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this is the page introduction of the PS( Polystyrene) and
partly of the products made my virgin or recycle polypropylene like CD Jewel
Case,DVD Super Jewel Box and CD calendar Case
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Polystyrene IPA: // (IUPAC Poly(1-phenylethane-1,2-diyl)), sometimes abbreviated
PS, is an aromatic polymer made from the aromatic monomer styrene, a liquid
hydrocarbon that is commercially manufactured from petroleum by the chemical
industry. Polystyrene is one of the most widely used kinds of plastic.
Polystyrene is a thermoplastic substance, normally existing in solid state at
room temperature, but melting if heated (for molding or extrusion), and becoming
solid again when cooling off. Pure solid polystyrene is a colorless, hard
plastic with limited flexibility. It can be cast into molds with fine detail.
Polystyrene can be transparent or can be made to take on various colors.
Solid polystyrene is used, for example, in disposable cutlery, plastic models,
CD and DVD cases, and smoke detector housings. Products made from foamed
polystyrene are nearly ubiquitous, for example packing materials, insulation,
and foam drinks cups.
Polystyrene can be recycled, and has the number "6" as its recycling symbol.
Unrecycled polystyrene, which does not biodegrade, is often abundant in the
outdoor environment, particularly along shores and waterways, and is a form of
pollution.
Polystyrene was discovered in 1839 by Eduard Simon,[1] an apothecary in Berlin.
From storax, the resin of the Turkish sweetgum tree (Liquidambar orientalis), he
distilled an oily substance, a monomer which he named styrol. Several days
later, Simon found that the styrol had thickened, presumably from oxidation,
into a jelly he dubbed styrol oxide ("Styroloxyd"). By 1845 English chemist John
Blyth and German chemist August Wilhelm von Hofmann showed that the same
transformation of styrol took place in the absence of oxygen. They called their
substance metastyrol. Analysis later showed that it was chemically identical to
Styroloxyd. In 1866 Marcelin Berthelot correctly identified the formation of
metastyrol from styrol as a polymerization, process. About 80 years went by
before it was realized that heating of styrol starts a chain reaction which
produces macromolecules, following the thesis of German organic chemist Hermann
Staudinger (1881?C1965). This eventually leading to the substance receiving its
present name, polystyrene.
The company I. G. Farben began manufacturing polystyrene in Ludwigshafen,
Germany, about 1931, hoping it would be a suitable replacement for die-cast zinc
in many applications. Success was achieved when they developed a reactor vessel
that extruded polystyrene through a heated tube and cutter, producing
polystyrene in pellet form.
In 1959, the Koppers Company in Pittsburgh, Pennsylvania, developed expanded
polystyrene (EPS) foam
The chemical makeup of polystyrene is a long chain hydrocarbon with every other
carbon connected to a phenyl group (the name given to the aromatic ring benzene,
when bonded to complex carbon substituents). Polystyrene's chemical formula is
(C8H9)n; it contains the chemical elements carbon and hydrogen. Because it is an
aromatic hydrocarbon, it burns with an orange-yellow flame, giving off soot, as
opposed to non-aromatic hydrocarbon polymers such as polyethylene, which burn
with a light yellow flame (often with a blue tinge) and no soot. Complete
oxidation of polystyrene produces only carbon dioxide and water vapor. |
Extruded polystyrene
Extruded polystyrene (PS) is economical, and is used for producing plastic model
assembly kits, plastic cutlery, CD "jewel" cases, smoke detector housings,
license plate frames, and many other objects where a fairly rigid, economical
plastic is desired. Production methods include stamping and injection molding.
Polystyrene Petri dishes and other laboratory containers such as test tubes and
microplates play an important role in biomedical research and science. For these
uses, articles are almost always made by injection molding, and often sterilized
post-molding, either by irradiation or treatment with ethylene oxide. Post-mold
surface modification, usually with oxygen-rich plasmas, is often done to
introduce polar groups. Much of modern biomedical research relies on the use of
such products; they therefore play a critical role in pharmaceutical
research.[9] |
Recycling
The resin identification code symbol for polystyrene
Currently, the majority of polystyrene products are not recycled because of a
lack of consumer awareness regarding suitable recycling facilities and methods.
Expanded polystyrene can be used to make park benches, flower pots, and toys.
However, polystyrene "recycling" is not a closed loop, producing more
polystyrene; polystyrene cups and other packaging materials are instead usually
used as fillers in other plastics, or in other items that cannot themselves be
recycled and are thrown away.[citation needed]
Manufacturers can make stationary, hangers, seedling containers, photoframes,
cornices, and skirtings from recycled PS.[11]
Recycled EPS is used in many metal casting operations. It can be combined with
cement to be used as an insulating amendment in the making of concrete
foundations.[citation needed] American manufacturers have produced insulated
concrete forms made with approximatley 80% recycled EPS since 1993. |
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