PC及PC/ABS共混物的疲劳裂纹扩展研究

研究了聚碳酸酯(PC)和PC/ABS高分子材料的疲劳裂纹扩展规律,利用改进柔度法测量其裂纹扩展速率,采用扫描电子显微镜(SEM)观察其断口形貌,分析疲劳裂纹扩展机理.在较大裂纹扩展速率(10-6～10-3mm/cycle)范围内,PC/ABS的疲劳裂纹扩展速率可以用Paris公式da/dN=9·5587×10-5(ΔK)2·88381来描述.高分子材料PC的疲劳裂纹扩展速率约为高分子材料PC/ABS的3倍.高分子材料PC/ABS疲劳裂纹面上的特征以韧窝为主,较低裂纹扩展速率对应较小的韧窝,较高裂纹扩展速率对应较大的韧窝.高分子材料PC疲劳裂纹面有明显的不连续裂纹扩展带,其裂纹面相对较平.

FATIGUE CRACK GROWTH BEHAVIOR OF PC AND PC/ABS

The fatigue crack growth behavior of polycarbonate(PC) and the alloy of PC and acrylonitrile-butadiene-styrene(PC/ABS) is experimentally investigated in this paper.An improved compliance method is employed to measure the fatigue crack length of these polymers.The fatigue crack growth law from low(10-6 mm/cycle) to high(10-3 mm/cycle) growth rate is obtained for polymer PC/ABS,which could be fairly represented in terms of stress intensity factor through the well-known Paris law,i.e.da/dN=9.5587×10-5(ΔK)2.88381.The fatigue crack growth rate of PC is about two times higher than that of PC/ABS.Variation of the crack growth rate in the lower crack growth rate region is larger than that in the higher crack growth rate region.For PC/ABS,dimple features are observed on the fatigue fracture surfaces of PC/ABS alloy for the crack growth rate region tested in the experiment,which are coarser for larger crack growth rate,smoother for smaller crack growth rate.The fatigue crack surfaces for PC are smoother than that for PC/ABS,and discontinuous crack growth bands are observed.