FTIR研究交联聚氨酯脲弹性体的结构对动态性能的影响

用傅立叶变换红外光谱法(FTIR)研究交换PUU的结构指出,化学交联键的存在使得氢键化的NH吸收位置向高波数方向移动,同时羰基区内完全有序的氢键化脲羰基(1642cm-1)吸收较弱,完全有序的氨酯羰基(1693cm-1)吸收谱带观察不到.随着温度的升高,氢键化的NH吸收强度逐渐减弱,谱带吸收位置向高波数方向移动.FTIR结果揭示了交联PUU弹性体内部微相混合程度较线性PUU的高,交联PUU弹性体的回弹性在同温度下小于线性PUU的回弹性,随温度的升高,交联PUU弹性体极性键间的氢键化作用较易破坏,分子的柔顺性增加较快,交联PUU的回弹性增加幅度较大.交联密度越大,回弹性越小,压缩生热越大.硬段含量越高,材料的生热现象越严重.扩链剂的用量增加,对交联PUU的回弹性和压缩生热影响不大,但它显著地改善了PUU的疲劳性能.

INVESTIGATION OF THE EFFECT OF THE STRUCTURE ON THE DYNAMIC PROPERTIES FOR CROSSLINKED PUU ELASTOMERS BY FTIR

Investigation of structure for crosslinked PUU by FTIR showed that the band site for hydrogen bonded NH groups shifted to high wavenumbers,the absorbance of the band of carbonyl for ordered urea link at 1642 cm~(-1) was weaker than that of linear PUU,and the absorbance for the ordered urethane carbonyl wasn't observed in the spectrum for the crosslinked PUU,because of the presence of crosslinks.It was also observed that with the increase of temperature,the absorbance of hydrogen bonded NH group decreased,while its band site shifted to higher wavenumbers.The FTIR results revealed that the mixed degree of the micro hard phase was higher than that of linear PUU,the resilence of the crosslinked PUU was lower than that of the linear PUU,and with the increase of temperature,the hydrogen bond among the polar groups was easily destroyed,and the flexibility of the soft segment increased,and the enhance of the resilence for the crosslinked PUU was higher than that of the linear PUU.The higher the crosslink density,the lower the resilence of the PUU,and the heat buildup became strong with the increase of crosslink density and the hard segment content.However,the change of the extender molar ratio hardly affected the resilence and the heat buildup,but it did improve the flexible fatigue properties of the PUU elastomers significantly.