POLYSTYRENE AND STYRENE COPOLYMERS

Polystyrene is with a present day sales volume of 8,5 million tons a y ear one of the most important thermoplastics worldwide. Its unique pro perty profile makes polystyrene an ideal material for housings, refrig erator inliners and demanding packaging applications, when transparenc y and/or surface quality as well as stiffness are important. Its econo mic success is due to its favourable price/performance ratio and also not least to its excellent processability as an amorphous material. In this contribution the versatility and potential for innovation of pol ystyrene and its copolymers are discussed. Using standard and impact m odified polystyrene, it is shown how the maturity of the polymerisatio n process, the broad spectrum of product modifications as well as proc essing know how of this class of materials have helped to promote the breakthrough of this product to an acknowledged plastic material. Mode rn polystyrene variations are increasingly meeting the special propert y requirements of other materials, like for example high heat resistan t PPE/PS-I blends, weather resistant ASA and AES plastics, tough and c rystal clear star polymers or hydrogenated and unhydrogenated elastome rs. A special feature of polystyrene is that it is one of the few mono mers which can be polymerised using all the known methods for vinyl mo nomers to produce high molecular weight products. Thus the newest poly merisation techniques using metallocene catalysed and anionic polymeri sation methods lead to products with the property profile of engineeri ng plastics. Polystyrene will continue to grow in the future and thus increase in importance, especially while it can be easily depolymerise d and in the form of styrene monomer recycled.