Abstract
Several approaches are found in the literature together with a large number of patents describing the preparation of prepregs. It is very desirable that prepregs are produced using simplified manufacturing processes. The prepreg must be pliable, easy to handle, be shelf stable and meet the end use performance requirements for which it was designed. Resin systems should have low viscosities to facilitate impregnation of the reinforcement and air removal during the process. The prepreg should be tack free; the resin must not drain or migrate and cure at a specific temperature within a specified time. Most common resin materials used in the preparation of prepregs are epoxy intermediates.
However, epoxy resins are limited by the type of substrates to which they can be successfully applied and their ability to conform to irregular surfaces. This paper describes a unique process for producing prepregs from relatively low viscosity unsaturated polyester resins. These same resins can be formulated to increase viscosity within minutes or hours after initial impregnation of the reinforcement. Final viscosities may be from a few thousand centipoises to several million and are attainable without altering the reactive monomer or primary backbone of the polymer. Stability and curing properties will be presented together with potential applications.
