Effect of maleic anhydride–grafted polypropylene coupling agent on mechanical properties of HDPE composites filled with grape leaves fiber

The excellent mechanical and other useful characteristics of grape leaves fiber (GLF) can potentially be explored to prepare bioactive compounds, biocomposites, biomass fuels, etc. This agricultural and winery waste has not been utilized properly to generate valuable bioproducts. This waste biomass can potentially be used as a novel reinforcement in the polymer composite industry. A coupling agent is still needed to overcome the drawbacks associated with a new fiber and improve the compatibility between GLFs and high-density polyethylene (HDPE). Therefore, maleic anhydride–grafted polypropylene (MAPP) was chosen in this study as a coupling agent to reduce the surface tension between GLF and HDPE for improved fiber-matrix adhesion. GLF was used as a reinforcing filler at different concentrations of 5wt.%, 10wt.%, 20wt.%, and 30wt.%. The HDPE/GLF composites with or without maleic anhydride–grafted polypropylene (MAPP) were prepared using a twin-screw extruder. The GLFs were investigated for granulometric analysis, thermogravimetric analysis, FTIR, fiber drying, moisture content, water activity, color measurement, tensile testing, surface morphology, and thermal properties. The effect of coupling agent and fiber loading on the thermal behavior, tensile properties, and surface morphology of composites was investigated here.