Polystyrene

In-depth explanation of Polystyrene

Polystyrene is an addition polymer of styrene, the vinylbenzene monomer, and is produced by free radical polymerisation. General-purpose polystyrene is clear, rigid and brittle, while high-impact polystyrene includes rubber particles for toughness. Expanded polystyrene foam is made by trapping a blowing agent such as pentane in the polymer, which expands on heating to form a lightweight, insulating material that is mostly air. Polystyrene is hard to recycle economically and persists in the environment, where it fragments into microplastics. Foam cups and food containers are common applications.

Going deeper: Polystyrene

Key ideas: Addition polymer of styrene (phenylethene), CH2=CH-C6H5, by free radical polymerization. The bulky phenyl groups prevent crystallization, so general-purpose PS is clear, brittle and amorphous. Expanded PS (foam) is made by blowing with pentane, is over 95 percent air and used for packaging and insulation. Code 6.

Common mistakes and connections: A common slip is saying foam is a different polymer. It dissolves in acetone and other nonpolar solvents. Styrene is a suspected carcinogen and the polymer is hard to recycle and persists as litter. Links to benzene chemistry, copolymers (ABS, SBR) and microplastics.

Visualization of Polystyrene

Polystyrene forms by addition polymerisation: styrene units add one after another through radical chain growth without losing any atoms. The interactive lesson shows this as a live animation or chart.

Worked example and use case

Expanded polystyrene is used in cool boxes and building insulation because it is mostly trapped air.

Where Polystyrene fits in Biochemistry, Environment & Industry

Polystyrene is topic 61 of 127 in Biochemistry, Environment & Industry.

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• Polymer Molecular WeightAdvanced
• Plastic RecyclingBeginner

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