酸性介质对橡胶材料在盐雾环境下老化行为的影响研究

目的研究SO_2、稀硫酸两种酸性介质对橡胶材料在盐雾环境下老化行为的影响。方法以乙丙橡胶、丁腈橡胶为试验对象,分别以SO_2、稀硫酸为酸性介质,开展"SO2-盐雾"、"稀硫酸-盐雾"试验,利用宏观形貌观察、拉伸性能测试方法,结合扫描电子显微镜和傅里叶红外光谱技术,分析两种酸性介质对橡胶材料老化过程的影响。结果乙丙橡胶在"SO2-盐雾"复合环境中暴露48 h后,表面由紫色变为淡蓝色;暴露12d后,表面出现密集的脱落坑和长条状的粉化带,亚甲基含量略微降低,第三单体中,残余双键特征吸收峰消失。丁腈橡胶在"SO2-盐雾"环境中暴露12d后,橡胶断裂拉伸强度保留率降低至75%,聚合物中的酰胺键、亚甲基含量显著降低。结论"SO2-盐雾"复合试验对橡胶材料的侵蚀作用更加剧烈,丁腈橡胶暴露12 d后的断裂拉伸强度损失率比在"稀硫酸-盐雾"环境下高出14.39%。SO_2气体加速了橡胶中填充剂颗粒的析出、脱落过程,造成橡胶表面出现变色、脱落等缺陷,导致橡胶材料的拉伸性能降低。

Effect of Acidic Medium on Aging Behavior of Rubber Materials in Salt Fog Environment

Objective To study the effect of SO2 and dilute sulphuric acid on aging behaviors of rubber materials under salt spray environment. Methods With SO2 and dilute sulfuric acid as acid medium, SO2- salt spray and dilute sulfuric acid salt spray test were carried out with ethylene propylene rubber and butadiene-acrylonitrile rubber as the test objects. The aging effects of the two acidic media on the rubber materials were analyzed by means of macroscopic morphology observation and tensile property test, combined with SEM and FTIR. Results After exposure to SO2- salt spray for 48h, the surface of EPDM changed from purple to light blue; after exposure for 12 days, the surface appeared dense shedding pit and long strip pulverization, with the content of methylene content decreased slightly and the absorption peak of the residual double bond in the third monomer disappeared. After 12 days of exposure in the SO2- salt spray environment, the retention rate of tensile strength of NBR decreased to 75% with the amide bond and methylene content in the polymer decreased significantly. Conclusion The damage caused by SO2- salt spray test on rubber material is more intense. The loss rate of tensile strength of NBR exposed for 12 days is 14.39% higher than that under dilute sulfuric acid -salt spray environment. SO2 accelerates the precipitation and exfoliation process of filler particles in rubber, resulting in defects such as discoloration and shedding of rubber surface and the tensile properties of rubber materials reduced.