Study on the mechanical properties of unsaturated polyester sandwich biocomposites composed of uniaxial warp-knitted and non-woven viscose fabrics

In this work, tensile, flexural and the low-velocity impact response of regenerated biodegradable warp-knitted and non-woven viscose fabric reinforced unsaturated polyester (UP) sandwich biocomposites are reported. Four different types of sandwich laminates comprised of different configurations as well as various weight fractions of warp knitted/non-woven fabrics were manufactured by vacuum infusion moulding (VI). The influence of warp knitted/non-woven ratios in the sandwich surface layers and core layer and lay-up configurations on the tensile, flexural and low velocity impact damage characteristics have been investigated. It was observed from the experimental results that fibre lay-up configurations have a considerable effect on the mechanical properties of regenerated cellulose reinforced sandwich biocomposites. The tensile strength was increased from 50 MPa for sandwich laminate SL1 (22 wt-% of reinforcement) to 160 MPa for sandwich laminate SL4 (39.8 wt-% of reinforcement). Similar trend was observed for impact behaviour, showing the best penetration resistance by SL4 laminate.