Butyl Rubber-Aluminum Adhesion: The Effect of Acidic and Alkaline Environments on Adhesion Strength

Butyl rubber as a commercial elastomer has got many applications in various products such as tires, protective clothes, sealants, hose (steam and automotive), inner coating of tanks, etc. Considering these usages, butyl rubber might be subjected to acidic or alkaline environments. Acid and alkaline materials can diffuse through the rubber and cause degradation of its structure which leads to deterioration of rubber properties including adhesion strength. In this study, the effects of environments having different pH values on adhesion strength between rubber compounds-based on butyl rubber and bromobutyl rubber-and aluminum surface are investigated. Samples were immersed in solutions with different pH values of 0.7, 3, 7, 11 and 13.7. By conducting tensile and tack tests, changes in adhesion strength and tackiness property of samples are studied. Considering the broad range of examined pH values, results demonstrate that solutions with more acidic and alkaline pH values severely reduce adhesion strength and leads to about 60% reduction in adhesion. However, pH values closer to neutral pH have a less negative effect and cause up to 49% decrement in adhesion strength. Furthermore, Samples which were immersed in alkaline solutions lost their tackiness property, whereas the samples which were immersed in acidic solution retained their tackiness. However, in these cases, tack property was reduced to 1/7 of its value before being immersed in the acidic solution.