茂金属间规立构聚丙烯结晶动力学研究

用ＤＳＣ和密度法对茂金属间规立构聚丙烯（ｓＰＰ）样品进行了等温和非等温结晶动力学研究．测得平衡熔点Ｔ０ｍ为１５８℃，平衡熔融热焓ΔＨ０ｍ为３７ｋＪ／ｍｏｌ，侧表面自由能σ＝５２ｅｒｇ／ｃｍ２，折叠链表面自由能σｅ＝６９ｅｒｇ／ｃｍ２，链堆砌功ｑ＝３３７５ｋＪ／ｍｏｌ．对非等温结晶过程研究表明，由熔体结晶的ｓＰＰ具有非均相成核，三维球状生长机理．成核与生长活化能ΔＥ＝７３１ＫＪ／ｍｏｌ

ISOTHERMAL AND NON-ISOTHERMAL CRYSTALLIZATION KINETICS OF SYNDIOTACTIC POLYPROPYLENE

Isothermal and non\|isothermal crystallization kinetics of a syndiotactic polypropylene(sPP) sample synthesized by new metallocene catalyst at different annealing temperatures and different cooling rates have been investigated by using differential scanning calorimetry(DSC) and density analysis.The equilibrium melting temperature(T0m) is 158 by Hoffman\|Weeks method.The equilibrium heat of fusion(H0m) is 88J/g in terms of the density analysis and DSC methods. The lateral and end surface free energies derived from the Lauritzen\|Hoffman spherulitic growth rate equation are =5.2erg/cm\+2 and \-e=69erg/cm\+2, respectively. The work of chain folding is determined to be q=33.75kJ/mol. Modified Avrami equation and Ozawa equation can be used to describe the non\|isothermal crystallization behavior. And a new and convenient approach by combining the Avrami equation and Ozawa equation in a same crystallinity is used to describe the non\|isothermal behavior as well. The crystallization activation energies are evaluated to be 737kJ/mol and 731kJ/mol for isothermal crystallization and non\|isothermal crystallization, respectively. The Avrami exponent n is 1.51.6 for isothermal crystallization procedure, while the Avrami exponent n\-t is 2.53.5 for non\|isothermal crystallization procedure. This indicated the difference of nucleation and growth between the two procedures.\=