Overview
GPPS (general-purpose polystyrene) is a homopolymer styrenic resin. It is transparent in unfilled form, rigid, and easy to injection mould or extrude into sheet. It is more brittle and less impact-resistant than high-impact polystyrene (HIPS) or engineering styrenics.
Thermal behaviour is typical of amorphous polymers: no sharp melting point but softening over a range; sensitivity to stress cracking in contact with some oils and solvents.
Material properties
- High stiffness and surface gloss
- Good dimensional stability in rigid parts
- Limited notch toughness; avoid sharp internal corners without radii
Processing
Drying is often mild compared with hygroscopic polymers but pellets should be kept sealed to avoid surface moisture that can cause silver streaking. Venting in the screw and mould helps with styrenic volatiles during processing.
Uses
Disposables, optical clarity parts (where thickness allows), display items, blending into HIPS or specialty compounds, and some sheet/thermoforming grades.
Origin: South Africa.
