聚乙二醇型聚氨酯软硬段对其相变储热性能的影响

以不同分子量的聚乙二醇(PEG)为软段,MDI-BDO为硬段,采用两步法溶液聚合合成一种具有固-固相变储热性能的聚氨酯材料.通过DSC,WAXD等测试手段对体系的软硬段结晶性,微相分离,相变可逆性及循环热稳定性进行研究,结果表明,聚氨酯中硬段的存在对软段结晶有着很大的影响,当软段分子量达到2000或以上时,软段才具有较大的结晶度和熔融相变焓,且硬段含量必须高于一定值才能形成较为完善的物理交联网络以保证材料在发生相变时维持固体状态.同时符合这两个条件的试样能具有较好的固-固相变储热性能.就软段PEG含量及分子量对材料储热性能的影响进行了研究,通过调节软段含量与分子量得到一系列具有不同相变焓和相变温度的聚氨酯固-固相变储热材料.经测试还发现,该材料具备很好的相变可逆性和循环热稳定性,是一类很有开发前景的相变储热材料.

EFFECT OF HARD AND SOFT SEGMENTS ON THE HEAT STORAGE PROPERTIES OF POLYETHYLENE GLYCOL-BASED POLYURETHANES

A series of novel solid-solid phase transition heat storage polyurethanes with various molecular weight PEG based soft segments and MDI-BDO based hard segments were synthesized by two-step solution polymerization.DSC,WAXD were used to study the crystallization of the soft and hard segments,microphase separation,phase transition reversibility and thermal cycling stability of the polyurethanes.The results indicated the crystallizability of soft segment was depressed by the introduction of hard segments in the polyurethane,and the soft segments were not able to crystallize until its average molecular weight was above 2000,and the hard segments were not able to form sufficient domains until its content reaching a certain value,those are the two essential conditions for the polyurethanes having good solid-solid phase transition heat storage properties.In addition,the effects of soft segment content and soft segment molecular weight on heat storage properties of the polyurethanes were also studied.The materials also show great phase transition reversibility and reasonably good stability throughout the cycling process and can be considered as promising phase change materials.