LG Chem Ningbo Yongxing ABS HI-121 is a high-impact acrylonitrile-butadiene-styrene copolymer supplied from the Yongxing production platform in Ningbo, China. The HI prefix denotes the high-impact series; the numerical suffix 121 separates the grade from adjacent flow-modified and super-impact variants such as HI-121H and HI-100. The resin consists of a styrene-acrylonitrile continuous phase and a dispersed polybutadiene-rich rubber phase. The resulting morphology provides notched impact resistance higher than general-purpose ABS grades while retaining predictable melt viscosity and low mould shrinkage typical of ABS. The packaging label on domestic Chinese shipments may identify the producing entity as LG Chem Yongxing; for export documentation the grade is listed as LG Chem ABS HI-121 with the Ningbo Yongxing facility code. Because the manufacturer does not issue a separate plant-specific datasheet, the global LG Chem HI-121 data set is referenced below. All cited values are typical lot-average figures and are not certification limits.

What Drying and Melt-Temperature Limits Apply Before Injection Molding?

Before melt processing, the granulate is conditioned in a closed-loop dehumidifying dryer. Moisture content must be reduced below 0.1 % w/w; ABS is hygroscopic, and residual moisture above this threshold promotes splay, gate blush, and loss of notched Izod impact from degradation of the polybutadiene phase at processing temperatures. A desiccant bed with a dew point of -20 °C to -30 °C, hopper inlet temperature of 80 °C to 85 °C, and residence time of 2 h to 4 h is used for normal pellet feed. Under relative humidity above 60 %, drying time should be extended to 4 h to 6 h or a moisture analyzer should be used to confirm residual moisture before start-up.

Processing on production-scale reciprocating-screw machines with L/D ratios of 20:1 to 24:1 and compression ratios of 2.5:1 to 3:1 is common for unfilled ABS. Screw speed is set to keep screw-recovery time below cooling time, typically 60 rpm to 120 rpm depending on screw diameter; back pressure of 5 bar to 10 bar assists melt homogenization without excessive shear heating. Cushion is maintained at 3 mm to 5 mm. Melt temperature at the nozzle is kept between 220 °C and 240 °C; prolonged residence time above 250 °C, particularly beyond 5 min, accelerates polybutadiene oxidation and yellowing. Mold temperature between 40 °C and 60 °C provides adequate gloss, weld-line strength, and part ejection. For thin-wall parts below 1.5 mm nominal wall thickness, fill time is commonly 0.4 s to 0.8 s; thicker parts tolerate slower velocities. Specimen preparation for mechanical testing follows ISO 294-1 or ASTM D3641.

Mechanical Benchmark Data and Specimen Conditioning

Specimen preparation follows ISO 178, ISO 527-2, and ISO 179-1/1eA protocols after conditioning at 23 ± 2 °C and 50 ± 5 % RH for 88 h per ISO 291 unless otherwise specified. The following table summarizes typical lot-average values for LG Chem ABS HI-121; these values are not certification limits and should not be used for safety-critical design without reviewing the lot-specific certificate of analysis. Because the Ningbo Yongxing plant does not publish a separate local datasheet, the data set below reflects the global HI-121 grade specification and is common to LG Chem ABS production sites. Lot-to-lot variation in polybutadiene rubber content, styrene-acrylonitrile molecular weight, and additive package may shift notched impact and melt flow by up to 10 %.

The values in the table should be interpreted as conditioned-state short-term mechanical data, not long-term creep or fatigue properties. Flexural modulus and tensile yield are strongly affected by specimen orientation, gate geometry, and cooling rate; parts moulded under high injection speed may exhibit frozen-in molecular orientation that raises tensile yield in the flow direction but reduces transverse elongation. The notched Izod value is thickness-dependent; 3.2 mm specimens typically report higher values than 6.4 mm specimens because plane-strain constraint at the notch tip increases with section thickness. Rockwell hardness remains relatively insensitive to processing conditions but correlates with styrene-acrylonitrile acrylonitrile content and can be used as a lot-consistency check after moulding.

Rheological characterization by capillary rheometry shows shear-thinning behavior typical of ABS graft systems. Capillary viscosity at 240 °C and 1,000 s⁻¹ is used for mold-filling calculations; values near 180 Pa·s to 220 Pa·s are representative for the high-impact series, although the exact lot value is obtained from the certificate of analysis. Mould shrinkage is generally 0.4 % to 0.6 % in the flow direction and 0.5 % to 0.7 % transverse, depending on wall thickness and packing pressure. After 48 h, additional post-moulding dimensional change is usually less than 0.05 % when parts are adequately packed.

In thin-wall electronic enclosure tooling with nominal wall thickness of 2.0 mm, gate land thickness is typically 1.0 mm to 1.5 mm, runner diameter is 5 mm to 6 mm, and vent depth is kept at 0.02 mm to 0.03 mm to minimize gas burn at the end of fill. On a 120-ton hydraulic toggle press with a P20 mould insert, melt temperature near 230 °C and mold temperature near 50 °C produce stable filling; flow lengths beyond 150 mm from a single edge gate may require a second gate to prevent excessive cavity pressure loss and weak weld lines. Weld strength in this grade typically retains 60 % to 80 % of the unnotched tensile-breaking force when mold temperature remains above 45 °C; below this temperature knit-line weakness becomes visible in drop-impact testing.

When Flowability Is Prioritized over Low-Temperature Ductility

The distinction between HI-121 and adjacent LG Chem high-impact grades is observed in spiral-flow and notched-impact comparisons. HI-121 occupies a mid-flow, mid-impact point in the series. HI-121H raises melt flow rate for thin-wall and multicavity tools; the trade-off is a decrease in notched Izod impact and slightly lower weld-line elongation. Published comparative data from the manufacturer place HI-121H melt flow rate roughly 30 % to 50 % higher than HI-121 under 220 °C/10 kg, while its notched Izod impact is 10 % to 20 % lower. HI-100, by contrast, raises polybutadiene rubber-phase content or adjusts rubber particle-size distribution to increase low-temperature ductility and notched Izod impact; its melt flow rate is significantly lower than HI-121, making it less suitable for long-flow or thin-wall parts. HI-121 is therefore specified where cycle time and impact resistance are both required at moderate levels; HI-121H is selected for high-cavitation or pin-gated tools; HI-100 is selected for thick-wall components requiring maximum crack arrest, such as luggage shells, crash-relevant interior retention features, or appliance bases subjected to repeated impacts.

Grade substitution in either direction should be validated by mold-flow simulation using measured melt flow rate, pressure-volume-temperature data, and thermal conductivity. A switch from HI-121 to HI-100 without increasing melt temperature or gate size can produce short shots or elevated cavity pressure near the machine clamp limit. Conversely, substituting HI-121H for HI-121 may require a longer holding-pressure profile because the lower melt viscosity reduces gate-seal time and increases backflow if switchover is delayed. Cooling time differences are small; dimensional stability is similar among the three grades, so tool steel changes are generally not required, but process parameters and cushion control must be re-established.

Regulatory declarations for LG Chem Ningbo Yongxing ABS HI-121 are supplied on a lot-specific basis. The base resin is typically assessed against EU RoHS 2011/65/EU as amended by (EU) 2015/863 for lead, mercury, cadmium, hexavalent chromium, PBB, PBDE, and the four phthalate categories. REACH SVHC disclosure follows Article 33 and requires review of the current candidate list; finished articles containing more than 0.1 % w/w of an SVHC must be evaluated by the formulator. The unfilled grade carries UL 94 HB flammability classification at the tested thickness; it is not a flame-retarded grade and should not be specified for enclosures requiring V-0 performance unless a flame-retardant additive package is qualified and re-evaluated under the end-use standard. Chemical compatibility is limited in contact with ketones, esters, low-molecular-weight chlorinated solvents, and some aromatic hydrocarbons; environmental stress-crack testing under ASTM D543 or ISO 22088 should be performed for applications exposed to cleaning fluids, adhesive solvents, or sunscreen. Service temperatures below -40 °C are generally outside the intended design envelope because the polybutadiene rubber phase stiffens and impact energy absorption becomes more rate-dependent. Moulders receiving material from the Ningbo Yongxing site should verify the certificate of analysis for melt flow rate and notched Izod impact before releasing production lots, because plant batch records may differ from the global datasheet within typical grade tolerances.