ABS TERLURAN GP-30 from INEOS Styrolution is an unfilled, general-purpose injection moulding grade based on acrylonitrile-butadiene-styrene terpolymer. The melt volume rate is 28 cm³/10 min at 220 °C and 10 kg nominal load according to ISO 1133-1:2022. The density is 1040 kg/m³ under ISO 1183. The grade is used for thin-wall housings, appliance trim, consumer electronics, toys, and electrical enclosures. Injection moulding is performed with a melt temperature between 230 °C and 260 °C and a mould temperature between 40 °C and 70 °C. At a wall section of 1.5 mm, natural and coloured compounds are normally rated UL 94 HB. The material is not intended for high-heat load-bearing components above 100 °C or for long-term outdoor UV exposure without stabilization.

Why Does the Processing Window Favor Thin-Wall Injection Moulding?

Drying requirements are determined by storage conditions and regrind ratio. At relative humidity above 60%, pre-drying is specified because residual moisture above 0.1% by weight can generate splay, silver streaking, and weak weld lines during fast filling. Dehumidified-air drying at 80 °C for 2 h to 4 h with inlet air dew point below -20 °C is the standard recommendation. Hopper dryers with insufficient residence time are not usually adequate when regrind exceeds 20% of the total shot weight because moisture re-absorption and particle-size variation reduce drying uniformity. Sealed original packaging stored below 60% relative humidity can be processed after 2 h drying, while material exposed for more than 15 days may require the full 4 h cycle.

Reciprocating-screw injection moulding machines with three-zone screws and L/D ratios between 20:1 and 25:1 are common. Screw compression ratios of 2.0:1 to 2.5:1 provide adequate homogenization without excessive shear heating. The shot weight should remain between 30% and 80% of machine barrel capacity to control residence time. A melt cushion of 2 mm to 4 mm is maintained to ensure consistent hold-pressure transfer and to buffer check-ring leakage. Rear, centre, and front barrel zones are typically set in the range of 220 °C to 250 °C; the nozzle is held between 230 °C and 250 °C. Melt temperatures above 270 °C should be avoided because thermal degradation produces yellowing, free radicals, and a measurable loss in notched impact toughness. In multi-cavity tools, cavity pressure sensors located at the last-fill cavity provide a more reproducible switchover signal than time-based transfer, particularly when runner geometry is long or valve-gate timing varies.

Injection back pressure between 5 bar and 15 bar is used to control melt density and colourant dispersion. Higher back pressure can increase screw recovery time and shear heating beyond the intended viscosity range. Injection pressure typically falls between 80 MPa and 120 MPa, depending on flow length, wall thickness, and gate design. For thin-wall parts below 1.5 mm, profiled injection velocity is recommended to keep the flow front above 200 °C and to avoid premature freeze-off. Holding pressure is set at 50% to 70% of peak injection pressure and maintained until gate freeze. Tool venting depths of 0.02 mm to 0.03 mm are typical for unfilled ABS to prevent burn marks and short shots at high fill speeds. In hot-runner systems, pressure drop should be verified with cavity pressure measurement; gate diameters below 0.8 mm shorten the hold-time window and may require an increased melt temperature near 250 °C to maintain pack.

The mechanical property profile separates GP-30 from high-impact ABS and from fibre-reinforced ABS. A tensile modulus of 2500 MPa under ISO 527-2 indicates a stiff unfilled grade. The tensile yield stress is 45 MPa and the tensile yield strain is 2.5%; these values support rigid snap-fit features but not deep post-mould cold forming. The Charpy notched impact value of 25 kJ/m² at 23 °C under ISO 179-1/1eA places the product in the medium-impact ABS segment. At -30 °C, the value falls to 9 kJ/m², which defines a low-temperature service boundary for impact-loaded parts. The Vicat softening temperature of 97 °C under ISO 306 and heat deflection temperature of 96 °C under ISO 75-2 are typical for general-purpose ABS; components requiring dimensional stability above 100 °C under load require high-heat ABS or ABS/PC grades.

Mould shrinkage of 0.4% to 0.7% under ISO 294-4 is used for tooling calculations. Because the grade is unfilled, shrinkage is relatively isotropic compared with glass-fibre-reinforced ABS, but gating and orientation still introduce measurable differences between flow and transverse directions. Mould filling orientation can increase transverse shrinkage by up to 0.1% absolute in high-shear areas near gates. These data should be verified on prototype tools because pigmentation and regrind content shift shrinkage within the published range.

Controlling Surface Gloss and Flow-Line Visibility Through Tool Temperature

Gloss development in ABS is governed by replication of the mould surface and by the rheological condition of the flow front. Tool temperature is the primary external variable. At mould temperatures below 40 °C, rapid cooling freezes the melt before it fully reproduces polished tool steel, producing a matte or streaked surface on high-flow GP-30. At mould temperatures between 60 °C and 70 °C, surface replication improves but cooling time increases by approximately 10% to 20% relative to 40 °C operation. For textured mould surfaces, tool temperature variation across the cavity should be held within ±5 °C to avoid visible gloss differences. Conformal cooling or high-conductivity tool inserts are specified when wall stock varies by more than 50% within the same part. In production, gate blush and jetting are more common when the melt temperature is below 230 °C and the injection speed is high. Increasing the nozzle and front-zone temperature to 240 °C to 250 °C mitigates jetting because the flow front remains cohesive. However, raising melt temperature above 260 °C can produce brown streaks near hot-runner valve pins due to local stagnation. Loss of notched impact can occur before visible discoloration in over-heated regrind fractions, so melt residence time should be tracked in tandem with colour measurements.

Flow-line visibility is also controlled by injection speed and gate entrance. High-speed injection in the range of 100 mm/s to 200 mm/s reduces flow-line contrast by raising the fountain-flow temperature, but excessive speed entrains air if venting is insufficient. A short shot study followed by cavity pressure measurement is used to set the switchover point; switchover at 95% to 98% of total shot volume prevents over-packing and jetting streaks. In-mould labelling and hot-stamping are possible on GP-30. Process validation is required because excessive melt temperature can distort labels, while low temperature can produce poor label adhesion. Metallization and plating require grade-specific adhesion testing because butadiene distribution and mould release agents influence plate adhesion. Published data for this specific configuration is limited, so plating lines must qualify the exact colour-compounded lot.

When Comparing Against High-Flow and High-Impact ABS Grades

The GP series is differentiated primarily by melt volume rate and notched impact strength. GP-30 fills more easily than GP-22 because the MVR changes from 19 cm³/10 min to 28 cm³/10 min; this reduces fill pressure in hot-runner multi-cavity tools and allows shorter injection time. The Charpy notched impact value falls from 27 kJ/m² to 25 kJ/m² at 23 °C. That 2 kJ/m² penalty is acceptable when the limiting defect is a short shot or a flow line rather than impact fracture. GP-35, with MVR of 34 cm³/10 min, is selected for wall sections below 1.5 mm and high-flow paths; its Charpy notched impact decreases to 22 kJ/m². The viscosity differences also affect screw torque and melt pressure: higher-flow grades generate lower back pressure at the same screw speed, but may require smaller check-ring clearances to prevent backflow.

Compared with high-impact ABS grades, GP-30 has lower rubber content and therefore lower multi-axial impact and elongation at break. The tensile modulus of high-impact ABS is often below 2100 MPa, whereas GP-30 remains at 2500 MPa. Components requiring puncture resistance, deep cold draws, or automotive interior trim subjected to knee and head impact should be evaluated against high-impact ABS or ABS/PC blends rather than GP-30. Conversely, GP-30 provides better surface hardness and less mould deposit than many high-rubber ABS grades, which is relevant for unpainted parts with high gloss requirements. With regard to melt strength, GP-30 is lower than GP-22, which means foamed or gas-assisted structures may show cell collapse if pressure decay is not controlled. In chemical foaming with endothermic blowing agents, GP-30 requires lower melt temperature in the range of 220 °C to 240 °C and higher injection speed to maintain a homogeneous cell distribution. Published data for this specific configuration is limited; trial work with actual tool geometry is required before production release.

Application practice on production-scale equipment shows that GP-30 is used in multi-cavity tools with valve-gated hot runners and conventional cold-runner systems. For housings with wall stock between 2.0 mm and 3.0 mm, melt temperature is often held near 240 °C to 250 °C and mould temperature near 60 °C to reduce visible flow lines and improve surface gloss. In thin-wall electronic enclosures below 1.5 mm, higher injection velocity and upper-range melt temperatures are required to fill before freeze-off. The grade is also suitable for snap-arm and self-tapping screw bosses when nominal wall thickness remains above 2.0 mm; below this, stress concentration at sharp corners can produce cracking under impact. Rib radii should be increased beyond 0.5 mm for parts exposed to sub-zero impact loads.

Chemical Resistance Boundaries and Stress-Cracking Solvents

ABS is not resistant to aromatic hydrocarbons, ketones, esters, chlorinated solvents, and strong organic acids. Continuous contact with toluene, xylene, ethyl acetate, methyl ethyl ketone, or trichloroethylene produces swelling, stress cracking, or dissolution. Molded-in stress increases the sensitivity to environmental stress cracking; exposure to dilute acids, alkalis, and aqueous salt solutions is accepted at ambient temperature, but elevated temperature and applied stress reduce the threshold. Components that contact brake fluid, fuel, or solvent-based cleaners should be tested with production parts, not only standard tensile bars. Bending stress applied to a chemical-exposed surface can initiate cracking at loads below the dry short-term yield stress.

UV exposure without carbon black, UV stabilizer, or coating leads to yellowing and surface embrittlement. GP-30 is not formulated for long-term exterior weatherability. Flammability classification is UL 94 HB at 1.5 mm; flame-retardant ABS grades are required for V-0 requirements. Regulatory declarations for REACH and RoHS 2011/65/EU are lot-specific and must be obtained through the supplier. Food-contact and medical-use declarations are not automatic and require explicit written confirmation for the specific compound formulation.