紫外加速老化对聚碳酸酯力学和光学性能的影响

Effect of ultraviolet accelerated aging on mechanical and optical properties of polycarbonate

为分析紫外加速老化对聚碳酸酯力学和光学性能的影响,采用实验室荧光紫外灯源暴露实验法,研究聚碳酸酯透光率、黄色指数、拉伸性能和弯曲性能随紫外辐照时间和辐照强度的变化规律。结果表明,聚碳酸酯的透光率随着辐照时间和辐照强度的增加而降低,延长辐照时间和增加辐照强度导致材料黄色指数增加。红外光谱显示,紫外加速老化使得聚碳酸酯内部生成有色基团,影响材料光学性能。聚碳酸酯的拉伸强度和断裂伸长率随着辐照时间和辐照强度的增加而降低,紫外加速老化导致材料受辐照面产生微裂纹和孔洞等缺陷,拉伸作用会使微小缺陷扩展并引发断裂。当受压面为辐照面,聚碳酸酯的弯曲强度随着辐照时间的延长和辐照强度的增加而升高,辐照面缺陷在受压状态下不易扩展并且增加了材料表面刚度,使得弯曲强度提高。聚碳酸酯的拉伸模量和弯曲模量受老化时间和辐照强度影响较小,这是因为紫外加速老化对分子量影响较小。

In order to explore the effect of accelerated UV aging on the mechanical and optical properties of polycarbonate, the changes of polycarbonate’s transmittance, yellow index, tensile properties and flexural properties with aging time and radiation intensity were studied by using the method of exposure to laboratory fluorescent ultraviolet lamps source. The results show that the light transmittance of polycarbonate is decreased with the increase of UV aging time and radiation intensity. According to FT-IR, several colored groups are created in polycarbonate because of prolonging the aging time and increasing the radiation intensity, which affects the optical property of polycarbonate. The tensile strength and elongation at break of polycarbonate are decreasd with the increase of UV aging time and irradiation intensity. The microcracks and holes on surface of polycarbonate are produced by longer aging time and higher radiation energy, which expand under tensile load and cause fracture. The flexural strength of polycarbonate is increased with the increase of UV aging time and irradiation intensity if the testing surface is irradiated. The degradation layer formed on the surface of the material increases the stiffness of polycarbonate, which leads to the increase of strength. The tensile modulus and bending modulus of polycarbonate are less affected by aging time and irradiation strength because UV accelerated aging has little effect on molecular weight.