Distribution of the cure degree for the thick GFRP laminates

The glass fiber reinforced epoxy resin polymer (GFRP) laminates with thickness of 85 mm were manufactured by the vacuum infusion molding process (VIMP), cured by one-side rigid mould heating. The temperature curves at different thickness positions during curing were examined, which shows large temperature changes in the thickness direction. The curing kinetics of the epoxy resin system was studied under isothermal curing conditions by differential scanning calorimetry (DSC) technique. The cure kinetic equations based on the autocatalytic kinetic model were established and were verified by the experimental data. A method of accumulation by time dispersing steps was set up and used to calculate the dist ribution of the degree of cure curves at different thickness positions in the curing course. The results show that there were large differences of real time degree of cure in pre-curing process, but the high equivalent degree of cure could be achieved by the post-curing process. This method could be used to calculate the asymmetrical distribution of the degree of cure in the curing course and optimize the curing stage.