Chen, Shiou-Shan (Raytheon Engineers & Constructors). Styrene, the simplest and most important member of a series of aromatic monomers, is produced in large quantities for polymerization Its versatility has resulted in the manufacture of plastics, including polystyrene, ABS, SAN, styrene-butadiene latex, SBR, and unsaturated polyester resins. Polystyrene accounts for 65% of total styrene demand. Rapid growth in styrene production has been seen worldwide since 1970, including, since the 1980s, in the Pacific Rim. Many factors contribute to its growth. Chief among these are that it can be polymerized and copolymerized under a variety of conditions by common methods and that the raw materials, benzene and ethylene, are produced in large quantities in refineries and can be supplied through pipelines. The two process routes used com. for manufacture of styrene, dehydrogenation, and coprodn. with propylene oxide, are covered. Both routes use ethylbenzene as the intermediate. The commodity nature of the product and easy access to licensed processes have enabled new producers in developing countries to enter the global styrene market. Timing is important as price fluctuates broadly and rapidly. A large number of styrene derivatives have been reported, and several have been used for manufacturing small-volume specialty polymers, including vinyltoluene, para-methylstyrene, α-methylstyrene, and divinylbenzene.