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通过光学显微镜(OM)和差示扫描量热仪(DSC)对长链支化聚丙烯(LCBPP)和线性等规聚丙烯(Linear-iPP)的等温及非等温结晶动力学作了详细的研究.OM结果显示:在等温结晶过程中,由于LCBPP中长支链的存在阻碍了链段的扩散,导致其晶体生长速度比Linear-iPP的慢.然而,DSC结果显示:在等温结晶过程中,LCBPP的结晶总速度比Linear-iPP的要快得多.这是因为对于两种PP来说,等温结晶过程都是一个成核控制的过程,LCBPP较快的成核速度导致了它的结晶总速度较快.Avrami分析指出,LCBPP和Linear-iPP具有相近的成核和生长机制.而在非等温结晶过程中,随着降温速度的加快,两种PP的结晶速度均加快,但是在任何一个对应的降温速度,Linear-iPP的结晶速度都要快于LCBPP.这意味着对两种PP来说,非等温结晶过程是一个生长控制的过程,LCBPP较慢的链段扩散速度导致了其较慢的结晶总速度.
The isothermal and non-isothermal crystallization kinetics of long-chain branched polypropylene (LCBPP) and linear-isotactic polypropylene (Linear-iPP) were studied in detail by optical microscopy (OM) and differential scanning calorimetry (DSC) .OM results show that: in the isothermal crystallization process, due to the existence of long chain branches in LCBPP hindered the diffusion of the segment, resulting in its crystal growth slower than Linear-iPP However, DSC results show that: in the isothermal crystallization process, The total crystallization speed of LCBPP is much faster than that of Linear-iPP because the isothermal crystallization process is a nucleation-controlled process for both PPs and the faster nucleation rate of LCBPP leads to its total crystallization Speed.Avrami analysis pointed out that LCBPP and Linear-iPP have similar nucleation and growth mechanism.In non-isothermal crystallization process, with the accelerated cooling rate, the crystallization rate of the two PP are accelerated, but in any one For the two PPs, the non-isothermal crystallization process is a growth-controlled process, and the slower chain segment diffusion rate of LCBPP leads to a slower rate of crystallization than the LCBPP of Linear-iPP Slow total crystallization speed.