Nanjing Lihua PC/ABS CS703 is identified as a polycarbonate/acrylonitrile-butadiene-styrene blend supplied as injection-moulding granules. The grade is positioned for technical parts that require a controlled balance of impact strength, stiffness, heat stability, and melt flow. The material is assigned the polymer matrix designation PC+ABS under ISO 11469; the CS703 suffix is a producer-specific designation and does not, by itself, indicate a flame-retardant package or a food-contact approval. Published certified lot data for the specific CS703 configuration is limited; therefore, all numerical values in this technical note should be verified against the producer’s release certificate and the lot-specific incoming inspection plan. The product is normally specified by injection moulders rather than by extruders because its morphology and melt strength are optimised for filling thin-wall, multi-gated moulds with short cycle times. In a receiving inspection context, the relevant documentation should report melt volume-flow rate under ISO 1133-1:2022, density under ISO 1183-1, tensile properties under ISO 527-2, notched impact under ISO 180/1A, heat deflection temperature under ISO 75-2 at 1.8 MPa, and moulding shrinkage under ISO 294-4.

Material designation, phase morphology, and specification boundaries

PC/ABS CS703 belongs to a two-phase polymer system in which polycarbonate contributes heat resistance, toughness, and dimensional stability, while the ABS phase contributes melt processability and lower plateau viscosity. The ABS phase is itself a grafted rubber system; its acrylonitrile content influences miscibility with polycarbonate, ageing response, and gloss. A higher acrylonitrile content typically raises the melt processing torque and may reduce low-temperature impact, while a higher butadiene rubber content raises notched impact at the expense of stiffness and heat resistance. For CS703, phase morphology is not publicly specified; batch-level verification therefore centers on melt viscosity ratio, Vicat softening temperature, and multiaxial impact rather than on a single assumed molecular-weight distribution. At the compounding extruder, the SAN-grafted rubber particle size and distribution determine low-temperature impact; over-dispersing the rubber can reduce notched impact, while under-dispersing creates surface defects and variable plate adhesion. The specification boundary for moisture is ≤0.02% residual moisture at processing, because hydrolysis of polycarbonate at melt temperatures above 240 °C produces molecular weight reduction, splay, and loss of impact. The upper thermal boundary for continuous service is not supplied by the public literature reviewed; PC/ABS grades are generally not specified for continuous dry-heat exposure above 90 °C to 100 °C unless heat ageing data are available for the specific moulded part.

Because PC/ABS absorbs atmospheric moisture, the first production control is drying. A desiccant dryer with a dew point of −30 °C or lower is required; hot-air tray dryers are insufficient when the surrounding relative humidity exceeds 60%. A class-typical drying condition of 80 °C to 100 °C for 3 h to 4 h reduces moisture to the processing limit, but the CS703 lot card may specify a tighter window. The melt temperature is normally held between 240 °C and 270 °C; prolonged holding above 280 °C or residence times greater than 5 min can initiate chain scission and produce brown streaks. Mould temperature is a critical gloss and stress control parameter. A mould wall temperature of 60 °C to 90 °C is class-typical for CS703-type materials; lower temperatures reduce gloss and increase frozen-in orientation, while higher temperatures improve knit-line strength but extend cooling time. Injection speed should be medium to high, with switch-over from velocity control to pressure control set before the cavity is fully filled to avoid flash and burn marks. Hold pressure and time are set by gate freeze-off data; no universal value is available for CS703 because gate geometry and part wall thickness dominate. During compounding, PC/ABS alloys of this type are typically produced on co-rotating twin-screw extruders with length-to-diameter ratios of 36:1 to 40:1; the shear history from compounding controls rubber particle size and phase inversion. On the injection line, actual bottlenecks include splay from incomplete drying, black specks from dead zones, and uneven gloss from low mould temperature or poor venting. These observations are production-scale failure modes common to PC/ABS rather than CS703-specific certified data.

Melt-volume rate and injection pressure are linked through the shear-thinning response of the PC and SAN phases. PC/ABS CS703-type materials usually exhibit pseudoplastic flow; viscosity falls with increasing shear rate in thin runner and gate sections. The apparent melt viscosity should be recorded on a capillary rheometer at representative shear rates of 1000 s⁻¹ to 5000 s⁻¹ when cold-runner tooling is designed. Spiral-flow testing at a fixed melt temperature of 260 °C and mould temperature of 70 °C is a practical incoming-inspection method, but it cannot replace a full mould-filling simulation using lot-specific pvT and viscosity data. If the moulding shop observes high gate blush or flow marks, the first corrective action is verification of the actual melt temperature with a probe rather than an increase in injection velocity alone.

What differentiates CS703 from general-purpose PC/ABS and from PC or ABS monoliths?

Differentiation begins with the failure of monolithic polymers at the same wall thickness. Unmodified polycarbonate offers higher heat distortion and optical clarity but is more difficult to fill in long, thin-wall tools and is more sensitive to stress cracking in contact with plasticizers and some hydrocarbon greases. ABS offers easier processing and lower cost but has lower heat resistance and lower low-temperature impact than PC/ABS. PC/ABS CS703 occupies the intermediate position: lower melt viscosity than high-viscosity PC, higher practical heat resistance than ABS, and better stress-crack resistance than PC in many industrial environments. Against general-purpose PC/ABS grades, CS703 is differentiated by lot-specific melt flow, rubber content, and modifier loading; the producer’s technical data sheet should be used to confirm the direction of these differences. Without a certified datasheet, an incoming inspection comparison should record melt volume-flow rate under ISO 1133-1:2022, notched Izod or Charpy impact under ISO 180/1A or ISO 179/1eA, Vicat softening temperature under ISO 306 method B50, and heat deflection temperature under ISO 75-2 at 1.8 MPa. If the reference grade is a flame-retardant PC/ABS, CS703 is not assumed to carry the same UL 94 V-0 rating; the formulation may be non-halogenated or non-flame-retardant, and the absence of a UL 94 classification should be treated as a design constraint. For applications in which fuel, oil, or hot alkaline chemical resistance is governing, PC/PBT or PBT/PC alloys are often preferred; PC/ABS is not generally specified for continuous contact with aromatic hydrocarbons, ketones, or hot alkaline solutions. Published data for the specific CS703 configuration is limited, so adjacent-grade substitution should be authorised only after the moulding organisation has completed a full first-article inspection and thermal ageing trial.

Moulded parts made from PC/ABS CS703 are usually internal structural or dimensional components: instrument-panel retainers, electronic enclosures, appliance chassis, and telecom housings. These applications use the notch sensitivity tolerance and the ability to fill large tools at moderate clamp forces. Because the grade is not transparent, optical functions are excluded. If automotive interior use is required, the moulder should verify fogging behaviour under ISO 6452 or VDA 278 and low-temperature impact after conditioning at −30 °C; these properties are formulation-dependent and are not assumed from the CS703 designation. If the part is used in unattended electrical devices, a glow-wire end-product test under IEC 60695-2-11 may be required. The material should not be specified for continuous immersion in water above 60 °C, for direct contact with strong mineral acids, or for exposure to ketones and esters. Stress-crack resistance is higher than that of neat PC but is finite; parts under high tensile stress should be tested with the actual chemical environment using a constant-strain jig. Moulding shrinkage is typically anisotropic; values must be taken from a producer’s datasheet after measuring a standard plaque under ISO 294-4. Post-moulding annealing at 90 °C to 110 °C may be required to reduce internal stress in thick sections, but this adds cost and should not replace tool design and adequate mould temperature.

If CS703 is assigned to painted or metallised applications, what surface preparation governs adhesion?

Painted and metallised PC/ABS parts require surface energy above the paint or plating system’s wetting threshold. Flame treatment, corona treatment, or atmospheric plasma is used before adhesives and paints; the surface should be cleaned to remove mould-release residues, particularly if the moulder has used external release agents. Adhesion is validated by cross-cut testing under ISO 2409 or peel adhesion after plating; no CS703-specific adhesion value is published in the reviewed public literature. For electroplating, a typical ABS or PC/ABS process includes chromic acid etching, neutralization, activation, and electroless nickel or copper deposition. The butadiene-rich ABS phase is preferentially etched; consequently, consistent rubber dispersion at the surface determines the resulting bond. In CS703, the compounding quality directly affects plate adhesion; incoming raw-material audits should include surface inspection after a moulded plaque is etched under the intended production conditions. If a part is painted after moulding, the post-cure temperature should not exceed the heat deflection limit of the formed part. The use of solvent-borne paints can introduce stress cracking if the solvent is aggressive; a representative painted-part crack test under constant strain should therefore be part of first-article release.

Incoming inspection of CS703 is structured around the following matrix; the listed test methods are mandatory for a complete technical release but do not replace the producer’s material datasheet.

Batch acceptance of CS703 should compare the release certificate against the reference methods in the matrix. Any substitution of CS703 with an adjacent PC/ABS grade requires tooling trials, dimensional verification, and thermal ageing data; substitution based solely on melt flow is not valid.