螺杆剪切对聚丙烯/石墨烯微片纳米复合材料形态和性能的影响

Effect of Screw Shearing on Morphology and Properties of Polypropylene/Graphene Microchip Nanocomposites

组合螺杆结构形成了三种不同的剪切力场,研究了螺杆剪切对聚丙烯（PP）/石墨烯微片（GNP）纳米复合材料微观形态、结晶、导电性、导热性和力学性能的影响。结果表明：高剪切、长停留时间的剪切作用可有效将GNP剥离至更薄的片状,同时提高了GNP在PP中的分布均匀性,利于导电导热网络的形成,从而提高了PP/GNP纳米复合材料的结晶度、电导率和热导率;GNP用量在渗流阈值附近时,螺杆剪切剥离和分布GNP的效果更加显著,可大幅提高电导率,同时剪切作用对电导率的提升作用大于对热导率的提升;当GNP用量从3%增至15%时,PP/GNP纳米复合材料的拉伸强度略有降低,但均高于PP的拉伸强度;增强螺杆剪切作用可提高复合材料的拉伸强度,但其断裂伸长率降低。

The combined screw structure has formed three different shear force fields. The effect of screw shear on the microstructure, crystallization, conductivity, thermal conductivity and mechanical properties of polypropylene（PP）/graphene microchip（GNP） nanocomposites has been studied. The results show that： the shearing effect of high shear and high residence time can effectively peel the GNP to a thinner sheet, and improve the distribution uniformity of GNP in PP, which is conducive to the formation of conductive and heat conducting network, thereby improving the crystallinity, electrical conductivity and thermal conductivity of PP/GNP nanocomposites. When the amount of GNP is near the seepage threshold, the effect of screw shear stripping and GNP distribution is more significant, which can significantly improve the conductivity. Meanwhile, the effect of shear effect on conductivity is greater than that of thermal conductivity. When the amount of GNP increases from 3% to 15%, the tensile strength of PP/GNP nanocomposites is slightly lower, but it is higher than the tensile strength of PP. The tensile strength of the composite can be increased by the shear effect of the reinforced screw, but the elongation at break of the composite is reduced.