Curing shrinkage and process parameter optimization of epoxy resin based on FBG strain monitoring

Temperature and strain in a representative liquid molding epoxy resin were in-situ monitored by Fiber Bragg Grating (FBG) sensors throughout different curing processes and post-curing processes. Curing shrinkage regularity of the resin in different processes was derived from its linear volume variation transformed from the strain evolution in resin. Process parameters of experiential curing and post-curing processes were validated and optimized based on the curing shrinkage. The results show that conversion degree and glass transition temperature of the liquid moldingresin cured at 80℃ are 90% and 85℃ respectively, which are higher than resin cured at 75℃. However, total curing shrinkage of the resin cured at 80℃ is only 5% higher than cured at 75℃. The strain in resin becomes constant after 180 min in isothermal procedure of 120℃ post-curing, which means the resin is cured completely. There is no need to extend the post-curing time.