PLA/jute fabric laminate composites: influence of weight percentage on mechanical properties and fracture behavior

Polylactic acid (PLA) is a widely studied and characterized bio-based polymer with biodegradable characteristics. Its use in environmentally friendly composite laminates is a recent field of research. In this work, we prepared eco-friendly PLA/Jute laminate composites and PLA flat sheets of 2 mm thickness using compression molding. Various experiments were performed to obtain composite plates with excellent quality. However, the successful configuration was the interleaved arrangement of PLA pellets/Jute fabrics stacking/PLA pellets. Scanning electron microscopy observations revealed no voids or delaminations, so the PLA pellets adequately impregnated the jute fiber fabrics. The number of jute fiber layers strongly influenced the mechanical properties of PLA. The stiffness of the composites increased progressively up to 145% compared to neat PLA, with an inverse behaviour in ductility, which decreased up to 60% in the composite with four layers of jute fiber fabrics. The strength did not show a clear trend and was attributed to the weight fraction of PLA. When the weight fraction is predominantly PLA, fracture occurs due to the brittleness of PLA, but when the weight fraction is mainly jute fiber, the tensile strength increases, and fracture occurs due to fiber failure. In all cases, PLA and the composites showed brittle behaviour. The storage modulus was noticeably improved by the stiffness provided by the jute fiber fabric layers, even above the glass transition temperature, where the thermomechanical properties of PLA were inferior. The trend in fracture behaviour shown by PLA/Jute laminates is almost the same as that previously observed in the mechanical behaviour under tension, indicating that the weight fraction strongly influences the impact strength of PLA/Jute composites. The impact strength of PLA decreased by approximately 39% in PLA/Jute-2 composite but increased up to 9% in PLA/Jute-4 laminate. The fracture surface of PLA neat differs from that of PLA/Jute composites, where the crack propagation characteristics are not so evident. The results allow for continued research into developing biodegradable thermoplastic ecological compounds that can be recycled to create products geared toward the circular economy.