聚醚氨酯的微区形态

<正> 聚醚氨酯热塑弹性体是属于(AB)n类型的线型多嵌段共聚物,包括交替的硬段和软段单元.自从1966年Cooper和Tobolsky首先提出聚氨酯具有微相分离的本体结构之假设以后,至今已有大量文献报道了这类材料结构形态与性能关系的研究结果. Wilkes和Koberstein等使用SAXS研究了聚氨酯体系的形态特征.一般认为,聚氨酯材料的微相结构包括一个叠层状或类似叠层状形态,由相分离的软段和硬段组成,平均尺寸为100A的数量级,在软硬段微区之间还存在一相混合的过渡区,其厚度可以从几个埃至几十个埃.然而,SAXS虽然能够高分辨地给出多相体系相分离情况的定

DOMAIN MORPHOLOGY OF POLYURETHANES

The microdomain morphology of a series of MDI/BDO/PTMG segmented polyurethane block copolymers has been observed by transmission electron microscope. The microdomain size ranging from several tens to a few hundreds A is in the same order with that measured from SAXS. The degree of the microdomain size dispersion increases with increasing the hard segment content in the copolymers. These observed microdomains can be considered as the basic morphology of the hard segment domains and the variation of their sizes and shapes can be related to the content and length distribution of the hard segments. The microdomains exhibit the tendency to aggregate and form the macrodom'ains which are larger in size (usually from several thousands A to a few μm) and usually were mistaken for the basic morphology of the hard-segment domains in previous publications.