Polystyrene (PS) is a polymer synthesized from styrene monomer by free radical addition reaction, the chemical formula is (C8H8)n. It is a colorless and transparent thermoplastic with a glass transition temperature above 100°C, so it is often used to make various disposable containers that need to withstand the temperature of boiling water, and disposable foam lunch boxes, etc.

　　Uses

　　Polystyrene is easy to process and mold, and has the advantages of transparency, cheapness, rigidity, insulation, and good printability. It can be widely used in light industry market, daily use decoration, lighting indication and packaging. In the electrical aspects is a good insulating material and thermal insulation materials, can be made of a variety of instrument shells, lampshades, optical and chemical instrument parts, transparent film, capacitor dielectric layer, etc..

　　It can be used in powder and emulsion cosmetics. It can be used for powder with good compressibility, and can improve the adhesion of powder. It gives skin luster and lubricity, and is an advanced filler instead of talc and silica.

　　Environmental issues

　　Due to its small mass (especially foaming type) and low residual value, polystyrene is not easily recycled. Usually polystyrene cannot be recycled by the kerbside method. However, industry has also made great improvements in the reuse of expanded polystyrene, and many new methods of densifying it have emerged. Such methods, which can increase its density, typically result in a density increase of 15 slugs/ft3 (translator's note: 1 slugs/ft3 = 1.94055 g/cm3) and create a suitable center for recycling operations on clean polystyrene.

　　Material type

　　Synthetic materials

　　Plastics.

　　Polyethylene; polyvinyl chloride; polystyrene; polyvinyl alcohol; polypropylene; polyacrylic acid; polybutylene; polyisobutylene; polysulfone; polyformaldehyde; polyamide; polycarbonate; polylactic acid; polytetrafluoroethylene; polyethylene terephthalate; epoxy resins; phenolic resins; polyurethane

　　Synthetic rubber.

　　SBR; SBR; NBR; Neoprene; Neoprene

　　Synthetic fibers.

　　Polypropylene; polyester; nylon; acrylic; spandex; vinylon; nylon; dacron; kevlar

　　Impact Resistant

　　Impact-resistant polystyrene is an amorphous polymer resulting from the graft polymerization of styrene monomer and rubber, or a physical blend of polystyrene and rubber (usually polybutadiene rubber). The resulting polymer is tough, usually white (transparent grades are also available), and very easy to extrude and mold. Its toughness is largely determined by the ratio of rubber components and the amount used. Representative properties of impact resistant PS are: bending and tensile strengths of 13.8 to 48.3 MPa (varies with rubber and additive content); elongation 10 to 60%; gloss 5 to 100%. Visual transparency ranges from excellent to poor, with a shrinkage rate of about 0.006 and a coefficient of thermal expansion identical to that of transparent PS. Impact resistant PS has no change in performance after sterilization by γ-rays, and has the same solvent resistance as transparent PS. Impact PS melt index of 1-10g/min, Vicat softening point of 215 ° F. Commercial production of impact-resistant polystyrene with enhanced properties has a wide range of market prospects. Some of the special grades already available include: ultra-high gloss grades, high transparency grades, abrasion resistant grades, environmental stress-cracking resistant (ESCR) grades, high modulus grades, low gloss grades, and grades with low residual monomer styrene content.

　　The outstanding characteristics of impact-resistant polystyrene are easy processing, excellent dimensional stability, high impact strength and high rigidity. For HIPS only in heat resistance. Oxygen permeability, UV stability and oil resistance have some limits. Chemical and performance impact-resistant polystyrene is made by dissolving polyethylene rubber in styrene monomer prior to the polymerization reaction. Although HIPS can be made by suspension polymerization, the principal polymerization method is currently used for the industrial production of HIPS. In the ontogenic polymerization process, the styrene monomer/rubber/additive mixture is passed through a series of reactors with a conversion rate of 70-90%. The polymerization reaction requires heating or the addition of an initiator to complete the reaction, followed by heating in a vacuum to remove the volatile residual monomer from the resin, which is then pelletized and sold.

　　The continuous development of polystyrene technology has allowed manufacturers to produce grades with more outstanding properties than standard grades of PS. Many of the properties of polystyrene cannot be achieved at the same time, such as the desire to improve the impact strength, you have to sacrifice gloss, etc.. Some new resins have emerged that have the gloss of ABS, but also have a high degree of toughness. Some grades have been developed, such as those that are resistant to various fats and oils when used in food packaging, and those that are resistant to chlorofluorocarbon (CFC) blowing agents when used in refrigeration machines. Flame retardant grades (UL V-0 and UL 5-V), impact resistant polystyrene have been produced and are widely used in TV housings, commercial machinery and electrical products. These resins are easier and less expensive to process than many flame retardant engineering resins.

　　Vulcanizable

　　Used in the manufacture of everything from teacups to household insulation. The performance of the foam (such as density and impact strength) depends on the size and distribution of the pores, both of which are controlled by the dispersion, percentage content and volatility of the blowing agent added, representative of which are pentane and isopentane. Flame retardant grade expanded polystyrene with halogenated hydrocarbons as flame retardants, widely used as acoustic insulation layer of buildings and engineering use. The blowing agent SAN has been used to manufacture floating products and other gasoline resistant products.

　　Copolymers

　　They have very good toughness. The main varieties are: styrene-acrylonitrile copolymer (SAN), styrene-maleic anhydride copolymer (SMA), styrene-butadiene-styrene copolymer (SBS), styrene-acrylate copolymer, and modifiers based on them.SAN has a higher heat deflection temperature than transparent PS, and its solvent resistance has been improved, with excellent resistance to permeation. Rubber-modified SANs include resins such as acrylate-butadiene-styrene copolymer (ABS) and acrylate-styrene-acrylate copolymer (ASA). s-MA has a higher heat deflection temperature than transparent PS, up to 40°F, and it has excellent transparency and gloss. s-MA can be rubber-modified or reinforced with glass fibers. s-SBS and various modifiers of s-SBS can be used as improved SBS and various modifiers of SBS can be used as components to improve impact resistance, flexibility and flowability for the production of adhesive and flexural products such as mastic, shoe soles, asphalt felts, etc. SBS is also used to produce transparent impact PS.