Processing Characteristics of Synthetic Tire Rubber

Abstract The processing characteristics of synthetic tire rubber, such as is being made in the government program, are sufficiently different from those of natural rubber to require different laboratory and factory treatment. Since the laboratory tests used for the evaluation of processing characteristics were developed for natural rubber, it is not surprising that they are not so satisfactory for synthetic rubber. The purpose of this paper is to discuss some of the characteristics of synthetic tire rubber, and to describe certain tests which have been found useful for evaluating different types of synthetic rubber or different compounds of the same synthetic rubber. In the course of the development, it has been necessary to evaluate rubbers with a wide variety of processing properties. As production has increased, there has been less variation in the output from any one plant. As the newer and larger plants come into full production, we can expect greater uniformity from each plant and between different plants. We can also look forward to gradual improvements in processing characteristics. This development will be ensured by adequate laboratory methods for evaluating processing properties. This discussion is based in part on variations encountered in development work and in part on the properties of the present production from one plant.