Polystyrene is a type of polymer that is transparent, rigid, brittle, and moderately strong in its unmodified state. It is a plastic made by polymerization, which combines the building block compound called styrene. Polystyrene is used in different forms, including as foam, film, and rigid plastic, for applications from food packaging to electronics protection. While polystyrene’s uses are flexible and it features a low shrink rate, it also flows slowly and can come out brittle. Polystyrene is food safe, though over time it can leach styrene. It’s commonly used in injection molding, and manufactured by companies such as Dow and Trinseo.

What is Polystyrene?

Polystyrene, also known as poly-phenylethene, is a polymer made up of repeating molecules called styrene. It is a thermoplastic polymer, meaning it softens and melts when heated and can be reused. It is an excellent electrical insulator and is resistant to chemicals such as acids and bases. Solid polystyrene is transparent due to the lack of crystalline arrangements of the styrene molecules. It is a brittle material with poor UV resistance. It also has a relatively low glass transition temperature of 100ºC, where the polymer begins to soften before melting. Polystyrene is designated with recycling code number 6, and it can be melted and reused in different shapes or forms.

Polystyrene is usually combined or co-polymerized with other compounds to form plastics with improved properties. For example, polystyrene is combined with methyl methacrylate to form Poly (styrene-co-methyl methacrylate) or PSMMA. The resulting material has higher clarity with enhanced UV and chemical resistance. Another popular plastic called Acrylonitrile Butadiene Styrene (ABS) results from the co-polymerization of acrylonitrile and butadiene with polystyrene. As a result, ABS possesses high tensile strength, weldability, moldability, and dimensional stability.

What Are the Uses of Polystyrene?

Polystyrene is used across all industries, from toys and parts of consumer goods to insulation and packaging materials. It is also the ingredient for the synthesis of new plastics. Polystyrene is used in its solid, film, and foam form, forms the polymer matrix in composites, and works as the basis for co-polymerized plastics.

• Solid or rigid form: this polystyrene type is transparent, rigid, brittle, and moderately strong in its unmodified state.
• Foam form: the most notable use of polystyrene is in a foam form, also known as Expanded Polystyrene (EPS).
• Film Form: films made from polystyrene are transparent, durable, and printable.
• Composites: Polystyrene is used as a base polymer matrix to fabricate fiber reinforced composites.
• Co-polymerized Polystyrene: polystyrene is usually combined with other compounds to synthesize plastics with unique properties. These include ABS, SBR, SAN, and HIPS.

Plates and cups can be made from polystyrene, as can sound dampening foam and protective lamination over posters and other products. Wind turbines and corrosion-resistant pipes can also be made of polystyrene. Its co polymerized forms of ABS, SBR, SAN, and HIPS can be used for applications from 3D printed prototypes to optical fibers rubber gaskets to automotive gas tanks.

What is the Difference Between Polystyrene and Polypropylene?

The difference between polystyrene and polypropylene is their durability; unlike polystyrene, polypropylene is resistant to more forms of damage. Both polystyrene and polypropylene are polymers, i.e., large molecules with repeating smaller structural units or monomers. Styrene is the monomer for polystyrene, whereas propylene is for polypropylene. Polypropylene is one of the most used plastics in the production of households, food containers, electronics parts, packaging, automotive components, and other industries. Unlike polystyrene, polypropylene is more resistant to UV and organic solvents.