Ski Rubber, Polyisoprene, Similar to Natural Rubber

Abstract

Abstract Years of research at the S. V. Lebedev All-Union Scientific Research Institute for Synthetic Rubber have provided industry with a number of methods for making synthetic rubber from isoprene. Of all the known synthetic rubbers this comes closest to natural rubber in structure and properties; it is the best available substitute of natural rubber, possessing a high degree of elasticity and strength. The present article is a brief summary of the basic work on isoprene rubber done by the Scientific Research Institute of the Tire Industry. On the basis of this work recommendations were made for the development of the production of synthetic isoprene rubber and the substitution of isoprene rubber for natural rubber in the manufacture of heavy duty truck tires. By using different polymerization processes it is possible to produce isoprene rubbers whose chain structures are very similar, but whose molecular weights, and therefore physical and technological properties, are very different. The cis structure of the 1,4 polyisoprene chains is the basic structural element of the new isoprene polymer. Therefore these synthetic isoprene rubbers (SKI) obtained through catalytic polymerization when vulcanized show a crystalline structure when x-rayed in the stretched state. The x-ray photographs also show that the geometric distribution of interference spots in SKI rubbers corresponds to the distribution of interference spots in natural rubber, but that the relative intensities of the crystalline, liquid, and amorphous scatterings in the two rubbers are different (Figure 1).