扩链剂结构对PTMG/MDI型聚氨酯结构和性能的影响

Influence of Chain Extender Structure on Structure and Properties of PTMG/MDI Type Polyurethane

以聚四氢呋喃醚二醇(PTMG)为软段,4,4′-二苯基甲烷二异氰酸酯(MDI)为异氰酸酯组分,分别以1,4-丁二醇(BDO)、二乙二醇(DEG)和对苯二酚二羟乙基醚(HQEE)为扩链剂,合成了3种聚氨酯(PU)试样,即BPU、DPU和HPU。通过傅里叶红外光谱仪(FTIR)、力学测试仪器、扫描电子显微镜(SEM)、差示扫描量热仪(DSC)、旋转流变仪、维卡软化点测试仪和热重分析仪对3种试样的结构和性能进行测试表征。结果表明,HPU的微相分离程度和结晶程度最高,其邵A硬度和撕裂强度最大,分别为94.4 HA和118.3 N/mm;BPU的微相分离程度和结晶程度居中,其100%定伸模量、拉伸强度、断裂伸长率和冲击弹性最大。HPU的耐热变形性能最优,其维卡软化温度可达165.6℃。含有醚氧键的扩链剂(DEG)减弱了PU的微相分离,并且,热稳定性下降,而含有苯环的扩链剂(HQEE)能促进PU的微相分离,并提升热稳定性。

1,4-butanediol(BDO),diethylene glycol(DEG) and hydroquinone dihydroxyethyl ether(HQEE) were used as chain extenders respectively,and three kinds of polyurethane(PU) samples were prepared by using polytetramethylene ether glycol(PTMG) as the soft segments and 4,4'-diphenylmethane diisocyanate(MDI) as the hard segments,namely BPU,DPU and HPU.The structure and properties of the three samples were characterized by Fourier infrared spectrometer(FTIR),mechanical testing instrument,scanning electron microscope(SEM),differential scanning calorimeter(DSC),rotary rheometer,vicat softening point tester and thermogravimetric analyzer.The results showed that HPU had the highest degree of microphase separation and crystallization,and its Shore A hardness and tear strength were the largest among the three PU,which were 94.4 HA and 118.3 N/mm,respectively.BPU had the middle degree of microphase separation and crystallization,and its 100% constant modulus,tensile strength,elongation at break and impact elasticity were the largest.HPU had the best heat deformation resistance,and its vicat softening temperature was 165.6 ℃.The chain extender containing ether oxygen bond(DEG) could weaken the microphase separation and deteriorate the thermal stability of PU,while the chain extender containing benzene ring(HQEE) could promote the microphase separation and improve the thermal stability of PU.