Adhesion of Synthetic Rubbers to Various High Molecular Substrates

In previous work the adhesion of certain synthetic rubbers to cellophane was investigated. In the present paper we present the results of determination of the adhesion of a considerably larger number of rubbers of varying nature to varying substrates, both polar and nonpolar—cellophane, polyamide and polyethylene films—and also two elastomers—the polar rubber SKN-40 and the nonpolar polyisobutylene. The resulting data allow us to draw certain conclusions as to the influence of the molecular structure of adherend and substrate. The adhesion of rubbers to substrates is defined by the film stripping resistance P, in g/cm. The joints were made by plying up a film of substrate (of cellophane washed free of glycerin, of polyamide, or of polyethylene) or of fabric covered with a substrate (SKN-40, polyisobutylene) with fabric strips to which the polymer under investigation had previously been applied from a solution. Not less than 0.025 g/sq. cm of the polymer was applied to the fabric strips, this being sufficient to give reproducibility of results. The plying up was effected by rolling the assembled halves of the joint with a rubber roller, which gave higher pressures than those required to achieve full contact of the surfaces of the elastomeric adherend and the substrate. Such a method of producing joints has definite advantages from the point of view of procedure over the method employed previously, because it makes possible elimination of the influence of prolonged and varying time of interaction of the adherend with the substrate in the drying out which is inevitable in joining an adherend by a solution.