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E-Glass Fibre

Topics Covered

Background

Fibre Manufacture

Composition

Key Properties

Applications

Composite Materials

Background

E-Glass or electrical grade glass was originally developed for stand off insulators for electrical wiring. It was later found to have excellent fibre forming capabilities and is now used almost exclusively as the reinforcing phase in the material commonly known as fibreglass.

Fibre Manufacture

Glass fibres are generally produced using melt spinning techniques. These involve melting the glass composition into a platinum crown which has small holes for the molten glass to flow. Continuous fibres can be drawn out through the holes and wound onto spindles, while short fibres may be produced by spinning the crown, which forces molten glass out through the holes centrifugally. Fibres are cut to length using mechanical means or air jets.

Fibre dimension and to some extent properties can be controlled by the process variables such as melt temperature (hence viscosity) and drawing/spinning rate. The temperature window that can be used to produce a melt of suitable viscosity is quite large, making this composition suitable for fibre forming.

As fibres are being produced, they are normally treated with sizing and coupling agents. These reduce the effects of fibre-fibre abrasion which can significantly degrade the mechanical strength of the individual fibres. Other treatments may also be used to promote wetting and adherence of the matrix material to the fibre.

Composition

E-Glass is a low alkali glass with a typical nominal composition of SiO2 54wt%, Al2O3 14wt%, CaO+MgO 22wt%, B2O3 10wt% and Na2O+K2O less then 2wt%. Some other materials may also be present at impurity levels.

Key Properties

Properties that have made E-glass so popular in fibreglass and other glass fibre reinforced composite include:

         Low cost

         High production rates

         High strength, (see table 1)

         High stiffness

         Relatively low density

         Non-flammable

         Resistant to heat

         Good chemical resistance

         Relatively insensitive to moisture

         Able to maintain strength properties over a wide range of conditions

         Good electrical insulation

Table 1. Comparison of typical properties for some common fibres.

Materials

Density (g/cm3)

Tensile Strength (MPa)

Young modulus (GPa)

E-Glass

2.55

2000

80

S-Glass

2.49

4750

89

Alumina (Saffil)

3.28

1950

297

Carbon

2.00

2900

525

Kevlar 29

1.44

2860

64

Kevlar 49

1.44

3750

136

The advantageous properties of E-glass generally outweigh the disadvantages which include:

         Low modulus

         Self abrasiveness if not treated appropriately leading to reduced strength

         Relatively low fatigue resistance

         Higher density compared to carbon fibres and organic fibres.

Applications

Composite Materials

The use of E-Glass as the reinforcement material in polymer matrix composites is extremely common. Optimal strength properties are gained when straight, continuous fibres are aligned parallel in a single direction. To promote strength in other directions, laminate structures can be constructed, with continuous fibres aligned in other directions. Such structures are used in storage tanks and the like.

Random direction matts and woven fabrics are also commonly used for the production of composite panels, surfboards and other similar devices.

 

Primary author: AZoM.com

 

Date Added: Aug 30, 2001 | Updated: Jun 11, 2013
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