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

本研究旨在阐明弹性体中微相分离结构在机械疲劳作用下的变化，开发高性能医用弹性体。在较宽的温度和频率范围内，通过静态和动态红外吸收二色性测量，研究了不同软段分子量的分段型聚脲（SPUU）的变形机理。结果表明：(1)软段的取向能力在高温和低频下均有所下降。这是由于在高温或低频下，通过降低软段矩阵中有效交联的数量来增加软段的有效长度。(2)高软段分子量的spu中硬段的负取向能力随温度升高而降低，而低分子量的负取向能力与温度和频率无关。这可以根据硬段区域内黏聚力的差异来解释。研究了主链中含有聚二乙基硅氧烷组分（PES）的分段聚氨酯（SPU）的力学和取向行为，揭示了以下事实：(1)从拉伸开始，硬段和软段都是正取向的，这与SPU完全不同。这可以解释为硬段的凝聚力较低。(2)力学和热性能随软段分子量的变化而有系统的变化。分子量越大，微相分离的完成度越高。(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.