Effect of compaction parameters on preform permeability and mechanical properties of unidirectional flax fiber composites

Abstract

This paper presents the effect of compaction parameters on the permeability to resin, tensile and flexural performances of unidirectional (UD) composites made of UD flax-mat reinforcements. In these reinforcements the UD fiber yarns are held together by a thin mat layer of short flax fibers. Reinforcements were compacted in dry or wet conditions at ambient or high temperature prior to permeability testing and composites molding with the resin transfer molding (RTM) process. A micrographic analysis of the morphology and structure of the laminates prior to and after tensile testing was also performed. It is found that hot and wet compaction do not change the permeability. Moreover, after molding with compacted reinforcements, the tensile strength increases while the tensile modulus is not affected. It also leads to a substantial increase in the flexural properties (strength and modulus). This means the chosen compaction parameters are appropriate for preforming this type of reinforcement.