不同端基及分子量聚氧乙烯的结晶行为研究

通过偏光显微镜和DSC技术，较为详细地研究了不同端基及分子量PEO的结晶行为，当PEO的分子量大于6000g/mol时，分子量对其结晶行为的影响逐渐变得很小，当分子量介于6000g/mol-2000g/mol时，为一临界分子量区，分子量变化对其结晶能力有很大的影响。氯乙基酯端基PEO链的折叠结晶受限较大，结晶度损失较大，而且，当分子量降至临界分子量区时，PEO结晶受限对端基体积更加敏感，结晶能力大大降低，羟基端基对结晶熔融焓（ΔHf)的影响与分子量的大小有强烈的关系，Tm仅随着端基体积的变大而下降。

CRYSTALLIZATION BEHAVIOR OF POLY(ETHYLENE OXIDE) WITH DIFFERENT MOLECULAR WEIGHTS AND END GROUPS

The crystallization of polymers, which is one of the most important ordering behaviors for polymers, has been an important topic in polymer physics for the past several decades. Chain folding in polymer lamella crystals is the key mechanism, which distinguishes polymer crystallization and morphology from that of small molecules. Most of studies were conducted on low molecular weight poly (ethylene oxide (PEO) fractions to help understand the polymer crystallization. The crystallization behavior of PEO with different end groups and molecular weights were reported. The crystallization ability of PEO studied was characterized with optical microscopy and DSC technologies. The experimental results show that the end goup of ClCH 2COO- can damage the crystallization of PEO more seriously than -OH end group, moreover, the extent of crystallization damage owing to end goup depends heavily on the molecular weight of PEO fractions. When the molecular weight of PEO fractions are higher than 6000 g/mol, the influence of end group on crystallization become very small. But, the end group can heavily decrease the degree of crystallization of PEO fractions, if the molecular weight of PEO decreases from 6000 g/mol to 2000 g/mol.