What is polystyrene? (POLYSTYRENE)
Chemically, polystyrene is a long-chain hydrocarbon in which the variable carbon centers are attached to phenyl groups (the name given to ring benzene). The chemical formula of polystyrene is n (CH8H8). It contains the chemical elements carbon and hydrogen.
The properties of the material are determined by the short-term adsorption of the tub on the waltz between the polymer chains. Because molecules are long-chain hydrocarbons made up of thousands of atoms, the overall tensile force between the molecules is large.
When heated (or rapidly deformed due to a combination of viscoelastic and thermal insulation properties), the chains become more compatible and overlap. This intermolecular looseness (as opposed to high intermolecular strength due to hydrocarbon strength) gives the material a state of flexibility and elasticity. The ability of the system to deform at temperatures above the temperature at which its glass is converted to polyester (and generally heat-softenable polymers) allows it to be easily softened into various shapes when heated.
History of polystyrene
Polystyrene was first discovered by Edward Simon in 1839, who did not really know what valuable material he had discovered. Commercial production of styrene monomer and its polymerization dates back to 1934, when Dow was able to synthesize styrene from petroleum products and then polymerize it. At the same time, a similar process is taking place in West Germany. The experience gained from this product during World War II led to the fact that in the post-war years, polystyrene was not only recognized as an expensive electrical insulator, but also as a thermoplastic plastic, cheap and with good properties.
Over time, with the publication of various theories (including Hermann Staudinger’s 1922 theory of the polymer), BASF eventually developed a two-step process for the production of polystyrene foam in the early 1950s. In this process, the first step involves the preparation of granules containing a uniform distribution of puffing agent by the suspension polymerization method of styrene monomer, which in the second step, this material is processed in a mold. Ease of production of the product in any shape and size was one of the advantages of this method that led to its development. This material was first produced in 1950.
Types of POLYSTYREN
Polystyrene is a synthetic polymer of styrene monomer (a petrochemical) that is divided into three main categories: conventional, durable and expandable:
General Purpose PolyStyren (GPPS)
High Impact PolyStyren (HIPS)
Expandable PolyStyren (EPS)
Production Process
Polystyrenes are plastics made of styrene monomer. The most popular plastics in this family are Impact Polystyrene Modified Polystyrene, Acrylonitrile Styrene (SAN) and Acrylonitrile Butadiene Styrene (ABS).
In general, chain polymerization is the reaction of combining monomer molecules together to form large polymer molecules. In this method, there is no change in the composition of the element and in the polymerization process, no by-product is obtained. The chain polymerization reaction is used for compounds that have one or more unsaturated bonds.
Synthesis of PS monomer
The raw materials required for the synthesis of polystyrene monomers are ethylene and benzene, which react together in the synthesis process to form ethylbenzene. Further processes (dehydration) are performed on it to convert it to vinyl benzene monomer or Styrene. Other necessary additional materials are acrylonitrile (AN) and buta-DN rubber. Using a heat reaction or catalyzed styrene monomer, the polymerization process begins to produce an amorphous polymer.
Various additives are added to the PS to give it the desired properties, e.g.
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Emollients
Releasing or releasing agents and stabilizers
Polystyrene-based formulations also use various other additive groups, such as dyes, flame retardants (FRs), UV stabilizers, or shock modifiers. GPPS is typically chosen because of its transparency, rigidity, and suitability for a variety of applications. MIPS or HIPS are used when more flexibility or high impact strength is required.
HIPS and MIPS include butane rubber as a copolymerizing agent to increase toughness, which causes the color of the product to become dull and opaque.
Uses of polystyrene
The first and most important way to use polystyrene is disposable plastic containers. These dishes, which play a very important role in everyday life and industry today, are used because of their transparency and density. After transparency, the high strength of this plastic causes it to be used in the manufacture of most sanitary ware, children’s toys, sports equipment and even in the automotive industry. Of course, polystyrene has another special property, and this property is the dielectric property of the molecules that make it up. This makes this plastic one of the most important compounds in the electrical industry.
