不同异氰酸根指数对水性聚氨酯结构和性能的影响

Effect of Different Isocyanate Indexes on Structure and Properties of Waterborne Polyurethane

以聚碳酸酯二醇(PCDL)为软段,异佛尔酮二异氰酸酯(IPDI)为硬段,4,4′-二羟甲基丙酸(DMPA)为亲水扩链剂,三乙胺(TEA)为中和剂,水合肼(HZ)为扩链封端剂,采用预聚体缩聚法制备出含不同异氰酸根指数(R值)的水性聚氨酯。通过X射线衍射仪(XRD)、差示扫描量热仪(DSC)、热失重分析仪(TG)、接触角、力学性能等来研究不同R值对水性聚氨酯结构和性能的影响。结果表明,在氮气保护下,不同R值的水性聚氨酯薄膜在5%、20%时的热失重率变化不大,水性聚氨酯薄膜的分解主要为硬段和软段两部分的分解,且软段的玻璃化转变温度(T g)随着R值的增加而降低,有利于水性聚氨酯微相结构的分离。当R值为1.5时,水性聚氨酯薄膜的拉伸强度为45 MPa,断裂伸长率为423%,具有优异的力学性能。

The prepolymer polycondensation method was used to prepare waterborne polyurethanes with different isocyanate indexes(R values),taking the polycarbonate diol(PCDL)as the soft segment,isophorone diisocyanate(IPDI)as the hard segment,4,4′-dimethylolpropionic acid(DMPA)as the hydrophilic chain extender,triethylamine(TEA)as a neutralizing agent,and hydration incorporation(HZ)as a chain extension terminal blocking agent.The different R values on the structure and properties of waterborne polyurethane were characterized by Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),differential scanning calorimetry(DSC),thermogravimetric analyzer(TG),contact angle,mechanical properties and so on.The results show that the thermal weight loss values of waterborne polyurethane films with different R values at 5%and 20%do not change much under nitrogen atmosphere.The decomposition of the waterborne polyurethane film is mainly the hard segment and the soft segment,and the glass transition temperature(T g)of the soft segment decreases with the increase of R value,which is beneficial to the separation of the waterborne polyurethane microphase structure.When the R value is 1.5,the tensile strength of the waterborne polyurethane film is 45 MPa,and the elongation at break is 423%,which has excellent mechanical properties.