STYRON 666D,685,685D and 697 are general purpose thermoplastic polystyrene resins produced by joining styrene monomer molecules into long polymer chains ranging from 100 to 20,000 monomer units per chain. They are noncrystalline. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on corrosion resistance as well as casting, forming, and joining. Filing Code: P-34. Producer or source: The Dow Chemical Company.