Comparative study between dry and wet properties of thermoplastic PA6/PP novel matrix-based carbon fibre composites

Abstract

Abstract The aim of the study is to develop and investigate the suitability of thermoplastic composites for underwater applications. PA6/PP/PP-g-MA (70 wt%/30 wt%/3 phr) blend is used as a novel matrix to synthesize UDCF composites with balanced strength and toughness even in humid conditions. This novel matrix has around 60% lower water absorption capacity compared to PA6. Short carbon fibres (SCF) and unidirectional carbon fibre fabric (UDCF with 12K rovings) are used as reinforcements. X-ray CT data of injection-molded SCF composites revealed good wetting. However, in the case of compression-molded UDCF composites, a few unwetted zones were found. Comparing dry and wet samples, wet-matrix, wet-SCF composite and wet-UDCF composites had 40, 15, and 25% reduction in their tensile strengths, respectively. However, the impact strength of wet-matrix and wet-UDCF composites increased by 67 and 61%, respectively. Hence, SCF composites having a wet tensile strength of 46 MPa can be used in preparing underwater components due to the low number of interfacial voids. UDCF composites having more interfacial voids are recommended for humid conditions wherein the wet impact strength (11.4 J) and wet tensile strength (266 MPa) are the main criteria.