Zhejiang Yima PC/ABS YM700A is an unfilled polycarbonate/acrylonitrile-butadiene-styrene alloy supplied for injection molding. The grade is positioned between unmodified polycarbonate and standard ABS to reduce melt viscosity relative to polycarbonate while retaining higher heat deflection temperature than ABS. Model designation is YM700A, with optional color and additive suffixes appearing on commercial documentation. Published batch-certified values for YM700A are limited in openly accessible supplier documents; consequently, numerical ranges below are identified as class-typical for unfilled PC/ABS when grade-specific values are not available.

What Drying and Melt-Processing Constraints Apply to YM700A?

Pre-drying in a desiccant-bed or dehumidifying dryer with a dew point of -30 °C to -40 °C is required to reduce surface and absorbed moisture below 0.02% by weight. Drying at 80 °C to 100 °C for 3 h to 4 h is representative for unfilled PC/ABS; supplier confirmation for YM700A is required. Moisture above 0.05% by weight promotes hydrolytic chain scission of the polycarbonate segment during plastication, producing splay marks, silver streaking, reduced weld-line strength, and lower notched impact values. On manufacturing lines with relative humidity greater than 60%, hopper residence time for dried pellets should not exceed 30 min unless the hopper is purged with dry air.

Melt temperature measured at the nozzle with an immersion thermocouple should be maintained at 240 °C to 270 °C for unfilled PC/ABS. Barrel profile temperatures from feed to nozzle are typically 230 °C, 250 °C, 260 °C, 260 °C, and 265 °C; mold temperature should be held at 60 °C to 80 °C. Injection pressure between 70 MPa and 120 MPa is commonly necessary, with hold pressure 50 MPa to 80 MPa and back pressure 3 MPa to 7 MPa. A medium-shear single-flight screw with L/D ratio 20:1 to 24:1 and compression ratio 2.0:1 to 2.5:1 is preferred; excessive screw speed or back pressure raises melt temperature above 290 °C and initiates ABS-phase degradation.

At melt temperatures above 290 °C or at barrel residence times exceeding 6 min, the butadiene component of the ABS phase generates chromophore-bearing decomposition products and releases volatile organic by-products that can corrode mold surfaces at the parting line. Machine shutdown with YM700A in the barrel should be limited to 15 min at melt temperature; purging with general-purpose ABS or a commercial PC purge compound is required before extended idle periods. Contact with polyoxymethylene or polyvinyl chloride residues must be avoided because trace acidic decomposition products catalyze polycarbonate degradation.

Rheological characterization of PC/ABS alloys of this class shows pseudo-plastic shear-thinning behavior. At 260 °C and 1,000 s⁻¹, apparent shear viscosity is typically 100 Pa·s to 250 Pa·s, but published data for this specific configuration is limited. Melt volume-flow rate measured to ISO 1133-1:2022 at 260 °C and 5.0 kg for general unfilled PC/ABS is normally 8 cm³/10 min to 20 cm³/10 min. The MVR value for YM700A must be taken from the supplier certificate of analysis because it influences hold-pressure decay and gate freeze time.

Mechanical Property Profile and Comparative Position

Class-typical mechanical data for unfilled PC/ABS tested on injection-molded Type 1A specimens to ISO 527-2:2012 indicate a tensile stress at yield of 50 MPa to 60 MPa and nominal tensile strain at break of 10% to 40%. Flexural modulus to ISO 178:2019 is typically 2,200 MPa to 2,600 MPa. Notched Charpy impact strength to ISO 179-1/1eA:2010 at 23 °C is 30 kJ/m² to 60 kJ/m², but the value falls to 10 kJ/m² to 15 kJ/m² at -30 °C for standard unmodified grades. Heat deflection temperature under 1.82 MPa load to ISO 75-2:2013 is 100 °C to 115 °C; Vicat softening temperature to ISO 306:2022, method B50, is commonly 115 °C to 130 °C. These values are class-typical and are not a batch certificate for YM700A.

Compared with unmodified polycarbonate, PC/ABS of the YM700A class shows lower melt viscosity and better resistance to stress cracking from plasticizing agents in flexible PVC wire insulation, but lower heat deflection temperature and reduced transparency. Compared with standard ABS, PC/ABS of this class shows higher notched impact at low temperature and higher heat resistance, but higher density and greater sensitivity to hydrolytic degradation. Compared with glass-filled PC/ABS grades, YM700A class is unfilled and therefore provides lower flexural modulus but better weld-line strength and lower abrasion on mold surfaces.

Thin-wall electrical enclosures molded from YM700A are evaluated on production-scale injection molding machines with clamp force from 800 kN to 2,500 kN. Gate geometry should be assigned using fill simulation to maintain shear rates below 50,000 s⁻¹ at the gate, because higher shear rates generate localized melt temperatures above 290 °C and embrittle the weld-line region. For a 1.2 mm nominal wall section, the class-typical flow length for unfilled PC/ABS at 260 °C melt temperature and 80 MPa injection pressure is 45 cm to 70 cm; however, published data for this specific configuration is limited.

Electrical and electronic housings molded from YM700A are routinely checked for comparative tracking index. The value of CTI for unfilled PC/ABS is commonly 250 V to 600 V to IEC 60112:2020, depending on pigmentation and additive package. If flame retardance is required, the component is evaluated to IEC 60695-11-10:2013 at the end-use minimum wall thickness; a UL 94 yellow card for YM700A is not repeated here because public supplier documentation is limited.

When Low-Temperature Ductility and Heat Resistance Must Be Balanced in Automotive Substrates

In automotive interior lower substrates and electronic control housings, YM700A is processed with mold temperatures at the upper end of the 60 °C to 80 °C range to minimize molded-in stress and to stabilize post-mold shrinkage. Process capability is tracked by short-shot weight and pressure-drop curves rather than by crystallization events, because PC/ABS is amorphous. Dimensional stability under thermal cycling is tested to ISO 16700:2016 or an OEM-specific protocol between -40 °C and 85 °C. For painted or adhesive-bonded applications, surface polarity after processing should be verified with a contact angle goniometer; contaminant residues from mold release agents reduce adhesion to polyurethane adhesives.

Power tool housings molded from unfilled PC/ABS are subjected to panel-level drop testing from 1.0 m onto concrete at -20 °C after conditioning to ISO 291:2008. Class-typical PC/ABS shows ductile failure at thicker bosses and ribs but may exhibit brittle fracture if knit lines occur near high-impact load paths; radiused transitions and minimum boss wall thickness of 2.5 mm reduce notch sensitivity. Non-destructive evaluation by micro-CT is used to quantify void content below 0.1% at the knit-line plane.

Mold shrinkage for unfilled PC/ABS is anisotropic and generally 0.4% to 0.7% along flow and 0.3% to 0.6% transverse to flow at 3 mm nominal wall thickness. Post-mold shrinkage at 85 °C for 2 h is typically less than 0.1%. Shrinkage measurement is performed on plaques molded to ISO 294-4:2018 after 24 h conditioning at 23 °C and 50% relative humidity. These data are class-typical for unfilled PC/ABS and should not substitute for batch-specific dimensional inspection of YM700A components.