Lotte Chemical ABS GT-5100 is an injection-moulding grade of acrylonitrile-butadiene-styrene terpolymer in the Starex ABS series. The grade is specified for moulded components that require controlled melt flow, stable surface appearance after tool finishing, and mid-range mechanical stiffness. The product is supplied as cylindrical pellets, and lot-specific certificates report moisture content, melt mass-flow rate, and notched impact results. This technical introduction is based on standardised specimen preparation and current manufacturer datasheet values for natural material. Final part qualification must use the latest supplier revision because colourants, regrind content, and processing temperatures alter mechanical response and regulatory status.

Which Standardised Test Methods Define the Material Specification?

Specimens for the values below are prepared according to ISO 294-1:2017 and conditioned according to ISO 291:2008 at 23°C and 50% relative humidity for 24 h. Testing is performed on unfilled natural-grade material unless otherwise specified. The values are representative single-point data from current supplier documentation, not design allowable values.

Melt mass-flow rate at 220°C with 10 kg load places GT-5100 in the medium-flow injection-moulding range. A higher-flow grade will fill multi-cavity thin-wall tools with lower injection pressure, but the increase in flow typically accompanies a reduction in notched impact strength at 23°C and a greater tendency to jet near restricted gates. The notched Izod value of 21 kJ/m² is reported on Type A specimens per ISO 180:2023; weld-line impact values in moulded parts are lower and must be measured on production tools.

Regulatory status is formulation-dependent. Natural GT-5100 should not be considered food-contact cleared unless the supplier provides written confirmation under FDA 21 CFR 177.1020 or EU Regulation (EU) No 10/2011 for the specific lot. Converters must verify the safety data sheet for REACH constraints on substances present above 0.1% by weight and exclude cadmium- or lead-based pigments for RoHS Directive 2011/65/EU compliance. The material does not contain halogenated flame retardants as supplied, but recycled post-industrial streams can alter this profile.

Predrying is mandatory when pellet moisture exceeds 0.05% by weight. In a closed-loop desiccant dryer with a dew point of -40°C to -30°C, inlet air at 80°C to 85°C for 2 h to 4 h reduces retained moisture to an acceptable level for injection moulding. Drying times longer than 5 h are not recommended; even dry air at these temperatures can accelerate yellowing and shift melt viscosity downward. Hopper airflow should be calibrated to pellet throughput, typically 0.08 m/s to 0.10 m/s across the bed for hoppers up to 100 kg/h throughput.

Batch-to-batch variance observed on production lines is most commonly caused by regrind ratio. At regrind fractions above 20 wt%, melt flow can rise by 5% to 10% after thermal history and shift packing behaviour. Re-extrusion reduces low-boiling additives and can lower gloss. If recycled material is used, lot-level melt mass-flow rate must be measured according to ISO 1133-1:2022 before establishing hold pressure. In compounding-side evaluations, dispersion of colour concentrates in a co-rotating twin-screw extruder with L/D 32:1 at melt temperature of 220°C to 240°C produced acceptable pigment distribution; at melt temperatures below 210°C, pigment agglomerates appeared on polished surfaces.

When Moisture Uptake Exceeds 0.1% Before Melt Processing

When pellets are exposed to relative humidity above 60% without sealed storage, equilibrium moisture uptake in ABS can approach 0.35% by weight. Feeding material with moisture above 0.1% into an injection barrel generates silver streaks and surface roughness; the effect is more severe in hot-runner tools because the melt is held at 240°C for longer periods. A shut-off nozzle or screw decompression does not remove dissolved moisture; it only reduces drool and decompression-related gas accumulation.

At barrel temperatures above 230°C, residual moisture can contribute to hydrolytic chain scission of the styrene-acrylonitrile phase, reducing tensile elongation at break before visible surface defects appear. For this reason, thermal drying is considered a boundary condition, not a pre-treatment option. Incompatibility with amine-based additives is a documented processing risk for ABS materials. Low-molecular-weight primary amines can accelerate hydrolysis of acrylonitrile groups and reduce melt strength at processing temperatures. If a colour masterbatch or processing aid contains amine-functionalised additives, compatibility must be verified by melt-flow stability tests over 10 min at 240°C.

Independent of drying, the melt-processing window is bounded by surface appearance at the lower end and thermal degradation at the upper end. Barrel settings of 200°C to 220°C in the rear zone, 210°C to 230°C in the centre zone, 220°C to 240°C in the front zone, and 220°C to 240°C at the nozzle provide a starting point for cold-runner tools. Mould temperature of 40°C to 80°C is used; higher mould temperatures improve gloss and melt-line strength but extend cycle time. Back pressure between 0.5 MPa and 1.0 MPa and screw surface speed of 0.1 m/s to 0.3 m/s are typically sufficient for colour dispersion without excessive frictional heating.

Injection pressure should be set by the minimum pressure required to fill 95% to 98% of the cavity without flash. Holding pressure is typically 50% to 70% of that peak pressure and is maintained until gate freeze. Shot size should fill 40% to 70% of the available barrel volume to avoid excessive residence time. A screw with 20:1 to 24:1 L/D ratio and compression ratio 2.5:1 to 3.0:1 is acceptable; high-shear screws with narrow channels can raise melt temperature beyond the 250°C limit at high screw speed.

Comparative Positioning Against Alternative ABS Grades

Compared with general-purpose low-flow ABS grades in the Starex series, GT-5100 is formulated to give a higher melt mass-flow rate while maintaining room-temperature notched impact. The trade-off is a reduction in continuous service temperature relative to heat-resistant ABS grades that contain alpha-methylstyrene or maleic anhydride. The heat deflection temperature of 88°C at 1.80 MPa places GT-5100 below typical heat-resistant grades, which may exceed 105°C by ISO 75-2:2013 Method A. Components requiring continuous under-bonnet air temperatures above 90°C should be re-specified.

Differences from flame-retardant grades are more direct. GT-5100 is not formulated with halogenated or phosphorus-based flame-retardant systems and does not claim UL 94 V-0 at 1.5 mm. The standard rating reported for this grade is HB at 1.5 mm. In electroplating, GT-5100 can be etched with standard chromic acid/sulphuric acid baths, but the rubber-phase particle size distribution is not optimised for all plating lines; lot-specific peel adhesion tests are required. Compared with extrusion grades, the lower molecular weight associated with higher flow reduces melt strength and makes GT-5100 unsuitable for profile or sheet extrusion where sag and die-swell control are critical.

Chemical resistance of GT-5100 follows ABS behaviour: aromatic hydrocarbons, ketones, and esters attack the styrene-acrylonitrile matrix. Brief contact with isopropyl alcohol can induce environmental stress cracking in stressed parts; compatibility tests according to ISO 22088 or ASTM D543 are required before use with cleaning fluids, adhesives, or paint thinners. Published data for direct comparative testing of GT-5100 against every neighbouring grade is limited; the processing differences described here are therefore restricted to documented formulation and flow characteristics rather than fitted multi-point datasets.

Melt Rheology Data Indicate a Shear-Thinning Plateau below 100 s⁻¹

Rheological data for unfilled ABS show pseudoplastic behaviour, with apparent shear viscosity decreasing from approximately 200 Pa·s at 100 s⁻¹ to 25 Pa·s at 1,000 s⁻¹ at 220°C. This shear-thinning behaviour permits filling of long thin-section tools, but it also means gate shear rate strongly influences local temperature and surface gloss. At shear rates above 10,000 s⁻¹, melt temperature can rise locally and decompose the polybutadiene phase; venting depths of 0.02 mm to 0.04 mm and gate land lengths below 1 mm should be evaluated through cavity-balance trials.

Production machines with clamp force between 800 kN and 6,000 kN have been used for GT-5100 without modification, provided screw throughput and residence time are controlled. At barrel temperatures above 240°C, total residence time should not exceed 5 min; at 250°C the allowable residence time is shorter, and any stoppage longer than 10 min should be followed by purging with general-purpose ABS or polystyrene. Black specks, odour associated with styrene degradation, or a drop in injection pressure at constant temperature indicate polymer degradation and require immediate barrel purge.

Typical injection moulding applications reported for GT-5100 include domestic appliance housings, small electrical equipment covers, office equipment panels, and non-structural interior trim. In these applications, mould temperature of 50°C to 60°C is used to balance surface gloss and dimensional stability. Lower mould temperatures reduce cycle time but increase residual stress, which can reduce weld-line strength and environmental stress cracking resistance. Weld-line strength in a single-gated tensile bar is generally 60% to 70% of the unnotched value at the recommended melt temperature; published data for this specific configuration is limited, and converters should perform internal weld-line testing according to ISO 527-2:2012 before final part release.