聚酰胺的长期紫外光氧老化行为

采用紫外光加速老化,研究了聚酰胺(尼龙6)在空气环境中的紫外光氧老化行为。结果表明,在光氧老化过程中,交联反应占主导地位,其凝胶含量和比浓黏度增加;复杂的氧化反应和材料的后期结晶使其力学强度有所升高,而冲击韧性下降;光氧老化使尼龙6端羧基含量增加,而端氨基含量减少;在老化中尼龙6分子与空气中氧气和氮气发生反应,但在试样最表层没有O-C=O结构存在。

The Long-Term Ultraviolet-Oxidative Aging Behavior of Polyamide

The long-term ultraviolet-oxidative accelerated aging behavior of polyamide(pure PA6 and stabilized PA6) was studied in the air environment.The results show that during the ultraviolet-oxidative process,the molecular cross-linking reaction of PA6 predominates,resulting in the increase of gel concentration and reduced viscosity of PA6.The complex oxidative reaction and secondary crystallization increase the tensile strength and bending strength of PA6 and decrease elongation at break and notch charpy impact strength of PA6.The end group analysis shows that ultraviolet-oxidative aging leads to the rise of the concentration of carboxylic acid and the decrease of the concentration of amine end group. The XPS analysis show that PA6 can react with N2 and O2 during aging,and there is no O-C=O group on the surface of samples.Compared with pure PA6,there is a relatively small change of the behaviors for the stabilized PA6,indicating of higher ultraviolet-oxidative stability.