多元醇对对苯二异氰酸酯基聚氨酯微孔弹性体的形态与性能影响

以对苯二异氰酸酯(PPDI)、1,4-丁二醇、水、聚四氢呋喃醚多元醇(PTMEG)和氢化端羟基丁二烯多元醇(HLBH)为原料,采用两步法制备出聚氨酯微孔弹性体样品。通过傅里叶变换衰减全反射红外光谱(FTIR-ATR)、动态机械分析(DMA)、差示扫描量热仪(DSC)、万能材料试验机等技术手段对样品的微相分离、耐低温性能、动态生热进行了系统表征。结果表明,两种多元醇结构对泡孔尺寸影响不大,微孔尺寸在100~300μm之间,其中以150μm尺寸左右的泡孔居多;HLBH制备的聚氨酯微孔弹性体硬段形成的氢键数量多于PTMEG制备的微孔弹性体,具有更好的微相分离;由于较好的微相分离结构,HLBH样品在-30~150℃具有很宽的模量平台区,而PTMEG样品受软段的低温结晶影响,在0℃以下模量急剧上升,HLBH样品低温下的刚度变化优于PTMEG样品;同时HLBH样品的滞后生热亦小于PTMEG样品,具有更好的动态疲劳性能。

Effect of Polyols on the Morphology and Properties of 1,4-Phenylene Diisocyanate-Based Microcellular Polyurethane Elastomers

Microcellular polyurethane elastomers were obtained by a two-step polymerization using 1,4-phenylene diisocyanate(PPDI), 1,4-butanediol(BDO), water, polyethylene tetrahydrofuran ether polyol(PTMEG) and hydrogenated hydroxyl-terminated butadiene polyols(HLBH) as raw materials. Fourier reflection infrared(FTIR-ATR), dynamic mechanical analysis(DMA), differential scanning calorimetry(DSC), universal material testing machine, dynamic fatigue testing machine were used to systematically characterize the microphase separation, low temperature resistance, dynamic heat build-up of the samples. The results show that the microcellular size of the specimens based on two polyols is 100~300 μm wherein the 150 μm is the majority, indicating that the structure of polyols has little influence on the microcellular size. Due to more H-bonds between hard segments, HLBH-based microcellular polyurethane elastomers show better microphase separation than that of PTMEG. There is a wide modulus platform region at -30~150 ℃ in the modulus-temperature curve for HLBH-based specimens due to its proper microphase separation structure. However, due to the crystallization of the soft segments at low temperature, the modulus of PTMEG-based specimens increases dramatically under 0 ℃. The stiffness of HLBH-based specimens surpasses that of PTMEG-based specimens at low temperature, and the hysteresis heat production of HLBH-based specimens is less than that of PTMEG-based specimens. Therefore, the former shows better dynamic fatigue performance.