双峰PE生产工艺对其结晶行为和力学性能的影响

Influence of production process of bimodal polyethylene resin on its crystallization behavior and mechanical properties

采用高温液相凝胶渗透色谱仪、广角X射线衍射仪和拉力机,研究了双峰聚乙烯(PE)生产中环管反应器和气相反应器的工艺参数对双峰PE产品的结晶行为和力学性能的影响。结果表明:环管反应器聚合产物的结晶度随停留时间的延长而减小,气相反应器产物的结晶度随n(H2)/n(C2H4)下降、n(1-C4H8)/n(C2H4)增大和床层分配率增加而减小,双峰PE的拉伸屈服应力和拉伸弹性模量随其结晶度和相对分子质量增加而减小。

The influences of process parameters of the loop reactor and gas phase reactor on the crystallization behaviour and mechanical properties of bimodal polyethylene resin were studied by high temperature liquid phase gel permeation chromatography （GPC） instrument, wide angle X-ray diffractometer （WAXD） and tensile strength tester. The results show that the erystallinity of the resultant polymer decreases with extending residence time in the loop reactor, while the crystallinity of the polymer decreases with decreasing the molar ratio of H2 to C2H4 arid increasing the molar ratio of 1-C4H8 to C2H4 and the allocation rate of the fluidized bed in the gas phase reactor. The tensile stress at yield and modulus of elasticity in tension of the bimodal polyethylene are reduced with the rise in the crystallinity and relative molecular mass of the resin.