Improved Mechanical and DC Electrical Properties of PP/PE Blend by Grafting

Polypropylene (PP) has the advantages of excellent insulation performances and recyclability after retired. But $P P$ has large rigidity and poor toughness, which cannot meet the requirements of high voltage direct current (HVDC) cable. Moreover, the electrical and mechanical properties of modified PP insulating materials are difficult to coordinate. In this paper, maleic anhydride (MAH) was severally grafted onto P P and P E to increase the compatibility between PP and polyethylene (PE) to improve the mechanical properties of PP. At the same time improve its electrical properties. The mechanical properties of P P and P E blends before and after grafting M A H were tested, and the influences of MAH grafting on the compatibility of P P and P E blends were investigated. The influence of grafted MAH on the DC electrical properties of P P and P E blends was analysed by testing conductivity and DC breakdown strength. Infrared spectra show that MAH is successfully grafted onto P P and P E. The stress-strain curves show that the mechanical strength of P P / P E blends decreases rapidly, and the mechanical strength of P P / P E blends after grafting is significantly improved. Conductivity and DC breakdown strength test results show that at $80^{\circ} \mathrm{C}$, the $D C$ electrical properties of $P P / P E$ blends are impaired, and the electrical properties of grafted $P P$ and $P E$ blends are slightly better than PP.