Polystyrene is a synthetic polymer of styrene monomers. Styrene is used as a main component in the production of many types of plastics. Styrene is naturally present in some foods such as strawberries, cinnamon and coffee.
“Polystyrene” is typically a type of transparent thermoplastic that is produced both in dry form and in hard compressed foam. In general, polystyrene polymer is transparent, hard and brittle, which can be changed by using a combination with different materials and can be used in different products as desired.
The clear and hard type of “polystyrene” is commonly used in the manufacture of medical equipment, food containers, smoke detectors, food storage containers, coffee cups, etc. Expanded polystyrene (Ionolite) is used to protect electrical and sensitive goods in the packaging industry.
Production of polystyrene
“Polystyrene”, like other polymer plastics, consists of a polymerization process. This type of polymer is the result of the internal bonding of styrene monomers to each other during the polymerization process.
In the polymerization process, first the bond of the vinyl group in carbon styrene is broken and joined to another carbon styrene which is in the same state. The newly formed bond is much stronger than the previous bond in the monomer. Therefore, the styrene de-polymerization process is difficult to perform.
“Polystyrene” Attic
This type of polymerization is the most important type of “polystyrene” production. To produce Attic polystyrene, phenyl groups are randomly distributed on both sides of the polymer chain. This placement model prevents the formation of a linear form randomly and provides the required amount of active monocytes in the polymerization medium to form regular shapes until the desired crystal state is reached.
Sindotechnical polystyrene
Ziegler-Nata method is used for syndotactic pleasing. . In this process, the phenyl group is selectively directed to one side of the hydrocarbon chain. This model of polystyrene is its most crystalline form, which is formed at a temperature of 270 c. This polymerization reaction is performed in the presence of a catalyst.
Global production capacity of polystyrene
In 2016, the global production capacity of polystyrene was 14.7 million tons. China is the largest producer of polystyrene in the world, and Asia is the largest producer of polymer in the world, accounting for 55.1% of total production. The largest consumer of polystyrene is Asia, followed by North America with 17% and Europe with 16.3%.
Properties of polystyrene plastic:
Suitable thermal insulation
Electrical insulation
Excellent resistance to dilute acids and bases.
High temperature glass is a liquid and viscose that makes it possible to make a variety of products
High expandability and flow in the mold
Normally, polystyrene is slow-burning.
Physical properties of polystyrene:
Chemical formula n (C8 H8)
Density 0.96 to 1.06 grams per cubic centimeter
Melting point C 240 for isotactic polystyrene
Insoluble in water
Thermal conductivity in foam mode W / (M.K) 0.033
Light refractive index 1.6 and dielectric constant 2.6
Different forms of polystyrene
“Polystyrene” is one of the most important and widely used types of polymers in the world, and styrene copolymers have over millions of tons in the year of production.
In general, styrene polymers are classified into 3 different types:
GPPS
Ordinary “polystyrene”, also known as clear crystal polystyrene. This type of plastic is completely transparent, hard and is produced in the type of granules 2 to 5 mm. It has high impact strength and good heat resistance, as well as dielectric properties and high strength.
HIPS
High-strength polystyrene, known under the brand name “Hypec”, usually contains 5 to 10% butadiene rubber to produce products with high impact resistance. HIPS is actually a copolymer of polystyrene with a side arm. The process of copolymer formation occurs when some free radicals react with a polybutadiene double bond.
EPS
This type of “polystyrene” contains fine particles and contains propane gas, which is a blowing agent. Expanded polystyrene or ionolite is a thermal insulation that has its own disadvantages and advantages.
Applications of polystyrene plastic
“Polystyrene” is the most common type of polymer that is used to produce many products in the electronics, medical, lighting, automotive, packaging, construction and other industries. A wide range of products made of “polystyrene” is produced by injection molds in products such as disposable utensils and containers, cups, CDs, cosmetics, etc.
Another common product that is not actually a final product and is used as a raw material for other factories or in the construction industry is “polystyrene” laminate panels and “polystyrene” compressed foam sheets.
Plexiglas sheet:
The use of Plexiglas sheets is in the manufacture of molds, models, signs, boards, etc. In general, this type of sheet has a general use and has the following characteristics:
Waterproof, lightweight, heat sensitive, durable, non-toxic and odorless, excellent moldability, constant dimensions and very low water absorption, heat and electricity insulation, economical
Physical properties of “polystyrene” sheet:
- Molding temperature: 160 c to 180 c
- Maximum application temperature c8
Compressed “polystyrene” foam:
“Polystyrene” compressed foam is another functional product of this polymer that is used in various industries. The combination of the polymer with the foaming agent causes the formation of this foam.
This product is used in the packaging and refrigeration industries due to its high impact resistance. Annual packaging industries use “polystyrene” extensively
Compressed “polystyrene” foam is also used in the construction industry for insulation, molding, decor and ready-made facades and interior decorations such as non-load-bearing beds and columns.
General properties of “polystyrene” foam:
- Lightweight with easy portability
- recyclable
- Easily coated with epoxy resins.
- Excellent heat insulation
- Suitable for interior and exterior work of the building
- Resistant to moisture and pressure
- Reasonable price with high durability
- Ability to produce in various dimensions and sizes
Polystyrene foam is mainly produced in 2 ways.
Expanded polystyrene (EPS)
EPS is a white polystyrene foam made from expanded polystyrene granules. The expanding factor in the formation of this foam is the flammable substance pentane, which is the main application of this insulation (EPS) in the packaging industry, food insulation boxes (COLD BOX) and model making, etc.
Extruded Polystyrene Insulation Foam (XPS)
XPS is another type of polystyrene insulation foam that has a stronger surface and a much higher compressive strength.Also, its thermal resistance and water vapor penetration resistance are much higher. Its density is from 35 to 45 kg per cubic meter. . Its polymer is non-expanding polystyrene granule or GPPS which is produced by extrusion method by melting this granule at high pressure.
It has a uniform texture with closed and impermeable cells and has a very low heat transfer coefficient and very high resistance to moisture penetration and the passage of sound and pressure.
In three colors, green, blue and pink, it is commercially known in the world, but it is also produced in other colors, and its main use is in the construction, refrigeration, road construction and billboard industries.
