Effect of Preparation Processes on PTC Performance of TiB2-CB/PE Composite

A TiB2-CB/PE composite was prepared by melt-blending process.After hot pressing molding under the conditions of temperature of 130,160,180 ℃and pressure of 3,6,8 MPa,annealing treatment(120,130 ℃) and silane crosslinking were carried out respectively.The effects of hot pressing process,annealing temperature and crosslinking process on PTC performance and PTC mechanism were investigated.The results show that PTC properties of the composite increased at first and then decreased with the increase of hot-pressing pressure and hot-pressing temperature.An appropriate hot-pressing temperature and cooling mode could increase the crystallinity of the composite,and the higher crystallinity corresponded to the more obvious PTC effect.The composite with crystallinity of 48.4%,room temperature resistivity of 4.47 Ω·m and PTC intensity of 5.1 could be obtained by hot-pressing with pressure of 6 MPa,temperature of 160 ℃ and cooling in the air.The peak resistivity and PTC transition temperature of the composite all could be increased after annealing treatment.After silane crosslinking treatment,the composite could get more stable thermal cycling property and lower NTC effect.The PTC effect of the composite was closely related to the crystallization area melting and recrystallization of polyethylene matrix.