styrenakrylonitryl

Styrenakrylonitryl, abbreviated SAN, is a transparent, rigid thermoplastic polymer produced by the random copolymerization of styrene and acrylonitrile. The acrylonitrile content typically ranges from about 19 to 33 percent by weight, which enhances chemical resistance and heat performance relative to polystyrene.

SAN offers a combination of clarity, surface hardness, and dimensional stability. Its glass transition temperature is higher than that of polystyrene, usually around 100–120 °C depending on composition. The material is processable by common thermoplastic methods such as injection molding and extrusion, and it can be molded into thin-walled parts with good surface quality. Compared with polystyrene, SAN shows improved chemical resistance and weathering stability, although its impact resistance is generally lower than that of ABS or polycarbonate. SAN is also relatively rigid and dimensionally stable, making it suitable for precise, clear components.

Applications for SAN include packaging, housings and covers for electronics, kitchenware, and automotive interior parts. It is frequently used where clarity and chemical resistance are required. SAN is sometimes combined with other polymers or modified with impact modifiers to improve toughness, or used as a blend with polycarbonate (PC/SAN) to balance processability, clarity, and heat resistance.

Industrial production of SAN employs free-radical polymerization in various media, such as emulsion, suspension, or solution processes. The material can be recycled within standard plastics recycling streams where available. Environmental and aging considerations include potential yellowing under prolonged UV exposure, which can be mitigated with stabilizers for outdoor applications.