表面直接氟化改性对有机玻璃弯曲疲劳性能的影响

本文使用表面直接氟化改性来改善有机玻璃的弯曲疲劳性能。测试了改性前后有机玻璃的断裂韧性与弯曲强度，重点研究了不同缺口形式的有机玻璃在改性前后的弯曲疲劳性能变化并分析了疲劳裂纹扩展过程。弯曲疲劳寿命的测定结果表明有机玻璃的疲劳性能在表面直接氟化改性后得到明显改善，表面氟化层的结构约束效应是有机玻璃疲劳寿命提高的主要原因。此外，在疲劳断裂面上观察到规律性的条纹带形貌，疲劳条纹带的形成与裂纹尖端银纹区的产生具有一定的联系。表面直接氟化改性后疲劳条纹带扩展速率的降低也充分证明了有机玻璃疲劳寿命的提高。研究结果证明，表面直接氟化改性修复是一种提高有机玻璃疲劳性能的可行方法，对有机玻璃的工业使用具有指导意义。

Effect of Surface Modification by Direct Fluorination on Bending Fatigue Behaviors of Poly (Methyl Methacrylate)

The surface direct fluorination was utilized in this paper to improve the bending fatigue behavior of Poly (methyl methacrylate) (PMMA). The effect of the surface direct fluorination on the fracture toughness and bending strength of PMMA were firstly tested. Then the bending fatigue behaviors, including the fatigue life as well as the fatigue crack propagation process of PMMA with different types of pre-notch before and after surface direct fluorination were comprehensively studied. The experimental result of the bending fatigue life showed that the fatigue performance of PMMA was improved significantly after surface direct fluorination, which was accounted for the structural constraining effect of the fluorinated surface layer. In addition, the evolution of the regular striation morphology on the fatigue fracture surface was found to be correlated to the occurrence of the craze at the crack tip. As another evidence of the improvement of the fatigue life of PMMA, the propagation rate of fatigue striation decreased obviously after the surface direct fluorination. This work showed that the surface direct fluorination is a feasible approach to improve the fatigue property of PMMA, which provided useful guidance for substantial industrial application.