低乙烯含量共聚聚丙烯链结构和相结构与应力应变行为的关系

研究了两种典型的低温抗冲共聚聚丙烯(ICPP)的应力应变行为及温度依赖性,其低温应力应变行为揭示ICPP具有优异的低温抗冲性能和综合力学性能的结构本质.从初始弹性模量、屈服应力及断裂伸长随温度变化所显示的变化规律进一步确认了两种ICPP的序列结构特征和相结构特征.断裂伸长变化显示了乙丙橡胶相的增韧作用,屈服应力变化显示了分散相对基质结合紧密程度的影响,弹性模量则与基质的结晶状况和结晶形态有着比较密切的关系,同时也与乙丙橡胶相和聚丙烯基质的玻璃化转变温度密切相关.

The Relationship Between Chain Structure and Phase Structure and Tensile Stress-Strain Behavior of Copolymer Polypropylene with Low Ethylene Content

In our published works, it has been proved that the impact copolymer polypropylene (ICPP) has characteristic chain structure and phase structure which make CPP exhibit excellent low-temperature impact strength. The tensile stress-strain behavior at low temperature of impact copolymer polypropylene strongly discloses the structure nature why impact copolymer polypropylene has so excellent lowtemperature impact strength and comprehensive mechanical properties. The dependence of Young′s modulus, stress yield and the elongation at break on the variation of the temperature can be explained by the characteristic chain structure and characteristic phase structure of the impact copolymer polypropylene.The difference of the elongation at break between the homopolymer and copolymer indicates that ethylenepropylene rubber acts as the toughening phase in the impact copolymer polypropylene. The difference of stress yield between the two-copolymer polypropylenes comes from the difference of the adhesion between the rubber particles and the matrix PP. The Young′s modulus is closely related to the crystallinity of the matrix PP, the size of the spherulite and the size distribution, and the glass transition temperature of both ethylene-propylene rubber and PP matrix can also give important influence on it.