对苯二异氰酸酯基聚氨酯弹性体交联度对其形态与摩擦性能的影响

Effect of Molecular Cross-linking Degrees on the Morphology and Tribological Properties of 1,4-Phenylene Diisocyanate-Based Polyurethane Elastomers

聚氨酯弹性体的摩擦性能在诸如船舶、汽车、生物医用等领域具有十分重要的意义,而通过化学修饰策略实现该类材料摩擦性能的精细设计,仍具有十分迫切的研究需求和广泛的应用前景。本工作以对苯二异氰酸酯(PPDI)与聚四氢呋喃醚二醇(PTMG)为原料,通过调节1,4-丁二醇与三羟甲基丙烷两种扩链交联剂的混合比例,采用预聚体法合成了具备不同交联度的PPDI基聚氨酯弹性体。其中,傅里叶变换衰减全反射光谱(FTIR-ATR)、广角X射线衍射(WAXD)、差示扫描量热仪(DSC)等表征结果表明,聚氨酯弹性体中硬段和软段的结晶度随交联度的提升均呈下降趋势。同时,力学测试表明,材料的弹性模量随之降低,而PPDI基聚氨酯弹性体摩擦系数则明显增大。此外,滞后回环曲线表明,交联度的改变影响了PPDI基聚氨酯弹性体的阻尼特性,而聚氨酯弹性体阻尼的差异在其摩擦性能对速率的依赖关系中则有所体现。本工作由此提出,利用不同交联度下PPDI基聚氨酯中软硬段结晶度的变化,在对材料弹性模量和损耗模量进行可控调节的同时,能够实现对其摩擦性能的改变,为PPDI基聚氨酯弹性体的摩擦性能调控提供了一种简单有效的途径。

The friction properties of polyurethane elastomers are of great significance in areas such as marine,automotive,and biomedical applications. However,the fine design of friction properties of such materials through chemical modification strategies still has urgent needs in research and application prospects. In this work,p-phenylene diisocyanate（ PPDI） and polytetramethylene ether glycol（ PTMG） were used,and the PPDI-based polyurethane elastomers with different degrees of cross-linking were synthesized through varing the molar ratio of two chain extenders of 1,4-butanediol and trimethylolpropane. Results of the Fourier transform attenuated total reflection spectra（ FTIR-ATR）, wide-angle X-ray diffraction（ WAXD） and differential scanning calorimetry（ DSC） indicate that the crystallinity of both hard segment and soft segment in polyurethane elastomer is inhibited with the increase of cross-linking degree. Meanwhile,the results of mechanical test show that the elastic modulus of the material decreases,while the friction coefficient of PPDIbased polyurethane elastomer increases. In addition,the hysteresis loop curve shows that the change in the degree of cross-linking also affects the damping properties of the PPDI-based polyurethane elastomer,and the difference in the damping of the polyurethane elastomer is also reflected in the dependence of the friction performance on the rate. This work therefore proposes that by using different degrees of crossl-inking,the crystallinity of hard and soft segments in PPDI-based polyurethane can be changed,which leads to the difference in the elastic and the loss modulus of the material,and the friction properties can thus be controlled,which provides a simple-to-achieve and effective way for the regulation of frictional properties of PPDI-based polyurethane elastomers.