高压下聚甲醛和聚氧化乙烯的熔融温度测量

Melting Temperature Measurement of Polyoxymethylene and Poly(ethylene oxide) under High Pressure

研究聚合物在预置过冷度和压力下的结晶行为,前提条件是了解高压下聚合物的熔融和结晶温度。本文采用差热分析法测量了50~300 MPa压力范围内聚甲醛和聚氧化乙烯的熔融温度。实验表明聚甲醛和聚氧化乙烯的熔融温度随着压力的增加而升高,拟合的T_(m)(P)关系式分别为T_(m)(K)=441.2+0.1044P(MPa)和T_(m)(K)=345.1+0.1143P(MPa)。对回收样品进行XRD分析,发现100、200、300 MPa压力下聚甲醛和聚氧化乙烯熔体的凝固结构,具有与常压下熔体凝固相同的晶型,表明该相在300 MPa以内为稳定相。本文的实验结果为开展高压下聚甲醛和聚氧化乙烯熔体的结晶研究提供了参考。

The melting temperature and crystallization temperature under high pressure are of importance for studying the high-pressure crystallization and annealing of polymers. In this study, the melting temperature of polyoxymethylene(POM) and poly(ethylene oxide)(PEO) were measured by the differential thermal analysis method in the range of 50~300 MPa. It was found that the melting temperatures of POM and PEO increased with the increasing pressure. The fitted T_(m)(P) relationships were T_(m)(K)=441.2+0.1044P(MPa) and T_(m)(K)=345.1+0.1143P(MPa) for POM and PEO, respectively. The XRD analysis revealed that the recovered samples which crystallized under 100, 200 and 300 MPa had the same structure with that under ambient pressure, indicating that the structure of crystal phase is stable up to 300 MPa. The experimental results in this study provide reference data for the high-pressure crystallization and annealing of POM and PEO.