DSC法测定聚乙烯结晶度的研究

Determination of Polyethylene Crystallinity by DSC

研究了用DSC法测定聚乙烯 (PE)结晶度的理论和新方法。通过X射线衍射 (WAXD)及常规DSC法对测得的不同PE的结晶度进行了对比 ,探讨了DSC技术对测定高聚物结晶度的合理性。通过调制式DSC(MDSC)对PE热容的研究 ,证明了在低温下存在着小晶片的熔融 ,进而能显著影响所测定的PE的结晶度。最后提出了由于PE结晶度的大小与环境温度密切相关 ,故用DSC技术测定其结晶度时 。

Theory and means of the determination of crystallinity of polyethylene by DSC was studied.By comparing the crystallinity data of WAXD and conventional DSC,the rationality of determination of polymer's crystallinity by DSC was discussed.It was verified that there exists small crystal's melting under lower temperature which can influence the crystallinity's experimental value considerably.The result can also be confirmed by measuring the heat capacity(C p) of related samples using modulated DSC(MDSC).It was pointed out that as PE's crystallinity values were closely related to their environmental temperature,it was very important to select the range of temperature of baseline on DSC curves when conducting the measurement on PE's crystallinity.