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Studies on segmented polyurethane—urea elastomers: Structure and properties of segmented polyurethane—ureas having the binary hard segment components

 

作者: Hideaki Ishihara,  

 

期刊: Journal of Macromolecular Science, Part B  (Taylor Available online 1983)
卷期: Volume 22, issue 5-6  

页码: 763-782

 

ISSN:0022-2348

 

年代: 1983

 

DOI:10.1080/00222348308245754

 

出版商: Taylor & Francis Group

 

数据来源: Taylor

 

摘要:

Studies on the structure and properties of segmented polyurethane-ureas having binary hard segment components have been made using infrared dichroism, small-angle x-ray diffraction, and mechanical testing. The results clarify the effect of the domain structure of the hard segments on the mechanical hysteresis behavior of the segmented polyurethane—urea elastomers. Experiments were carried out for film specimens prepared from poly(tetramethylene glycol), 4, 4'-diphenylmethane diisocyanate, and chain extenders such as ethylenediamine and hydrazine. The domain structures of the hard segments were controlled by blending segmented polyurethane-ureas having different chain extenders. The chain-extending reactions were conducted both simultaneously and in a stepwise manner during polymerization using two different chain extenders. The experimental results revealed that the mechanical hysteresis greatly decreased for the specimens of segmented polyurethane-ureas with binary component hard segments which were randomly copolymerized using the mixture of two different chain extenders. It is suggested that the decrease of hysteresis is related to the microdomain structure of segmented polyurethane-ureas composed of small fragments of lamellae. The small lateral size is caused by the restriction of crystal growth in the direction of hydrogen bond formation due to the heterogeneous hard segment components. This hysteresis phenomenon could be verified by the fact that the transverse orientation of the hard segments decreased in the case of the segmented polyurethane-ureas having randomly copolymerized hard segments. To impart the property of ideal rubber elasticity to segmented polyurethane-urea, it is deduced that it is important to control the hard segment domain structure so that it does not form higher-order structures such as lamellae of large lateral size.

 

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