Formosa Chemicals & Fibre Co., Ltd. (FCFC) supplies the acrylonitrile-butadiene-styrene terpolymer grade AG25AT within the TAIRILAC ABS portfolio. The material is classified as a high-flow general-purpose injection moulding grade, with a nominal melt mass-flow rate of 25 g/10 min determined under ISO 1133-1:2022 at 220 °C and 10 kg load. Specification values remain subject to lot-specific certificates of analysis; the data presented below are representative values and are not to be interpreted as release limits. Table 1 summarises physical, mechanical, thermal, and moulding-shrinkage data generated on injection-moulded specimens conditioned at 23 °C and 50 % relative humidity according to ISO 291.

The inverse relationship between melt mass-flow rate and notched impact resistance should be considered in material selection. AG25AT provides lower melt viscosity than medium-flow ABS grades, which shortens fill time in multi-cavity tools; however, its notched Izod impact values are lower than those obtained with lower-flow TAIRILAC ABS grades specified for deep-draw or low-temperature impact applications. In applications requiring ISO 180/A notched Izod impact values above 20 kJ/m² at 23 °C, an impact-modified grade should be evaluated instead. For thin-wall electrical enclosures and appliance housings with nominal wall thickness between 1.2 mm and 3.0 mm, the balance of flow and stiffness is typically sufficient. Moisture absorption of unfilled ABS at equilibrium is approximately 0.2–0.4 wt% at 23 °C and 50 % RH per ISO 62. The diffusion process is surface-controlled at the granulate scale; therefore hopper-dryer air flow and dew point are more useful process controls than total residence time alone. Karl Fischer titration (ISO 15512) is preferred over loss-on-drying because loss-on-drying may over-report moisture in materials with low volatile content.

What Conditions Govern Reliable Injection Moulding of AG25AT?

Before processing, the granulate must be dried. ABS is not as hydrolysis-sensitive as polycarbonate, but residual moisture in the feed system is the dominant cause of surface splay, silver streaking, and internal voids. The resin should be dried in a dehumidifying hopper dryer with a dew point of -30 °C or lower at 80 ± 5 °C for 3–4 h to reduce residual moisture to 0.05 wt% or less, measured by ISO 15512 Karl Fischer titration or an equivalent calibrated moisture analyser. Storage of open bags at relative humidity above 60 % should be limited to 2 h before drying, because moisture uptake can exceed 0.1 wt% in uncontrolled shop-floor conditions. Drying residence times beyond 8 h at 80 °C can shift colour toward yellow as the styrene-acrylonitrile phase undergoes thermal oxidation; processors with interrupted shifts should reduce dryer inventory rather than hold hot material overnight.

Melt temperature control is the critical processing threshold for AG25AT. Barrel temperature profile from feed to nozzle should be set between 180 °C and 240 °C, with a maximum melt temperature of 260 °C as measured by a needle pyrometer. Melt temperature should not deviate more than ±5 °C from the established process for a given tool; above 260 °C, the butadiene rubber phase undergoes accelerated oxidation, causing brown streaking, odour, and loss of impact toughness. Total residence time at melt temperature should not exceed 5 min. If machine interruption exceeds this, the barrel should be purged with a general-purpose ABS or acrylic purge compound.

Screw configuration affects melt homogeneity and shear heating. A general-purpose screw with L/D ratio between 20:1 and 24:1 and compression ratio between 2.0:1 and 2.5:1 is adequate for AG25AT. The shot size should be maintained between 50 % and 80 % of rated barrel capacity; smaller shots increase residence time, while larger shots can produce melt temperature variation. Back pressure is commonly set at 0.5–1.0 MPa hydraulic pressure, and screw rotation speed should be adjusted to avoid frictional overheating. Production-scale injection moulding of high-flow ABS grades similar to AG25AT shows that screw recovery time and peak injection pressure are lower than for 15 g/10 min general-purpose grades; however, published data for AG25AT in this specific configuration is limited.

Mould temperature should be maintained between 40 °C and 80 °C. Higher mould temperatures improve surface gloss, weld-line appearance, and dimensional stability, but increase cooling time. For close-tolerance parts, the mould should be controlled with turbulent water flow at a temperature tolerance of ±2 °C across all cavities. Injection speed is normally set to medium or high to fill thin sections before the flow front freezes; excessive velocity can cause jetting and gate blush, particularly with pin gates. Packing pressure should be applied until the gate freezes, typically with packing pressure 60–80 % of the injection peak and packing time determined by gate seal studies.

Common injection moulding defects observed with high-flow ABS grades include gate blush, jetting, sink marks, and weld-line splay. Gate blush in AG25AT is usually mitigated by reducing injection speed at the gate and using a slight radius on the gate entrance. Sink marks indicate insufficient packing or premature gate freeze; packing time should be increased until part mass stabilises. Silver streaks are generally associated with moisture, not melt temperature, and the first corrective action should be verification of dryer dew point and air flow rather than barrel temperature reduction.

Where AG25AT is used in valve-gated hot-runner tools, the manifold and drop temperatures should not exceed 230 °C to prevent stagnant resin from degrading in dead spots. Tool vent depths of 0.02–0.04 mm and gate land lengths of 0.5–1.0 mm are typical for high-flow ABS. Regrind addition should be limited to 20 wt% with virgin material; higher regrind ratios can increase melt viscosity variation and reduce the reproducibility of impact results.

Comparative Property Mapping Across TAIRILAC ABS Grades

AG25AT is differentiated from adjacent FCFC ABS grades primarily by its melt rheology. The higher melt mass-flow rate is obtained through controlled molecular weight distribution and not by external plasticiser addition; this distinguishes the grade from lower-flow general-purpose injection moulding grades that retain higher notched impact strength. Table 2 provides a comparative property matrix based on published technical-bulletin ranges for TAIRILAC ABS injection moulding grades; values are typical only and do not replace lot-specific certificates of analysis.

Compared with lower-flow extrusion grades, AG25AT shows lower melt elasticity and lower die swell, which is less critical for injection moulding but can reduce orientation-induced warpage in larger flat parts. The trade-off is a reduction in ductility under high-speed impact conditions. AG25AT should not be selected when the specification requires notched Izod impact strength above 20 kJ/m² at 23 °C or ductile failure at -30 °C; high-impact TAIRILAC ABS grades or polycarbonate/ABS blends are appropriate in such cases. AG25AT is an unfilled, non-flame-retardant grade. It is not a substitution for flame-retardant ABS grades rated UL 94 V-0 at 1.5 mm. Where regulatory flammability requirements apply, a flame-retardant grade with documented UL yellow card should be used.

Rheological characterisation of high-flow ABS grades under capillary conditions indicates that apparent shear viscosity at 1000 s⁻¹ and 220 °C commonly falls between 80 Pa·s and 150 Pa·s, while lower-flow 15 g/10 min grades are typically in the 150–250 Pa·s range. The difference in pressure drop across a thin-wall flow path scales roughly with the viscosity ratio under equivalent geometry; therefore AG25AT can reduce injection pressure requirements in thin sections. Published data for AG25AT in this specific configuration is limited, but the relative ranking is established by melt mass-flow rate testing.

When Thin-Wall Dimensional Stability Dictates Material Selection

Thin-wall components such as router housings, set-top boxes, and appliance control panels place simultaneous demands on melt flow and post-moulding dimensional stability. The high melt mass-flow rate of AG25AT permits filling of wall sections as low as 1.2 mm without excessive injection pressure, provided gate location and venting are optimised. Mould shrinkage of 0.4–0.7 % per ISO 294-4 allows tool designers to maintain flatness and hole-to-hole tolerances; however, shrinkage anisotropy between flow and transverse directions can reach 0.1–0.2 percentage points, so tooling compensation should be derived from actual gate layout studies rather than generic material data.

Weld-line performance is flow-dependent. High-flow ABS grades form weld lines with lower skin thickness and may exhibit a greater loss of notched impact strength at the weld line than lower-flow grades. For AG25AT, published data for this specific configuration is limited; processors should assess weld-line impact retention with a gate configuration representative of production tooling, using notched specimens cut across the weld line. In applications where weld lines occur in visible or impact-loaded regions, increasing mould temperature to 70–80 °C and using sequential valve gating can shift the weld line and improve cosmetic quality.

Electrostatic dissipative properties are not inherent to AG25AT. The material is suitable for general electrical enclosures where surface resistivity remains in the insulative range above 1 × 10¹² Ω/sq per IEC 62631-3-2; applications requiring static dissipation or conductive behaviour require a dedicated carbon-filled or inherently dissipative polymer. Colour stability is managed through standard colour compounding. AG25AT is available in natural and selected pre-coloured lots; custom colours require twin-screw compounding with masterbatch, and the let-down ratio must not exceed the masterbatch supplier’s recommended range. The base resin has no inherent UV stabilisation; outdoor weatherability is limited, and components exposed to continuous UV should be specified with a UV-stabilised or painted grade.

Documentation for RoHS Directive 2011/65/EU and Commission Delegated Directive (EU) 2015/863 is normally available for AG25AT, but the presence of lot-specific additives in custom colours requires separate confirmation. REACH SVHC statements should be requested per shipment. The grade is not certified for food-contact use as a general statement; suitability for 21 CFR 181.32 or EU 10/2011 must be confirmed with FCFC technical service. Flammability is typically UL 94 HB at 1.5 mm, without a V-class rating.