材料期刊网

应用示差扫描量热计（DSC）研究了用低分子量聚乳酸（PDLLA）接枝与未接枝两种处理的纳米羟基磷灰石（n-HA）对聚乙丙交酯（PLGA）等温结晶行为及熔融行为的影响,采用Avrami方程处理其等温结晶过程,计算结晶动力学参数;同时用配带热台的偏光显微镜（POM）研究了其结晶的晶核形态。结果表明该体系等温结晶行为可以用Avrami方程来描述;加入n-HA的两种复合材料及PLGA其结晶最快的温度都是110℃,且都是随着结晶温度的提高结晶速率变慢,但接枝的n-HA对提高PLGA基体的结晶速率、熔点及结晶活化能都比未接枝处理的要小。偏光显微镜研究得出加入n-HA的两种复合材料及PL-GA其球径形态相似,且都随温度升高而使结晶速度降低,但加入未接枝的n-HA比接枝后的结晶更快。以上结果说明接枝处理后的n-HA提高了两相界面结合,因而n-HA的异相成核能力比未接枝处理的要差。

The influence of n-HA with surface grafted low molecular weight PDLLA on the isothermal rystallization and melting behaviour of PLGA were investigated by DSC.The Avrami equation had been used to analyze isothermal crystallization,and the correlative kinetics parameter values were given.Moreover,the crystal morphology of them were observed by a polarized optical microscopy（POM） with automatic hot-stage thermal unit.The results showed that the Avrami equation was suitable for describing the isothermal process in this system.The fastest crystallization temperature of the two n-HA/PLGA composites and PLGA were all at 110℃,and the crystallization rate slowed with increasing crystallization temperature.However,the surface grafting treatment of n-HA had a poorer effect on the crystallization rate,melting point and crystallization activiation engery of PLGA than that of the unmodified of n-HA.Besides,the POM results showed the crystal morphology of the two n-HA/PLGA composites and PLGA were similar,and the nucleation speed of them were all lower with the higher crystallization temperature.However,the n-HA/PLGA composites with unmodified n-HA particles displayed the highest nucleation speed among the three samples.It indicated that the un modified n-HA acted as an more effective heterogeneous nucleating agent than the surface grafting treatment of n-HA.All the results showed the surface grafting treatment of n-HA had better bonding interface,so that it had a poorer nucleating effect on the crystallization of PLGA,comparing with n-HA/PLGA composite filled with un modified n-HA.