This used wood flour fibres in phenolic resin as the thermoset polymer matrix.
As the fibres were only short this material had relatively low bulk strength, but still improved surface hardness and good mouldability.
A wide range of polymers are now produced in glass-filled varieties, including polyamide (Nylon), acetal homopolymers and copolymers, polyester, polyphenylene oxide (PPO / Noryl), polycarbonate, polyethersulphone[4] Bulk moulding compound is a pre-mixed material of resin and fibres supplied for moulding.
Some are thermoplastic or thermosetting, others are chemically cured and are mixed with a catalyst (polyester) or hardener (epoxy) before moulding.
[5] These use a substrate of fabric sheets made from long fibres, draped to shape in a mould and then impregnated with resin.