An Overview of Glass Fibre

An Overview of Glass Fibre

P.M. Shahriar Hossain
Department of Textile Engineering
Northern University Bangladesh

 

What is Glass Fibre?
Glass fibres are the materials consisting of extremely fine glass fibres, used in making various products, such as yarns, fabrics, insulators, and structural objects or parts. It is also called spun glass. The global glass fibres industry has a rather high concentration. Glass fibres are made from extremely fine fibres of glass based on silica. High strength glass fibres are from aluminosilicates attenuated at higher temperatures into fine fibres ranging from 5 to 24 μm.

glass fibre

What are the Properties of Glass Fibre?

  1. Glass fibres have excellent heat resistance at relatively low cost.
  2. They retain approximately 50% of room temperature tensile strength at 700°F (371°C); approximately 25% at 900°F (482°C).
  3. Softening point of 1555°F (846°C) and a melting point of 2075°F (1121°C).

History of Glass Fibre:

  • The ancient Egyptians was the first civilization that made glass, and turn it into glass fibres, they used it for decoration; unaware of the potential that lay within it.
  • In 1936, Owens corning company patented the glass fibres with only $1.
  • After 1870, john player developed a process for mass production of glass strands with a steam jet process.
  • Owens corning is still the largest glass fibres producer.

Types of Glass Fibre:

Glass fibre Type Description Tensile Strength (GPa)
E-glass E for good electrical insulation. 1.7–3.5
S-glass S for high silica, able to withstand high temperatures. 2.0–4.5
C-glass C for corrosion resistant. 1.7–2.8
Cemfil Alkali resistant glass fibre.

As to the raw material glass used to make glass fibres or nonwovens of glass fibres, the following classification is known:

  • A-glass: With regard to its composition, it is close to window glass. In the Federal Republic of Germany it is mainly used in the manufacture of process equipment.
  • C-glass: This kind of glass shows better resistance to chemical impact.
  • E-glass: This kind of glass combines the characteristics of C-glass with very good insulation to electricity.
  • AE-glass: Alkali resistant glass.

Generally, glass consists of quartz sand, soda, sodium sulphete, potash, feldspar and a number of refining and dying additives. The characteristics, with them the classification of the glass fibres to be made, are defined by the combination of raw materials and their proportions. Textile glass fibres mostly show a circular.

Chemical Composition of Glass Fiber:

Oxide Pyrolysis residual glass fibre PFG glass
SiO2 55.00 52.86
CaO 22.90 20.36
Al2O3 13.90 13.95
B2O3 6.35 6.03
Na2O 0.79 5.82
MgO 0.34 0.24
K2O 0.29 0.24
Fe203 0.23 0.25
TiO2 0.12 0.20
SrO 0.11 0.02
ZrO2 0.01 0.02

Note: Chemical composition is % by weight.

Chemical Structure of Glass Fibre:
In the polymer it forms SiO4 groups which are configured as a tetrahedron with the Silicon atom at the center, and four oxygen atoms at the corners. These atoms then form a network bonded at the corners by sharing the oxygen atoms.

Chemical Structure of Glass Fibre
Fig: Chemical Structure of Glass Fibre

Physical Structure of Glass Fibre:

  • Holey fibres are created by stacking liny hollow glass tubes around a small solid glass rod forming a cylinder 3cm across and a meter long.
  • Each hole can be less than a micro in diameter.
  • The positioning and size of the hole affect the way light is being transmitted.
  • By introducing holes which are of a similar size to the wavelength of light, light of different wavelengths can be passed.

Physical, Chemical and Mechanical Properties of Glass Fibre:
Glass fibre is hard fibre. Its tenacity is so high. It is in second position regarding on tenacity. After Kevlar, aramid, glass fibre is stand on. The production glass fibre is not so easy. The chemical composition of glass fibre is important to decide because it depends on the final product properties.

Here, I have presented a list of physical and chemical properties of glass fibres. I think this will help you to identify glass fibres from other fibres.

Physical properties of glass fibre:
The physical properties of glass fibres are given below:

  1. Tenacity: 6.3-6.9gm/den
  2. Density: 2.5gm/c.c
  3. Elongation at break: 3%
  4. Elasticity: Bad
  5. Moisture Regain: 0%
  6. Resiliency: Excellent
  7. Ability to protest friction: Not good
  8. Color: White or color less
  9. Ability to protest friction: It can protect up to 315oC temperature. It loses energy after passing 315 degree Celsius.
  10. Lusture: Bright to light

Chemical properties of glass fibre:
The chemical properties of glass fibre given below:

  1. Acids: Hydro choric acid and hot phosphoric acid causes harm to the glass fibres.
  2. Basic: It has enough protection ability to alkali.
  3. Effect of bleaching: Bleaching agent does not cause harm to glass fibres.
  4. Organic solvent: It does not change on organic solvents.
  5. Protection ability against mildew: It does not affected by mildew.
  6. Protection ability against insects: Insects does not affect on glass fibres.
  7. Dyes: It is not possible to dye after production. But it could be color before production by adding dye in the solution bath.
  8. Effect of sun light: Sun light does not change the glass fibers properties.

Mechanical Properties of Glass Fibre:

Glass Fibre Mechanical Properties
Fig: Glass Fibre Mechanical Properties

Is Glass A Polymer?
Most glass is made from sand, and when we melt down the sand, we usually add some sodium carbonate. This gives us a tougher glass with a structure that looks like this. These linear, and yes, inorganic materials have a structure very similar to glass, and they are considered polymers.

What is GSM in Glass Fibre?
GSM stands for grams per square meter (g/m2). Material with a higher GSM weighs more than material with a lower GSM. Most general use microfibre is between 200-350 GSM.

What is the Difference between Glass Fibre and Fibreglass?
Fiberglass is made of small glass fibres that are connected together to form a material. The glass is made of silicon and not carbon. Both carbon fiber and fibreglass are used to make bodies and hulls of ships because of their strength and light weight, but they are also suited for other uses.

Various Properties of Different Glass Fibres:

Properties E-glass AR-glass S-glass
Tensile Strength (Gpa) 3.5 3.5 4.6
Modulus (Gpa) 73.5 175 86.8
Elongation (%) 4.8 2 5.4
Density (g/cc) 2.57 2.68 2.46
Refractive Index 1.547 1.561
Coefficient of Thermal Expansion (107/oC) 50-52.0 75.0 23-27.0
Dielectric Constant RT, 1010 Hz 6.1-6.3 5.0-5.1

Process Flow Diagram of Glass Fibre:

Process Flow Diagram of Glass Fibre
Fig: Process Flow Diagram of Glass Fibre

Manufacturing Process of Glass Fibre:

Manufacturing Process of Glass Fibre
Fig: Manufacturing Process of Glass Fibre

Manufacturing process of glass fibres:

  • Mixing silica sand, limestone, boric acid and other minor ingredients.
  • The mixture is heated until it melts at about 1260°C/2300°F.
  • Letting  the molten glass flow through fine holes. (In a platinum plate)
  • The glass strands are cooled, gathered and wound. (Protective coating may be added.)
  • The fibres are drawn to increase the directional strength.
  • The fibres are woven into various forms for use in composites.

Top Five Glass Fibre Manufacturer and Their Origin:

Manufacturer Origin
Owens Corning Corporation United States
Saint, Gobain, Vetrotex France
China’s Jushi Group China
PPG Industries Inc. United States
Shandong Taishan fibreglass Co. Ltd China

Cross-Section of Glass Fibre:

Cross section of glass fiber
Fig: Cross section of glass fiber

Advantages and Disadvantages of Glass Fibres:

Advantages:

  1. Does not corrode.
  2. Excellent workability.
  3. Invisible on the Finished Surface.
  4. Control and prevention of cracking in the fresh concrete.
  5. Overall enhancement of durability and mechanical properties.
  6. Effective at very low dosage.
  7. Homogeneous mix.
  8. Safe and easy to handle.

Disadvantages:

  1. Ultraviolet sensitive unless surface is coated with gel cot.
  2. Poor ventilation.

End Uses of Glass Fibres:

  • Filament windings around rocket cases
  • Exhaust nozzles
  • Heat shields for aeronautical equipments
  • Wall paneling
  • Boat hulls and seats
  • Fishing rods

References:

  1. High-Performance Fibres by J W S Hearle
  2. Handbook of Textile Fibre Structure, Volume 2: Natural, Regenerated, Inorganic and Specialist Fibres Edited by S.J. Eichhorn, J.W.S. Hearle, M. Jaffe and T. Kikutani
  3. Fiber Technology for Fiber-Reinforced Composites Edited by Ozgur Seydibeyoglu, Amar Mohanty, Manjusri Misra
  4. Mechanics of Fiber and Textile Reinforced Cement Composites by Barzin Mobasher

You may also like:

  1. Glass Fiber: Types, Properties, Manufacturing Process and Uses
  2. Glass Fiber Composites: Properties, Manufacturing and Applications
  3. Carbon Fiber: Its Manufacturing Process and Uses
  4. Different Types of Man Made Fibers with Their Application
  5. Nylon: The First Synthetic Fiber
  6. Problems of Man-made Fibers & Methods of Rectification
  7. Kevlar Fiber: Types, Properties, Manufacturing Process and Applications
  8. Aramid Fibers: Types, Properties, Manufacturing Process and Applications
  9. High Performance Polyethylene Fibers – An Overview
  10. Recent Developments in High Performance Fibers

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