Research On Mechanical And Dielectric Properties Of Elastomer And Plastomer Modified Polypropylene

Polypropylene(PP)resins are widely used in power capacitors due to their stable chemical properties,good tensile properties and excellent dielectric properties.However,pure PP resin has poor flexibility under low temperature working environment,and has a high probability of brittle fracture,which hindered its further application in power cables.Mechanical properties can be improved effectively by adding thermoplastic elastomers to PP,but the insulation properties of the elastomer are poor,and the crystalline regularity of PP is reduced,the breakdown strength of the material is significantly reduced.Therefore,by toughening and modifying the PP,method for regulating blends system and obtaining it with better electrical performance becomes possible for it to be widely used in the high-voltage cable industry,and has broad development prospects.In this paper,PP is used as the matrix resin,polyolefin elastomer(POE)and polyolefin plastomer(POP)are used as fillers.Different content of POE/PP and POP/PP blends were prepared by SEM,mechanical test,DMA,electrical conductivity test,breakdown performance,etc,for PP,POE/PP and POP/PP.The microscopic morphology,mechanical properties,electrical conductivity,dielectric loss and AC and DC breakdown strength of different blends were compared.The SEM results show that PP and elastomer are ‘island structures’,in which the addition of body content,the island phase concentration increases,the island phase size increases,and the POP blend system exhibits stronger dispersion.By measuring the dielectric loss tangent,it is shown that POP/PP has lower dielectric loss and relative dielectric constant.The tensile mechanical test results show that the composite material 165 °C is only 11.25%,and the yield stress of the blended material blended with 30wt% POE in the tensile test decreased obviously,with the maximum elongation at break.The results of DMA test showed that the incorporation of elastomeric POE significantly reduced the elastic modulus of PP at room temperature compared with plastid POP.The results of electrical conductivity test show that the electrical conductivity of composites is higher than PP at different temperatures,and the conductivity of POP/PP system is significantly lower than that of POE/PP system.The results of AC and DC dielectric strength tests show that the dielectric strength of the blends at different temperatures is less than PP,and the breakdown strength of the five materials decreases with the increase of temperature,30wt% of which the mass fraction of POP/PP composites has the closest dielectric strength to PP.The "island structure" in the elastomer/PP blend increases the toughness and flexibility of PP.The less co-monomer content of plastomer POP reflects the better compatibility with PP,which greatly maintains the electrical properties of pure PP.