Microstructural-mechanical properties relationship in single polymer laminate composites based on polyamide 6

Abstract This paper studies the flexural and the impact properties of polyamide 6-based knitted reinforced single polymer composites (KSPCs) prepared by compression molding of powder-coated textile structures. To prepare matrix component, polyamide 6 microparticles (MPs) were synthesized by activated anionic ring-opening polymerization of e-caprolactam in solution and then used for powder-coating of the knitted structures. The influence of the reinforcements' architecture, plies orientation, stacking order and fiber content on the final mechanical properties of KSPCs were investigated. Rib1 × 1 and Jersey knitted structures were selected as reinforcements and treated by a stretching-annealing procedure to modify their mechanical properties. The anisotropic tensile and compression properties imparted by the knitted structures were found to be the major factors determining the impact and flexural behavior of KSPCs. Moreover, reinforcement's crossover points, the plies orientation and the presence of a transcrystalline layer at the matrix-reinforcement interface were identified as relevant parameters. The fracture mechanism of KSPCs was linked to the morphology and crystalline structure of the resulting composites and investigated by simulation and finite element analysis of knitted reinforcements.