温度循环老化对聚丙烯表面耐刮擦性能的影响

Effect of Temperature Cyclic Aging on Scratch Resistance of Polypropylene Surface

主要研究温度循环老化(1次温度循环老化试验为室温至90℃保持999min,然后自然冷却至室温保持0.5h)对聚丙烯(PP)材料表面耐刮擦性能的影响。通过拉伸试验、压缩试验、差示扫描量热分析和刮擦试验对PP力学性能、皮层结晶度和耐刮擦性能进行了测试。结果表明,在研究范围内,随温度循环次数的增加,PP材料拉伸和压缩性能变化幅度较小且呈无规律变化,而其耐刮擦性能包括刮擦深度随刮擦法向力增加的幅度以及相同法向力下的摩擦系数总体呈先明显升高而后趋于稳定的变化趋势,材料皮层结晶度则呈先降低而后趋于稳定的变化趋势,表明耐刮擦性能与皮层结晶度的变化趋势具有一定的相关性,即PP皮层性能对PP材料耐刮擦性能有重要影响。该结论对改善PP服役过程中耐刮擦性能有一定的指导意义。

The effects of temperature cyclic aging(one temperature cycle means that,firstly,the temperature rises from room temperature to 90℃,after holding for 999 minutes,the samples cool in the furnace to the room temperature for keeping 0.5 hour)on the scratch resistance of polypropylene(PP)surface were mainly investigated.Through tensile tests,compression tests,differential scanning calorimetry analysis and scratch tests,the mechanical properties,crystallinity of surface layer and scratch behaviors of PP were tested.The experimental results show that,with the increase of temperature cyclic times,the tensile and compressive properties do not show significant change within the scope of the study,and the changes are not regular.However,the scratch responses of PP,i.e.,the increment extent of scratch depth with increase of scratch normal force and friction coefficient under the similar normal force during scratch process,first show obvious increments and then tends to be stable generally.The crystallinity of surface layer decreases firstly and then tends to be stable.The change trends of the scratch responses have a certain relationship with the crystallinity of surface layer,which indicates the surface scratch resistance of PP is mainly influenced by the properties of surface layer of PP.This conclusion has certain guiding significance for improving the scratch resistance of polypropylene during its service.