聚氨酯磨粒侵蚀的机理

研究了聚氨酯分别在含石英砂的清水、聚丙烯酰胺（ＰＡＭ）溶液和氢氧化钠溶液三种介质条件下，磨粒侵蚀过程中所发生的表面物理效应和表面化学效应。利用扫描电子显微镜（ＳＥＭ）、光电子能谱仪（ＸＰＳ）和傅立叶表面红外仪（ＦＴ－ＩＲ－ＡＴＲ）对聚氨酯在磨损前后的表面形貌、元素组成、结合能和官能团作了分析。发现聚氨酯磨粒侵蚀的物理效应是运动颗粒对材料表面的微切削、材料的高疲劳破坏以及塑性断裂，而表面化学效应主要有分子链断裂、热降解、水解和氧化降解。

MECHANISMS OF POLYURETHANE ABRASIVE EROSION

The physical and chemical effects of abrasive erosion on polyurethane surface in three different fluid mediums (H2O, PAM and NaOH) containing quart particles were investigated respectively. The surface profile, element constitutions, binding energies and functional groups of polyurethane surfaces before and after abrasive erosion were analyzed using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and fourier transform infrared spectrometer (FT-IR). The surface physical effects of abrasive erosion process were resulted from micro-cutting, high-cycle fatigue and plastic fracture. The surface chemical effects of polyurethane during abrasive erosion are resulted from (1) mechanical rupture of macromolecular chains and the position of fracture at the conjunctions of hard parts and soft parts, and also at the soft parts of macromolecular chains of polyurethane; (2) thermal decomposition of the ureldo-formic-ester groupo and the condensation-two-uraminoes groupo; (3) hydrolysis of cabamate groups;(4) surfacial oxidative degradation. The degree of hydrolysis in fluid mediums of PAM and NaOH is higher than that of H2O, and the main products are low molecular polymer containing some groups. The degree of oxygenation in fluid mediums of H2O is the most among the three different mediums.