

2008, Paper 228, pp.18

3-D WOVEN PI PREFORM JOINTS: AN

ENABLING TECHNOLOGY FOR LARGE

of the new preforms are described and the advantages of the preforms, which include ease of joining, superior joint strength and process fl exibility, are detailed Structural applications are demonstrated and validation of various aircraft structures (from risk reduction to full scale level) based on the preforms is covered 12 refs

Beier U; Wolff-Fabris F; Fischer F; Sandler J K W; Altstadt V; Hulder G; Schmachtenberg E; Spanner H; Weimer C; Roser T; Buchs W

Bayreuth,University; Erlangen-Nurnberg,University; Eurocopter Deutschland GmbH

In order to achieve a superior overall mechanical performance of composites based on stitched preforms for demanding aircraft applications, innovative thermoplastic stitching yarns are comparatively evaluated in carbon fi bre-reinforced epoxy composites Low-melting temperature yarns based on polyamide and phenoxy in comparison

to a standard polyester yarn allow prestabilisation of the dry preforms by thermobonding and lead to signifi cantly reduced laminate disturbances following liquid composite moulding; thereby minimising the degradation of the resulting composite strength properties While the softening polyamide yarns allow partial rearrangement

of the carbon fi bres during the resin injection process, the dissolution and subsequent phase-separation of the phenoxy can induce a further local toughening of the epoxy matrix The improvements in overall composite performance when using stitching yarns are partly due to the particular yarn material but also depend on variations

in linear yarn density Last but not least, it is demonstrated that stitching seams close to a bolted joint have only little effect on the bolt bearing strength of the stitched composite whereas seams running directly through the hole and oriented in the load direction induce small degradation

of the bolt bearing strength 32 refs Copyright (c) 2008 Elsevier Ltd

EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY;

THE PERFORMANCE OF NOVEL

POLYETHERIMIDES IN A LOW EARTH ORBIT

ENVIRONMENT

Stienstra M M; Dingemans T; Van Eesbeek M; Rohr T

Delft,University of Technology; ESA/ESTEC

The performance of a new series of all-aromatic

polyetherimides prepared from either

biphenyltetracarboxylic dianhydride or

3,3’,4,4’-oxydiphthalic dianhydride and diamines consisting of 1,2

or 3 additional aryloxy units with either para, meta or ortho

substitutions was investigated under simulated low Earth

orbit conditions The effect of polymer backbone structure

on the thermooptical stability of the polyetherimides under

simulated UV radiation and atomic oxygen exposure was

examined and the performance of these new polymers

compared with that of Kapton and Upilex to assess their

suitability for space applications 9 refs

EUROPEAN COMMUNITY; EUROPEAN UNION;

NETHERLANDS; WESTERN EUROPE

Accession no.1027810

Item 28

International Journal of Adhesion and Adhesives

29, No.1, 2009, p.77-90

ENVIRONMENTAL EFFECTS ON THE AGEING

OF EPOXY ADHESIVE JOINTS

Doyle G; Pethrick R A

Strathclyde,University

Adhesive bonded joints are exposed to a range of different

environments in aerospace applications This paper

reports dielectric and mechanical analysis of

aluminium-epoxy bonded adhesives joints exposed to de-ionized

water, aqueous urea solution and salt water at 65 deg.C

The changes observed are the results of plasticisation

and corrosion In the case of the aqueous urea solution,

passivation of the oxide by the urea reduced the rate of

corrosion Sea water contains mobile ions and a new

feature is detected associated with fi liform corrosion

The non-polar media aviation fuel and hydraulic fl uid are

able to plasticise the adhesive and there is a consequent

reduction in the strength of the joint Propylene glycol,

although it is polar solvent, produces limited plasticisation

and degradation of the joints Dichloromethane was very

aggressive and produced a rapid loss of strength of the

joints 23 refs Copyright (c) 2008 Elsevier Ltd

EUROPEAN COMMUNITY; EUROPEAN UNION; UK; WESTERN

on plastic sheets for applications including flexible displays and an electronic skin to cover an entire aircraft

to monitor crack formation The so-called “nanonet” technology - circuits made of numerous carbon nanotubes randomly overlapping in a fi shnet-like structure - has been plagued by a critical fl aw: the network is contaminated with metallic nanotubes that cause short circuits The discovery solves this problem by cutting the nanonet into strips, preventing short circuits by breaking the path of metallic nanotubes

I l l i n o i s U n i v e r s i t y a t U r b a n a - C h a m p a i g n ; Purdue,University

in this regard Its Envirez 1807 polyester resin made with

a 75/17/8% content ratio of petroleum, soybean oil and ethanol has been used since 2002 in Class A exterior styling panels on all John Deere combines, as well as many of the OEM’s tractor models and hay balers The National Composite Center is looking at reinforcing structural SMC with biomaterials such as natural fi bre and recyclate Hexcel is making big news with its application of HexMC carbon fi bre SMC in the large window frames on Boeing’s new 787 Dreamliner commercial aircraft With base resin and compound prices rising, along with costs for the energy

to conduct processing, some moulders are extending their technology grasp by adding in-house compounding

WORLD

Accession no.1026357

Item 31

ANTEC 2008 Proceedings of the 66th SPE Annual

Technical Conference held Milwaukee, Wi., 4th-8th

May 2008

Brookfi eld, Ct., SPE, 2008, p.1977-1981

IMPROVING THE THERMAL CONDUCTIVITY

OF EPOXY HYBRID NANOCOMPOSITES FOR

The poor thermal conductivity of polymer based

composites has long been a deterrent to their increased

use in high end aerospace applications In this study, the

thermal conductivity of Epoxy-Carbon fi bre composites is

improved dramatically by a novel method of incorporating

carbon nanoparticles into the system A comprehensive

study of the preparation and properties of the highly

thermally conductive Epoxy-Carbon fibre-Carbon

nanofi bre composites is presented 7 refs

USA

Accession no.1026196

Item 32

ANTEC 2008 Proceedings of the 66th SPE Annual

Technical Conference held Milwaukee, Wi., 4th-8th

May 2008

Brookfi eld, Ct., SPE, 2008, p.1256-1259

IMPROVING ADHESION PERFORMANCE

BETWEEN LOW SURFACE TENSION

COMPOSITE AND DISSIMILAR SUBSTRATES

Wolf R A

Enercon Industries Corp

(SPE)

The growing demand for high performance plastic

components for automobile, aerospace, medical and

electronic applications has made the job of formulating

paints, adhesives and coatings more challenging Composite

plastics having low surface energies but which deliver

high-strength, low-weight performance are becoming more

prevalent Adhesion to the surfaces of these composites, as

well as between dissimilar high performance materials, is

being solved by atmospheric pretreatment technologies

This paper links specifi c atmospheric surface pretreatment

improvements in adhesion to an array of composite and

dissimilar materials 2 refs

USA

Accession no.1025816

Item 33

Chemical Weekly

LIV, No.1, 19th Aug.2008, p.174

NEW NANOMATERIAL MAKES PLASTIC

STIFFER, LIGHTER AND STRONGER

It is briefl y reported that a Michigan State University research team has developed a nanomaterial that makes plastic stiffer, lighter and stronger The material xGnP Exfoliated Graphite NanoPlatelets will be instrumental

in the development of new and expanded applications

in the aerospace, automotive and packaging industries The nano-scale material, which is electrically and thermally conductive, has reduced flammability and barrier properties The graphene nanoparticles are being manufactured by a new startup company, XG Sciences, which has an exclusive licence to manufacture the material The researchers are already looking ahead to more uses for the product, such as recyclable, economical or lightweight units to store hydrogen for the next generation of fuel cell-powered autos Attention is being directed to high-end applications where substantial changes can be made

in the way electronics, fuel cells, batteries and solar cells perform as a result of using the material

at least an order of magnitude greater than any of-the-art polymeric materials reported The actuating characteristic mainly originated from the electrostrictive contribution, presumably due to interfacial polarisation The composite intrinsically formed a unimorph during the fabrication process to actuate without the need for additional inactive layers The tunable multifunctionality and structural reinforcement achieved in these composites could contribute to the design of intelligent and durable components for future aerospace vehicles as well as terrestrial applications 27 refs

RESIN FILM INFUSION FOR AIRCRAFT

APPLICATIONS

Lopez-Quintana S; Leal L; Casado J; Poveda J; Diez S;

De Benito A

CIDAUT; Aries Complex SA

A report is presented on the manufacture of aircraft using

the resin fi lm infusion process 26 refs

EUROPEAN COMMUNITY; EUROPEAN UNION; SPAIN;

ASSESSING CONVENTIONAL AND ADVANCED

NDI FOR COMPOSITE AIRCRAFT

Roach D

The rapidly increasing use of composites as structural

aircraft materials has brought with it the challenge of

making sure damage inspection can keep pace Accurate

non-destructive inspection (NDI) methods are a necessity

to ensure aircraft airworthiness and passenger safety

Over the last several years, a series of experiments

have been designed and implemented to assess how

well both conventional and advanced NDI techniques

can detect voids, disbonds, delaminations and impact

damage in honeycomb structure, solid laminates and

adhesively bonded structures The test programme, called

Composite Flaw Detection Experiments, was undertaken

at the Federal Aviation Admin Airworthiness Assurance

NDI Validation Center (AANC), operated and staffed

by Sandia National Laboratories Many of the AANC

composites activities are conducted under the auspices of

the Commercial Aircraft Composite Repair Committee

(CACRC) This article discusses the CACRC’s Inspection

Task Group’s Probability of Detection experiments, some

of the results gathered thus far, and potential applications of

new technology for effective NDI on composites-intensive

aircraft as they enter commercial service

US,Federal Aviation Administration

“EX SITUÖ CONCEPT FOR TOUGHENING THE

RTMABLE BMI MATRIX COMPOSITES, PART I:

IMPROVING THE INTERLAMINAR FRACTURE

TOUGHNESS

Qunfeng Cheng; Zhengping Fang; Xiao-Su Yi; Xuefeng

An; Bangming Tang; Yahong Xu

Zhejiang,University; Beijing,National Key Laboratory

of Advanced Composites; Beijing,Research Institute of

Aerospace Special Materials and Technology

Interlaminar fracture toughness of bismaleimide

composites, as used for aerospace applications, was achieved using an ex-situ resin transfer moulding process with a polyether ketone (PEK)thermoplastic The process was briefl y described, and samples were evaluated against

an untreated base sample using double cantilevered beam tests or end notch fl exure test to assess mode 1 or mode 2 fracture toughness respectively Fractured samples were examined using scanning electron and optical microscopies, and it was shown plastic deformation and rupture of the PEK phase was responsible for fracture toughening The toughening mechanism was discussed 26 refs

Takeda S; Mizutani T; Nishi T; Uota N; Hirano Y; Iwahori Y; Nagao Y; Takeda N

Japan,Aerospace Exploration Agency; Tokyo,University; KADO Corp

The structural health monitoring of a carbon reinforced epoxy resin composite laminate panel fabricated via vacuum-assisted resin transfer moulding and containing embedded fi bre Bragg grating (FBG) sensors and optical fi bres was investigated by measurement of residual internal strains during curing and post-curing and during four-point fl exure by means of refl ection spectra of the FBG sensors The results are discussed in comparison with those obtained using conventional strain gauges and

fibre-fi nite element analysis, and in terms of potential aerospace applications 5 refs

in its present form, attempts are being made to improve manufacturing both the material and parts made from it, to increase its range of applications Festo produces electric handling solutions for carbon fi bre production and has been carrying out pioneering work with the Textile Composites Group at Manchester University’s School of Materials The project aims to use Festo’s automation range to cut waste and improve the dimensional strength in carbon fi bre products Rockwell Automation has recently worked with DuPont on its Kevlar line During an update of DuPont’s

Maydown Kevlar production plant in Derry, Rockwell

replaced the existing dated PLC units with Allen-Bradley

NON-HALOGEN FIRE RESISTANT PLASTICS

FOR AIRCRAFT INTERIORS

Lyon R E; Emrick T

Atlantic City International Airport; US,Federal Aviation

Administration; Massachusetts,University

Strategies for developing fi re-proof aircraft cabin materials

are reviewed in the light of environmental legislation

restricting the use of halogens in plastics Fire tests

for aircraft materials are indicated and fi re resistance

mechanisms of plastics are outlined and described in terms

of their effect on heat release rate in fl aming combustion

Finally, the results are reported of fi re tests carried out on

non-halogen polymers, including polyphenylsulphone,

polyester carbonate and bishydroxydeoxybenzoin-based

polyarylate, polyphosphonate and

poly(arylate-co-phosphonate), which are optically clear and potentially

useful for aircraft cabin applications 34 refs

Texas,University at Austin; Lehigh University

In the large field of nanotechnology, polymer matrix

based nanocomposites have become a prominent area of

current research and development Exfoliated clay-based

nanocomposites have dominated the polymer literature but

there are a large number of other signifi cant areas of current

and emerging interest This review will detail the technology

involved with exfoliated clay-based nanocomposites

and also include other important areas including barrier

properties, fl ammability resistance, biomedical applications,

electrical/electronic/optoelectronic applications and fuel

cell interests The important question of the “nano-effect’’

of nanoparticle or fi bre inclusion relative to their larger

scale counterparts is addressed relative to crystallisation

and glass transition behaviour Of course, other polymer

(and composite)-based properties derive benefi ts from

nanoscale fi ller or fi bre addition and these are addressed

284 refs Copyright (c) 2008 Elsevier Ltd

Rao S; Rao R M V G KIndia,National Aerospace LaboratoriesThree types of bifunctional epoxy-amine matrix systems (two room temperature (RT) cure types and one elevated temperature (ET) cure type), used for aerospace composite applications, were cured in a domestic microwave oven Microwave cure schedules equivalent to vendor-specifi ed thermal cure schedules were evolved for each resin system, using the glass transition temperature (T”g) as the index of cure completion Both continuous and pulsed microwave heating modes were employed The cure status and cure uniformity were assessed using differential scanning calorimetry (DSC) and thermal imaging techniques The studies showed that pulsed microwave-heated samples exhibited greater degree and uniformity of cure (both in terms of temperature attained and the T”g shown across the samples), compared to the continuous microwave-heated samples for all the resin systems studied 16 refs Copyright (c) 2008 Elsevier Ltd

MATERIAL AND PROCESS INNOVATIONS: CHANGING OUR WORLD

(SAMPE)Over 250 papers dealing with aspects of materials and process innovations were presented at the SAMPE ‘08 conference Papers were presented under the following main headings: adhesives and bonding; advancements

in non-destructive evaluation; aircraft applications technologies; biomaterials; civil engineering and infrastructure; design and analysis; durability, impact and damage; electrical properties of composites and nanocomposites; high temperature resins and coatings; alternative energy applications; automotive and fl ame retardant applications; metals and ceramics; natural materials; nanomaterials; pressure vessel technology; process development and manufacturing; resin infusion; resins and interfaces; sandwich cores; smart materials, including shape memory materials; structural health monitoring; testing and test methods; textile and preform technology; thermoplastics; and tooling, repair and composites affordability

USA

Accession no.1021971

Item 44

Journal of Reinforced Plastics and Composites

27, No.8, 2008, p.835-850

AN EXAMINATION OF FAILURE CRITERIA

FOR NOTCHED ORTHOTROPIC CERAMIC

MATRIX COMPOSITE LAMINATES

Yeh H-Y; Murphy K S; Yeh H-L

California,State University; Taiwan,I-Shou University

The application of the Yeh-Stratton failure criterion to

newly developed fi bre-reinforced orthotropic ceramic

matrix composite laminates based on an aluminoborosilicate

fabric impregnated with a silica-alumina matrix was

investigated analytically in comparison with experimental

test data for laminates containing a central crack under

tensile loading and with linear elastic stress models The

results are discussed in comparison with those for graphite

fi bre-reinforced epoxy resin composite laminates and in

terms of aerospace applications 19 refs

MESOPOROUS VANADIA WITH UNUSUAL

DUCTILITY AT CRYOGENIC TEMPERATURES

Leventis N; Sotiriou-Leventis C; Mulik S; Dass A;

Schnobrich J; Hobbs A; Fabrizio E F; Luo H; Churu G;

Zhang Y; Lu H

Missouri,University of Science and Technology;

US,NASA,Glenn Research Center; Ohio Aerospace

Institute; Oklahoma,State University

An aerogel-like composite material was prepared by

casting a conformal diisocyanate-derived polymer coating

on the bird-nest like skeletal framework of mesoporous

vanadia and its physicochemical and mechanical properties

investigated The nanoencapsulated vanadia exhibited

a highly unusual ductility at cryogenic temperatures

and did not fail even under high strain compression

The high strength of the nanoencapsulated vanadia was

attributed to interlocking of skeletal nanoworms and the

high ductility to sintering-like melting and fusion of the

polymer coating under compression The composites

are considered suitable for applications, such as armour,

cryogenic fuel containers and landing gear for aerospace

DEVELOPMENT OF CRYOGENIC COMPOSITE

OVER-WRAPPED PRESSURE VESSELS (COPVS)

DeLay T; Patterson J; Noorda J; Schneider J

NASA,Marshall Space Flight Center; HyPerComp Engineering Inc.; Mississippi,State UniversityThe results of a feasibility study on the development

of cryogenic composite over-wrapped pressure vessels for aerospace and other applications, involving the development and evaluation of materials, test methods and tank design, are reported The mechanical properties and burst pressures of composite vessels fabricated using carbon fi bre-reinforced epoxy resin or urethane resin systems with aluminium liners of different thicknesses were investigated experimentally at cryogenic temperatures, and the results are discussed in terms

of potential savings in weight compared to alternative existing designs 3 refs

MECHANICAL AND PHYSICAL EVALUATION

OF NEW CARBON FIBRE/PEEK COMPOSITES FOR SPACE APPLICATIONS

Kilroy J P; O’Bradaigh C M; Semprimoschnig C O AComposites Testing Laboratory Ltd.; Eire Composites; European Space Agency

The thermomechanical properties of laminates fabricated using a commercially available carbon fi bre-reinforced poly(etheretherketone) composite pre-impregnated tape processed under pressure-formed autoclave conditions were investigated by tensile, compression, fl exure, in-plane shear and interlaminar shear testing over a wide range of temperatures, and fracture toughness, moisture uptake and DSC measurements The results are compared with those for laminates fabricated using thermoplastic in-situ automated tape placement and are discussed in terms of the fabrication of large composite structures such as cryogenic fuel tanks for aerospace applications 19 refs

EUROPEAN COMMUNITY; EUROPEAN UNION; IRELAND; NETHERLANDS; WESTERN EUROPE

information on material alternatives, as well as core,

acoustic and anti-blast applications

AUSTRALIA; EUROPEAN COMMUNITY; EUROPEAN UNION;

FRANCE; MALAYSIA; SCANDINAVIA; SOUTH KOREA;

SWEDEN; UK; USA; WESTERN EUROPE

Recent advances in composites for aerospace applications

are reported, focusing upon products from Hexcel,

including Hexweb HRH-36 Flexcore honeycomb made

from Kevlar paper and reinforced with a high

temperature-resistant phenolic resin, HexMC, a new kind of

cost-effective carbon fibre epoxy moulding concept and

Hextool composite tooling material based on HexMC

Some examples of Hexcel’s products on display at the

Farnborough Airshow are included

FABRICATION OF CLOSED-CELL POLYIMIDE

INVERSE OPAL PHOTONIC CRYSTALS WITH

EXCELLENT MECHANICAL PROPERTIES AND

THERMAL STABILITY

Xiao Chen; Lihua Wang; Yongqiang Wen; Yuqi Zhang;

Jingxia Wang; Yanlin Song; Lei Jiang; Daoben Zhu

Beijing,Institute of Chemistry; Chinese Academy of

Sciences; Yan’an,University; Beijing,Graduate University

Closed-cell fl uorinated polyimide inverse opal photonic

crystals (IOPC)s were fabricated using core-shell

poly(styrene-methyl methacrylate-acrylic acid) colloidal

spheres as the template and their heat stabilities,

morphologies, photonic band gaps, contact angles,

hardnesses and elastic moduli investigated The mechanism

of formation of the closed-cell structure was studied

and properties of the closed-cell fl uorinated polyimide

IOPCs compared with those of open-cell polyimide

IOPCs prepared using PS colloidal spheres as a template

The closed-cell polyimide IOPCs were thermally and

mechanically stably and were considered potentially

suitable for use in thermal insulation, energy absorption

and aerospace applications 20 refs

The resin infusion process is outlined and two examples of extreme infusion environments, namely high-temperature infusion for composite parts in the aerospace industry and ambient isothermal resin infusion for tooling applications, are described The fi rst example shows that the resin fl ow front can be detected during high-temperature infusion even through caul plates and the second one demonstrates that active sensors are needed to detect isothermal infusion

SWITZERLAND; WESTERN EUROPE

Beier U; Fischer F; Sandler J K W; Altstadt V; Weimer C; Spanner H; Buchs W

Bayreuth,University; Eurocopter Deutschland GmbH

A comparative assessment of the infl uence of assembly seams based on two different thermoplastic yarn types on key in-plane and interlaminar properties of carbon fi bre-reinforced epoxy composite is presented Non-crimped fabric (NCF) composites prepared with a thin low melting-temperature polyamide stitching yarn showed an overall mechanical performance similar to that of the non-stitched equivalent, independent of the stitch geometry In contrast, comparable composites prepared with a thicker standard unwashed polyester yarn revealed a clear reduction in compression and apparent interlaminar shear strength, with the exact level of degradation depending on the stitch geometry These deviations in mechanical performance are explained

on the basis of a fundamental microstructural difference of the composites following resin transfer moulding Using the thinner meltable but immiscible polyamide yarn in the stitched preforms instead of the standard polyester yarn appears to reduce localised fi bre undulations; an effect most likely inducing the observed enhancements in key composite properties relevant for aircraft applications

22 refs Copyright (c) 2008 Elsevier Ltd

EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE

THRESHOLDS OF POLYMERIC MATERIALS

FOR AEROSPACE APPLICATIONS

Hirsch D; Williams J; Beeson H

US,NASA,Johnson Space Center

The results are reported of a study of the effects of pressure

on the oxygen concentration fl ammability thresholds of a

range of polymeric materials, including polyoxymethylene,

PE, PTFE, aliphatic polyamide, PCTFE, PDMS,

fl uoroelastomer, SBR, nitrile rubber, polychloroprene and

EPDM, for aerospace applications For the range of total

pressures tested, the oxygen concentration and oxygen

partial pressure fl ammability thresholds show a near linear

dependence on total pressure and appear to increase with

increasing oxygen concentration (and oxygen partial

pressure) thresholds 10 refs

The mechanical properties of scaled specimens of fi

bre-metal laminates consisting of an aluminium alloy and

a self-reinforced thermoplastic composite based on

polypropylene fibres in a polypropylene matrix were

investigated by a series of quasi-static tensile and fl exural

tests and low-velocity impact tests Scaling effects in the

laminates were studied by comparison of the test results to

a scaling law that predicts response parameters based on

a simple geometrical relationship of the input parameters,

and the results are discussed in terms of engineering

applications especially in aerospace components 25 refs

EUROPEAN COMMUNITY; EUROPEAN UNION; UK; WESTERN

MODELING AND ANALYSIS OF THICKNESS

GRADIENT AND VARIATIONS IN

VACUUM-ASSISTED RESIN TRANSFER MOLDING

PROCESS

Li J; Zhang C; Liang R; Wang B; Walsh S

Florida A & M University; US,Army Research

Laboratory

As vacuum-assisted resin transfer moulding (VARTM)

is being increasingly used in aerospace applications, the

thickness gradient and variation issues are gaining more

attention Typically, thickness gradient and variations result

from the infusion pressure gradient during the process and

material variations Pressure gradient is the driving force

for resin fl ow and the main source of thickness variation After infusion, an amount of pressure gradient is frozen into the preform, which primarily contributes to the thickness variation This study investigates the mechanism

of the thickness variation dynamic change during the infusion and relaxing/curing processes A numerical model was developed to track the thickness change of the bagging

fi lm free surface A time-dependent permeability model as

a function of compaction pressure was incorporated into an existing resin transfer moulding (RTM) code for obtaining the initial conditions for relaxing/curing process Control volume (CV) and volume of fl uid (VOF) methods were combined to solve the free surface problem Experiments were conducted to verify the simulation results The proposed model was illustrated with a relatively complex part 17 refs

as elsewhere in the aerospace sector, is aluminium Twelve composite-overwrapped pressure vessels are currently in orbit, mounted externally on the ISS and protected from micrometeoroids by thin aluminium bumpers Elsewhere

on the ISS, composites form about 40 storage, payload and system racks The racks were built by Boeing from graphite/epoxy composites by hand layup of a framework

of rectangular tubes and I-beam sections as well as skin panels A relatively new type of composite, featuring a shape-memory polymer matrix, soon might be available

to designers of in-space deployment systems for solar arrays, communication antennae and optical systems One example is the Elastic Memory Composite Hinge created

by Composite Technology Development Carbon fi bre composite technology for unmanned planetary exploration vehicles is well developed The composites used have

to go from the ambient Earth temperature at which they were assembled, to the autoclave temperature of about

177 deg.C, to the extreme cold in space and on Mars

epoxy and later aramid/epoxy However, improvements in

fi bre properties since then have made carbon/epoxy the SRM

material of choice More recently, composites have been

adopted for fi rst-stage boosters, payload adaptors and payload

fairings The design of launch vehicle structures is driven

primarily by stiffness ATK Launch Systems Group produces

the GEM (graphite epoxy motor) family for Boeing’s Delta

launch vehicles as well as Orion rocket motors for Orbital

Vibration loads are a signifi cant design issue for spacecraft

CSA Engineering’s expertise is viscoelastic materials,

or VEMs, which are typically rubbery materials that can

reduce vibration amplitudes and peak dynamic stresses One

successful application was a space truss structure experiment

For manned space vehicles with crew modules, composites

could eventually fi nd use on NASA’s latest initiative, the

Constellation, a Space Shuttle replacement that is expected

to return astronauts to Earth’s Moon by 2020

The continued push for aircraft weight reduction is

driving composites growth in cabin applications Today,

composites are used for fl oor and ceiling panels, overhead

stowage bins, partitions, window and door surrounds,

cabin and galley walls, lavatory modules, food and drink

trolleys, cargo hold liners and ventilation ducts Inroads

are also being made into seating components such as rails

and pedestals, which are still primarily manufactured of

Composites continue to earn their way into fl ight-critical

aircraft components with help from innovative fabrication

strategies The incursion of autoclaved prepreg composites

into fl ight control surface structures has a history that

goes back several decades Today, however, a variety of

material and process innovations are enabling a dramatic

upswing in metal-to-composite conversions This article

presents examples which are representative of many

creative applications These include: composite wings;

resin transfer moulded wing spars; one-piece wingskins;

vacuum-assisted resin-transfer moulded trailing edges;

fi breglass-reinforced thermoplastic leading edges; tail

structures; pultruded tail stringers; hand layered rib trusses;

and resin transfer moulded prepreg wingtips

is shown that the adhesives and bonding agents developed ensure effi cient operation of adhesively-bonded joints in the temperature range from -196 to 1600 deg C 9 refs

McConnell B K; Pethrick R AStrathclyde,UniversityThe results are reported of a study of the mechanism of water uptake and desorption in dicyandiamide- and amine-cured epoxy resin adhesives (AF 163-2K and Epibond 1590) used in aerospace applications Uptake and loss of moisture are monitored gravimetrically, using broad band dielectric, DMTA and thickness measurements performed as

a function of time at various temperatures Uptake and loss profi les for the adhesives are compared and resorption studies performed on Epibond 1590 adhesive Differences between the adhesives are rationalised in terms of the different abilities

of the matrix to interact with the water molecules 26 refs

EUROPEAN COMMUNITY; EUROPEAN UNION; UK; WESTERN EUROPE

Accession no.1017691

Item 62

Silicone Elastomers 2008 Proceedings of the Second International Conference held Munich, Germany, 12th-13th March, 2008