聚丁二酸丁二醇酯的自成核结晶行为

利用差示扫描量热仪(DSC)研究了自成核对聚丁二酸丁二醇酯(PBS)的结晶行为的影响. 研究结果表明, PBS的有效自成核温度处理区间为118～120 ℃. PBS经自成核处理后结晶温度提高, 可以在100~118 ℃温度区间内迅速结晶. 同时, 研究了自成核处理后样品在100～104 ℃范围内的等温结晶行为、动力学过程及熔融行为. 结果表明, 随着等温结晶温度的升高, 结晶速率变慢, 熔融曲线出现多重熔融峰. Hoffman-Weeks方程分析结果表明, 自成核处理对PBS的平衡熔点没有影响. Avrami等温结晶动力学方程适合分析自成核处理样品的等温结晶动力学过程, 获得其动力学参数K与n, 其中n值偏大的原因在于自成核的样品结晶生长点增多. 根据Arrhenius方程, 计算获得PBS自成核处理后等温结晶活化能为-286 kJ/mol.

Effect of Self-nucleation Process on Isothermal Crystallization Behavior of Polybutylene Succinate

Self-seeding nucleation technique can improve the nucleation efficiency of semi-crystalline polymers, reduce the crystal particle size and improve polymer performance. The appropriate temperature scope of self-seeding nucleation, the effect of self-seeding nucleation on crystallization and subsequent melting behavior of bio-degradable poly(butylenes succinate)(PBS)were studied by DSC. The results show that the suitable temperatures of self-seeding nucleation for PBS are scope of 118 ℃ to 120 ℃. The crystallization temperature of PBS increases obviously(about 20 ℃) after suffered the self-seeding nucleation process. Isothermal crystallization in the range of temperature between 100 ℃ and 104 ℃ after melting for 5min at 118 ℃ were investigated, and the isothermal crystallization kinetics were analyzed by Avrami equation. The results suggest that the Avrami equation also can be applied to analysis the isothermal crystallization process of self-seeding nucleation PBS samples and the relative parameters including K and n were calculated. The n value is high closing to 6, which results from the increasing of the growth point in crystal nucleus. The melting processes after isothermal crystallization were analyzed and the equivalent melting point of PBS was discussed by Hoffman-Weeks Equation. Multiple melting peaks can also be found on the heating DSC curves and there is no effect of the self-seeding nucleation process on equivalent melting point of PBS. Additionally, based on Arrhenius equation, the isothermal crystallization active energy of self-seeding nucleation PBS was calculated and the value was -286 kJ/mol.