Polystyrene

Polystyrene is a synthetic polymer manufactured from the monomer called styrene. It is one of the most widely used plastics due to its cost effectiveness and durability in normal atmospheric conditions. Polystyrene is thermoplastic in nature i.e. it is solid in natural state but flows when heated above 100 degrees Celsius. Structurally, it is a hydrocarbon with alternating carbons and benzene rings.

Though polystyrene has numerous applications, it is not bio-degradable and hence considered to be anti-environment. This is due to the fact that it is inert and on burning, releases carbon dioxide.

Polystyrene is prepared by a process called polymerisation, wherein monomers link together to form long chains. 

Polystyrene comes in several forms, listed below:

• Moulded Polystyrene: This is the most common form. The shape is derived through vacuum forming or injection moulding. Highly rigid and durable, it finds wide applications in lab equipment, license plates, device housings, etc.
• Foam Polystyrene: This is a closed-cell foam which is rigid, tough and has high thermal insulation properties. When ingrained with graphite, it has even higher insulation. However, despite having closed cells, this form is not completely water-proof. Foam polystyrene can have two sub-forms:
  •  Expanded Polystyrene Foam: This form is far more rigid and durable with closed cells and hence it is used for refrigerator trays, bowls, etc.
  •  Extruded Polystyrene Foam: This variant provides a better surface roughness than the above variant and is commonly used in architectural models.

There are two common types of Polystyrene:

• General Purpose Polystyrene (GPPS): For applications where strength does not matter much, this brittle, but rigid and inexpensive form of polystyrene is used.
• High Impact Polystyrene (HIPS): Due to its inherent fragile nature, pure polystyrene is not suitable for building sturdy items such as toys and appliance parts. It is mixed with 5-10% butadiene rubber to produce a robust and strong substance called High Impact Polystyrene or HIPS. This is commonly promoted as ‘high impact plastics’.