PP-g-AN对PP抗紫外老化效果评价及作用机理研究

Study on Anti-UV Aging Effect and Reaction Mechanism of PP-g-AN in PP/PP-g-AN blends

通过力学性能测试、扫描电子显微镜形貌分析等对PP接枝丙烯腈(PP-g-AN)的抗紫外老化效果进行了评价;采用紫外可见光(UV–VIS)吸收光谱、X射线光电子能谱(XPS)等对PP/PP-g-AN共混物中PP-g-AN的抗紫外老化可能的作用机理进行了研究。结果表明,PP-g-AN具有明显的抗紫外老化作用,紫外加速老化2 000 h后,PP/PP-g-AN共混物的拉伸强度为22.5 MPa,远高于纯PP的13.4 MPa。PP-g-AN在共混物中通过发挥两种作用来提高PP的抗紫外老化性能:一是氰基的基态-激发态-基态跃迁过程,释放能量;二是氰基反应成环后的共轭结构N N NN易发生自由基加成反应,能够捕捉自由基,减少PP吸收的自由基数目。

The effects of PP-g-AN on the PP / PP-g-AN blends were evaluated by the mechanical properties testing and SEM. PP / PP-g-AN blends were investigated by the UV- Visible（UV-VIS） absorbance spectrum and X-ray photoelectron spectroscopy（XPS） to confirm the possible anti-UV aging reaction mechanism. The results show that PP-g-AN has an obvious antiaging effect in the PP/PP-g-AN blends, the tensile strength reachs 22.5 MPa for PP/PP-g-AN blends and only 13.4 MPa for PP when aging 2 000 h. The possible reaction mechanism are discovered with two aspects： firstly, --CN transites from ground state to excited state and then goes back to ground state for releasing energy; secondly, the conjugate ring-structure generated by --CN will capture free radicals quickly by radical addition reaction, as a result that PP absorbs less free radicals.