高熔体流动速率抗冲共聚聚丙烯的结构与性能研究

Studies on structure and properties of high⁃impact copolymerized polypropylene with high melt flow rate

为提升高熔融抗冲共聚聚丙烯(IPC⁃J)的刚韧平衡性能,结合抗冲共聚聚丙烯(IPC⁃H)工艺,将IPC⁃J的乙烯含量和乙丙橡胶(EPR)中乙烯含量提高到了12.4%(质量分数,下同)和54%。对IPC⁃J、IPC⁃H、IPC⁃1和IPC⁃2等分别进行了分子链段结构和聚集态表征,结果显示,对比IPC⁃H的微观结构,IPC⁃J的EPR含量从19.4%增至22.8%,重均分子量(Mw)从2.0×10^(5)g/mol减至1.9×10^(5)g/mol,特性黏度(IV)从1.80 dL/g增到1.86 dL/g,分子量分布指数(MWD)从8.9增至10.7,EPR的最大分子量从1.1×10^(6)g/mol增至1.2×10^(6)g/mol;更多的、相对较长的长乙烯结晶链段有助于改善分散颗粒粒径,占比最大的粒径范围从0.3~0.6μm升至0.6~0.9μm;常温和低温冲击强度分别提升至11.0 kJ/m^(2)和5.7 kJ/m^(2)。以300 kt/年聚丙烯生产工艺为基础,在不改变齐格勒⁃纳塔(DQ)型催化剂体系的条件下,通过提高乙烯含量和EPR中乙烯含量实现了高熔融抗冲聚丙烯性能最大优化。

To improve the rigidity⁃toughness balance of high⁃impact copolymerized polypropylene with high melt flow rate(IPC⁃J),the ethylene content and the ethylene content in ethylene propylene rubber(EPR)were increased to 12.4 wt%and 54 wt%,respectively,by combination with the high⁃impact copolymerized polypropylene(IPC⁃H)technology.Meanwhile,the molecular segment structures and aggregation morphologies of IPC⁃J,IPC⁃H,IPC⁃1,and IPC⁃2 were investigated.The results indicated that the EPR content of IPC⁃J increased from 19.4 wt%to 22.8 wt%,its weight av⁃erage molecular weight(Mw)decreased from 2.0×10^(5)to 1.9×10^(5)g/mol,its intrinsic viscosity increased from 1.80 to 1.86 dL/g,its molecular weight distribution index increased from 8.9 to 10.7,and the maximum Mw of EPR increased from 1.1×10^(6)to 1.2×10^(6)g/mol,compared to those of IPC⁃H.The relatively longer ethylene crystalline chains with a greater amount were beneficial to enlarging the dispersed particle size.This resulted in a transformation of the maximum proportion region from 0.3~0.6 to 0.6~0.9μm,which promoted higher impact strength of 11.0 kJ/m^(2)at 20℃and 5.7 kJ/m^(2)at-20℃.The rigidity⁃toughness balance of the IPC with a high melt index were fully optimized through in⁃creasing the ethylene content and the ethylene content of EPR,according to the production technology for 300⁃kt/a poly⁃propylene without changing the Ziegler⁃Natta⁃type catalyst system.