A comparison study on the melt crystallization kinetics of long chain branched and linear isotactic polypropylenes  

作　　者：ZENG Wei LIU JiChun ZHOU JunFeng DONG JinYong YAN ShouKe 

机构地区：[1]Beijing National Laboratory for Molecular Sciences, and Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China [2]State Key Laboratory of Polymer Physics and Chemistry and Key Laboratory of Engineering Plastics, Chinese Academy of Sciences, Beijing 100080, China [3]Key Laboratory of Polymer Science and Nanotechnology, College of Chemical Engineering and Pharmaceutics, Henan University of Science and Technology, Luoyang 471003, China

出　　处：《Chinese Science Bulletin》2008年第2期188-197,共10页

基　　金：the Outstanding Youth Fund and the National Natural Science Founda-tion of China (Grant Nos. 50521302, 20574079 and 20423003)

摘　　要：The isothermal and non-isothermal crystallization kinetics of LCBPP and linear-iPP was investigated by optical microscopy and differential scanning calorimetry (DSC). The optical microscopy results in the isothermal crystallization process show that the crystals of LCBPP grow slower than the crystals of the linear-iPP. This originates from the low chain mobility, or in other words, the lower chain diffusion rate of LCBPP due to the existence of long side chains. The DSC results in the isothermal crystallization process show that the LCBPP exhibits, however, a higher overall crystallization rate with respect to the linear-iPP. This is related to the higher nucleation ability of LCBPP since the isothermal crystallization process of both LCBPP and linear-iPP are nucleation-dominated. Avrami analysis indicates that the nucleation nature and crystal growth manner of LCBPP and linear-iPP are about the same. The analy- ses of the non-isothermal crystallization processes indicate an increment in crystallization rate with increasing cooling rate. But at any cooling rate, the linear-iPP crystallizes more quickly than the LCBPP. This implies that the non-isothermal crystallization processes of LCBPP and linear-iPP are diffu- sion-dominated, in which the lower chain diffusion rate of LCBPP results in the slower crystallization of it.The isothermal and non-isothermal crystallization kinetics of LCBPP and linear-iPP was investigated by optical microscopy and differential scanning calorimetry （DSC）. The optical microscopy results in the isothermal crystallization process show that the crystals of LCBPP grow slower than the crystals of the linear-iPP. This originates from the low chain mobility, or in other words, the lower chain diffusion rate of LCBPP due to the existence of long side chains. The DSC results in the isothermal crystallization process show that the LCBPP exhibits, however, a higher overall crystallization rate with respect to the linear-iPP. This is related to the higher nucleation ability of LCBPP since the isothermal crystallization process of both LCBPP and linear-iPP are nucleation-dominated. Avrami analysis indicates that the nucleation nature and crystal growth manner of LCBPP and linear-iPP are about the same. The analyses of the non-isothermal crystallization processes indicate an increment in crystallization rate with increasing cooling rate. But at any cooling rate, the linear-iPP crystallizes more quickly than the LCBPP. This implies that the non-isothermal crystallization processes of LCBPP and linear-iPP are diffusion-dominated, in which the lower chain diffusion rate of LCBPP results in the slower crystallization of it.

关 键 词：聚丙烯 长链分岔 线性全规聚丙烯 结晶动力学 

分 类 号：TQ325.14[化学工程—合成树脂塑料工业]