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

This paper studies theflexural and the impact properties of polyamide 6-based knitted reinforced single polymercomposites (KSPCs) prepared by compression molding of powder-coated textile structures. To prepare matrixcomponent, polyamide 6 microparticles (MPs) were synthesized by activated anionic ring-opening poly-merization ofε-caprolactam in solution and then used for powder-coating of the knitted structures. The influenceof the reinforcements' architecture, plies orientation, stacking order andfiber content on thefinal mechanicalproperties of KSPCs were investigated. Rib1 × 1 and Jersey knitted structures were selected as reinforcementsand treated by a stretching-annealing procedure to modify their mechanical properties. The anisotropic tensileand compression properties imparted by the knitted structures were found to be the major factors determiningthe impact andflexural behavior of KSPCs. Moreover, reinforcement's crossover points, the plies orientation andthe presence of a transcrystalline layer at the matrix-reinforcement interface were identified as relevant para-meters. The fracture mechanism of KSPCs was linked to the morphology and crystalline structure of the resultingcomposites and investigated by simulation andfinite element analysis of knitted reinforcemenents.This work was partially financed by FEDER funds through the COMPETE program and by national funds through FCT – Foundation for Science and Technology within the project POCI-01-0145-FEDER 007136. SDT thanks FCT for his Ph.D. Grant SFRH/BD/94759/2013. NVD thanks for the financial support of FCT in the frames of the stra tegic project UID/CTM/50025/2013. Finally, ZZD is thankful to FCT for the SFRH/BSAB/130271/2017 personal research grant. All authors gratefully acknowledge the support of the project TSSiPRO-NORTE-01-0145-FEDER-000015 funded by the regional operational program NORTE 2020, under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund