Study On Preparation And Properties Of PTC Composite By MLLDPE/LDPE/CB

The polymer matrix PTC composite is a new functional material, which hasimportant theoretical research value and widely application prospects, especiallythe PTC polyethylene composite widely used in Petroleum, chemical, medical,electronic, etc. in our country. But some issues of PTC composite are still to beresolved, such as the PTC strength is not high enough and the stability is poor,which limit the further application of the PTC polyethylene composite. In thispaper, the relation of crystalline between PTC characteristics is studied throughmLLDPE, nucleating agent and rheology modifier. And the affect of heattreatment on PTC characteristics was studied, moreover laying the foundation forpreparing high-performance PTC Composites.The results of the mLLDPE/LDPE/CB composite DSC analysis and PTCintensity test showed: the crystallinity of the composites with mLLDPE could beimproved, and the melting curve was bimodal. When the mass ratio of MLLDPEand LDPE was1/1, the crystallinity was80.8%, the PTC intensity was8.1,transition temperature of resistance-temperature Characteristic was92.5℃,which increased by43.6%,12.3%and11%respectively, Compared toPolyethylene samples; Moreover, the crystallinity and PTC intensity of thecomposites with nucleating agent could be improved, when the amount ofnucleating agent was0.3wt%, the crystallinity was86.9%, the PTC intensity was8.4, transition temperature of resistance-temperature Characteristic was109.5℃,which increased by45.5%,3.5%and15.7%respectively, Compared toPolyethylene samples.The affect of theology modifiers on mLLDPE/LDPE/CB compositesrheology was studied, against poor processing flow of mLLDPE. The resultsshowed that adding rheology modifier could improve the deformability of composite. When the amount of modifier was3wt%, the deformability of PTCcomposite was better.The effect of heat-treat condition on the properties PTC composites isresearched, orthogonal test datas were analyzed through the range analysis andmultivariate linear regression, the best heat treatment condition was deal withnatural cooling in the air after heat treatment at80℃three hours. Under thiscondition, PTC intensity was8.3, surface temperature was75.2℃, wereincreased by3.5%,6.2%, comparing with untreated Samples respectively. Start-up current was0.73mA, was lower13.4%than that of untreated Samples.