Prem Machine Tools (India)
Prem Machine Tools (India)
Sector 53, Faridabad, Haryana
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Company Factsheet


Basic Information
IndiaMART TrustSeal
Nature of Business
Manufacturer
Total Number of Employees
Upto 10 People
Year of Establishment
1992
Legal Status of Firm
Proprietorship Firm
Annual Turnover
Rs. 1 - 2 Crore
GST No.
06BIOPS2628R1ZC

Structure and Properties

The chemical make up 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 (C8H8)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. Because of its chemical inertness, polystyrene is used to fabricate containers for chemicals, solvents, and foods.

This addition polymer of styrene results when vinyl benzene (styrene) monomers (which contain double bonds between carbon atoms) attach to form a polystyrene chain (with each carbon attached with a single bond to two other carbons and a phenyl group).

Polystyrene is generally flexible and can come in the form of mouldable solids or viscous liquids. The force of attraction in polystyrene is mainly due to short range van der Waals attractions between chains. Since the molecules and long hydrocarbon chains that consist of thousand of atoms, the total attractive force between the molecules is large. However, when the polymer is heated (or, equivalently, deformed at a rapid rate, due to a combination of viscoelastic and thermal insulation properties), the chains are able to take on a higher degree of conformation and slide past each other. This intermolecular weakness (versus the high intra-molecular strength due to the hydrocarbon backbone) allows the polystyrene chains to slide along each other, rendering the bulk system flexible and stretchable. The ability of the system to be readily deformed above its glass transition temperature allows polystyrene (and thermoplastic polymers in general) to be readily softened and molded with the addition of heat.

A 3-D model would show that each of the chiral backbone carbons lies at the center of a tetrahedron, with its 4 bonds pointing toward the vertices. Say the -C-C- bonds are rotated so that the backbone chain lies entirely in the plane of the diagram. From this flat schematic, it is not evident which of the phenyl (benzene) groups are angled toward us from the plane of the diagram, and which ones are angled away. The isomer where all of them are on the same side is called isostatic polystyrene, which is not produced commercially.

Ordinary atactic polystyrene has these large phenyl groups randomly distributed on both sides of the chain. This random positioning prevents the chains from ever aligning with sufficient regularity to achieve any crystallites, so the plastic has a very low melting point, Tm<<TRT. But metallocene-catalyzed polymerization can produce an ordered syndiotactic polystyrene with the phenyl groups on alternating sides. This form is highly crystalline with a Tm of 270 °C (518 °F).

Extruded polystyrene is about as strong as unalloyed aluminium, but much more flexible and much lighter (1.05 g/cm3 vs. 2.70 g/cm3 for aluminium).

Forms Produced

Polystyrene is commonly injection molded or extruded, while expanded polystyrene is either extruded or molded in a special process. Polystyrene copolymers are also produced; these contain one or more other monomers in addition to styrene. In recent years the expanded polystyrene composites with cellulose[7][8] and starch[9] have also been produced.

Extruded closed-cell polystyrene foam is sold under the trademark Styrofoam by Dow Chemical. This term is often used informally for other foamed polystyrene products.

Polystyrene is used in some polymer-bonded explosives:

Name Explosive ingredients Binder ingredients
PBX-9205 RDX 92% Polystyrene 6%; DOP 2%
PBX-9007 RDX 90% Polystyrene 9.1%; DOP 0.5%; resin 0.4%

Copolymers

Pure polystyrene is brittle, but hard enough that a fairly high-performance product can be made by giving it some of the properties of a stretchier material, such as polybutadiene rubber. The two such materials can never normally be mixed because of the amplified effect of intermolecular forces on polymer insolubility (see plastic recycling), but if polybutadiene is added during polymerization it can become chemically bonded to the polystyrene, forming a graft copolymer which helps to incorporate normal polybutadiene into the final mix, resulting in high-impact polystyrene or HIPS, often called "high-impact plastic" in advertisements. One commercial name for HIPS is Bextrene. Common applications of HIPS include toys and product casings. HIPS is usually injection molded in production. Autoclaving polystyrene can compress and harden the material.

Several other copolymers are also used with styrene. Acrylonitrile butadiene styrene or ABS plastic is similar to HIPS: a copolymer of acrylonitrile and styrene, toughened with polybutadiene. Most electronics cases are made of this form of polystyrene, as are many sewer pipes. SAN is a copolymer of styrene with acrylonitrile, and SMA one with maleic anhydride. Styrene can be copolymerized with other monomers; for example, divinylbenzene for cross-linking the polystyrene chains.

Disposal and Environmental Issues

Polystyrene is not easily recycled because of its light weight (especially if foamed) and its low scrap value. It is generally not accepted in kerbside (curbside) collection recycling programs. In Germany, however, polystyrene is collected, as a consequence of the packaging law (Verpackungsverordnung) that requires manufacturers to take responsibility for recycling or disposing of any packaging material they sell.

Burial

Foam cups and other polystyrene products can be safely buried in landfills, since it is as stable as concrete or brick. No plastic film is required to protect the air and underground water.
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Reach Us
Rakesh Kumar Sharma (Proprietor)
Plot No. 101, Road No. 5 Saroorpur Industrial Area
Sector 53, Faridabad- 121004, Haryana, India



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