152 Miracles Ahead! 



Rubber Co., "but it's the best substitute we have." Others 

 agree that Buna S is the synthetic most similar to natural rub- 

 ber in processing and performance characteristics. It may be 

 vulcanized with sulphur and rubber accelerators and cured to 

 hard rubber. Its resistance to atmospheric deterioration is 

 slightly higher than that of natural rubber. Buna S has been 

 found satisfactory for use in passenger tires, without the addi- 

 tion of natural rubber. Although coarser and rougher than 

 natural rubber, Buna S has no offensive odor (only a faint 

 tarry odor). When the first Buna S tires hit the market in 

 1944 the motorist will be unable to tell the difference between 

 them and the prewar natural-rubber tires. 



On heavy-duty tires Buna S must be mixed with natural 

 rubber to get best results. Thirty per cent of natural rubber 

 is used for heavy-duty treads and carcasses and about 10 per 

 cent for the tire tubes. 



How Synthetic Rubber Is Made 



The word "buna" was first used in Germany "bu" stand- 

 ing for butadiene and "na" coming from natrium, the classi- 

 cal name of sodium. The letter S stands for styrene. Buna S 

 is a copolymer produced by the polymerization of approxi- 

 mately three parts of butadiene with one part of styrene. Let 

 us start at the beginning and translate that sentence into non- 

 technical terms if possible. 



A monomer is a material composed of molecules corre- 

 sponding to the individual units of a polymer. 



A polymer is a giant molecule formed when hundreds of 

 thousands of the original molecules of the material have been 

 linked up together end to end like boxcars in a train. This 

 linking together, or polymerization, gives a rubberlike mate- 

 rial its bounce, elasticity, and resiliency. Natural rubber is a 

 polymer of a single material called isoprene, but most syn- 



