Tel:
86-27-83372627
86-27-83372628
86-27-83372629
Fax:
86-27-83372625
E-mail:
info@sinicline.net
Polystyrene and its chemical property |
|
| Release time:2013-05-07 Source:admin Reads: | |
| Polystyrene is a synthetic aromatic polymer made from the monomer styrene, a liquid petrochemical. Polystyrene can be rigid or foamed. General purpose polystyrene is clear, hard and brittle. It is a very inexpensive resin per unit weight. It is a rather poor barrier to oxygen and water vapor and has relatively low melting point. Polystyrene is one of the most widely used plastics, the scale of its production being several billion kilograms per year. Polystyrene can be naturally transparent, but can be colored with colorants. Uses include protective packaging such as peanuts, containers, lids, belt hangers, tumblers, and disposable cutlery. As a thermoplastic polymer, polystyrene is in a solid state at room temperature but flows if heated above about 100 °C, its glass transition temperature. It becomes rigid again when cooled. This temperature behavior is exploited for extrusion, and also for molding and vacuum forming, since it can be cast into belt hangers with fine detail. It is very slow to biodegrade and therefore a focus of controversy, since it is often abundant as a form of litter in the outdoor environment, particularly along shores and waterways especially in its foam form. In chemical terms, polystyrene is a long chain hydrocarbon wherein alternating carbon centers are attached to phenyl groups. It contains the chemical elements carbon and hydrogen. Since the molecules are long belt hangers that consist of thousands of atoms, the total attractive force between the molecules is large. When heated, the chains are able to take on a higher degree of conformation and slide past each other. This intermolecular weakness confers flexibility and elasticity. This is an order of magnitude faster than the most rapid rate of polystyrene degradation identified. It is consistent with the T2GGM polystyrene degradation model, which considers the rate-limiting step for polystyrene degradation to be the breakup of polystyrene, rather than the degradation of styrene. |
