Curing characteristics of particulate‐filled thermosets

A model to describe the effect of participate fillers on the heat transfer and curing characteristics of a thermosetting polymer is presented. It is assumed that the reaction kinetics are not altered by the addition of the filler and that the thermal characteristics of the composite are adequately described by the “spherical inclusion model.” The model is used to examine the effect of fillers on several important molding characteristics: time‐temperature profiles, peak temperatures, extent of reaction, and gel time. Results are presented for the curing of a typical polyester resin with varying filler content and filler type (glass, calcium carbonate, and aluminum). These results indicate that: mold cycle time can be reduced at higher filler content by increasing the mold temperature without inducing thermal degradation, and the progression of cure fronts through the thickness of the mold is significantly altered with increasing filler content; at low filler content the cure front progresses from the centerline toward the wall; at higher filler content, the cure front progresses from the wall toward the centerline.