Polystyrene is a type of plastic, a synthetic material found in many everyday items. Plastics are defined as synthetic or semi-synthetic materials primarily composed of polymers. Like other plastics, polystyrene is manufactured through chemical processes to exhibit properties such as durability, lightness, and moldability.
Understanding Plastics
Plastics are materials characterized by their polymeric structure. A polymer is a large molecule made up of many repeating smaller units called monomers. These monomers link together in long chains through polymerization, forming the plastic. Plastics are produced through industrial chemical processes, typically originating from petroleum or natural gas. This allows for the creation of materials with tailored properties, making them highly versatile for a wide range of applications.
Polystyrene’s Place in the Plastic Family
Polystyrene is classified as a synthetic thermoplastic polymer. It is created from the monomer styrene, an aromatic hydrocarbon, with many repeating styrene units linked together in a long chain. As a thermoplastic, polystyrene becomes soft and pliable when heated above its glass transition temperature and then solidifies again upon cooling. This property allows polystyrene to be melted and reshaped multiple times, making it suitable for manufacturing processes like molding and extrusion.
Everyday Uses of Polystyrene
Polystyrene is encountered daily in two primary forms, each with distinct applications, including rigid, clear polystyrene known for its transparency, hardness, and brittle nature. This form is commonly used for items such as disposable cutlery, CD cases, and clear food containers. Expanded polystyrene (EPS), often recognized by the brand name Styrofoam, represents the foamed version of the material. This lightweight foam offers excellent thermal insulation and shock absorption. It is used in insulation for buildings, protective packaging (like packing peanuts), and disposable cups and food trays.
Polystyrene and the Environment
Polystyrene is identified by recycling code #6, indicating it is technically recyclable. However, its recycling presents challenges. The material’s lightweight and bulky nature makes it uneconomical to transport to recycling facilities. Furthermore, polystyrene used in food packaging often becomes contaminated with food residues, making it difficult to process. Consequently, a substantial amount of polystyrene ends up in landfills, where its slow degradation rate contributes to persistent waste accumulation. Due to these environmental concerns, alternatives are being explored, including other polymer-based foams, starch-based materials, and molded pulp.