Polystyrene is the cheapest transparent plastic and the easiest to mould, which keeps it in disposable packaging, display items and appliance liners. Crystal PS gives water-clear parts at very low cost; HIPS adds rubber for toughness and an opaque, uniform surface that takes print and lamination well. Neither survives solvents or high heat, so the application decides.
Typical values for standard moulding grades. Exact figures depend on the specific compound or grade — confirm against your drawing before quoting.
Key properties
| Propiedad | Typical value |
|---|---|
| Densidad | 1.04 – 1.05 g/cm³ |
| Tensile strength | 20 – 45 MPa |
| Flexural modulus | 2.0 – 3.3 GPa |
| HDT at 1.8 MPa | 70 – 85 °C |
| Mould shrinkage | 0.4 – 0.7 % |
| Light transmission | 88 – 90 % (crystal PS) |
Values are typical for unfilled moulding grades at 23 °C unless stated. Glass-filled and specialty grades differ.
Typical applications
- Disposable packaging and clamshells
- Point-of-sale display and signage
- Refrigerator and appliance liners
- Cosmetic and medical packaging
- CD cases and media housings
Processing notes
- Melt 200 – 250 °C, mould 30 – 60 °C. PS processes over a wide window, which is why it is often used for trial shots.
- Dry 2 h at 70 – 80 °C for optical parts. For packaging grades, drying is usually unnecessary.
- PS is brittle in thin sections and solvent-sensitive. Avoid contact with adhesives containing ketones or aromatics.
- For HIPS, specify the rubber content — 5 % and 12 % behave very differently in impact and in surface gloss.
Frequently asked questions
Is PS suitable for food packaging?
Yes, in food-contact grades. Crystal PS is common for bakery and produce packaging; HIPS for dairy containers. We supply the migration declaration for the grade used.
Why is PS cheaper than ABS?
Lower polymer cost and a wider processing window, which means shorter cycles and less scrap. Where the part does not need ABS impact strength or heat resistance, PS is the rational choice.
Related materials
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