THE INFLUENCE OF STAMPING TEMPERATURE ON THE PROPERTIES OF A GLASS MAT THERMOPLASTIC COMPOSITE

The effect of varying the mold temperature on the mechanical propertie s of a stampable thermoplastic composite has been examined. A series o f tensile, flexure and impact tests have shown that a distinct mold te mperature dependency exists. This is most evident under impact loading conditions where it has been shown that the energy absorbing capacity of a material stamped at a low temperature is almost twenty-five perc ent lower than that of a similar composite molded at a much higher tem perature. It is concluded that residual stresses resulting from the hi gher cooling rate may be in part responsible for this significant diff erence in impact resistance. It is also possible that greater damage o ccurred during the flow process in the lower temperature mold. A subse quent heat treatment cycle designed to simulate the passage of a compo nent through a paint oven has been shown to improve quite significantl y the energy absorbing capability of the material.