Characterization of mechanical properties of stab-resistant angle-ply flexible composites

In this study, we fabricated para-aramid flexible angle-ply-laminated hybrid composites based on weft-knitted reinforcements. Here, four kinds of weft-knitted reinforcements with rib, interlock, punto di roma, and two-thread fleecy were prepared using para-aramid spun yarn. They were then compounded with silicone rubber and waterborne polyurethane–acrylate using the coating method. The layers were angle-plied to produce stab-resistant, weft-knitting-reinforced, flexible laminated hybrid composites. Tensile and tearing strengths of the para-aramid-knitted reinforcements were investigated. Relevant response analyses were chosen to evaluate the influence of three independent variables, including weft-knitted structures, matrix types, and ply orientations. The results showed that the mechanical properties of the composites were dependent on weft-knitted structures and matrix types. The fabric with high strength and the degree in approximate isotropy of stress in all composites was most suited for the reinforcement of the flexible stab-resistant composite. The optimum design with the best stab-resistant property was punto di roma/waterborne polyurethane–acrylate with a ply orientation angle of [0°/0°/0°/0°]. The interlaminar adhesion of flexible stab-resistant composite based on waterborne polyurethane–acrylate can be improved by increasing the surface roughness of fabric structure or modifying its surface.