polystyrene

This material is recognized by two distinct physical states: a rigid, clear plastic used for durable items and a lightweight, expanded foam used for cushioning. The foam version is frequently associated with environmental concerns due to its persistence in nature and its common colloquial identification as Styrofoam. As a chemical substance and material, it is treated as an uncountable noun. It does not have a plural form in standard usage; instead, quantities are described using partitive phrases such as a block of polystyrene or a sheet of polystyrene.