软段分子量对氨纶的微相分离程度与拉伸性能的影响

分别采用分子量为1 400,1 800,2 200,2 600,3 000的不同聚四亚甲基醚二醇和4,4'–二苯基甲烷–二异氰酸酯反应,得到预聚体,用N,N–二甲基乙酰胺作为溶剂配制34.5%的预聚体溶液,后用乙二胺/丙二胺混合物扩链,制成纺丝原液。然后采用溶液干法纺丝得到5种氨纶样品,利用傅立叶变换红外光谱分析仪测试分析了上述样品的氢键化程度,再采用小角X射线系统和动态力学分析仪研究了软段分子量对氨纶的微相分离程度的影响,最后选择万能材料试验机测试其拉伸性能。结果表明:随着软段分子量增加,硬段含量减少,氨纶的氢键化程度、微相分离程度和断裂强力均为先增大后减小,在分子量为2 200时达到最大值;同时,断裂伸长率先减小后增大,在分子量为2 200时为最小值。

Influence of Molecular Weight of Soft Segment on Microphase Separation and Tensile Properties of Spandex

The prepolymer was obtained by the reaction of MDI and PTMG with different molecular weights (1400,1800, 2200,2600,3000),34.5% prepolymer solution was prepared with DMAc as solvent,and then spinning solution was prepared by expanding chain with EDA/PDA mixture. Then 5 kinds of spandex samples were obtained by dry spinning,the degree of hydrogen bonding of these samples was measured by Fourier transform infrared spectrometer. The influence of molecular weight of soft segment on the microphase separation of spandex was also studied by using small angle X ray system and dynamic mechanical analyzer. Finally,the universal material testing machine was selected to test its tensile properties. The results show that with the increase of molecular weight of soft segment,the content of hard segment decrease. Furthermore,the degree of hydrogen bonding, microphase separation and fracture strength of polyurethane all increase until molecular weights 2200 and then decrease. The elongation at break decrease until molecular weights 2200 and then increase with increasing molecular weight of soft segment.