Vulcanization of Rubber with Synthetic Resins

Abstract

Abstract Natural and synthetic rubber can be vulcanized with several vulcanizing agents other than sulfur, though sulfur and sulfur compounds are the only agents of practical value. A combination of rubber and synthetic resin can be successful only when chemical bonds are formed. It has been found that this is the case with certain synthetic resins, and that natural and synthetic rubber can be vulcanized with these resins, without adding any other agent or filler, in much the same way as with sulfur. An example of these resins is the resol from pentaphene (p-t-amylphenol) and formaldehyde. Data are given for the technical properties of rubber-resin vulcanizates. Catalysis or a similar effect is produced by magnesium oxide, which increases the tensile strength, while hexamethylenetetramine prevents the reaction. Balata can be vulcanized with the same synthetic resins as rubber; with gutta-percha the effect of heating with rubber-vulcanizing resins is the same as with sulfur. The probable configuration of the rubber-resin vulcanizates consists of two systems of entangled thread-molecules, which are interlinked at a limited number of points by primary valence bonds.