Rheo-Optical Studies on High Performance Elastomers for Medical Use.

本研究的目的是阐明机械疲劳引起的弹性体微相分离结构的变化，开发高性能医用弹性体。通过静态和动态红外吸收二色性测量，研究了不同软段相对分子质量的嵌段聚氨基甲酸乙酯S在较宽的温度和频率范围内的变形机理，发现：(1)在高温或低频下，软段的取向能力降低。这是由于在高温或低频条件下，通过降低软段基质中的有效交联数，增加了软段的有效长度。(2)高软段分子量的SPUU硬段负取向能力随温度升高而降低，而低分子量SPUU的负取向能力与温度和频率无关。这可以基于硬段领域内聚力的差异来解释。研究了主链上含有聚二甲基硅氧烷(PES)的嵌段聚氨基甲酸酯(SPU)的力学行为和取向行为，发现：(1)硬段和软段从拉伸开始都是正向取向的，这与SPUU完全不同。这可能是由于硬段的粘聚力较低所致。(2)随着软段相对分子质量的增加，其力学和热学性质发生了系统的变化。相对分子质量越高，微相分离的完成程度越高。(3)软段中的PES组分降低了PTMG的结晶能力，但提高了软段和硬段之间微相分离的完成程度。

It was the purpose of this research to clarify change of microphase separated structure in elastomers due to mechanical fatigue and to develop high performance elastomers for medical use.1. Static and dynamic infrared absorption dichroism measurements were performed in order to study the deformation mechanism of segmented poly (urethaneurea) s (SPUU), having different soft segment molecular weights, over a wide range of temperatures and frequency, and the following facts were disclosed :(1) The capability of orientation for the soft segments decreases at high temperature or low frequency. This is due to increase in the effective length of the soft segments by lowering the number of effective cross-links in the soft segment matrix at high temperature or low frequency.(2) The capability of the negative orientation of the hard segments in SPUU having high soft segment molecular weight decreases with increasing temperature but that of low molecular weight does not depend either temperature or frequency. This can be explained based on differences in cohesive force in hard segment domains.2. The mechanical and orientation behavior of segmented polyurethan (SPU) with a polydinethylsiloxane component (PES) in the main chain was investigated, and the following facts were disclosed :(1) Both hard and soft segments are oriented positively from the beginning of stretching, which is completely different from SPUU. This can be explained by low cohesive power of the hard segments.(2) Systematic variations in the mechanical and thermal properties were found with the soft segment molecular weight. The higher the molecular weight, the higher the degree of completion in microphase separation.(3) The PES component in the soft segment reduces the capability of crystallization of PTMG but raises the degree of completion in microphase separation between the soft and hard segments.