New Trends in Technologies: Devices, Computer, Communication and Industrial Systems doc

For example-photochromic materials that change colour in response to light; shape memory alloys and polymers which change/recover their shape in response to heat and electro- and magneto

New Trends in

Technologies:

Devices, Computer, Communication and Industrial Systems

edited by

Prof Meng Joo Er

SCIYO

Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher No responsibility is accepted for the accuracy of information contained in the published articles The publisher assumes no responsibility for any damage or injury to persons or property arising out of the use of any materials, instructions, methods

or ideas contained in the book

Publishing Process Manager Jelena Marusic

Technical Editor Teodora Smiljanic

Cover Designer Martina Sirotic

Image Copyright Palto, 2010 Used under license from Shutterstock.com

First published November 2010

Printed in India

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Additional hard copies can be obtained from publication@sciyo.com

New Trends in Technologies: Devices, Computer, Communication and Industrial Systems,

Edited by Prof Meng Joo Er

p cm

ISBN 978-953-307-212-8

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Overview of Multi Functional Materials 1

Parul Gupta and R.K.Srivastava

Polymer Materials and Its Properties 15

Jana Šišáková

New Technologies and Devices

to Increase Structures’ Safety to Dynamic Actions 43

Viorel Serban, Madalina Zamfi r, Marian Androne and George Ciocan

Advances in CAD/CAM Technologies 67

Mircea Viorel Drăgoi

Computer Simulation of Plaque Formation

and Development in the Cardiovascular Vessels 95

Nenad Filipovic

Economic Impact of Information and Communications Technology – Identifying Its Restraints and Exploring Its Potential 119

Ksenija Vuković and Zoran Kovačević

Operating System Kernel Coprocessor for Embedded Applications 135

Domen Verber and Matjaž Colnarič

Modern Internet Based Production Technology 145

Dobroslav Kováč, Tibor Vince, Ján Molnár and Irena Kováčová

eLearning and Phantasms 165

M.sc Ivan Pogarcic and B.sc Maja Gligora Markovic

Model of the New LMS Generation with User-Created Content 179

Dragan Perakovic, Vladimir Remenar and Ivan Jovovic

BEPU Approach in Licensing Framework,

including 3D NK Applications 197

F D’Auria, N Muellner, C Parisi and A Petruzzi

Capabilities and Performances

of the Selective Laser Melting Process 233

Sabina L Campanelli, Nicola Contuzzi,

Andrea Angelastro and Antonio D Ludovico

Experimental Analysis of the Direct Laser Metal Deposition Process 253

Antonio D Ludovico, Andrea Angelastro and Sabina L Campanelli

Low-Shock Manipulation and Testing

of Micro Electro-Mechanical Systems (MEMS) 273

Carlo Ferraresi, Daniela Maffi odo, Francesco Pescarmona,

Omar Bounous, Luciano Bonaria and Maurizio Straiotto

Magnetically Nonlinear Dynamic Models of Synchronous Machines: Their Derivation, Parameters and Applications 291

Gorazd Štumberger, Bojan Štumberger, Tine Marčič

Miralem Hadžiselimović and Drago Dolinar

Potential for Improving HD Diesel Truck Engine Fuel

Consumption Using Exhaust Heat Recovery Techniques 313

D.T Hountalas and G.C Mavropoulos

New Trends in Effi ciency Optimization of Induction Motor Drives 341

Branko Blanusa

Modelling of Concurrent Ddevelopment of the Products,

Processes and Manufacturing Systems in Product Lifecycle Context 359

Jan Duda

Printing as an Alternative Manufacturing Process

for Printed Circuit Boards 375

Huw J Lewis and Alan Ryan

Recent Development of Fast Numerical Solver for Elliptic Problem 403

Mohammad Khatim Hasan, Jumat Sulaiman,

Samsul Ariffi n Abdul Karim, and Mohamed Othman

The Role of Computer Games Industry and Open Source Philosophy

in the Creation of Affordable Virtual Heritage Solutions 421

Andrea Bottino and Andrea Martina

From the metallurgists who ended the Stone Age to the shipbuilders who united the world’s peoples through travel and trade, the past witnessed many marvels of engineering prowess As civilization grew, it was nourished and enhanced with the help of increasingly sophisticated tools for agriculture, technologies for producing textiles, and inventions transforming human interaction and communication Inventions such as the mechanical clock and the printing press irrevocably changed civilization.

In the modern era, the Industrial Revolution brought engineering’s infl uence to every niche

of life, as machines supplemented and replaced human labor for countless tasks, improved systems for sanitation enhanced health, and the steam engine facilitated mining, powered trains and ships, and provided energy for factories

In the century just ended, engineering recorded its grandest accomplishments The widespread development and distribution of electricity and clean water, automobiles and airplanes, radio and television, spacecraft and lasers, antibiotics and medical imaging, and computers and the Internet are just some of the highlights from a century in which engineering revolutionized and improved virtually every aspect of human life

In this book entitled “New Trends in Technologies: Devices, Computers, Communications and Industrial Systems’, the authors provide a glimpse of the new trends of technologies pertaining to devices, computers, communications and industrial systems The book comprised

of 22 very interesting and excellent articles covers core topics ranging from “Overview of Multifucntional Materials” to “New Technologies and Devices to Increase Structures’ Safety

to Dynamic Actions in Devices”, “Advances in CAD/CAM Technologies” to “Operating System Kernel Coprocessor for Embedded Applications” in Computers and “Modern Internet-based Production Technology” to “BEPU Approach in Licensing Framework including 3D

NK Applications” in Communication It also covers topics pertaining to industrial systems ranging from “A Review of Work on Oscillatory Problems in Francis Turbines” to “The Role

of Gaming Theory and Open Source Philosophy in the Creation of Affordable Virtual Heritage Solutions” The book will serve a unique purpose through these multi-disciplinary topics to share different but interesting views on each of these exciting topics which form the backbone

of Engineering Challenges for the 21St Century

I would like to thank all the authors for their excellent contributions in the different areas of their expertise It is their domain knowledge, enthusiastic collaboration and strong support which made the creation of this book possible I sincerely hope that readers of all disciplines will fi nd this book valuable

Editor

Professor Meng Joo Er

School of Electrical and Electronic Engineering

Nanyang Technological University

Overview of Multi Functional Materials

1Department of Mechanical Engineering, Moradabad Institute of Technology (Uttar

Pradesh Technical University), Moradabad, Uttar Pradesh,

2Department of Mechanical Engineering, Motilal Nehru National Institute of Technology

(Deemed University), Allahabad, Uttar Pradesh,

India

1 Introduction

Until relatively recent times, most periods of technological development have been linked to changes in the use of materials (eg the stone, bronze and iron ages) In more recent years the driving force for technological change in many respects has shifted towards information technology This is amply illustrated by the way the humble microprocessor has built intelligence into everyday domestic appliances However, it is important to note that the IT age has not left engineered materials untouched, and that the fusion between designer materials and the power of information storage and processing has led to a new family of

engineered materials and structures

The development of materials science has lead to the introduction of a new kind of material-

“smart” material Smart materials not only have the traditional structural material functions

But also have functions such as actuation, sensibility and microprocessing capability in the materials family , we find three major materials : metals ceramic and polymer and among those polymers being the youngest members find wide application in comparison to metals and ceramics In every sectors of our society the recent progress in smart materials has taken the new momentum in the materials science and technology the board spectrum

of applications of smart materials cover the biomedical , environmental , communication defence , space , nanotechnolgical fields of research with tremendous progress The present report describes the application of smart materials in terms of opportunity and future

challenges

Smart materials referred to materials that will undergo controlled transformations through physical interactions Smart Materials are materials that respond to environmental stimuli, such as temperature, moisture, pH, or electric and magnetic fields For example-photochromic materials that change colour in response to light; shape memory alloys and polymers which change/recover their shape in response to heat and electro- and magneto-rheological fluids that change viscosity in response to electric or magnetic stimuli Smart Materials can be used directly to make smart systems or structures or embedded in structures whose inherent properties can be changed to meet high value-added performance needs.The different types of smart materials include piezoelectric, shape-memory alloys, electro-active conductive polymers, electrochromic materials, biomaterials,

alloy has to satisfy specific qualifications related to the following properties:-

a Technical properties, including mechanical characteristics such as plastic flow, fatigue and yield strength and behavioural characteristics such as damage tolerance and electrical, heat and fire resistance

b Technological properties, encompassing manufacturing, forming, welding abilities, thermal processing, waste level, workability, automation and repair capacities

c Economic criteria, related to raw material and production costs, supply expenses and availability

d Environmental characteristics, including features such as toxicity and pollution

e Sustainable development criteria, implying reuse and recycling capacities If the functions of sensing and actuation are added to the list, then the new material/alloy is considered a smart material

2 Classification of smart materials

Types of materials

a Piezoelectric Materials

b Shape memory alloy (SMA)

c Electro-active conductive polymers

an electric current within the material The mechanical pressure is therefore converted to voltage Natural piezoelectric materials are crystalline materials that exhibit the piezoelectric effect Often they are strong physically and chemically inert The piezoelectric effect can also be found in synthetic polycrystalline ceramics which can be designed to have other specific properties that make individual ceramics useful in many different applications Piezoelectric materials are often linked to pyroelectric effects Often a material can undergo both effects - one converting mechanical stress energy into electrical energy and the other converting from heat energy A piezoelectric material does not, however, always show the pyroelectric effect as well as the piezo

Piezoelectric materials have two unique properties which are interrelated When a piezoelectric material is deformed, it gives off a small but measurable electrical discharge Alternately, when an electrical current is passed through a piezoelectric material it experiences

a significant increase in size (up to a 4% change in volume) Piezoelectric materials are most widely used as sensors in different environments They are often used to measure fluid compositions, fluid density, fluid viscosity, or the force of an impact An example of a piezoelectric material in everyday life is the airbag sensor in your car The material senses the force of an impact on the car and sends and electric charge deploying the airbag

2.2 How do it works

Piezoelectric materials have two crystalline configurations One structure is organized, while the other is not Organization of the structure has to do with polarization of the molecules that make up the material Hence, a non-polarized material has a non-organized structure, while the polarized material is organized To polarize the material, voltage or electricity must be conducted through it As a result of this electrical force, the molecules of the material reorient themselves, thus changing the shape of the material; this is called electrostriction The picture below shows this process at a microscopic level Change in shape can produce mechanical force, as well as changes in physical characteristics (like density, shown below)

Non-polarized material: Polarized material:

Electricity is produced with

Input of electricity

shape change is produced with

input of shape change Fig 1

Similarly, if mechanical force is exerted on the material to change its shape, an electrical field

is produced; this is called piezoelectric effect Electrostriction and piezoelectric effect are opposite phenomena In the graphic below, a thin piezoelectric material within a plastic sheath is being bent, and electricity is being generated and passed through the red wires at the PZT is the most popular piezoelectric material in use

Fig 2

Its physical properties can be optimized for certain applications by controlling the chemistry and processing of this material Therefore, it can have a variety of compositions, geometries, and applications Limitations in its use are related to high excitation voltages needed, mechanical durability, and stability in coupling the material to the control system and/or structure Some piezoelectric materials are:

applied (the substance is squeezed or stretched) Conversely, a mechanical deformation (the substance shrinks or expands) is produced when an electric field is applied This effect is formed in crystals that have no center of symmetry To explain this, we have to look at the individual molecules that make up the crystal Each molecule has a polarization, one end is more negatively charged and the other end is positively charged, and is called a dipole This

is a result of the atoms that make up the molecule and the way the molecules are shaped The polar axis is an imaginary line that runs through the center of both charges on the molecule In a monocrystal the polar axes of all of the dipoles lie in one direction The crystal

is said to be symmetrical because if you were to cut the crystal at any point, the resultant polar axes of the two pieces would lie in the same direction as the original In a polycrystal, there are different regions within the material that have a different polar axis It is asymmetrical because there is no point at which the crystal could be cut that would leave the two remaining pieces with the same resultant polar axis Figure 3 illustrates this concept

Fig 3 Mono vs Crystals

In order to produce the piezoelectric effect, the polycrystal is heated under the application of

a strong electric field The heat allows the molecules to move more freely and the electric field forces all of the dipoles in the crystal to line up and face in nearly the same direction (Figure 4)

Fig 4 Polarization of Ceramic Material to Generate Piezoelectric Effect

The piezoelectric effect can now be observed in the crystal Figure 5 illustrates the piezoelectric effect Figure 5a shows the piezoelectric material without a stress or charge If the material is compressed, then a voltage of the same polarity as the poling voltage will appear between the electrodes (b) If stretched, a voltage of opposite polarity will appear (c) Conversely, if a voltage is applied the material will deform A voltage with the opposite polarity as the poling voltage will cause the material to expand, (d), and a voltage with the same polarity will cause the material to compress (e) If an AC signal is applied then the material will vibrate at the same frequency as the signal (f)

Fig 5 Example of Piezoelectric Effect

Using the Piezoelectric Effect -The piezoelectric crystal bends in different ways at different

frequencies This bending is called the vibration mode The crystal can be made into various shapes to achieve different vibration modes To realize small, cost effective, and high performance products, several modes have been developed to operate over several frequency ranges These modes allow us to make products working in the low kHz range up

to the MHz range Figure 6 shows the vibration modes and the frequencies over which they can work An important group of piezoelectric materials are ceramics Murata utilizes these various vibration modes and ceramics to make many useful products, such as ceramic resonators, ceramic bandpass filters, ceramic discriminators, ceramic traps, SAW filters, and

buzzers

2.4 Application of piezoelectric materials

Piezoelectric materials may be used passively as sensors, or actively as actuators The piezoelectric sensors that will be used on this bridge include the PZT (lead-zirconate-titanate), a ceramic sensor, and PVDF (polyvinylidene fluoride), a polymeric sensor The PZT’s are extremely sensitive and very accurate, but due to their brittle nature, PZT’s are restricted to being point sensors Likewise, PVDF’s are also very sensitive and accurate However, PVDF’s are not as brittle and may be integrated to perform distributed measurements Therefore, PZT’s will be located primarily in critical areas, whereas the PVDF’s will be located along side the strain gauges

2.5 Shape memory alloy (SMA)

Shape memory alloys were discovered in 1932, however it was not until 1961 when the most common form was discovered - nickel-titanium (NiTi)Several NiTi products are can be seen

in the picture to the right A shape memory alloy (SMA) is a material that has the ability to

ability to return to a predetermined shape when heated When an SMA is cold, or below its transformation temperature, it has a very low yield strength and can be deformed quite easily into any new shape which it will retain However, when the material is heated above its transformation temperature it undergoes a change in crystal structure which causes it to return to its original shape If the SMA encounters any resistance during this transformation,

it can generate extremely large forces This phenomenon provides a unique mechanism for remote actuation

The most common shape memory material is an alloy of nickel and titanium called Nitinol This particular alloy has very good electrical and mechanical properties, long fatigue life, and high corrosion resistance As an actuator, it is capable of up to 5% strain recovery and 50,000 psi restoration stress with many cycles By example, a Nitinol wire 0.020 inches in diameter can lift as much as 16 pounds Nitinol also has the resistance properties which enable it to be actuated electrically by joule heating When an electric current is passed directly through the wire, it can generate enough heat to cause the phase transformation In most cases, the transition temperature of the SMA is chosen such that room temperature is well below the transformation point of the material Only with the intentional addition of heat can the SMA exhibit actuation In essence, Nitinol is anactuator, sensor, and heater all

in one material.Shape memory alloys, however, are not for all applications One must take into account the forces, displacements, temperature conditions, and cycle rates required of a particular actuator The advantages of Nitinol become more pronounced as the size of the application decreases Large mechanisms may find solenoids, motors, and electromagnets more appropriate But in applications where such actuators can not be used, shape memory alloys provide an excellent alternative There are few actuating mechanisms which produce more useful work per unit volume than Nitinol Nitinol is available in the form of wire, rod and bar stock, and thin film Examples of SMA products developed by TiNi Alloy Company include silicon micro-machined gas flow microvalves, non-explosive release devices, tactile feedback device (skin stimulators), and aerospace latching mechanisms If you are considering an application for shape memory alloys, TiNi Alloy Company can assist you in the design, prototyping, and manufacture of actuators and devices

Physical Properties of Nitinol

• Density: 6.45gms/cc

• Melting Temperature: 1240-1310° C

• Resistivity (hi-temp state): 82 uohm-cm

• Resistivity (lo-temp state): 76 uohm-cm

• Thermal Conductivity: 0.1 W/cm-° C

• Heat Capacity: 0.077 cal/gm-° C

• Latent Heat: 5.78 cal/gm; 24.2 J/gm

• Magnetic Susceptibility (hi-temp): 3.8 uemu/gm

• Magnetic Susceptibility (lo-temp): 2.5 uemu/gm

Mechanical Properties of Nitinol

• Ultimate Tensile Strength: 754 - 960 MPa or 110 - 140 ksi

• Typical Elongation to Fracture: 15.5 percent

• Typical Yield Strength (hi-temp): 560 MPa, 80 ksi

• Typical Yield Strength (lo-temp): 100 MPa, 15 ksi

• Approximate Elastic Modulus (hi-tem): 75 GPa, 11 Mpsi

• Approximate Elastic Modulus (lo-temp): 28 GPa, 4 Mpsi

• Approximate Poisson's Ratio: 0.3

Actuation

• Energy Conversion Efficiency: 5%

• Work Output: ~1 Joule/gram

• Available Transformation Temperatures: -100 to +100° C

Stress-Strain Characteristics of Nitinol at Various Temperatures

Fig 6

2.6 How do shape memory alloys works

In order to understand the way in which the shape memory effect occurs it is useful to understand the crystal structure of a SMA All shape memory alloys exhibit two very distinct crystal structures Which phase is present depends on the temperature and the amount of stress being applied to the SMA These phases as known as marten site which exists at lower temperatures and austenite for higher temperatures The properties of an SMA depends on which the amount of each crystal phase present

The two unique properties described above are made possible through a solid state phase change that is a molecular rearrangement, which occurs in the shape memory alloy Typically when one thinks of a phase change a solid to liquid or liquid to gas change is the first idea that comes to mind A solid state phase change is similar in that a molecular rearrangement is occurring, but the molecules remain closely packed so that the substance remains a solid In most shape memory alloys, a temperature change of only about 10°C is necessary to initiate this phase change The two phases, which occur in shape memory alloys are Martensite, Austenite Martensite is the relatively soft and easily deformed phase

of shape memory alloys, which exists at lower temperatures The molecular structure in this phase is twinned which the configuration is shown in the middle of Figure 4 Upon deformation this phase takes on the second form shown in Figure 4, on the right Austenite,

deformed Martensite phase is the same size and shape as the cubic Austenite phase on a macroscopic scale, so that no change in size or shape is visible in shape memory alloys until the Martensite is deformed

Fig 7 The Martensite and Austenite phases

Fig 8 Microscopic and Macroscopic Views of the Two Phases of Shape Memory Alloys The temperatures at which each of these phases begin and finish forming are represented by the following variables: Ms, Mf, As, Af The amount of loading placed on a piece of shape memory alloy increases the values of these four variables as shown in Figure 9 The initial values of these four variables are also dramatically affected by the composition of the wire (i.e what amounts of each element are present)

Fig 9 The Dependency of Phase Change Temperature on Loading

Fig 10 Microscopic Diagram of the Shape Memory Effect

2.7 Shape memory effect

The shape memory effect is observed when the temperature of a piece of shape memory alloy

is cooled to below the temperature Mf At this stage the alloy is completely composed of Martensite which can be easily deformed After distorting the SMA the original shape can be recovered simply by heating the wire above the temperature Af The heat transferred to the

cubic Austenite phase, which is configured in the original shape of the wire

The Shape memory effect is currently being implemented in:

• Coffepots

• The space shuttle

• Thermostats

• Vascular Stents

• Hydraulic Fittings (for Airplanes

Shape Memory Effect (SME) is a unique property of certain alloys exhibiting martensitic transformation Even though the alloy is deformed in the low temperature phase, it recovers its original shape upon heating to a critical temperature known as the Reverse Transformation Temperature (RTT) They are most commonly Nitinol, or nickel and titanium combined Less popular but still possessing the shape memory effect are gold cadmium, silver cadmium, copper-aluminum-nickel, copper tin, copper zinc, and copper-zinc-aluminum The same alloys have another unique property called superelasticity (SE) at

a higher temperature It is a large (0-18%) nonlinear recoverable strain upon loading (stretching) and unloading (unstretchiung)

The basic one-way shape memory effect-The actual mechanism of the shape memory effect

can be described simply as a reversible, thermoelastic, phase transformation between a parent austenitic phase and a martensitic phase The phase transformation occurs when a material in the austenitic phase is cooled below the martensite start temperature (Ms), where the two phases coexist The material must then accommodate the two phases without changing shape through a mechanism called twinning This is where mirror-image lattices form adjacent to the parent lattices The phase transformation is completed upon reaching the martensite finish temperature (Mf) The material can then be plastically deformed into another shape During this deformation the twinned martensite is converted to a deformed martensite The material remains deformed until it is heated to the austenite start temperature (As), and at this point the martensite begins to transform back into austenite Heating above the austenite finish temperature (Af) allows the material to regain its original shape (The extent to which the shape is regained usually depends on the type of SMA, amount of deformation, and the material’s thermomechanical history.) When cooled again the material does not automatically revert to the deformed shape This is called the oneway

shape memory effect The entire shape memory process can be repeated

2.8 Advantages and disadvantages of shape memory alloys

Some of the main advantages of shape memory alloys include:

• Bio-compatibility

• Diverse Fields of Application

• Good Mechanical Properties (strong, corrosion resistant)

There are still some difficulties with shape memory alloys that must be overcome before they can live up to their full potential These alloys are still relatively expensive to manufacture and machine compared to other materials such as steel and aluminum Most SMA's have poor fatigue properties; this means that while under the same loading conditions (i.e twisting, bending, compressing) a steel component may survive for more

than one hundred times more cycles than an SMA element

2.9 Applications for shape memory alloys

Bioengineering:

Bones: Broken bones can be mended with shape memory alloys The alloy plate has a

memory transfer temperature that is close to body temperature, and is attached to both ends

of the broken bone From body heat, the plate wants to contract and retain its original shape, therefore exerting a compression force on the broken bone at the place of fracture After the bone has healed, the plate continues exerting the compressive force, and aids in strengthening during rehabilitation Memory metals also apply to hip replacements, considering the high level of super-elasticity The photo above shows a hip replacement

Reinforcement for Arteries and Veins: For clogged blood vessels, an alloy tube is crushed

and inserted into the clogged veins The memory metal has a memory transfer temperature close to body heat, so the memory metal expands to open the clogged arteries

Fig 11

Dental wires: used for braces and dental arch wires, memory alloys maintain their shape

since they are at a constant temperature, and because of the super elasticity of the memory metal, the wires retain their original shape after stress has been applied and removed

Fire security and Protection systems: Lines that carry highly flammable and toxic fluids and

gases must have a great amount of control to prevent catastrophic events Systems can be programmed with memory metals to immediately shut down in the presence of increased heat This can greatly decrease devastating problems in industries that involve petrochemicals, semiconductors, pharmaceuticals, and large oil and gas boilers

Fig 12

their shape in the midst of a heated environment, memory metals are ideal

3 Applications of smart materials

• Piezoelectric materials - These ceramics or polymers are character-ized by a swift, linear shape change in response to an electric field The electricity makes the material expand

or contract almost instantly The materials have potential uses in actuators that control chatter in precision machine tools, improved robotic parts that move faster and with greater accuracy, smaller microelectronic circuits in machines ranging from computers

to photolithography printers, and health-monitoring fibers for bridges, buildings, and wood utility poles

• Electrostrictive and magnetostrictive materials - This refers to the material quality of changing size in response to either an electric or magnetic field, and conversely, producing a voltage when stretched These materials show promise in applications ranging from pumps and valves, to aerospace wind tunnel and shock tube instrumentation and landing gear hydraulics, to biomechanics force measurement for ortho-pedic gait and posturography, sports, ergonomics, neurology, cardiology, and rehabilitation

• Rheological materials - Smart materials encompass not only solids but also fluids, electrorheological and magnetorheological fluids that can change state instantly through the application of an electric or magnetic charge These fluids show promise in shock absorbers, dampers for vehicle seats and exercise equipment, and optical finishing

• Thermoresponsive materials - Shape memory alloys, the dominant smart material, change shape in response to heat or cold They are most commonly Nitinol, or nickel and titanium combined Less popular but still possessing the shape memory effect are gold cadmium, silver cad-mium, copper-aluminum-nickel, copper tin, copper zinc, and copper zinc aluminum They are useful in couplers, thermostats, automobile, plane and helicopter parts

• pH-sensitive materials - The most interesting of these are indicators that change colors

as a function of pH, and show promise in paints that change color when the metal beneath begins to corrode

• Electrochromic materials - Electrochromism is defined as the ability of a material to change its optical properties when a voltage is applied across it These materials are used as antistatic layers, electrochrome layers in LCDs (liquid crystal displays), and cathodes in lithium batteries

• Fullerenes - Spherically caged molecules with carbon atoms at the corner of a polyhedral structure consisting of pentagons and hexagons In one application of fullerenes as a smart material, they are embedded into sol-gel matrices to enhance optical limiting properties

• Smart gels - Engineered response gels that shrink or swell by a factor of 1000, and that can be programmed to absorb or release fluids in response to almost any chemical or physical stimulus These gels are used in many applications in agriculture, food, drug delivery, prostheses, cosmetics, and chemical processing

4 The future for smart materials-

The development of true smart materials at the atomic scale is still some way off, although the enabling technologies are under development These require novel aspects of nanotechnology (technologies associated with materials and processes at the nanometre scale, 10-9m) and the newly developing science of shape chemistry

Worldwide, considerable effort is being deployed to develop smart materials and structures The technological benefits of such systems have begun to be identified and, demonstrators are under construction for a wide range of applications from space and aerospace, to civil engineering and domestic products In many of these applications, the cost benefit analyses

of such systems have yet to be fully demonstrated

The Office of Science and Technology’s Foresight Programme has recognised these systems

as a strategic technology for the future, having considerable potential for wealth creation through the development of hitherto unknown products, and performance enhancement of existing products in a broad range of industrial sectors

The core of Yanagida’s philosophy of ken materials is such a concept This is democracy’ where the general public understand and ‘own’ the technology Techno-democracy can come about only through education and exposure of the general public to these technologies However, such general acceptance of smart materials and structures may

‘techno-in fact be more difficult than some of the technological hurdles associated with their development

5 Conclusion

Smart materials are poised to emerged from the laboratory of medical, defence and industrial applications Understanding and using these advanced materials in new product development efforts may make the difference between success and failure in today’s intensely competitive markets

It’s the profile job of the technocrats and management personnel to find out the promising materials for specific applications-when the use of smart memory alloys is to be replaced by

a smart polymer, the primary laboratories and companies who are developing these materials, to identify the key researchers and engineers in those fields With smart materials research taking place in hundreds of public and private sector labs across the globe, to get them available at once is difficult – yet they are vital for the advancement of technology and

to profit from new developments in this fast moving field

The concept of engineering materials and structures which respond to their environment, including their human owners, is a somewhat alien concept It is therefore not only important that the technological and financial implications of these materials and structures are addressed, but also issues associated with public understanding and acceptance

There are many possibilities for such materials and structures in the man made world Engineering structures could operate at the very limit of their performance envelopes and to their structural limits without fear of exceeding either These structures could also give maintenance engineers a full report on performance history, as well as the location of defects, whilst having the ability to counteract unwanted or potentially dangerous conditions such as excessive vibration, and effect self repair The Office of Science and Technology Foresight Programme has stated that `Smart materials will have an increasing range of applications (and) the underlying sciences in this area must be maintained at a

provide an opportunity for new wealth creating products

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devices_brake_begin.htm 2001

[25] Gupta P, Srivastava R.K., Gangwar M., “Opportunity and Challenges of Smart

Materials: A Review”, National seminar on APD, MNNIT allahabad, Feb.2006

Polymer Materials and Its Properties

2 Mixing aspects

There are common a lot of factors influence the final properties of article in manufacturing process These baseline impacts occur in case of quality and kind of deliver chemicals, particle size, its concentration, particle morphology, its specific surface Consequently these chemicals are mixing The main base of rubber mixture is a caoutchouc, according as natural

or synthetic By caoutchouc relates the term of plasticizing – this represents the process of reduction the molecular length of caoutchouc and occur from the elastic state to the plastic state during this time After the caoutchouc feeding into the masticator or calender (figure 1) occur to the heat generation and stress transmission on the polymer chains in consequence

of frictional forces between the machine components and visco-elastic material

Thus the caoutchouc plasticizing is mechanical – chemical process characterizing degrade of caoutchouc which leads to structure change and consequently change on mechanical and physical – chemical properties of caoutchouc

shear stress of caoutchouc masticated between rotors and mixing chamber wall

Fig 1 Schema of masticator (a) and calender (b)

The efficiency of mechanical tearing of caoutchouc molecules decreases by temperature and consequently is process of plasticizing delayed A rare behavior of temperature dependency

of minimal efficiency is observed by temperature scope of 115 – 120 °C on figure 2 There is occurred decrease efficiency of mechanical tearing of molecules in case on the left side and rising effect of heat oxidizing degradation of polyisoprene chains in case of right side Maximal plasticizing efficiency is achieved by temperature of 55 °C or temperature over 140

°C by case of natural caoutchouc Lower temperatures are used by calender plasticizing, higher temperatures are characterized for masticators

Fig 2 Plasticizing efficiency temperature dependence

Rotor mixing space chamber

At higher temperatures occur to radical creation by bonds refracting which is necessary chemical stabilized Long storage of this treated caoutchouc results in re-meshing and viscosity rising in consequence of un-stabilization Chemical chain plasticizing and stabilization practically ends by carbon black feeding There is occurred only physical chain reduction in consequence of re – mixing (reprocessing) Only natural caoutchouc is practically plasticizing Synthetic caoutchouc and caoutchouc with constant viscosity isn’t necessary to plasticize Altogether the physical plasticizing is first mixing step of each mixture but this effect isn’t as large as plasticizing of straight caoutchouc The oils decrease the plasticizing effect in mixtures

Temperature influence on plasticizing efficiency

The quality of caoutchouc plasticizing process in masticator affected following factors: dimensions of masticator, geometry of rotors, the dimension between rotor and chamber wall, state of machine filling, stress on the upper stop element, rotor speed, caoutchouc temperature, kind and concentration of plasticizing agent, time of plasticizing

Mixture preparation and especially its mixing is one of important processes in rubber industry because following mixtures processing, products properties and producing economy largely dependence on mixtures quality

Besides caoutchouc rubber mixture contains next approximately 10 chemicals (additions), table 1 Each chemical has specific role and therefore mixing purpose must provide the best homogeneity of mixture (most uniform distribution of chemicals in the whole caoutchouc mixture)

Elastomers – natural and synthetic caoutchouc, respectively their ratio 100

Fillers – active and inactive 0 – 200

Assistant rubber additives – plastic and adhesive agents 0 – 10

* PHR – parts per hundred rubbers (means elastomers – caoutchouc)

Table 1 Standard recipe for rubber mixture

After the caoutchouc plasticizing is coming the next step – blending – together the plasticizing there is a preliminary step of mixing where are the separate additions ( caoutchouc and fillers) moulded by rotors or calender into a coherent mass The blending action is described as a carbon black wetting by caoutchouc together an air voids expelling which was internally incorporated along with chemicals Before blending process with powder fillers occur to a large deformation of caoutchouc follow by bond chain tearing (plasticizing) This conditioned material is able to flow in the chamber of masticator during all the mixing process round The process of blending has two parallel mechanisms Primarily occurs to caoutchouc formation follow by its surface rising with consecutive filler wetting by caoutchouc matrix In the second mechanism is caoutchouc sharply deformed in consequence of bonds tearing, during which time occurred to transmission of tearing forces

on adjacent chains Bonds tearing allow rapid agglomerates coating by caoutchouc

agglomerates are these smashed Separate agglomerates are air filled by creation of weakly, partly composites Caoutchouc is gradually embossed to agglomerates what causes air elimination

The progressive carbon black wetting by polymer can be observed in case of machinery indirectly as an immediate loss of power the engine which specifies shear stress between mixture and rotor Where this time period is the time of carbon black incorporation (so called the incorporation time - BIT)

On macroscopic scale the dispersion of filler into a polymer matrix shows the following stages:

• The filler smears into striations following the deformation pattern of the polymer

• Agglomerates up to 10 to 100 micrometer in size appear

• Agglomerates are continuously broken and aggregates with an average size of 100 nanometers till 0.5 micrometers appear

• Smaller aggregates and primary particles appear on the expense of larger aggregates and agglomerates

Figure 3 illustrates the transition from large agglomerates into smaller aggregates and primary particles, and gives an indication of their dimensions

Fig 3 The filler aggregation and dispersion

Based on these phenomena, Yoshida described mixing as a three step process: transposition, insertion and breaking of the disperse system During transposition the system is subjected

to stretching deformation by shearing forces, which increases the interface between the disperse phase and the matrix, and results in a gradual insertion of the disperse phase into the matrix The particles of the dispersed phase are disrupted by shearing forces, and the size of agglomerates and aggregates is reduced The degree to which the filler finally has to

be dispersed depends on the quality requirements of the compound: the higher the degree

of dispersion, the better the properties But there is a lower limit to the aggregate size as the properties deteriorate with very small aggregate sizes and an increasing amount of primary particles

A more refined model of dispersive mixing separates the process into four different steps:

• Incorporation

• Plasticization

• Dispersion

• Distribution

In the initial stages of mixing before incorporation starts, two processes take place: The first process involves large deformations and subsequent relaxation of rubber domains, during which filler aggregates are sandwiched between rubber layers The second mechanism is based on the disintegration of the rubber into small particles, which are blended with the filler agglomerates and finally seal them inside

Incorporation

The incorporation of the filler is subdivided into two phases: formation of a rubber shell around the filler particles followed by filling up the voids within the filler agglomerates, in other words between the filler aggregates It includes a subdivision step: breaking of large agglomerates into smaller entities

Mastication and plasticization

Mastication and plasticization take place during the whole mixing process and result in a change of the rheological properties of the compound, especially a viscosity decrease of the polymer matrix by degradation of the elastomer chains Figure 4 gives a schematic view of the viscosity changes during mixing and the contributions of temperature increase and polymer breakdown to the viscosity decrease

Fig 4 Contributions of polymer breakdown and temperature increase to the viscosity decrease

Dispersion

At the end of the incorporation stage the majority of the filler is present as agglomerates They act as large, rigid particles, whose effective volume is higher than that of the filler alone due to rubber trapped inside the filler voids and the rubber immobilized on the surface The bound and occluded rubber increases the rate of dispersive mixing by increasing the effective radii of the filler particles: larger effective radii lead to higher stress during mixing The filler agglomerates are successively broken to their ultimate size, mainly

by shear stress Parallel with the reduction of the agglomerate size the interface between the matrix and the filler is increased, and the filler particles are distributed homogenously throughout the rubber matrix When the filler agglomerates decrease in size, the occluded rubber concentration is reduced The viscosity of the compound decreases and finally reaches a plateau region In general, the average particle size reaches a minimum value and

a further energy input does not result in a reduction of the size of the filler aggregates any more, as the mixing and dispersion efficiency is decreasing with reduced viscosity of the compound

In the distributive mixing step particles are spread homogenously throughout the polymer matrix without changing their size and physical appearance The thermodynamic driving force for this process is the entropy increase of the blend

Figure 5 illustrates the different mixing stages with respect to filler subdivision, incorporation, dispersion and distribution

Fig 5 Illustration of the different mixing stages for filler-polymer systems

An optimal dispersion is one that evenly distributes carbon black throughout the polymer down to the smallest carbon black unit, the aggregates A poorer dispersion results in larger agglomerates, figure 6

Fig 6 Scheme of aggregates and agglomerates

The stage of dispersion characterized the process efficiency demands the higher energy consumption than blending process Generally the dispersion stage is evaluated in

according to methodic of CABOT Company By using of this methodic is possibly to determine the quantify of un-dispersed carbon black and following particle size is possible

to merge the mixture into six different dispersion qualities accordance to figure 7

Letter rating

Fig 7 Quality ranking of dispersion

The behavior of energy consumption the masticator is characterized by two marked maximums The first maximum is created by caoutchouc feeding and ram down mixing The second is characterized by fillers feeding (carbon black or white fillers) First peak relates by caoutchouc tearing and raising the active surface, the second marked the agglomerates creation of bond caoutchouc – filler By sequential agglomerates smashing, the energy consumption decrease and the stage of filler dispersion accrue (mixing uniformity of primarily units) The mixture properties are changed by increased filler dispersion We can allege that Mooney viscosity decrease by improved filler dispersion Dispersion filler have different chemical contain, morphology (shape), density, color, hardness, specific surface and other physical – mechanical properties The morphology of dispersion fillers can be regular (spherical, fibrous, platy) or irregularly, figure 8

On behalf of observing purposes the mixing process were created various models studies which are able to ordered stage dispersion in rubber mixture e.g through the particle flow

in masticator Similarly rotor design, slit dimension and chamber profile affected the mixing process and therefore these parameters are optimizes by producers

Spherical Anisotropy Platy

Fig 8 The particle shape of dispersive fillers

Last step inducing the mixing process is the homogenization and viscosity reduction For a good uniformity is necessary excellent filler distribution in the whole volume of mixture This effect is possibly to achieve by becomingly processed mixing settlement together the time step of particular components feeding

For the first degree preparation of mixture (without the vulcanizing agents) are apply two ways of mixing:

• Conventional,

• Upside - down

By using of a conventional mixing occurs to filler incorporation into caoutchouc matrix at first Mixing time is longer and follows to temperature increase during mixing The final temperature can reach the value of 160°C Owing to the achievement of high stage of filler homogenization and consecutive achievement of necessary processed properties are feeding oils in the final mixing phase

In order to dispersive degree increase together homogeneity improvement are used so called processing additives (PA) in manufacturing process At the same time these additives minimize the energy state of process However is possibly to feed PA only in the first degree of mixing before fillers feeding The processing additives also decrease viscosity of mixture, but the efficiency isn’t the case of softeners To achievement of a minimal tolerance

in case of viscosity is important for the next processing operations – e.g extrusion, calandering

The UPSIDE-DOWN method of mixing uses the reverse practice and there is realize by high feeding of softeners and big particles of fillers Primarily are feeding the fillers, then are mixed softeners and last chemicals added into masticator are caoutchouc

However this method isn’t very useful for the mixtures includes high-activated fillers (high structural carbon black, active SiO2) or mixtures the high contains of soft mineral filler and oil together polymer with a high viscosity

The second mixing stage is characterized by vulcanizing agents mixing off Time of its adequate dispersion and homogeneity achievement considering physical properties is shorter than mixture preparation in the first stage The maximal temperature for finishing of mixing process is much below (max 120 °C) owing to the possibly reaction of sulphur with caoutchouc The decrease of viscosity is not so high than the first mixing stage

Besides the vulcanizing agents is convenient to adding the vulcanization inhibitors and retarders in the second stage of mixing process needs for consequently repeated processes linked to mixture warming – profile extruding, multi calandering, returnable wastes

processing The progressive methods enable mixing of the first and second stage in the same line equipment

Figure 9 shows a generalized torque-time profile of a mixing cycle for a carbon black compound, which is characterized by two torque maxima The first torque maximum corresponds to the point when all ingredients so far added to the compound are forced into the mixing chamber and the ram reaches its final position Time and height of the maximum depend on the composition of the compound, the fill factor of the mixing chamber, the activity and structure of the filler as well as the bound rubber fraction The region between the start of the mixing cycle and the first minimum is the region, in which mainly mastication of the polymer takes place and dispersion starts In the next zone dispersion and distribution of the additives including the filler occurs, and a second torque maximum is observed This torque maximum corresponds to the incorporation of the filler: the agglomerates are wetted by the polymer, entrapped air is removed and the compound reaches its final density Filler dispersion and polymer breakdown result in a fast torque decrease after the second peak down to a dispersion degree above 90%, and the kinetics can

be described by a first order law: The rate of agglomerate breakdown is proportional to the concentration of the agglomerates This period of steep torque reduction is followed by a period of a slower torque decrease, during which polymer breakdown and dispersion occur

to a very limited degree, shearing is reduced and homogenization starts

Fig 9 Generalized torque-time profile of a mixing cycle

The carbon black construction of units and particles influences the final properties Base particles have approximately sphere morphology, the furnace carbon black have a more complicated construction Elementary sphere particles are coupled into big formations, called

as primary structural aggregates which created chains or 3-D branched formations The aggregation of elementary particles into big formations represents a “structure” Primary structure means the joining of basic particles into primary structural aggregates which are resistant to mechanically destruction Primary structural aggregates may create bigger formations holding together by Van Der Waals forces, marked as secondary structure This structure has low strength and easier mechanically destruction, especially by mixing of carbon black to caoutchouc matrix The baseline particle contains the ligament of graphite layer Accordingly the created aggregate and chain have compact, cohesive formation where are

Interaction stage of caoutchouc and carbon black dependences on three factors:

• Size of interface between carbon black surface and caoutchouc, so called extensive factor The interface between carbon black and caoutchouc equals to composition of specific surface carbon black and its concentration in mixture

• Carbon black structure, so called geometric factor

• Surface activity or intensive factor

The size of particles and specific surface occurs; the softer are particles (i.e the more is specific surface) the difficulty are mixed into a caoutchouc matrix; the viscosity of mixture increases, there accrue the energy consumption for processing, the mixtures are more heated and the safety processing time shorten Particle size hasn’t an important effect on the mixture precipitation but meaningful influence affected the mechanical properties of vulcanizates By increasing of specific surface size (the decrease is particle size) are improving the properties detected by destructive examination: tensile strength, structure strength, wear resistance, hardness of vulcanizates increases The modulus of vulcanizates hasn’t directly dependency on particles size; the dynamical properties worsen by particle size decrease, the hysteresis increases

Carbon black structure has more effect on prepared mixtures processing as a final vulcanizates properties Otherwise the high structured carbon black are slower mixing into caoutchouc, but easier cause of good dispersion achievement and during mixing is created more joining caoutchouc Viscosity of carbon black mixtures increase by growing structure and consequently the mixtures are more heated

High structured carbon black increases the mixture anisotropy, mixtures are better extruding, they are less porous, the surface is smoother and profile edges are sharper Similar behavior is characterized by calandering, mixtures filled high structured carbon black have smoother surface and smaller precipitation Both causes induced due to structure influence and joining caoutchouc

The structure of vulcanizates has a respectable effect on modulus; the influence is linked to surface activity Strength and structural strength aren’t considerably affecting by vulcanizates structure A favorable effect is noted for wear resistance due to dispersion improvement Hysteresis dependences on particles size and isn’t markedly affected by structure

The surface activity a factor influences besides vulcanizing process, composition of carbon black surface also electric conductivity of vulcanizates By fewer oxygen compounds of carbon black, by softer particles and high structure the more conductive is filled vulcanizates

When the convectional carbon black is treated high temperatures (approximately 2700 °C) there occur a big transferring of carbon atoms in the inert atmosphere As a result is graphite carbon black with big crystalline planes on the surface The surface energy of basic planes is low and small is also the reinforcement effect For the smallest ordering and the highest surface energy was development so-called inverse carbon black Compared to conventional carbon black have inverse carbon black more mutual traversing planes and edges which leads to surface energy increasing

This special carbon black plays an important part by composition of treading mixtures with good adhesion and reduced rolling resistance

Vulcanization

The next step influenced the quality of preparing mixture is vulcanizing (curing) process This term is defined as a process when the temperature and vulcanizing system influence occur to the creation of chemical cross linked bonds among the caoutchouc chains Throughout the vulcanization the linear chain structure is changed on 3-D during which times are markedly affected physical – mechanical properties and caoutchouc is converting from the plastic into the elastic state The vulcanizates is characterized by its high reversible deformation by relatively low value of elasticity modulus due to creating cross linked structure By cross linking mesh creation is limited the caoutchouc macromolecules mobility especially occurring the:

• Insolubility of cross linked polymer, just swelling vulcanizates

• Polymer strength increase in the definite value by vulcanizing, by overrunning the optimal stage the strength decrease, but the modulus and hardness increase

• Increasing vulcanizing degree improving the strain resistance and dynamic fatique resistance There is mended structural strength, i.e resistance related with additional tearing of aborted sample

• Low vulcanizates sensitivity on temperature changes

• Elasticity and stiffness vulcanizates retaining in the wide temperature region

Vulcanization course and its basic characteristics (scorch time, optimal vulcanization time, difference between maximum and minimum torsion moment, cure rate index, eventually

reverse rate etc.) is most often evaluated on the basis of so called vulcanization curves

measured on different types of rheometers, figure 10 There could be free sulphur content in

a case of chemical changes, which decreases in vulcanization running In case of physical –mechanical values there are strength, tensile elasticity modulus, plastic deformation, and swelling

1– Scorch period, 2– fundamental meshing reaction, 3– structure changes created by meshing: a – marching, b – relaxation, c – reversion

Fig 10 The schematically dependence of torque versus vulcanizing time

The induction period (scorch) characterized the time interval; there occur to very slowly reaction of vulcanizing agents with caoutchouc and other additives, during which time are created soluble caoutchouc intermediate products This period length is important in term of vulcanizing system options for its safety mixture preparation and the next processing Accordingly influences the processing economy and vulcanizates quality

Tim

mechanical properties of caoutchouc mixtures by sequential transfer to vulcanizate

The last area of vulcanization curve is characterized by other reactions than vulcanizing agent meshing and therefore practically occurs to no affection of the total meshing stage This shape of vulcanizing curve dependences on used caoutchouc, vulcanizing system and vulcanizing temperature The rate of meshing reaction is decreasing or aborting in this phase These changes relate by the changes of cross links character Relaxation is an area on vulcanizing curve where are no property changes in case of vulcanizate The amount is presented by constant vulcanizate properties the heat stress for a term Especially this property consequential from the vulcanizate thermal stability enables the achievement of optimal properties practically in all tire sections by automotive production Reversion is the area of vulcanizing curve where occurs to the meshing density decrement and the vulcanizing properties become worsen

Marching is called the region area of vulcanizing curve where the meshing moderate increases; this type is vulcanization with a “walking” modulus By vulcanizing process is used an ability to heat transformation ( from metallic parts of vulcanizing press and mould, figure 11) from vulcanizing medium (steam, hot water) into tire Consequently occur these phases in process of compression moulding and vulcanizing:

• Caoutchouc mixtures flow – the mixture must perfect flowing into the parts of compression mould in this processing phase during which time the air is removing through the air channels The efficiency of moulding and vulcanizing process also affected on the flow rate of caoutchouc mixtures and rate of conversion to the meshing phase Ideal processing representation in a mould characterized the faster mixture flowing into the parts of mould and follow transition into a meshing phase By the very fast starting of meshing process is possibly risk in technical praxis where the imperfect mould filling can menace the flowing phase, whereas the cross link creation increase the viscosity and eliminate the flowing rate Because there is very important to choose the correct rate and time of steps so can occurred a worsen visualization and total quality decline of a tire

• The meshing of caoutchouc mixtures

• Vulcanization finishing by achievement of the vulcanizing optimum time

Fig 11 Segment moulds

Some of vulcanizates properties reach optimum values even before vulcanization optimum achievement, figure 12

1 – Tensile strength, 2 – Elongation at break, 3 – Hardness, 4 - Elasticity

Fig 12 Change of some properties of rubbers compounds during vulcanization

Modulus and the tensile strength at breaking are at low elongation proportional to their crosslink density ν, eventually reciprocal value of average molecular weight of rubber macromolecules segments between two cross-links Mc Their relative connection is described by the relation:

-2 c

ρ

= RTA*(λ-λ )M

Figure 13 – the mechanism of vulcanization with sulfur, accelerators and activators') shows the variation of modulus for natural rubber (NR) and synthetic styrene butadiene rubber (SBR) during vulcanization In both cases there is an induction period (called "scorch time") and an optimum vulcanization time, corresponding to the maximum value of the modulus

If vulcanization goes on, the modulus value decreases for NR, phenomenon which was

Fig 13 Variation of tensile strength and modulus with vulcanization time: (a) NR; (b) SBR The dependency of shear modulus G and temperature is shown in figure 14 Sulphur in position of vulcanizing agent is responsible and importantly factor for meshing of polymer chains, markedly affected also the temperature dependence of shear modulus In case of un-vulcanized caoutchouc the shear modulus decreasing by temperature dependency, by rising

of sulphur content over 0°C is constant or moderate increasing following sulphur content

Fig 14 Shear modulus of caoutchouc vulcanized by different stages in temperature

dependence, a) un-vulcanized, b) 0,5% of sulphur, c) 5% of sulphur

The influence of more polar Acrylonitrile Butadiene Rubber (NBR) caoutchouc versus polar caoutchouc SBR is shown by real dependence the elastic part torque moment (S´) versus time (t), figure 15 or elastic part of tear modulus (G´), figure 16

lesser-In both cases is the rising of elastic part torsion moment S´ following the adding the polar caoutchouc and the meshing become much faster

t [min]S´[ Nm]

NBR0NBR3NBR6NBR9NBR12NBR rising

Fig 15 The elastic part of torque moment versus time

Fig 16 The elastic part of torque moment versus real part of torsion modulus

measurement probe is possibly to perform this method, figure 17 The chamber wall acted as the second electrode

Fig 17 The probe fixation in the mixer chamber

The sensor (probe) location is important factor By the sensor location in the wall of chamber

is occurred the problem with a periodically washing by prepared mixture (mainly when the mixing chamber isn’t exactly filled) The “short circuit” following the carbon black and oil adding can occur in case of softening mixtures At the same time the sensor doesn’t provide the right information about the electrical conductivity of mixing blend The preferable case

of monitoring occurred if is the sensor located in the bottom part of mixing chamber where

is provide the continuous contact between sensor and mixing blend (holds also for not exactly filled chamber)

Case of figure 18 gives the electrical parameters information’s about the chemical coupling behavior into the mixing chamber; the capacity (C), impedance (Z) and resistance (R) measurements during mixing provide the relevant on-line characteristics

As was mentioned, at firs are feeding caoutchouc into a mixing chamber, the observed running is without some properties changes By adding of fillers and oil are the properties fluctuated, the impedance decrease, the capacity increase, following the high conductance fillers By the next mixing are the electrical parameters changed following the probability of

no segregated caoutchouc - creation of agglomerates or aggregates into the chamber by zigzag character The end of mixing process is considering by the little changes of parameters, approximately in time of 640 s – there is a probability of a good mixing Usually are the on-line mixing periods shorter in consequence of behavior observing than if it’s using classical mixture preparation following the achievement of energy consumption and quality rising

The quality aspect is important by the question of sample preparation – if the samples would be mixed or prepared by qualitative advance the “good” influence will be noted by its useful properties

Next are introducing the measurements of electrical parameters and atomic force microscopy as the “echo testing” of the quality preparation

The quality of prepared samples together a filler influence was evaluated by electrical measurements method The sample without filler content together the next three samples