聚氨酯的阻尼性能和形态结构的研究 Ⅰ.硬段分布对PPG -TDI-MOCA体系的影响

Study of the Damping Properties and Morphologies of Polyurethanes Ⅰ.Effect of the Hard Segments Arrangement on PPG-TDI-MOCA

研究了硬段的含量和交联度对PPG(聚氧化丙烯二醇) TDI(二苯基甲烷二异氰酸酯) MOCA(3,3′ 二氯 4,4′ 二氨基二苯甲烷)聚氨酯体系的动态力学性能的影响.结果表明:随着体系硬段含量的增加,材料的阻尼峰降低,而玻璃化转变温度变化较小;随着体系交联度的增加,聚氨酯在高温部分的阻尼因子提高,玻璃化转变温度向高温方向拓展,软段被"硬化";但当交联度过大时,软段间的链缠结较多,低温部分的阻尼因子下降.用原子力显微镜技术研究了硬段含量对PPG TDI MOCA体系的形态结构的影响,发现在硬段质量分数从28.43%增加到42.08%时,软段相区为连续相,但硬段微区的密度和尺寸明显增大,而且软硬段的界面变得清晰,相分离程度变大.

The polyurethanes with different contents of hard segment were synthesized from hydroxyl terminated polypropylene oxide oligomers, toluene diisocyanate(TDI) and 3,3′- dichloro-4,4′-dianilino methane (MOCA) as chain extender. Their dynamic mechanical properties measurements were carried out. It was found that with the increase of the content of hard segments, the glass transition temperature(T_(g) ) did not change and the value of the tanδ peak decreased linearly. For the polyurethanes extended by the mixture of trimethylolpropane(TMP) and MOCA, tanδ peaks shifted to higher temperature and increased in magnitude with the increase of degree of chemical cross-linking as the molar ratio of TMP and MOCA is in the range from 0∶1 to 1∶1. As the molar ratio is in the range from 1∶1 to 2.6∶1, the magnitude of tanδ further increased and T_(g) unchanged. At higher the molar ratio was higher than 2.6∶1, the tanδ decreased in magnitude. Atomic force microscope (AFM) measurements results showed that soft segments formed the only continuous phase when hard segment content was in the range from 28.43% to (42.08%.) The sizes of hard segment domains increased with increasing the hard segments content.