An Investigation of Mechanical Properties and Breakdown Strength of Polypropylene/Ultra-High Molecular Weight Polyethylene Nanocomposites

This work studies the effects of surface-modified magnesium oxide (MgO) nanofiller on the mechanical properties and AC breakdown strength of polypropylene (PP) and ultra-high molecular weight polyethylene (UHMWPE) composites. The inclusion of nanoparticles results in improved interfacial interactions as a consequence of the transition from separate crystallization to co-crystallization. Thus, nano-MgO enhances the breakdown strength of PP/UHMWPE by acting as a compatibilizer between the PP/UHMWPE. UHMWPE decreases Young’s modulus and ultimate tensile strength while increasing elongation at yield point in the PP matrix. PP/UHMWPE has increased elasticity due to weak interfacial adhesion. The addition of nano-MgO, however, promotes stronger bonding between PP and UHMWPE phases, providing stiffer composites than those without MgO. There are no apparent differences between PP/UHMWPE and PP/UHMWPE/MgO regarding ultimate tensile strength. It is obvious that the dielectric breakdown strength and elastic enhancement are significantly influenced by the interfacial adhesion between the polymers.