Tribo-mechanical and structural characterizations of LLDPE matrix bio-composite reinforced with almond shell micro-particles: effects of the processing methodology

The objective of this research work is to examine the effect of mixing operation in the reinforcement of linear low density polyethylene (LLDPE) with almond shell powder (ASP). Two groups of bio-composites mixed in solid state and melt extrusion state were developed by the standard thermo compression molding process. For each group of bio-composites developed, the mass percentage of ASP was varied from 5 % to 40 %. Tensile and friction tests and micro structural analyzes were carried out. The main results show that the addition of ASP particles: decreases the maximum tensile stress and increases the rigidity of the two types of bio-composites produced. A significant improvement was observed in terms of maximum stress and Young's modulus of the bio-composites mixed in the molten state compared to those mixed in the solid state. Microscopic observations concluded that the melt-blended ASPs were better covered by the LLDPE matrix and the dispersion was successfully achieved. Friction tests have shown an improvement in tribological performance thanks to the addition of an optimal percentage of ASP equal to 20 % in the case of bio-composites mixed in the molten state. From this research work, it can be concluded that the LLDPE/ASP homogenization method influences the mechanical and tribological properties of bio-composites.