SYNTHETIC RUBBER RESEARCH 353 



dimethyl butadiene and butadiene itself. They were undoubtedly 

 "rubbers" of a sort but there could be no question about their inferiority 

 to the natural product. Even today the Russians persist in making their 

 synthetic rubber from butadiene and, although there have been improve- 

 ments, the polymer is still subject inherently to the same fundamental 

 difficulties of structure that existed when it was first synthesized by Lebedev 

 in 1911. 



The deficiencies in the early synthetic rubbers and the difficulty of synthe- 

 sizing natural rubber were appreciated in Germany where in the period 1935- 

 39 several plants were constructed to manufacture synthetic rubber, including 

 Buna S, on a large scale. By polymerizing together butadiene and styrene 

 instead of butadiene alone they achieved several advantages over previous 

 synthetic rubbers. The fact that the best opinion in this country decided 

 in favor of imitating German Buna S, shows that progress in Germany was 

 indeed substantial. As we have already indicated, however, improvements 

 were necessary in both the German product and process if it was to be 

 satisfactor>- for our use. The product developed in this country and now 

 being currently produced at the rate of nearly 700,000 tons per year, although 

 prepared from the same starting materials as German Buna S, therefore 

 differs from the latter in many important respects. The name Government 

 Rubber-Styrene, abbreviated GR-S, has been given to this product. 



History of the Development of Ideas of Composition 

 AND Structure of Polimers 



All rubbers, both natural and synthetic, as well as all organic plastics and 

 fibers belong to a class of substances called polymers. We now know that 

 they are constructed of large molecules, in turn built up of simple atomic 

 patterns (repeating units) joined end to end. Surprisingly, it was not until 

 about fifteen years ago that this idea gained general acceptance among 

 chemists. Since that time truly remarkable research progress on polymers 

 has been made. It is not our object to present a full account of this work 

 here. Most of it was carried on independently of its application to the 

 synthetic rubber problem but nevertheless has had a profound effect upon 

 it. A brief review of the growth of the present concepts of natural and 

 synthetic polymers will, however, help to emphasize the significance of the 

 more recent researches on synthetic rubber. 



For a long time chemists believed that naturally occurring polymers like 

 natural rubber, cellulose and silk were indefinite chemical compounds in 

 which the arrangement of the atoms was so complex as to defy analysis. 

 As has been mentioned, Faraday had shown in the case of natural rubber 

 that carbon and hydrogen atoms were present in the ratio of 16 hydrogens 



