热塑性聚酰亚胺热转变行为研究

Thermal Transition Behavior for Thermoplastic Polyimide

采用凝胶渗透色谱(GPC)测定一种热塑性聚酰亚胺(TPI)的分子量及其分布;利用差示扫描量热仪(DSC)测定TPI的玻璃化转变温度(Tg);考察了分子量大小、热处理温度和热处理时间对玻璃化转变温度的影响。结果表明:Tg随数均分子量的增大而增加,采用Kanig-Ueberreiter方程关联Tg与数均分子量,其线性拟合度最高;由于聚酰亚胺的结构特点———存在自由端基,在高温可发生固相热环化反应,相应其分子量随处理温度的升高和处理时间的延长而增大,表现为聚合物的Tg有所升高。

Molecular weight and molecular weight distributions of thermoplastic polyimide （TPI） were measured by GPC（Gel Permeation Chromatography）. And the glass transition temperature （Tg） of TPI was analyzed by DSC. The effect of factors, such as molecular weight, heat treated temperature and heat treated time, on Tg was also considered. The results showed that Tg was increased with the molecular weight, and the Kanig-Ueberreiter equation provided a good fit to Tf and number average molecular weight. Due to the PI structure feature--having the free end group, solid therm-cyclization could be carried out at high temperature. Accordingly, the molecular weight was increased with the heat treated temperature and time, and then, Tg was increased.