Polystyrene is a synthetic plastic polymer made from styrene monomers. It can be manufactured in different forms, from rigid solid parts to lightweight foams such as expanded or extruded polystyrene. Because it is easy to shape, insulate, and mass-produce, it is widely used in packaging, containers, and building insulation.
In technical work, the form of polystyrene matters as much as the base material. Foam versions contain large amounts of trapped air and behave very differently from dense plastic. That affects strength, heat resistance, recycling options, and how the material can be processed. In industrial chemistry, polystyrene can also serve as feedstock for conversion or recycling pathways, where controlled conditions determine whether it is reused, broken down, or transformed into other products.