Prepreg (preimpregnated fibres) are half-finished materials, made of continuous filament and uncured polymer matrix. The continuous filaments can be an unidirectional layer, fabric or rovings.

The prepreg resins are still arranged in the reactive B-status by having medium up to high viscosity.

They can be processed without any problems through supply of power and simultaneously forming actions.

The resins which are still low-molecular and meltable are transformed to the high-molecular unmeltable C-status.

Prepreg systems are based on multifunctional, special modified phenolic-, polyester and epoxy resins. They are manufactured with a curing system which is latent-reactive at room temperature but high-reactive at increased temperatures.

Structural elements with very good mechanical properties can be manufactured in combination with glass, carbon or aramid fibres.

Prepregs can be processed with machines or by hand and due to the machined pre-impregnation they have a steady high quality.

In practice mainly glass- (GRP), carbon- (CFRP) and aramid fibres are processed to prepregs, in this case different resin systems are used.

Mainly phenolic-, polyester and epoxy resin systems are used.