Glass fiber Manufacture and Applications

 The scientific basis for the development of the modern reinforcing glass fiber stems from the work of  Raw materials such as silicates, soda, clay, limestone, boric acid, fluorspar o

Glass Fiber: Manufacturing &

Applications

Aravin Prince Periyasamy

Asst Prof/ Textile Chemistry D.K.T.E Society’s Textile Engineering College, Ichalkaranji

Dist- Kolhapur, M.S, 415116 aravinprince@gmail.com

History……

 Ancient Egyptians made containers of coarse fibers drawn from heat softened glass

 Napoleon’s funeral coffin was decorated with glass fiber textiles

 By the 1800s, luxury brocades were manufactured by co-weaving glass with silk, and at the Columbia Exhibition of 1893

 The scientific basis for the development of the modern reinforcing glass fiber stems from the work of

 Raw materials such as silicates, soda, clay, limestone, boric acid, fluorspar or various metallic

oxides are blended to form a glass batch which is melted in a furnace and refined during lateral flow

to the fore hearth

Introduction

 Glass in the form of fibers has found wide and varied applications in all kinds of industry because it is the most versatile industrial materials known today

 All glass fibers derived from compositions containing Silica, which are available

in virtually unlimited supply

 They exhibit useful bulk properties such as Hardness, Transparency, Resistance To Chemical Attack, Stability, and Inertness, as well as Desirable Fiber Properties such as Strength, Flexibility, and Stiffness

 Glass fibers are used in a number of applications which can be divided into four basic categories: (A) Insulations, (B) Filtration Media, (C) Reinforcements, And (D) Optical Fibers

Types of Glass Fiber

 As per ASTM C 162 the glass fiber were classified according to the end use and chemical compositions

E, Electrical Low Electrical Conductivity

S, Strength High Strength

C, Chemical High Chemical Durability

M, Modulus High Stiffness

A, Alkali High Alkali Or Soda Lime Glass

D, Dielectric Low Dielectric Constant

 A GLASS – Soda lime silicate glasses used where the Strength,

Durability, And Good Electrical Resistivity

 C GLASS Chemical Stability In Corrosive Acid Environments

 D GLASS – Borosilicate glasses with a Low Dielectric Constant For

Electrical Applications

 E GLASS – Alumina-calcium-borosilicate glasses with a maximum

alkali content of 2 wt.% used as general purpose fibers where strength and High Electrical Resistivity are required

 ECRGLAS® – Calcium aluminosilicate glasses with a maximum alkali content of 2 wt.% used where strength, electrical resistivity, and acid corrosion resistance are desired

 AR GLASS – Alkali Resistant Glasses composed of alkali zirconium

silicates used in cement substrates and concrete

 R GLASS – Calcium aluminosilicate glasses used for reinforcement where added strength and acid corrosion resistance are required

 S-2 GLASS® – Magnesium aluminosilicate glasses used for textile

substrates or reinforcement in composite structural applications which

require high strength, modulus, and stability under extreme temperature and corrosive environments

 More than half the mix is Silica Sand ,

 Other ingredients are Aluminum, Calcium and Magnesium Oxides, and Borates

Manufacturing

Glass Fiber Manufacturing Process

The fiber manufacturing process has effectively two variants One

involves the preparation of marbles, which are re-melted in the

fiberisation stage

The other uses the direct melting route, in which a furnace is

continuously charged with raw materials which are melted and refined

as that glass reaches the forehearth above a set of platinum–rhodium bushings from which the fibers are drawn

The two processes are described in Figures 6.2 and 6.3.2 Glass fibers are produced by rapid attenuation of the molten glass exuding through nozzles under gravity

The glass viscosity between 600 and 1000P

The rate of fiber production at the nozzle is a function of the rate of flow

of glass, not the rate of attenuation, which only determines final diameter of the fiber

Furnace For Glass Melting

Fiberglass Forming Process

 The molten glass flows to platinum/ rhodium alloy bushings and then through individual bushing tips and orifices ranging from 0.76 to 2.03 mm (0.030 to 0.080 in) and is rapidly quenched and attenuated in air (to prevent crystallization) into fine fibers ranging from 3 to 35 μm

 Mechanical winders pull the fibers at lineal velocities up to 61m/s over an applicator which coats the fibers with an appropriate chemical sizing to aid further processing and performance of the end products

Furnace

ingredients dissolve into molten glass

"refractory" bricks that must periodically be replaced

Bushings

 The molten glass flows to

numerous high heat-resistant platinum trays which have

thousands of small, precisely drilled tubular openings, called

"bushings."

Design and Manufacture of Bushings for Glass Fiber Production

Filaments

 This thin stream of molten glass is pulled and attenuated (drawn down)

to a precise diameter, then quenched or cooled by air and water to fix this diameter and create a filament

Bunker,

Bushing,

Cooler

Sizing

 The hair-like filaments are coated with an aqueous

chemical mixture called a "sizing," which serves two

main purposes:

1) Protecting the filaments from each other during

processing and handling,

2) Ensuring good adhesion of the glass fiber to the resin Sizing thickness ~ 50 nanometers

 Immediately after cooling with water the fibers are coated with an aqueous size (usually an emulsion) in contact with a rubber roller

 The size (or finish) is crucial to the handle ability of the fibers and their

compatibility with the matrix

 The ‘finish’ therefore may consist of:

1 lubricant(s),

2 surfactant(s),

3 antistatic agent(s), and

4 an optional polymeric binder (emulsion or powder) used for fiber mats

Strands

 After the sizing is applied, filaments are gathered together into twine-like strands that go through one of three steps,

depending on the type of reinforcement being

made

Properties of Glass Fiber

Physical Properties

 High strength S- 2 Glass fibers’ annealed properties

measured at 20°C are as follows:

Other Properties…

Thermal Properties

 The viscosity of a glass decreases as the temperature increases

 Note that the S-2 Glass fibers’ temperature at viscosity is 150-260°C higher than that of E Glass, which is why S-2 Glass fibers have higher use temperatures than E Glass

Composite Properties

 Application of glass fiber composite materials depends on proper utilization of glass composition, size chemistry, fiber orientation, and fiber volume in the appropriate matrix for desired mechanical, electrical, thermal, and other properties

Strength and stiffness

 For glass this will be about 7GPa , but the practical strength would

be significantly less at about 0.07GPa

 A typical E-glass fiber can have a strength of 3GPa

Static Fatigue

 Glass fibers are subject to static fatigue,

 Which is the time-dependent fracture of a material under a constant load,

as opposed to a conventional fatigue test where a cyclic load is employed

Environmental Stress Corrosion Cracking (ESCC)

 E-glass fibers have a reduced lifetime under load and this is more severe

in an acidic environment

 This is generally referred to as environmental stress corrosion cracking

or ESCC

 Here, a synergism between stress and chemistry occurs as described in

the previous section under II

 At low loads and in alkaline environments, chemical corrosion dominates

but is stress assisted

Typical Tensile Strength of Glass Fiber

Glass Fiber Forms

Chopped-strand Production

 These are fibers which have been chopped to lengths of 1.5 to 50mm, depending on the application

 These are combined with thermoplastic or thermosetting resins for molding compounds

 Chopped strands are either soft- or hard-sized, depending on the molding application

Multiend Roving Process Production

Twisting

Texturising

 Texturizing is a process in which the glass yarn is subjected to an air jet

that impinges on its surface to make the yarn “fluffy’’

Glass Fiber Product Applications

THANK