ABS vs HIPS properties comparisons come up whenever a buyer tries to move a part down in cost without changing the tool. Both are rubber-toughened styrenics, both mould easily and both look similar in the hand, but ABS adds acrylonitrile to the chain and that one comonomer changes strength, heat resistance and chemical behaviour. This guide compares the two resins on the properties that decide part life and shows where a switch from ABS to HIPS is safe and where it fails.
ABS vs HIPS properties side by side
| Property | ABS | HIPS |
|---|---|---|
| Tensile strength | About 35-50 MPa | About 18-30 MPa |
| Notched Izod impact | 70-370 J/m, grade dependent | About 45 J/m |
| Flexural modulus | About 2.0-2.6 GPa | About 1.9 GPa |
| Heat deflection, 1.8 MPa | About 80-100 °C | About 70-85 °C |
| Chemical resistance | Fair; resists many oils and cleaners | Poor; many solvents attack it |
| Surface | Glossy, plates and paints well | Matte to semi-gloss |
| Drying before moulding | Required | Usually not needed |
| Recycling code | 7 | 6 |
Strength, impact and stiffness
HIPS toughness is real but shallow: it absorbs a single impact well at room temperature, yet its tensile strength and stiffness sit well below ABS across grades. ABS carries the butadiene rubber phase inside an acrylonitrile-strengthened matrix, so it holds higher tensile and flexural values and keeps impact at low temperature better. For parts that survive drops, snaps or loading in service, the ABS side of the table wins; for parts that only need to survive assembly, HIPS is often enough.
Heat and chemical exposure
The heat gap is the usual failure mode in a cost-down switch. HIPS softens roughly 10-20 °C earlier than ABS, so a part that lives near a warm appliance, in a car cabin or under constant load can distort in HIPS where ABS held shape. Chemically, ABS tolerates many oils, greases and household cleaners that attack HIPS; food contact parts that see fats, dairy or repeated washing should stay on ABS unless a specific HIPS grade has been validated for the duty.
Processing, surface and decoration
Both resins mould easily, but ABS absorbs moisture and needs drying, typically two to four hours at 80-100 °C, or the melt hydrolyses and parts show splay and brittle surfaces; HIPS usually runs straight from the bag. ABS is also the standard substrate for electroplating, taking an electroless base coat and a bright metal finish, while HIPS is not plated directly and reads matte unless high-gloss grades are specified. For UV exposure neither resin survives untreated, so outdoor parts need a stabilised grade or a coating regardless of the choice.
Cost and when a switch makes sense
HIPS is one of the lowest-cost rigid thermoplastics, which is why thermoformed trays, blister packs, displays and refrigerator liners are dominated by it. A high impact polystyrene vs abs decision is really a decision about how much acrylonitrile the part needs: keep ABS where the part carries load, sees heat, meets chemicals or gets plated, and move to HIPS where loads are light, service is indoor and price leads. Trial first: mould both, measure the part at its coldest and hottest service points, and check shrinkage, because the two resins are similar but not identical.
Writing the choice into an RFQ
Styrenic resin selection starts with the service environment: peak and continuous temperature, chemical contact, load, surface requirement and the two or three dimensions that matter. State the grade family rather than a brand, ask for the heat deflection and impact data on the specific grade quoted, and require the food contact declaration where the part touches food. For more context, see the plastic materials hub, the ABS grades guide and the ABS vs PC housing comparison, or shortlist suppliers via the verified manufacturer directory.
