Beijing Shousu PC/ABS 8046 is an unfilled polycarbonate/acrylonitrile-butadiene-styrene alloy supplied for injection molding applications in which a balance of melt flow, notched impact resistance, and dimensional stability is required. The designation 8046 identifies a manufacturer-specific grade within the Beijing Shousu PC/ABS portfolio; published data for this exact product configuration are limited. The class-level values cited in this document are drawn from unfilled medium-flow PC/ABS compounds and must be checked against the lot certificate before tool design, process release, or material substitution. Density for unfilled PC/ABS of this class is measured under ISO 1183-1:2019 in the range of 1.12 g/cm³ to 1.16 g/cm³. Melt volume-flow rate is conventionally determined under ISO 1133-1:2022 at 260°C and 5.0 kg; medium-flow PC/ABS grades commonly fall between 10 cm³/10 min and 25 cm³/10 min. A variation of ±3 cm³/10 min is sufficient to shift thin-wall injection pressure and should be included in process capability studies.

Moisture control is the first processing boundary. Polycarbonate-containing alloys hydrolyze when residual moisture exceeds 0.02 wt%; the visible defect on production-size injection molding machines is splay, often called silver streaking, and a measurable loss in notched Charpy impact when tested under ISO 179-1/1eA. Desiccant drying at 80°C for 3 h to 4 h with a supply-air dew point not higher than -30°C is the conventional boundary for virgin unfilled PC/ABS. When ambient relative humidity exceeds 60%, hopper dryers and open air conveying are inadequate because moisture regain occurs during transfer. Dried granules should be conveyed in closed lines and consumed within 1 h to 2 h at the machine throat unless a heated hopper is fitted. Regrind inclusion above the level validated during part qualification is not advised because repeated thermal history reduces polycarbonate molecular weight and narrows the impact safety margin.

What separates an unfilled PC/ABS alloy such as 8046 from PC homopolymer and ABS terpolymer?

Compared with PC homopolymer, unfilled PC/ABS lowers melt viscosity and improves flow length but sacrifices continuous heat resistance and optical transparency. Polycarbonate homopolymer tested under ISO 75-2:2013 method A at 1.8 MPa often reports heat deflection temperatures above 125°C; unfilled PC/ABS class values are typically between 100°C and 120°C. The alloy also exhibits better low-temperature ductility than some PC grades but lower chemical resistance. Compared with ABS terpolymer, PC/ABS 8046 raises the Vicat softening temperature and tensile modulus. ABS grades measured under ISO 306:2013/B50 commonly remain below 105°C, whereas unfilled PC/ABS of this class generally exceeds 115°C. The butadiene phase contributes notched impact strength but increases sensitivity to elevated processing temperatures and long residence times. If the grade is compared with flame-retardant PC/ABS, 8046 should not be considered a flame-retardant compound unless a UL 94 rating is explicitly stated on the lot documentation. Without such documentation, electrical enclosure requirements should not be assigned to the material.

The tabulated values are representative class-level data, not grade lot guarantees.

Glass-fiber reinforced PC/ABS grades are not direct substitutes for unfilled 8046. The addition of glass fiber at 10 wt% to 20 wt% raises tensile modulus above 4,000 MPa and heat deflection temperature by roughly 5°C to 15°C, but it also increases density, reduces surface gloss, and produces abrasive wear on reciprocating screw and barrel surfaces. Flame-retardant PC/ABS grades may require lower melt temperatures and more frequent purging due to acidic decomposition products from halogen-based or phosphorus-based additives. If 8046 is compared with PC/ASA or PC/PBT, the chemical resistance and low-temperature impact profiles differ; PC/PBT generally offers better solvent resistance, while PC/ASA provides better UV gloss retention. The selected grade should be based on the same wall thickness and test method because UL 94 ratings and mechanical values are thickness-dependent.

Rheological behavior in thin-wall sections should not be inferred solely from single-point MVR. The melt viscosity of unfilled PC/ABS is shear-thinning; capillary rheometry at 260°C and shear rates between 100 s⁻¹ and 1,000 s⁻¹ is used to generate viscosity curves for mold-filling simulation. Processing on a reciprocating screw injection molding machine with a length-to-diameter ratio between 20:1 and 24:1 and compression ratio between 2.0:1 and 3.0:1 is typical for this class. Melt temperatures below 250°C can produce short shots in parts with wall thickness below 1.2 mm; melt temperatures above 290°C or residence times beyond 10 min may initiate degradation of the butadiene phase, observed as black specks and yellowing in transparent or light-colored parts. The actual grade-specific window must be confirmed because flame-retardant or high-heat variants may differ. Weld-line performance in unfilled PC/ABS is governed by the temperature of the merging flow fronts; if the melt front temperature is below 240°C, tensile strength retention at a weld line under ISO 527-2:2012 often falls to 60% to 80% of the bulk value. Gate placement, sequential valve gating, and oil-heated mold channels set at 80°C to 90°C are common countermeasures.

Typical start-up settings for unfilled medium-flow PC/ABS on a 50 mm screw diameter injection unit include back pressure between 0.5 MPa and 1.5 MPa and screw speed between 40 min⁻¹ and 80 min⁻¹. These settings reduce unfused pellet formation without excessive shear heating. At 23°C and 50% relative humidity, dried PC/ABS pellets can regain measurable surface moisture within 30 min of exposure to uncontrolled plant air. Dryer audits should therefore record supply-air dew point, return-air dew point, and actual pellet-bed temperature. A dryer set point of 80°C does not guarantee an 80°C pellet bed when airflow is undersized for the material consumption rate. Mold-filling simulation inputs should be calibrated with lot-specific MVR and no-flow temperature data rather than generic material database values.

Paint and electroplating processes require exact surface conditioning. PC/ABS is electroplatable because the butadiene phase can be selectively etched by a chromic acid-based pretreatment, creating mechanical anchoring sites for electroless nickel or copper. The uniformity of etching depends on the dispersion of the butadiene phase and the level of frozen-in surface stress. Mold temperature below 70°C promotes skin orientation and uneven etch patterns; mold temperature above 90°C improves etch uniformity but may increase cycle time and require additional degassing due to volatile residuals. External mold release agents are not recommended for plated or painted surfaces because silicone-based films inhibit etch wetting and paint adhesion. For painted applications, adhesion testing under ISO 2409 cross-cut tape pull or equivalent automotive standards should be conducted on production parts, not laboratory plaques. Electrostatic painting may require a conductive primer because unfilled PC/ABS surface resistivity measured under IEC 62631-3-2 is generally above 10¹² Ω.

When moulded-in stress interacts with solvent-based cleaners and assembly lubricants

Unfilled PC/ABS is susceptible to environmental stress cracking in contact with strong alkalis, ketones, esters, chlorinated solvents, and aromatic hydrocarbons. Brake fluid, thread-locking adhesives, paint thinners, and aggressive alkaline degreasing solutions can reduce the strain required for cracking, especially when the part is press-fit or bolted. Validation should use the actual service fluid under ISO 22088-3:2006 bent-strip or equivalent strain-controlled exposure. The test identifies the maximum strain below which cracking does not occur; parts with local tensile stresses above that threshold must be redesigned or shielded. If an alkaline cleaner is mandatory, the cleaner concentration and contact time should be reduced, and assembled components should be stress-relieved or made with annealed prototypes. Chemical resistance data for unfilled PC/ABS do not transfer directly from PC homopolymer because the styrene-acrylonitrile and butadiene phases alter the sorption profile.

Regulatory screening for 8046 should include EU RoHS Directive 2011/65/EU Annex II restricted substances, REACH SVHC candidate list verification, and electrical and electronic product requirements under IEC 60695-2-12 glow-wire flammability where applicable. The absence of a grade-specific UL 94 Yellow Card for 8046 means no flame-retardant classification can be inferred; users requiring V-0, V-1, or 5VA performance should request the manufacturer’s test data or select a certified flame-retardant PC/ABS grade. Food-contact and medical device clearances are not automatically available for PC/ABS alloys. If the material is intended for food-contact applications, the regulatory statement must identify the applicable FDA 21 CFR section or EU framework regulation and include migration limits. No such clearance is asserted here.

Thermal aging, UV exposure, and moisture-absorption boundaries for unfilled 8046

Unmodified PC/ABS is not an outdoor weatherable grade. Prolonged outdoor UV exposure without a capstock or UV-stabilizer package leads to surface yellowing, micro-cracking, and a decline in notched impact. Indoor continuous service temperatures for unfilled PC/ABS of this class are often bounded at 85°C to 95°C when long-term thermal aging data are not available; the definitive boundary is the manufacturer’s UL 746B relative thermal index, if published. Moisture uptake at equilibrium under ISO 62:2008 at 23°C and 50% relative humidity for PC/ABS is generally below 0.25%, which is lower than polyamide 6/6 but still significant enough to alter dimensions in precision gaps by several hundredths of a millimeter. Dimensional stability is also affected by molded-in stress; post-mold shrink after 48 h at 85°C should be measured for tight-tolerance housings.

On the production floor, start-up with 8046 should begin after the injection unit has been purged with dried material. Melt temperature should be confirmed with a needle pyrometer at the nozzle rather than relying only on barrel zone set points, because thermocouple offsets can exceed 5 K in production equipment. Hot-runner systems should be started at the lower boundary of the melt-temperature window and raised only as needed to fill the cavity. If the tool previously ran a glass-filled polyamide, polyacetal, or PBT, residual melt residues must be purged before introducing PC/ABS; incompatible residues can delaminate at part surfaces or generate visible contamination. Processing and property comparisons between 8046 and other products should always use the same test method and specimen thickness. Values generated under different standards, such as ASTM D256 versus ISO 180/A, are not directly equivalent and can shift the perceived impact ranking of two materials.