辐照改性制备长支链型高熔体强度聚丙烯流变性能(Ⅱ)拉伸流变

通过辐照法制备了长支链型高熔体强度聚丙烯(LCB-HMSPP)，采用Rheotens熔体拉伸流变仪研究了辐照改性PP的熔体强度和拉伸流变行为，讨论了敏化剂含量、辐照剂量、高分子量物质和温度对PP拉伸流变行为的影响。研究结果表明：PP的熔体强度、拉伸应力、拉伸黏度等拉伸流变物理量随敏化剂增加而显著增强，并随辐照剂量呈先上升后下降的趋势，辐照剂量为5kGy时，熔体强度和拉伸黏度到达最大。添加极少量高分子量物质(UHMWPE)也能有效提高PP的熔体强度。LCB-HMSPP的熔体强度活化能显著降低，熔体强度温度敏感性下降，可在较宽的温度范围内表现出较高的熔体强度。

Rheological properties of high-melt-strength polypropylene with long-chain-branching structure prepared by 60Co-γ irradiation(Ⅱ)Extensional rheology

High-melt-strength polypropylene with long chain branching structure(LCB-HMSPP) was prepared by 60Co-γ ray irradiation in the presence of bi-functional monomerGttfert Rheotens extensional rheometer was used to characterize extensional rheological behavior of this LCB-HMSPPThe effects of sensitizer content, radiation dose, adding a small amount of high molecular weight component, as well as temperature were investigatedIt was indicated that melt strength, extensional stress and transient extensional viscosity were prominently enhanced after 60Co-γ ray irradiation. In addition, these extensional parameters increased with increasing sensitizer contentMelt strength, extensional viscosity reached a maximum when radiation dose approximately equaled to 5kGyAdding a small amount of ultra high molecular weight polyethylene(UHMWPE) could also play an important part in enhancing the extensional rheological behavior of PPThe activation energy of melt strength decreased with increasing sensitizer content and by adding a small amount of UHMWPELCB-HMSPP showed less temperature sensitivity than linear PP, and exhibited high melt strength, high extensional viscosity in a broad range of temperature.