【摘要】 利用傅里叶变换红外光谱仪、差示扫描量热仪、偏光显微镜、X射线衍射仪研究了重复挤出对等规聚丙烯(iPP)微观结构的影响，考察了iPP在不同温度和单轴拉伸应力水平下的蠕变响应。结果表明：iPP的蠕变响应与其重复挤出导致的结晶度、球晶尺寸及相对分子质量变化的竞争作用有关。随着挤出次数增加，iPP的结晶度提高，球晶尺寸先显著减小后缓慢增大，而相对分子质量则单调减小；抗蠕变性能先升高后下降，主要受结晶行为控制。不同温度、应力及挤出次数下的蠕变行为基本符合时温叠加原理，Burgers四元件模型对iPP不同挤出次数的蠕变数据均能进行较好拟合，其主要模型参数变化规律与iPP结晶性能变化规律基本一致。更多还原

【Abstract】 The effect of repeated extrusion on the microstructure of isotactic polypropylene(iPP) was studied by Fourier transform infrared spectrometer, differential scanning calorimeter, polarized microscope and X-ray diffractometer, and the creep responses of iPP under different temperatures and uniaxial tensile stress levels were investigated. The results show that the creep responses of iPP are related to the competition among changes in crystallinity, spherulite size and relative molecular mass caused by repeated extrusion. With the increase of extrusion times, the crystallinity of iPP increases and spherulite size decreases first and then increases slowly, while the relative molecular mass decreases monotonously.The creep resistance of iPP increases first and then decreases, which is mainly controlled by the crystallization behavior. The creep behaviors under different temperatures, stresses and extrusion times are basically in accordance with the time and temperature superposition principle. Burgers four-element model can better fit the creep data of iPP with different extrusion times, and the variation rule of main model parameters is basically consistent with the change rule in the crystallization properties of iPP.更多还原