Studies on Epoxy Resin Used in Fiber Reinforced Polymer Composites

The purpose of this study was to investigate the behaviour of brittle epoxy resin when modified by liquid rubber for higher flexibility and toughness. The resin and the liquid rubber used were diglycidyl ether of bisphenol-A (DGEBA) and hydroxyl terminated polybutadiene (HTPB), respectively. A silane coupling agent (SCA) was also utilised to improve the compatibility of HTPB and epoxy matrix. Four groups of specimens were prepared by using different orders of mixing of HTPB with SCA and hardener. Tension, bending and impact tests results indicated that strength and impact toughness values were increased in the specimens containing 1% HTPB and 2% SCA. Specimens containing HTPB rubber had highest flexibility than neat epoxy specimens. SEM studies indicated the formation of rubber domains and deformation lines in the epoxy matrix, which assessed the improvement in flexibility and toughness.