Properties of glass fiber polypropylene composites produced from split-warp-knit textile preforms

Properties of uniaxial and biaxial glass fiber/polypropylene composites based on split-warp-knit textile preforms and produced under various consolidation conditions were investigated. Consolidation was carried out at T = 210-260 degrees C, P = 1-3 MPa and t = 5-15 min, and the impact of each variable was studied by 3(2) full factorial experimental design. The analysis of variance of the obtained results has shown the different influence of the analyzed process conditions on the longitudinal and transverse properties of uniaxial composites, with both temperature and pressure being of high significance level. Higher longitudinal tensile properties were achieved after pressing at 240 degrees C and 3 MPa (15 min). However, for biaxial composites, similar values for tensile properties were obtained For samples pressed at 210, 225 and 240 degrees C (under 1-3 MPa). The role of PET stitching yarns is demonstrated in anisotropy of tensile strength for biaxial composites.