Polyvinyl alcohol (PVA) fibres

Polyvinyl alcohol (PVA) fibres have a high modulus and low elongation under load, which confers on them a high tenacity (the capacity to reinforce composites). They impart high strength and impact resistance to composites.

Their chemical resistance makes them suitable for use in fibre-cement products where they provide a better bond with cement than other organic polymers such as polypropylene; although the bond is not as good as with chrysotile asbestos. PVA fibers are tough and resistant to abrasion. The specific gravity of PVA is 1.3 which is half that of glass or asbestos. The PVA is available as chopped strands or continuous filament. The cost of PVA fibre is in the range from 2.50 to 15.00 US $/kg.

PVA fibres have the following properties:

Fibre diameter
13 16 26
Tensile strength MPa 1800 1790 1590
Young’s modulus GPa 38 37 32
Extension at break % 6,5 6,9 7,2

Compared against chrysotile asbestos, the strength and chemical resistance are adequate, but the cost and heat resistance are not favorable.

In the wet condition, PVA fibre may not be exposed to temperatures higher than 900C because PVA dissolves in hot water. This is a serious drawback for fibre-cement sheet products reinforced with PVA.

Substitutes for asbestos