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Handbook of Polymer Synthesis Second Edition Episode 2

Tham khảo tài liệu 'handbook of polymer synthesis second edition episode 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 2 Polystyrenes and Other Aromatic Poly vinyl compound s Oskar Nuyken Technische Universitat Munchen Garching Germany I. STYRENE Discovery of the styrene monomer is credited to Newman 1 who isolated it by steam distillation from liquid amber which contains cinnamic acid yielding styrene via decarboxylation. The first polymerization was described by Simon 2 . Commercial styrene polymerization was begun about 1925 3 . Cracking of ethylbenzene became the major manufacturing route for the monomer. The first commercialization was based on bulk polymerization using the can process 4 5 . Polystyrene production has grown by an average of 2.8 per year over the last 10 years reaching 8 500000 metric tons worldwide in 1995 6 . The most general-purpose polystyrene is produced by solution polymerization in a continuous process with the aid of peroxide initiation. Suspension polymerization is used for products for which a small spherical form is desirable. Emulsion polymerization is the method of choice for ABS resins. Polystyrene is a glasslike solid below 100 C. Below this temperature it shows considerable mechanical strength. Rubber-modified polystyrene is a two-phase system rubber dispersed in polystyrene being the continuous phase. Advantage is taken of the complex interaction of those systems in many applications in which high stress-crack resistance is needed. Polystyrene is nonpolar chemically inert resistant to water and easy to process. It is the material of choice for many food-packing optical electronic medical and automotive applications. Tensile strength can be increased by controlled orientation of polystyrene. A. Synthesis 5 7 All current styrene production starts with ethylbenzene followed by dehydrogenation over ferrum oxide catalysts yielding crude styrene 600-650 C k -CH2-CH3 ỳ ch ch2 h2 1 Copyright 2005 by Marcel Dekker. All Rights Reserved. Side reactions are reduced by keeping the conversion low or by adding water as a diluent. It is also possible to .