The Effect of Diisocyanate Isomer Composition on Optical and Adhesive Properties of Polyurethanes Based on 4,4-dicyclohexyl Methane Diisocyanate
Polyurethanes wereprepared having 47 wt ％ hard segments based on 4,4-dicyclohexyl methane diisocyanate (H12MDI) with trans, trans isomer contents in the 16 to 99 mol ％ range and 1,4butanediol chain extender. The soft segments is polytetramethylene glycol (PTMEG, Mw 1000). H12MDI with 25, 40, 60, 80 and 99％ trans,trans isomer contents were obtained from commercial H12MDI (16％ trans, trans) by fractional crystallization, and all polyurethanes were prepared by a two-step bulk polymerization procedure. The polyurethanes based on H12MDI with trans,trans contents of 40％ or higher yielded materials insoluable in N,N-dimethylformaide (DMF) and were generally opaque. Mechanical properties, such as tensile strength at break, decreased with increasing trans,trans content, while the Youngs modulus and Shore hardness increased. A decrease in adhesion strength is produced when content of t,t-H12MDI is above 25％. Wide-angle and small-angle X-ray scattering at room temperature were employed to characterize phase morphology. The mean macrolattice spacings between stiff fragments (STF) decreased in the order t,t-H12MDI-0.16 > t,t-H12MDI0.25 > t,t-H12MDI-0.40 > t,t-H12MDI-0.60 > t,tH12MDI-0.80 > t,t-H12MDI-0.99.
polyurethanes transparency elastomers morphology adhesion dicyclohexyl methane diisocyanate interlayer
Hou Junxian Li lei Liu Weidong Yan Yue Chen Xiangbao
Beijing Institute of Aeronautical Materials, Beijing 100095, China Beijing Institute of Aeronautical Materials,Beijing 100095, China
国际会议
2010 Asia-Pacific International Symposium on Aerospace Technology(2010 亚太航空航天技术研讨会 APISAT 2010)
西安
英文
885-887
2010-09-01（万方平台首次上网日期，不代表论文的发表时间）