Polystyrene (PS) is a predominantly amorphous thermoplastic polymer produced through the polymerization of styrene monomer (C₆H₅–CH=CH₂), forming a saturated carbon-carbon backbone with pendant phenyl groups. Conventional commercial PS possesses an atactic molecular configuration, in which the irregular arrangement of phenyl groups restricts crystallization and contributes to optical transparency, high rigidity, and dimensional stability. The bulky aromatic side groups restrict segmental chain mobility, resulting in a glass transition temperature typically ranging from 95-105°C, while the absence of crystalline reinforcement contributes to inherent brittleness and limited impact toughness.

Commercial PS resins are primarily classified into General purpose polystyrene (GPPS), a transparent, rigid homopolymer, and High impact polystyrene (HIPS), a multiphase rubber-modified material containing dispersed polybutadiene-rich domains. These elastomeric domains promote localized plastic deformation and energy dissipation under mechanical loading, improving fracture toughness while generally reducing optical transparency. Material performance and processing characteristics depend on molecular weight, molecular weight distribution, rubber content, particle morphology, and polymer formulation. 

PS Grades