Studies on Chlorinated Rubber

Abstract

Abstract 1. In the chlorination of rubber, the products have different combined chlorine contents which depend on the time of chlorination, but the final chlorination product seems to be C10H13Cl7, i. e., contains 64.7 per cent of chlorine. The rubber molecules disaggregate with advancing chlorination and the viscosities diminish. Accordingly the viscosity of rubbers containing the same chlorine contents vary with different conditions of preparation. 2. The properties of chlorinated rubbers vary with differences in their combined chlorine content; for a product to be thermostable and have high resistance to chemicals, it must contain over 60 per cent of chlorine. 3. The best method is to dissolve the pale crepe or F. A. Q. sheet in carbon tetrachloride and pass chlorine through the solution continuously while heating at 70–80°, with agitation. The reaction product is then separated from the solvent by distillation until the last trace of the solvent is removed, and is then washed with water free from acid impurities. 4. Chlorinated rubber has a high resistance to acids and alkalies and, above all, the permeability of films to water vapor is less than that of benzylcellulose. Moreover, chlorinated rubber is not explosive, and burns with difficulty. 5. The stability of four commercial products was studied, and an imported sample which had high stability was found to contain a stabilizer. Among various stabilizers tested, urea had the most beneficial effect. 6. As to the value of chlorinated rubber for varnish, there are many reports, and it is still in an experimental stage; but it has many properties which give the hope that it may be used as a special varnish after further studies by manufacturers and consumers. 7. By molding powdered chlorinated rubber under pressure and heat, a plastic which was easily removed in a short time was made. Its mechanical and electrical properties were tested and it gave attractive products with many pigments. Chlorinated rubber can be used as substitutes for plastics such as Bakelite or ebonite.