Electrical treeing of polyethylene blends with/without voltage stabilizer

This paper reports a new application of graphene as voltage stabilizer for polyethylene blends of the future environmental-friendly cable insulation materials. Electrical treeing in needle-plane electrode test objects of low-density polyethylene (LDPE) and its high-density polyethylene (HDPE), polypropylene (PP) blends with/without graphene were recorded by a real-time microscope observation system and a synchronized partial discharge (PD) detection system. The obtained results showed that the electrical tree initiation time of the LDPE decreased continually with the addition of 10 wt% HDPE and PP, respectively. It has been shown that the addition of 0.2 wt% graphene improves resistance of the tree inception of the LDPE and its blends. The LDPE/HDPE blended specimen with filled graphene had the longest tree initiation time (TIT) within all the tested samples, which was one time of the TIT of pure LDPE objects, and over 150% extension of the TIT of the unfilled LDPE/HDPE samples. It was also found that the graphene filled LDPE blends usually showed higher discharge magnitude than the pure LDPE material. It was postulated that the addition of grapheme would facilitate the PD in the tree channels of the samples with voltage stabilizer, but the influence of graphene voltage stabilizer on the microstructure and morphology of the blends could also enhance the tree inception resistance in the materials.