Physical-Mechanical properties of wood based composite reinforced with recycled polypropylene and cowpea (Vigna unguiculata Walp.) husk

Abstract

The need for a sustainable environment and biomass valorization has encouraged research on the recycling of agro and industrial wastes into roofing tiles, ceiling boards, particleboards and furniture. In this study, eco-friendly panels were produced from cowpea husk (CPH), wood chips (WC) and recycled polypropylene (rPP) at different CPH/WC weight percentages and a fixed weight of rPP as binder. The panels were produced by hot compression molding at 150 °C under 2.5 MPa and tested for mechanical (impact strength, modulus of rupture (MOR), modulus of elasticity (MOE)) and physical properties (water absorption (WA), thickness swelling (TS) and density). Fourier transform infra-red spectroscopy (FTIR) was used to study the functional groups in the composite board and raw materials used in addition to the chemical composition. Grey relational analysis was used to optimize performance to a single response, optimal performance was achieved with 80% WC and 20% CPH giving 9.41% water absorption, 15.28% thickness swelling, 1137 kg/m3 density, 0.127 J/mm impact, MOR of 17.96 MPa and MOE of 741.56 MPa. The physical properties evaluated satisfy the American National Standards Institute (ANSI) A 208.1 standard and confirms that the CPH, WC and rPP mixture can be used for the production boards with good dimensional stability and/or for use in applications where load bearing is not required in the construction industry such as ceiling boards and wall claddings.