软段对IPDI基透明聚氨酯弹性体微相结构与性能的影响

采用不同结构的软段、扩链剂l,4-丁二醇和异佛尔酮二异氰酸酯(IPDI)为主要原料合成了透明聚氨酯弹性体。研究了软段结构变化对聚氨酯弹性体的微相结构、力学性能、热稳定性及光学透明性的影响。结果表明,相对分子质量高的软段比相对分子质量低的软段更易结晶,耐低温性能更好;与聚氧四亚甲基二醇(PTMG)相比,聚酯型聚己二酸丁二醇酯二醇(PBAG)更易结晶。结晶尺寸在纳米级,材料的透明性可达85％以上。软段含量增加对软段区的结晶影响较小,但力学性能下降明显。混合多元醇的加入进一步提高了聚氨酯弹性体的微相分离程度,有利于软段结晶,在宏观上表现为拉伸强度和弹性模量明显增加。

Effect of Soft Segments on Microphase Structure and Properties of IPDI Based Transparent Polyurethane Elastomers

Transparent polyurethane elastomers (PU) were prepared based on different soft monomers-PBAG, PTMG or their combination, using isophorone diisocyanate (IPDI) as the crosslinker. DSC, WAXD and TG revealed that the nature and content of the soft monomers had effects on the microstruc-ture and properties of PU. It was showed that the larger chain length of the soft monomer resulted in higher degree of microphase separation, higher mechanical properties, better thermal stability, and enhanced cryogenic properties. Compared with PTMG, PU based on PBAG exhibited higher degree of microphase separation, better mechanical properties and thermal stability. When PBAG and PTMG were used in combination, even better mechanical properties were achieved owing to the increase in the degree of microphase separation. The crystal size of both soft- and hard-segments were at the nanometer scale which resulted in the high transparency of the PU elastomers.