LG Chem ABS HI-400 is a high-impact acrylonitrile-butadiene-styrene injection molding grade supplied by LG Chem Ltd. The material is classified under ISO 1043-1:2011 as ABS and is processed primarily by conventional screw injection molding. The grade is positioned for thick-wall components where notched Izod impact, low-temperature crack resistance, and molding stability are more critical than thin-wall flow length. Representative datasheet values place the melt mass-flow rate at 4.0 g/10 min under ISO 1133-1:2022 at 220 °C and 10 kg. The density is 1.05 g/cm³ under ISO 1183-1:2019. Mold shrinkage is stated as 0.4–0.7 % under ISO 294-4:2018.

What mechanical and thermal property values define the published datasheet profile?

Representative single-point values are provided by the manufacturer and are not guaranteed production limits. They are generated on conditioned specimens under the cited standards.

The tensile stress at yield of 41 MPa under ISO 527-2:2012 places HI-400 in the lower-stiffness portion of unfilled ABS grades. The flexural modulus of 2,150 MPa under ISO 178:2019 is used for short-term deflection calculations; design calculations for snap-fit deflections should use the secant modulus at the expected strain, not the initial tensile modulus. The notched Izod impact of 39 kJ/m² under ISO 180/A:2000 at 23 °C indicates high resistance to crack propagation. However, this value is not a fracture-mechanics parameter and should not be used directly for finite-element failure prediction. Published low-temperature Izod data for this exact grade are limited; parts exposed to impact below −20 °C require molded-part validation. The heat deflection temperature of 96 °C under ISO 75-2/B:2013 at 0.45 MPa is a short-term thermal indicator, not a continuous-use rating. Load-bearing components should incorporate a safety margin when surface or core temperatures exceed 70 °C.

Pre-drying is mandatory before melt processing. A desiccant dryer with a dew point at or below −30 °C should reduce pellet moisture to below 0.02 wt%. Drying at 80 °C for 2 h to 4 h is normally sufficient for virgin material from sealed containers; regrind addition above 20 wt% may require an additional hour. When ambient relative humidity exceeds 60 %, drying time should be extended to 4 h and the return-air dew point monitored. Residual moisture above 0.05 wt% promotes hydrolysis-induced surface splay and reduces notched Izod impact. A Karl Fischer titration or weight-loss moisture analyzer confirms pellet moisture before molding; pellet surface dryness is not sufficient evidence of internal dryness.

Barrel zone settings for a general-purpose screw with an L/D ratio of 20:1 to 24:1 are typically 190–210 °C rear, 210–230 °C center, 220–240 °C front, and 225–240 °C nozzle. Melt temperatures below 210 °C increase melt viscosity and may reduce knit-line impact; melt temperatures above 250 °C initiate thermal degradation of the polybutadiene phase, visible as brown streaks and a drop in notched Izod impact. Mold temperature should be maintained between 40 °C and 70 °C. The upper end improves knit-line impact and gloss but increases cooling time; mold temperatures below 35 °C can produce residual stress and inconsistent shrinkage. Back pressure is kept at 0.5–1.5 MPa. Screw speed for a 40 mm to 60 mm screw is limited to 40–80 min⁻¹. Melt residence time should not exceed 5 min at 240 °C; hot-runner dead spots and long residence times cause yellowing and loss of impact.

The melt mass-flow rate of 4.0 g/10 min is not sufficient for runner sizing. Capillary rheometry at 230 °C and shear rates of 100–10,000 s⁻¹ should be used for gate sizing; high-impact ABS of this flow class typically exhibits apparent viscosity in the range of 300–600 Pa·s at 1,000 s⁻¹. Thermal degradation in HI-400 is initiated by oxidation and chain scission in the polybutadiene phase. At melt temperatures above 250 °C, discoloration and impact loss become visible within a few minutes of stagnant residence. At 240 °C, residence should still be limited to 5 min because polybutadiene unsaturation is susceptible to free-radical oxidation. A nitrogen purge on the hopper does not replace proper drying, but it can reduce oxidative yellowing during long runs at high ambient humidity.

For mold clamping, cavity pressure in ABS tools is typically 250–400 bar. Hydraulic clamp force is estimated from projected area at this cavity pressure; a 150-ton machine is generally adequate for a total projected area near 600 cm², but long flow paths or high cavity counts may require 250 tons or more. Gate freeze before pack is a common short-shot cause. A gate diameter below 0.8 mm may freeze before the part is packed when nominal wall thickness exceeds 2.5 mm. Injection velocity should be moderate to high, but gate shear rates above 30,000 s⁻¹ can produce surface defects such as jetting or silver streaking.

Differences from LG Chem HI-121H appear in the melt-flow and impact balance

HI-400 is not a regrind or color variant of HI-121H. The representative comparison below, based on published datasheet values, shows the material selection trade-off between flow and impact.

The lower melt mass-flow rate of HI-400 means that the same flow path requires higher injection pressure or a larger gate. HI-121H is preferred for thin-wall parts with nominal wall thickness below 1.5 mm; HI-400 is preferred when the failure mode is impact crack initiation in sections above 2.5 mm. The difference in flexural modulus of approximately 250 MPa is relevant for snap-fit deflection calculations. The notched Izod difference from 39 kJ/m² to 25 kJ/m² is sufficient to change drop-test failure behavior in parts such as appliance housings or power-tool bodies. General-purpose ABS grades with flexural modulus above 2,300 MPa and notched Izod below 20 kJ/m² are not direct substitutes when crack initiation is the limiting failure mode. Heat-resistant ABS grades may offer higher Vicat values but often trade away impact; HI-400 does not provide the same upper-temperature resistance as a heat-resistant ABS with a Vicat above 105 °C.

Application profiles for HI-400 are concentrated in injection-molded housings, automotive interior trim, appliance panels, and electrical enclosures. In automotive glove-box shells and console side panels, the grade is specified where the component must withstand occupant contact without fracture at ambient temperature. For electrical enclosures, the controlling material requirement is often not tensile yield but impact after assembly; inserts, bosses, and self-tapping screws create stress concentrations. The notched Izod value of 39 kJ/m² under ISO 180/A:2000 supports ductile failure around these features. Weld-line impact is reduced when melt temperature is below 220 °C or mold temperature is below 40 °C. Gas entrapment in unvented blind pockets creates streaks and locally reduces elongation at break; vacuum venting or porous steel inserts in the last-filled areas are used to remove trapped gas. Published data for thick-section weld-line impact of this exact grade are limited; production qualification should include destructive testing on molded parts rather than relying solely on plaque data.

Paintability and plating performance are reported for ABS, but adhesion is surface- and process-dependent. Flame treatment or adhesion-promoting primers are used before painting; silicone-containing mold release agents are incompatible with most paint and plating processes. For chrome plating, the ABS etch system requires a butadiene-rich surface; regenerated or internally lubricated material can alter etch uniformity. No specific plating approval for HI-400 is implied by its ABS classification; platers should run adhesion tests on molded samples.

When a high-flow ABS is replaced by HI-400 in an existing mold

Mold filling is the first constraint. The lower melt mass-flow rate increases pressure drop through the sprue, runner, and gate. Existing tools designed for a 10 g/10 min grade may show short shots if the gate is below 0.8 mm. Injection pressure may need to be increased by 10–20 %, but machine pressure limits and flash formation at the parting line must be checked. Packing time should be increased when wall thickness exceeds 2.5 mm to control sink marks. Mold shrinkage is expected to remain in the 0.4–0.7 % range, so steel changes for shrinkage compensation are generally not required if the previous grade was an unfilled ABS with similar density. Hot-runner systems with small gates or reverse-taper nozzles may require higher manifold temperatures or valve-gate sequencing. The barrel should be purged with a high-flow ABS or dedicated purging compound before processing HI-400 to avoid retention of degraded material.

Lot-to-lot notched Izod impact in commercial ABS is typically controlled within ±5 % of the nominal value when tested under ISO 180/A at 23 °C and 50 % RH. Users should retain molded plaques from each batch and correlate them with part impact failures. Amine-based purge compounds or incompatible additives should be avoided because they can promote premature degradation and surface defects in ABS melt processing.

Regulatory and material compliance matrix

The natural formulation is normally listed as UL 94 HB. Flame-retardant versions or heavily pigmented masterbatches may alter the classification, so the specific compound must be tested at the final part thickness. The material is designated under ISO 11469:2016 by the marking >ABS< unless the purchaser specifies otherwise. The manufacturer generally declares compliance with RoHS Directive 2011/65/EU as amended by (EU) 2015/863 for restricted substances. REACH candidate-list SVHC content below 0.1 wt% is typically declared for the standard pellet grade; lot-specific declarations should be obtained for production parts. The grade is not intended for medical implants or food-contact packaging unless the final compound is explicitly tested under FDA 21 CFR or corresponding national legislation. Users are responsible for validating migration and extractables when indirect food contact is claimed.