INEOS Styrolution ABS TERLURAN HH-112 is a high-heat acrylonitrile-butadiene-styrene copolymer supplied in pellet form for injection molding and profile extrusion. The grade is identified by a Vicat softening temperature of 112 °C under ISO 306/B50, a heat deflection temperature of 102 °C under 1.8 MPa flexural stress according to ISO 75-2/A, and a density of 1.05 g/cm³ per ISO 1183-1. The melt volume rate is listed as 5.0 cm³/10 min at 220 °C and 10 kg load per ISO 1133-1:2022. These values place HH-112 above medium-heat ABS grades with Vicat values in the 96 °C to 100 °C zone and below super-high-heat ABS or polycarbonate/ABS blends with Vicat values above 120 °C. The grade is selected for automotive HVAC air outlets, electronic enclosures, small appliance housings, and interior trim components that are exposed to hot air surfaces beyond the continuous service range of unmodified ABS.

High-heat ABS chemistry achieves the elevated softening point by increasing the rigid-phase glass transition temperature through higher styrene-co-acrylonitrile content or alpha-methylstyrene incorporation. This raises Vicat temperature but reduces melt flow and narrows the thermal degradation window. The butadiene rubber phase remains the limiting constituent at upper melt temperatures, while the rigid styrene-co-acrylonitrile matrix controls the lower temperature boundary. The grade is not inherently flame retardant, and its low-temperature Charpy notched impact is lower than that of low-temperature ABS grades. The −30 °C value reported in supplier literature is approximately 6 kJ/m² under ISO 179-1/1eA. Designers should not treat HH-112 as a direct substitute for impact-modified ABS in cold-climate snap-fit applications without instrumented puncture testing at the minimum service temperature.

Residual moisture must be controlled before melt processing because high-heat ABS is processed at elevated melt temperatures that amplify hydrolysis and volatile generation. The pellets should be dried in a desiccant dryer at 80 °C to 85 °C for 2 h to 4 h when the dryer air dew point is −20 °C or lower. The target residual moisture is 0.10 % or less, measured by Karl Fischer titration or ISO 15512. If storage relative humidity exceeds 60 %, drying time should be extended to at least 4 h. Moisture above 0.15 % produces silver streaks near the gate and can reduce tensile yield stress measured under ISO 527-2 by hydrolytic chain scission at the rubber–matrix interface.

What Determines the Upper Melt Temperature Limit in High-Heat ABS?

For HH-112, the recommended melt temperature range in production-scale molding cells is 240 °C to 270 °C, measured by air shot at the nozzle. At melt temperatures below 240 °C, the high-heat matrix may not fully plasticate in short-residence screw designs, increasing recovery torque and causing visible delamination in thick bosses. Above 270 °C, degradation of the butadiene rubber phase becomes detectable as yellowing, brown streaking, and a decrease in Charpy notched impact strength after residence times exceeding 8 min to 10 min at melt temperature. Hot runner manifold and nozzle temperatures are typically set 5 °C to 10 °C above the nozzle melt temperature, but the total melt residence time in the manifold should remain below 10 min to avoid surface gloss loss and odour generation. These limits apply to standard three-zone screws with L/D ratios between 20:1 and 25:1 and compression ratios between 2.5:1 and 3.0:1. High-compression barrier screws may shift the lower melt temperature boundary by 5 °C to 10 °C.

Gate Freeze-Off, Filling Pressure, and Packing Requirements

The melt volume rate of 5.0 cm³/10 min is lower than that of many general-purpose ABS grades, so the required injection pressure for thin-wall parts is higher. In direct-gated tools with wall thickness 2.0 mm, hydraulic injection pressures of 80 MPa to 120 MPa are typical. In multi-cavity hot-runner tools, cavity pressure at switchover is often set between 45 MPa and 70 MPa. Gate diameters should be 0.8 mm to 1.2 mm for pin gates and no less than 0.5 mm for submarine gates to avoid premature freeze-off before packing compensation. The grade is processed with screw-forward packing profiles using a holding pressure of 60 % to 80 % of peak injection pressure for 4 s to 8 s in parts with nominal wall thickness 2.0 mm to 2.5 mm. For hot runner systems, manifold temperatures are maintained between 250 °C and 270 °C, with valve-gate pin actuation monitored for stiction caused by outgassing or partially degraded material when residence time exceeds the 10 min limit.

In automotive HVAC defroster outlets and instrument panel air ducts, part-level air temperature during defrost mode can exceed 95 °C for short durations. The 112 °C Vicat value provides a margin against visible deformation under constraint, but the final part must be validated in a heated fixture because the Vicat test is a single-point penetration experiment under 50 N load and does not reproduce assembled clip creep. For electronic adapter housings, internal transformer and power semiconductor hot spots may reach 100 °C to 105 °C under blocked-airflow conditions. The heat deflection temperature of 102 °C at 1.8 MPa may require additional ribbing or reduced mechanical load to prevent creep over the product service life. Small appliance parts such as toaster side panels and heater fan grilles are processed with high-gloss tool surfaces, but end-use approval requires product-specific thermal cycling and flammability testing, not raw-material datasheet substitution.

When Thermomechanical Stability Across Repeated Heat Cycles Is Specified

Components subjected to repeated heating and cooling cycles benefit from predictable mold shrinkage if the tool design accounts for post-mold dimensional change. For HH-112, linear mold shrinkage after 48 h at 23 °C is reported in the range of 0.4 % to 0.7 % per ISO 294-4, with lower values in heavily ribbed or fast-filled geometries and higher values in thick unfilled sections. Post-mold shrinkage after accelerated annealing at 80 °C for 1 h can add 0.05 % to 0.15 %, depending on packing and gate freeze-off. When assembly requires gap and flush tolerances of ±0.1 mm over a 300 mm length, tooling must compensate for post-mold shrinkage, or parts must be annealed before dimensional inspection. The coefficient of linear thermal expansion is typically 0.8 × 10⁻⁴ K⁻¹ to 1.0 × 10⁻⁴ K⁻¹ under ISO 11359-2, which is higher than glass-filled grades and lower than unfilled polypropylene.

Comparative Positioning Against Medium-Heat and Flame-Retardant ABS Grades

The primary selection difference between HH-112 and a medium-heat ABS is the thermal resistance of the rigid phase. A standard medium-heat Terluran grade may show a Vicat B/50 value in the 95 °C to 100 °C range, while HH-112 shifts that value to 112 °C. This allows integration into areas with sustained surface temperatures near 100 °C, provided mechanical stress is low. However, the higher rigid-phase content reduces melt flow, so thin-wall fill length at a given injection pressure is shorter than that of high-flow ABS grades, which may exceed 12 cm³/10 min at the same load. Compared with PC/ABS blends, HH-112 has a lower density of 1.05 g/cm³ and a lower melt temperature, which can reduce material consumption and energy input per shot, but its notched Charpy impact at −30 °C is lower. Selection of HH-112 over PC/ABS for interior structural parts therefore depends on whether thermal exposure is above 110 °C only in air and whether low-temperature ductility is governed by hinge or snap-fit requirements.

The mold temperature range is selected for surface replication and internal stress control. Mold temperatures between 60 °C and 90 °C improve knit-line strength and reduce visible flow lines in high-gloss automotive and appliance surfaces. When molding near the lower end of the range, excessive molded-in stress can be induced in thick sections because the rigid phase solidifies before complete packing. When molding near the upper end, cycle time increases because the high Vicat temperature of HH-112 requires mold cooling to remove sufficient enthalpy before ejection. For polished grain surfaces specified to SPI A-2 finish, mold deposits and outgassing are minimized by avoiding melt residence above 10 min and by avoiding external mold release agents that can migrate to the surface and reduce paint adhesion.

Which Regulatory and Compliance Documents Must Be Verified for This Grade?

Material selection for European Union and North American markets should be supported by supplier documentation confirming REACH registration under EC 1907/2006 and restriction status under REACH Annex XVII. For electrical and electronic equipment, the grade should be checked against recast RoHS Directive 2011/65/EU and subsequent delegated acts for lead, mercury, cadmium, hexavalent chromium, PBB, and PBDE. In the United States, food-contact applications require confirmation against 21 CFR 177.1020 for acrylonitrile/butadiene/styrene copolymers, but HH-112 should not be assumed to meet food-contact status without written confirmation for the specific colour and additive package. For automotive interior components, horizontal burn rate must be validated on the final part according to ISO 3795 or FMVSS 302; raw-material data do not replace component-level certification.

Chemical resistance of unfilled high-heat ABS is limited in contact with ketones, esters, and aromatic hydrocarbons. Cleaning solvents such as methyl ethyl ketone and toluene cause stress cracking in molded parts with high residual stress. For cleaning and deflashing operations, only water-based neutralizing agents or low-solvency alcohols should be used after compatibility testing per ISO 22088-3. Published data for this specific configuration is limited to general ABS chemical resistance charts; end-use immersion testing under production stress conditions is required before introducing any process aid, release agent, or cleaning solvent.