Breakdown of Rubbers

a technological operation in the rubber industry that facilitates the subsequent processing of rubbers, such as preparation of rubber blends and calendering. The purpose of breakdown, which is performed in blending equipment or in special units, is to decrease the high-elastic (reversible) deformation and increase the plastic (irreversible) deformation of rubbers. These changes in properties are due to a decrease in the molecular weight of the elastomer, resulting from its mechanical or thermal-oxidative degradation.

Natural rubber is the type of rubber that most often undergoes breakdown. Breakdown, which is one of the most difficult, labor-intensive, and energy-intensive operations in the rubber industry, is unnecessary in the processing of rubbers whose molecular weight is controlled during synthesis—for example, butadiene-styrene rubbers produced by low-temperature polymerization. Stereoregular rubbers, which are synthesized with the use of complex catalysts, are also processed without breakdown.