广角X-射线衍射对PET结晶度的研究

应用广角X-射线衍射(WAXD)来测定高聚物的结晶度可以分为相对法(CCI、ICI)与绝对法(HWM、CPRM、Ruland)两大类,但长期以来在文献上这些方法得出的结果往往差别很大,而且WAXD与其它的方法,如DSC、ρ、NMR、IR等往往也不相一致。本文就此两问题进行了系统的研究,不仅对WAXD与DSC、ρ测定结晶度的可靠性进行了讨论,更对WAXD的各种方法中,2θ应选的范围、是否应作校正、非晶散射如何扣除、相对法自身之间的关系、各种绝对法之间的关系、相对法与绝对法的关系等进行了仔细的研究。结论是:WAXD在可靠性与重复性方面优于DSC与ρ法,而且是其它方法的根据;绝对法优于相对法,各种绝对法有利有弊,而非晶散射的合理分离是最为关键的问题。

STUDIES ON THE CRYSTALLINITY OF PET BY WAXD

There are two kinds of methods to measure the crystallinity of polymers by WAXD-the relative method (CCI, ICI) and the absolute method (HWM, CPRM, Ruland-M). The results of various methods in the literature are often different. Results of WAXD also disagree with those of other methods (p, DSC, NMR FT-IR etc.). The present work investigated systematically on the differences between WAXD and DSC, p, the choice of 29 range, the effects of various corrections, the separation of amorphous scattering and the comparison between the relative method and the absolute methods etc. It is concluded that WAXD is better than DSC and p, the absolute methods are better than the relative methods and each absolute method has its advantage and shortage. The key problem still is the separation of amorphous scattering from the total scattering.