Glass fibre

Glass fibre is a relatively low cost fibre with high strength, elevated temperature resistance and superb dimensional stability.

It is not as soft, ductile, tough and wear resistant as chrysotile asbestos and thus it cannot be a universal substitute in products that require these properties, such as packing, mastics and sealants. Glass fibres have been used unsuccessfully to reinforce fibre-cement products. Even the alkali resistant glass fibres developed for this application were not sufficiently alkali-resistant. After one to five years the modulus of rupture dropped (50% ductility was reduced 75% and impact resistance was reduced 80%).

Glass fibre can be used in many products but it is subject to limitations. The abrasiveness of glass can lead to the rapid wear of the processing equipment. Glass fibre cannot withstand shearing and may not be treated in mixers that develop intense shearing. Products reinforced with glass fibres tend to fail prematurely if subjected to fatigue. In the case of molded products containing glass fibre, excessive spring back upon release from the mold can be a problem. Glass fibres used as chopped fibres, scrim or textiles in roofing underlay felts yield a product that tends to deforn and bulge when furniture is dragged across the floor.

Some products into which fibre glass is added are listed hereunder

Product Limitations
Papers Fatigue failure
Felts Durability
Electrical insulation                                     Cost
Pipeline wrap Short life
Asphalt shingles Moisture degradation
Molded plastics Spring back

The cost of glass fibres varies substantially depending upon their diameters and compositions. Costs ranging between 0.75 and 9 times the cost of the asbestos replaced have been reported. The unit costs of glass fibres are generally between 1.30 and 40.00 $/kg.

Glass fibres have the following properties:

Tensile strength 1250-3600 MPa
Young’s modulus 70-97 GPa
Diameter 8-12,5 micrômét
Density 2,54-2,7 g/cm3
Temperature limits 300-5380C

Compared against chrysotile asbestos, glass fibres are equivalent except with regard to brittleness, abrasiveness and to heat, moisture and alkali resistance.

Substitutes for asbestos – Marcel Cossette