The Effect of Degassing Agents on the Characteristics of Epoxy/Glass Fiber Composites

The presence of voids is an important factor to affect the properties of polymer composites. There are several causes for void formation, such as gas entrapment (most often wet air) during impregnation of the fibrous reinforcement with resin and volatiles arising from the resin system itself. The amount of entrapped air bubbles can sometimes be reduced if the resin system is subjected to a degassing process (e.g. aided by vacuum) or by using special chemical additives. The aim of this research is to investigate the effect of a degassing agent on the final properties of epoxy composites molded by RTM using glass-fiber mats or plain-weave cloths. The produced composites were evaluated under tensile, flexural, hardness and short beam testing, along with dynamical mechanical analysis (DMA). In general, the use of the additive did not ensure significant improvement in those mechanical properties that are primarily determined by the type and content of the fibrous reinforcement, such as tensile and flexural strength and modulus. However, the short beam strength and hardness results showed a positive effect with the inclusion of the additive, leading to better quality composites.