Effects of postcuring on mechanical properties of pultruded fiber-reinforced epoxy composites and the neat resin

The effects of postcuring on mechanical properties of pultruded fiber reinforced epoxy resin composites have been investigated for a simulation of postcuring in line with the pultrusion fabrication process. Composites of carbon, glass, and aramid reinforcement fibers were individually studied. The epoxy was a commercially available resin that was especially developed for pultrusion fabrication. The pultrusions were conducted at 400°F with postcures at 400, 450, 500, and 550°F. Measurements of the flexural, shear, and interlaminar fracture toughness properties showed that significant postcuring can occur within the time frame available during the pultrusion process. All three mechanical properties were degraded by the higher (500°F and 550°F) temperature postcures; photomicrographs suggest that the degradation was caused at the fiber-resin interface for all three fiber types.