SABIC ABS INP984 is an unfilled acrylonitrile-butadiene-styrene copolymer supplied in pelletized form for injection-molding conversion. The product code INP984 identifies an injection-molding grade within the broader SABIC ABS portfolio and is classified under ISO 1043-1 as ABS, with a continuous styrene-acrylonitrile matrix and a dispersed butadiene-based rubber phase. Incoming lots are typically released against a certified property schedule that includes density, melt volume-flow rate, tensile stress at yield, flexural modulus, notched Izod impact, and heat deflection temperature. The resin is supplied in moisture-barrier packaging because ambient moisture uptake can degrade impact retention and surface appearance before visible splay is detected. Typical injection-molding conversion uses a reciprocating-screw machine with a general-purpose screw; a 20:1 to 24:1 L/D ratio is common. INP984 is not positioned as a high-gloss or transparent grade, and it is not formulated for continuous use in uncoated exterior parts.

Current supplier documentation should be consulted for certified release limits. The representative property envelope in the following table is drawn from public datasheets and is not a production specification; lot-to-lot variation and colorant effects can shift individual values.

What Influences the Flow-Impact Balance in INP984 Relative to Other ABS Grades?

In a medium-flow ABS, the melt volume-flow rate is a primary classification variable. For INP984, melt flow is generally reported at 220 °C under 10 kg load using ISO 1133-1 or ASTM D1238. A medium-flow designation usually places the MVR between 8 cm³/10 min and 18 cm³/10 min. This is lower than high-flow grades used for thin-wall packaging and higher than low-flow extrusion grades. The flow-impact balance is not a simple linear trade-off; butadiene rubber content, grafting efficiency, and SAN molecular weight distribution determine how well the material retains notched Izod impact as melt flow increases. INP984's disclosure of a typical notched Izod range at 23 °C of 18–28 kJ/m² under ISO 180/1A positions it away from super-tough ABS grades that may exceed 30 kJ/m², yet above general-purpose low-impact grades that fall below 15 kJ/m².

In addition to MVR, capillary rheometry across shear rates from 100 s⁻¹ to 10 000 s⁻¹ can be used to confirm shear-thinning behavior. ABS melts are pseudoplastic; viscosity decreases as shear rate increases, but the rate of thinning is influenced by the butadiene phase and SAN molecular weight. If a converter transfers INP984 into a tool originally designed for a lower-flow ABS, the lower injection pressure may alter short-shot and flash boundaries. Direct substitution without rebalancing injection velocity and hold pressure is not recommended.

North American converters often use ASTM D638, ASTM D790, ASTM D256, and ASTM D648 equivalents. Cross-method comparisons are not directly interchangeable; notched Izod values expressed in J/m under ASTM D256 cannot be converted directly to kJ/m² under ISO 180/1A without accounting for specimen geometry and residual stress.

Moisture content above approximately 0.1 wt% at the feed throat introduces a hydrolysis risk in the SAN phase. The degradation mechanism is not limited to visible splay. Hydrolytic chain scission in the styrene-acrylonitrile phase lowers molecular weight, reduces melt strength, and causes a loss of notched impact that may be measured even after the molded surface appears acceptable. For incoming resin exposed to relative humidity above 60%, a desiccant dryer with a dew point of −30 °C or lower is specified. Drying at 80 °C for 2–4 h is commonly used; moisture analysis by ISO 15512 is preferable to fixed-time drying because silo residence, ambient humidity, and regrind fraction change the required drying load.

On the injection-molding machine, the processing window is constrained by both thermal degradation at the hot barrel and shear heating in the screw. Melt temperatures commonly lie between 230 °C and 250 °C. Above 260 °C, free styrene monomer can be generated by thermal depolymerization at measurable levels, and the rubber phase can undergo crosslinking or chain scission depending on residence time. If a hot-runner system is used, manifold temperatures above 250 °C require a protocol that limits total residence time to less than 5 min and uses a shut-off nozzle to prevent hold-time accumulation in the runner.

Thermal degradation in ABS is autocatalytic in the presence of oxygen. At barrel temperatures above 250 °C with air access, the butadiene phase can oxidize and the SAN phase can undergo chain scission. The resulting lower-viscosity melt may first appear as improved cavity fill, but impact strength and color shift may be degraded. This is one reason why the injection-molding cylinder should be purged with the material and the hopper should be kept closed in humid or dusty environments.

Screw speed and back pressure should be set to deliver a stable melt cushion without introducing excessive shear history. Back pressure from 5 bar to 10 bar and a screw surface speed in the range of 0.1 m/s to 0.4 m/s are typical starting conditions. High back pressure is sometimes used to improve melt homogeneity, but beyond 15 bar screw recovery time increases and the extra mechanical energy input narrows the thermal safety margin. Shot sizes between 20% and 80% of barrel capacity are standard; very small shots in large barrels increase residence time and support degradation.

When Wall Thickness Drops Below 1.2 mm in High-Cavitation Tools

As wall thickness falls below 1.2 mm, injection pressure required to fill the cavity increases nonlinearly because the melt viscosity is shear-thinning but cooling rate accelerates. Melt flow length in a spiral test is one screening measurement; published data for this specific configuration is limited, so mold trials using a cavity-pressure sensor are required. Cavity pressure at transfer from velocity to pressure control is typically monitored between 40 MPa and 70 MPa, depending on gate type. A drop in cavity pressure of more than 10% at the end of hold may indicate gate freeze too early and can produce sink or surface haze.

Weld lines in INP984 retain only part of the bulk impact strength. When weld lines form at the meeting of two flow fronts, the butadiene particles align with the melt front and do not bridge the interface as effectively as in the bulk. Notched Izod values at an unnotched weld line are not equivalent to bulk-data values; impact retention at weld lines may fall below 60% of the bulk figure. In load-bearing parts, weld lines should be moved away from high-stress regions or the part should be redesigned with a single gate.

Mold surface temperature influences gloss, shrinkage, and impact. A mold temperature of 40 °C to 60 °C is typical. Below 30 °C, the butadiene phase can freeze before complete packing, resulting in reduced impact and visible flow lines. Above 70 °C, cycle time increases and ejection may become difficult if the part is not sufficiently cooled; ABS can stick to polished cores if the surface temperature exceeds the Vicat softening onset under ejection load.

Mold shrinkage is typically in the range of 0.4% to 0.7% according to ISO 294-4, but actual shrinkage depends on wall thickness, gate location, packing pressure, and mold temperature. Thinner walls cool faster and show lower total shrinkage; thicker sections may exceed the range. Toolmakers should account for anisotropic shrinkage when developing a prototype mold.

Application screening for INP984 includes small-appliance housings, electrical enclosures, consumer goods, and automotive interior trim. The grade is not specified for underhood or load-bearing structural parts where continuous use temperature approaches the heat deflection temperature under 1.80 MPa. For enclosures requiring a UL 94 vertical flame rating, INP984 is not an appropriate substitute because its typical flammability classification is HB at 1.5 mm where certified; a flame-retardant ABS or PC/ABS blend should be selected.

Compared with high-gloss automotive interior ABS grades, INP984 may exhibit lower chemical gloss retention after exposure to heat and humidity. Differences in the rubber-phase particle size and SAN molecular weight distribution mean that part-surface gloss and scratch resistance are not equivalent to grades designed specifically for Class A interior surfaces. For electroplating, a platable ABS grade is preferred because it requires a controlled butadiene particle size distribution and a surface etching response that INP984 is not optimized to provide.

The product's mechanical range separates it from high-impact ABS grades. A super-tough grade may be selected for luggage shells or power-tool housings where high-speed impacts or subzero temperatures are anticipated. INP984 is formulated for a balanced room-temperature impact response, not for low-temperature ductility at −30 °C. Published data for low-temperature notched Izod values in this product is limited and should be obtained from the supplier before specifying cold-impact applications.

Optically clear ABS or MABS grades have a much smaller or absent butadiene scattering phase; INP984 is opaque. Colorability is possible with dry pigments or masterbatch, but colorant addition can shift heat deflection temperature and impact by several percent, so precolored lots require revalidation.

If INP984 is evaluated for sheet extrusion or blow molding, the medium-flow molecular weight distribution may not provide the required melt strength. Extrusion-grade ABS grades have a higher molecular-weight SAN phase and typically lower MFR values. INP984's lower viscosity can promote draw-down and thickness variation in unconstrained melt sections. ASA or AES grades replace the unsaturated butadiene rubber with an acrylic or EPDM rubber to reduce outdoor oxidation and yellowing. INP984 retains a butadiene phase and therefore requires UV stabilization or painting for exterior applications.

Regulatory Status, Handling Constraints, and Release Traceability

Material safety and regulatory documentation should be obtained from the supplier for each lot. The resin is supplied as pellets; handling should follow standard ABS dust-control and thermal-decomposition precautions. Processing above 260 °C can release styrene and degradation products, so local exhaust ventilation is required. Waste and regrind use is possible only when the regrind is clean, dry, and limited to a controlled fraction. Regrind addition above 25 wt% can alter melt viscosity and color consistency, and may reduce notched Izod impact. The change is not always linear; repeated heat histories can increase the SAN phase molecular weight distribution width, shifting the balance between flow and impact.

When regrind is added, the moisture load is not additive in a linear sense because the ground particles have higher surface area and can adsorb moisture faster than virgin pellets. A blend of 80 wt% virgin and 20 wt% regrind exposed to the same ambient conditions may reach the moisture limit earlier than the virgin pellets alone. Dryer residence time should be extended only after verifying moisture content, because over-drying may not be safe for all additive packages.

External mold release agents may interfere with subsequent painting or plating. Silicone-based release agents can migrate to the surface and reduce paint adhesion. If post-mold decoration is required, a non-silicone release or no external release is preferred. Food-contact status is not automatically assigned. If the final article is intended for food-contact use, the converter must verify the specific formulation, color package, and supplier certification against the intended use under applicable regional legislation. Published data for this specific configuration is limited.

Compliance for RoHS Directive 2011/65/EU and REACH is lot-specific and documented through supplier declarations. These declarations do not cover downstream additives, pigments, flame retardants, or processing aids added by the molder. If a converter introduces a masterbatch containing an SVHC substance, the final article is outside the resin supplier's declaration.

Batch release documentation typically includes lot number, production date, and measured values for density, melt flow, tensile yield, flexural modulus, Izod impact, and heat deflection. Converters should archive these records because they are required for PPAP-like submissions in automotive or electrical programs.