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21) Styrene Acrylonitrile (SAN) :
Styrene and acrylonitrile monomers can be copolymerized to form a random,
amorphous copolymer that has improved weatherability, stress crack resistance,
and barrier properties. The copolymer is called styrene acrylonitrile or SAN. The
SAN copolymer generally contains 70 to 80% styrene and 20 to 30% acrylonitrile.
This combination provides higher strength, rigidity, and chemical resistance than
polystyrene, but it is not quite as clear as crystal polystyrene and its appearance
tends to yellow more quickly.
Density 1.06 - 1.1 g/cm 3
Glass transition temperature 100 - 115 °C
Max / Min continuous Service temperature 65 - 95 °C / 20 °C
Melting Point 220 - 270°C
Drying of resin is recommended to avoid splay marks or streaking (70 - 80°C for 2 - 4
hours). A mould temperature of 50-80°C is recommended.
Strength : High Clarity and Rigidity, Improved chemical resistance over PS,
toughness, high transparency (transmitting 90% light), high flow and dimensional
stability, good scratch and grease resistance, Low cost
Limitations : Higher water absorption than polystyrene, Low thermal capability,
Low impact strength, Yellows more quickly than PS, Higher processing
temperatures, Flammable with high smoke generation, Sensivity to UV, Low
deflection temperature
Applications: Instrument panel lenses, Food Tumblers, Water pitchers, Blender
jars, Trays, Electrical, Battery cases, rigid cosmetic packaging, Refrigerator butter
doors, transparent medical parts and components.
22) Styrene Maleic Anhydride (SMA):
Polymer that is built-up of styrene and maleic anhydride monomers. The specific
reactivity of the anhydride groups results in the solubility of SMA in alkaline (water-
based) solutions and dispersions. SMA is available in a broad range of molecular
weights and maleic anhydride (MA) contents.
Density 1.05 - 1.08 g/cm 3
Glass transition temperature 110 - 115 °C
Max continuous Service temperature 75 - 100 °C
Melting point 200 - 280 °C
SMA is available as crystal clear granule, can be Injection Moulded and Extruded.
Strengths: its transparent appearance, high heat resistance (HDT: 90-120°C),
Excellent dimensional properties (low water absorption 0.1%), Good impact
strength even at low temperatures, Good processablity, Good stiffness, excellent
adhesion characteristics
Limitations: Low UV resistance, Attacked by ketones, aromatic hydrocarbons,
chlorinated solvents and organic esters.
Applications: in engineering plastic applications - Instrument panels, Roof and
floor consoles, Headliners, Glove box doors and Trim parts, in combination with
PMMA or to heat-boost other polymers materials like ABS or PVC, being soluble in
alkaline solutions used in field of sizing (paper), binders, and coatings, as
compatibilizing agent for normally incompatible polymers (e.g. ABS/PA blends),

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