利用SSA热分级技术研究共聚甲醛序列结构

连续自成核热退火技术(SSA)可以根据聚合物结晶序列长度进行选择性结晶热分级,选取四种结构组成相似但热稳定性不同的共聚甲醛(CPOM)试样,通过DSC,TG,~1H NMR、HCHO含量(GM值)以及SSA热分析技术研究了CPOM的热稳定性与其结晶序列分布之间的关系。表征结果显示,结晶性能参数主要受共聚单体含量影响;结晶链段分布窄,共聚单体分布更均匀,CPOM的GM值更小,热加工稳定性更好;含有不稳定端基,以及共聚单体分布不均匀会导致GM值偏高;SSA热分级结果与GM值之间有较好的对应关系。

Study on sequence distribution of copolyoxymethylene through SSA techniques

The successive self-nucleation and annealing(SSA) thermal fractionation technique offers a practical way to evaluate the chain crystallization behavior according to the length of polymer crystalline sequence. In this paper,four copolyoxymethylene(CPOM) samples with similar comonomer content and different thermal stabilities were chosen,and the relationships between thermal stability and crystalline sequence distribution were studied by DSC,TG,1H NMR,HCHO content(GM value) and SSA technique. The results showed that crystallization performance parameters were mainly affected by comonomer contents;SSA analysis results showed that the CPOM sample with more narrow crystallization sequence showed better thermal stability and lower GM value. The main factors lead to high GM value is due to the presence of unstable end groups and uneven distribution of comonomers. There was a good correspondence between SSA analysis results and GM values.