RIM聚氨酯脲的微相分离的DSC研究──硬段结构和含量对微相分离的影响

DSC Study of Microphase Separation in RIM Polyurethaneureas Elastomers──Effects of Hard Segment Structure and Concentration on Microphase Separation

用ＤＳＣ法研究了二乙基甲苯二胺和４，４＇－氨基二苯基甲烷（ＭＤＡ）扩链的硬段含量为２７％～６０％的两个系列的反应注射成型（ＲＩＭ）聚氨酯脲（ＰＵＵ）弹性体的微相分离。聚合反应动力学对ＲＩＭＰＵＵ的微相分离有很大影响．随着硬段浓度的增加微相分离程度下降，ＭＤＡ扩链系列聚合总反应速度快，微相分离驱动力弱，在硬段生成反应比软段生成反应快的条件下，该系列的微相分离程度较低。聚合总反应快，且硬段间氢键化作用很强的性质造成ＲＩＭＰＵＵ非平衡的形态。聚合总反应速度的增加相当于微相分离驱动力的下降。

The series of RIM(reaction injection molding) polyurethaneureas(PUU) based on urethane-modified 4,4'-diphenylmethane diisocyante,2000 molecular weight ethylene oxide endcapped poly(propylene oxide) polyether,and either diethyltoluene diamine(DETDA) or 4,4'-diphenylmethane diamine(MDA) were synthesized.The effect of hard segment structure and concentration on microphase separation has been studied by DSC.In this study,it is emphasized that polymerization kinetics plays an important role in the formation of phase structure in RIM PUU.The DSC results show that the extent of microphase separation decreases with the increase of hard segment concentration.A series of RIM PUU in which MDA is used as extender has the nature of faster overall rate of polymerization and weaker driving force for microphase separation,and the series of RIM PUU shows lower extent of microphase separation under the condition that reaction rate of hard segment formation is faster than that of soft segment formation in this paper.Non-equilibrium morphology is formed because of very fast overall rate of polymerization and the strong hydrogen bonding between hard segments.The increase of overall rate of polymerization corresponds to the decrease of driving force for microphase separation.Much further research is needed to clarify the nature of endothermic behavior from room temperature to about 200℃ in RIM PUU.