双开关温敏聚氨酯膜的制备及其透汽性

合成了3种温敏聚氨酯，并对不同的温敏聚氨酯共混体系的开关温度阀值(即软段相的转变温度)进行研究，探讨了双开关温敏聚氨酯膜的制备方法。结果表明：软段相组成和结构相似的TSPU(a)与TSPU(b) 的共混物仅具有1个开关温度；而软段相组成和结构不同的TSPU(a)与TSPU(c)共混物具有2个独立的开关温度。对共混膜的透汽性研究发现，在开关温度前后，共混膜的透汽性均发生了显著变化。其中：TSPU(a)与TSPU(b) 的共混膜只表现出单温度开关的特征；而TSPU(a)与TSPU(c)共混膜表现出双温度开关的特征。采用软段组成和结构不同的温敏聚氨酯共混，是获得双开关温敏聚氨酯膜的有效途径。

Preparation of polyurethane membrane with dual switch temperature sensitivity and its moisture vapor permeability

Three types of thermal sensitive polyurethane (TSPU) were synthesized, and the switch temperatures (the phase transition temperature of soft segment defined as switch temperature) of TSPU blends were investigated, along with preparation of polyurethane membrane with dual switch temperature sensitivity. The study indicates that the blend (TSPU(a) and TSPU(b)) with the similarity of constitution and structure in soft segment, has just a new switch temperature. However, the blend (TSPU(b) and TSPU(c)) with different constitution and structure in soft segment shows two independent switch temperature. According to moisture vapor permeability (MVP) analysis, it is found that when the temperature exceeded the switch temperature, the MVP of all the blends of TSPU changed markedly. Moreover, the blend of TSPU(a) and TSPU(c) shows just one switch temperature characteristic for MVP, but the blend of TSPU(b) and TSPU(c), shows dual switch temperature characteristics for MVP. So, it is believed that it is an efficient approach to preparing TSPU membrane with dual different switch temperatures by means of blending two types of TSPUs with different soft segments.