INEOS Styrolution ABS TERLURAN HI-121 is an unfilled, high-impact injection moulding grade of acrylonitrile butadiene styrene. The formal designation under ISO 1043-1 is ABS, with CAS number 9003-56-9. The polymer architecture consists of a continuous styrene-acrylonitrile copolymer phase and a dispersed grafted polybutadiene rubber phase. Typical reference values obtained under ISO protocols are not specification limits, but they provide a baseline for incoming inspection and part design. Density is reported at 1.04 g/cm³ according to ISO 1183-1. Melt volume-flow rate is 4.5 cm³/10 min at 220 °C under 10 kg load according to ISO 1133-1. Tensile modulus is 2000 MPa and tensile yield stress is 39 MPa according to ISO 527-2. Notched Charpy impact strength is 26 kJ/m² at 23 °C and 9 kJ/m² at −30 °C according to ISO 179-1/1eA. Vicat softening temperature VST/B/50 is 96 °C according to ISO 306. The grade is supplied as pellets for injection moulding. Lot-to-lot variation is controlled within commercial limits, but incoming inspection should include melt volume-flow rate, moisture content, and notched Charpy impact testing because processing history and colourants influence final mechanical behaviour.

What Limits the Injection Moulding Window for Terluran HI-121?

Processing is restricted by moisture sensitivity, shear history in the rubber phase, and residence-time-dependent thermal degradation. Predrying is mandatory when storage relative humidity exceeds 60%; residual moisture above 0.1% by weight hydrolyses the polybutadiene phase during plastication. The result is splay, silver streaks, weld-line weakness, and erratic notched Charpy impact data. Dehumidified-air drying at 80 °C for 2 h to 4 h is standard. Hopper-mounted desiccant dryers with a dew point below −20 °C are preferred over hot-air ovens because the latter cannot reliably achieve the required drying atmosphere in humid production halls. Condensation during transfer from cold storage should be avoided; sealed containers must equilibrate to production-hall temperature before opening.

Melt temperature measured at the nozzle should remain between 220 °C and 260 °C. Lower temperatures increase viscosity and required injection pressure, while higher temperatures accelerate polybutadiene oxidation and yellowing. Mould temperature is maintained between 30 °C and 60 °C. The upper range is used for high-gloss surfaces, for flow-length to wall-thickness ratios above 150:1, and for walls below 1.5 mm. The lower range may be used for thick sections where sink marks are controlled by holding pressure and cooling rate. Mould surface temperature uniformity should be held within ±5 °C to avoid differential shrinkage and cavity-to-cavity variance. Conventional single-screw injection moulding machines with screw L/D ratios of 20:1 to 25:1 and compression ratios of 2.0:1 to 2.5:1 are suitable. Back pressure of 5 bar to 10 bar and screw speed of 80 min⁻¹ to 120 min⁻¹ improve melt homogeneity without excessive shear heating. Holding pressure and time should be established by gate freeze studies; premature hold release leads to sink marks and voids near bosses, while excessive hold does not compensate for undersized gates. Gate diameter below 0.8 mm for wall sections above 2.0 mm may restrict flow and reduce impact strength near the gate. Residence time at melt temperatures above 250 °C should be kept below approximately 6 min. During interruptions, the barrel should be purged or set back to 180 °C to 200 °C. External mould release agents are generally unnecessary; silicone sprays can create residue that interferes with subsequent bonding, painting, or electroplating. If mould release is required, only diluted soap-free agents should be used after surface-finish validation. Hot-runner systems require independent nozzle temperature control between 230 °C and 250 °C with balanced manifold flow; poorly balanced hot-runner channels produce cavity-to-cavity impact variation.

The grade is specified for injection-moulded automotive interior trims, pillar claddings, glove box housings, vacuum cleaner bodies, small appliance frames, power-tool casings, and sports equipment shells. These applications use the combination of medium melt flow and high impact energy. In automotive interior components, the material is typically moulded at wall thicknesses of 1.5 mm to 3.0 mm and assembled with screws, clips, or snap-fit features. Snap-fit design should not rely solely on ISO 527 tensile data; local strain rate at engagement can exceed 10 s⁻¹, and design validation should include high-speed tensile or instrumented impact testing. For noise-sensitive interior assemblies, the material is not primarily designed for acoustic isolation. Thin-walled moulded ribs may radiate structure-borne noise and may require constrained-layer damping treatments. For paint adhesion, the moulded surface must be free of mould release and internally generated lubricants that can bloom to the surface. Power-washing and cross-cut adhesion testing according to ISO 2409 are recommended before final coating specification. The grade is not suited to transparent or translucent components because the rubber phase produces opacity. The unfilled grade does not contain slip or scratch-resistance additives; precompounded scratch-resistant ABS should be specified where surface marking is a design limit.

When low-temperature impact demands are evaluated alongside chemical exposure

Notched Charpy impact strength at −30 °C of 9 kJ/m² indicates that the material retains measurable but reduced energy absorption below freezing. The transition from ductile tearing to brittle fracture depends on local stress concentration, cooling rate during moulding, and chemical preconditioning. For components subjected to winter thermal cycling, design verification should include multiaxial impact tests on moulded plaques or finished parts, because single-notched Charpy data do not account for biaxial stress states at corners, holes, or snap-fit undercuts. At service temperatures below −30 °C, published data for this specific configuration is limited; safety-relevant parts should be validated on production tools rather than extrapolated from laboratory specimens.

Chemical exposure alters low-temperature impact retention. The styrene-acrylonitrile continuous phase is resistant to dilute acids, alkalis, and aliphatic hydrocarbons, but ketones, esters, chlorinated solvents, and aromatic hydrocarbons cause swelling, stress cracking, or local dissolution. Plasticisers and certain machining oils can migrate into the surface and reduce local glass-transition temperature, increasing brittleness at low temperature. Immersion tests according to ISO 175 followed by notched impact testing are recommended when chemical contact is continuous or intermittent at elevated temperature. For applications involving both sub-zero service and aggressive chemical exposure, higher-butadiene ABS grades or ASA may be required. In electroplating, HI-121 can be etched with chromic-sulphuric acid to promote metal adhesion; however, plating processes expose the moulded part to elevated temperature and chemical attack. Dedicated plating-grade ABS is normally recommended for mirror-bright decorative chrome unless HI-121 is validated on the specific plating line.

Tensile and thermal reference values are summarised below

Typical values are generated from dry-as-moulded specimens. They do not represent legal specifications and may vary with colour, regrind content, moulding conditions, and post-moulding storage.

Regulatory conformance and documentation boundaries

Compliance statements for REACH Regulation EC No 1907/2006 and RoHS Directive 2011/65/EU are colour-batch specific. The ABS polymer backbone is not typically classified as a substance of very high concern; nevertheless, additive packages, process stabilisers, and pigments require verification through the safety data sheet and product stewardship declaration. Lot-level certificates commonly report melt volume-flow rate, tensile yield stress, and notched Charpy impact strength. Manufacturing sites supplying Terluran grades are generally operated under quality management systems aligned with ISO 9001 and automotive-sector quality requirements such as IATF 16949. Flammability classification under UL 94 is thickness- and colour-dependent; natural and black grades may carry HB ratings at common wall thicknesses, but the current UL Yellow Card must be consulted before design release. The product is not a medical-grade material and is not supplied as implantable resin. For food-contact applications, regulatory references such as FDA 21 CFR 177.1020 may apply to the ABS resin family, but published data for this specific configuration is limited; migration limits should not be assumed without an explicit compliance letter for the exact colour and lot. Packaging and Packaging Waste Directive 94/62/EC heavy-metal limits are also subject to batch-specific confirmation.

Differences from other product chemistries determine selection boundaries. Against general-purpose ABS grades in the Terluran portfolio, HI-121 carries a higher butadiene content; the expected result is higher notched Charpy energy and lower tensile modulus. Components requiring maximum rigidity or surface hardness are better served by general-purpose or high-flow ABS unless impact performance governs. Against high-heat ABS grades such as Terluran HH-112, HI-121 has a lower Vicat temperature and should not be substituted in components where continuous service temperature exceeds approximately 80 °C under load or where heat deflection temperature under 1.8 MPa is the controlling design criterion. Against transparent MABS such as Terlux, HI-121 is opaque and cannot meet visible-light transmission requirements. Against ASA grades such as Luran S, HI-121 has lower long-term UV and weathering stability; unpainted exterior parts requiring colour retention should be specified in ASA or protected by UV-stable paint, film, or PMMA capping. Against flame-retardant ABS, HI-121 lacks halogenated flame-retardant additives and is not intended for electrical enclosures requiring V-0 or 5VA classifications. Against PC/ABS blends, HI-121 generally has lower heat resistance and may exhibit lower energy absorption at high strain rates in thick sections, but it offers lower density and easier flow in some geometries. Regrind use is permitted at typical levels up to 20% to 30% when clean and dry, but impact retention should be monitored because repeated processing reduces butadiene-particle toughening efficiency. Colour-matched custom formulations may show property shifts; datasheet values for natural resin should not be applied to heavily pigmented lots without testing. Chemical resistance data should be generated on final mouldings, not on granules, because orientation and cooling history influence environmental stress cracking. Failure analysis of field returns should include Fourier-transform infrared spectroscopy and differential scanning calorimetry to detect contamination by incompatible polymers such as polypropylene or polycarbonate, which reduces notched impact strength.