For previous reading, please refer to Plastics Materials (Part 7): In-Depth Analysis of Polycarbonate (PC).
PC/ABS alloy is a blend of polycarbonate (PC) and acrylonitrile-butadiene-styrene copolymer (ABS), is one of the most successful and widely used plastic alloys. It cleverly combines advantages of both materials: PC contributes high impact resistance, high heat resistance, and high strength, while ABS contributes easy processing, low cost, and good surface quality, while compensating for their respective disadvantages—PC's stress cracking and processing difficulty, ABS's insufficient heat resistance and impact resistance. With its comprehensive advantages of balanced rigidity and toughness, moderate heat resistance, easy processing, electroplating capability, and controllable cost, PC/ABS occupies a core position in automotive interiors, electronics, home appliances, communication equipment, is a "main force" of mid-to-high-end engineering plastics.

 

PC/ABS = PC (Polycarbonate) + ABS (Acrylonitrile-Butadiene-Styrene) copolymer, a typical "island structure":

Core logic of PC/ABS: 1+1>2. PC's high heat resistance and high impact resistance + ABS's easy processing and low cost. Simultaneously, ABS improves PC's stress cracking problem, PC compensates for ABS's insufficient heat resistance and impact resistance.
PC/ABS Island Structure and Toughening Mechanism

 

PC/ABS Toughening Mechanism: Rubber particles in ABS act as stress concentration points → inducing crazes and shear bands → absorbing impact energy. PC matrix provides high strength and high rigidity → bearing main load. Synergistic effect of both phases → superior rigidity-toughness balance compared to single materials.
Main Classifications of PC/ABS

 

PC vs ABS vs PC/ABS: How to Choose?

Selection Logic: Choose PC if heat resistance/impact resistance is insufficient; choose ABS if cost/processability is insufficient; choose PC/ABS for a balanced option. PC/ABS is the "most cost-effective mid-to-high-end engineering plastic."
Classification by General Purpose and High-Impact/Heat-Resistant Grades
General Purpose PC/ABS: HAC8250 is flagship grade of Kumho Sunny (a joint venture between Kumho Korea and Shanghai Rizhisheng), known for its high impact resistance, high flowability, and high cost-effectiveness, widely used in automobiles and home appliances. T65 is a classic general purpose grade from Bayer's Bayblend series, with good flowability (MFR 18), balanced overall performance, electroplating capability, making it a mainstay material for automotive interiors and electronic appliances.
High-Impact/Heat-Resistant PC/ABS T65 vs T85: How to Choose?
T65: Better flowability (MFR 18), suitable for complex molds and thin-walled parts; moderate impact resistance; slightly lower cost. T85: Higher impact resistance (60 vs 45 kJ/m²), better heat resistance (HDT 126℃ vs ~105℃), better low-temperature toughness; slightly lower flowability.
Simply put: Choose T65 for better flowability, choose T85 for better impact and heat resistance. Numerical naming convention: In T series, the higher number, the higher PC content, the better heat resistance and impact resistance, and the worse flowability.

Mechanical properties of PC/ABS are between those of PC and ABS, and can be customized by adjusting PC/ABS ratio.
Comparison of Typical Properties of Different Types of PC/ABS

Note: Above are typical ranges for materials of same grade. Specific values vary depending on PC/ABS ratio, rubber content, compatibilizer, and modification method.
Influence of PC Content on Performance
Performance of PC/ABS can be adjusted by its PC content:

Engineering Conclusion: Higher PC content results in better performance but also greater processing difficulty and higher cost. General-purpose PC/ABS typically has a PC content between 50% and 70%, representing a balance between performance and cost.
Yield Strength Ratio Analysis
Yield strength ratio (yield strength / tensile strength) of PC/ABS has following characteristics: General-purpose grade: High yield strength ratio (~0.85~0.9), exhibits some plastic deformation after yielding, elongation at break 50~100%. High-impact and heat-resistant grade: High yield strength ratio (~0.85~0.95), good toughness, elongation at break 50~80%. Flame-retardant grade: High yield strength ratio, significantly reduced elongation at break (flame retardants reduce toughness)
Engineering Conclusion: PC/ABS is a tough material—it has a distinct yield point and fractures only after undergoing plastic deformation following yielding. At room temperature, the toughness of PC/ABS falls between that of PC and ABS, significantly better than ABS but slightly lower than pure PC, yet its stress cracking resistance is better than PC.
Influence of Temperature on Performance
Performance of PC/ABS is between that of PC and ABS in terms of temperature sensitivity: Impact Strength: Decreases with decreasing temperature, but its low-temperature toughness is much better than ABS (still 30~50 kJ/m² at -30℃). Stiffness: Decreases with increasing temperature, HDT 95~130℃ (varies by grade). Dimensional Stability: Lower coefficient of thermal expansion than PC, resulting in good dimensional stability.
PC/ABS has better processability than PC but is slightly more difficult to mold than ABS.
Key Process Parameters

Other Molding Methods of PC/ABS: Extrusion: Sheets, Pipes, Profiles. Blow Molding: Bottles, Hollow Products. Electroplating: An important substrate for plastic electroplating. Thermoforming: Sheet thermoforming. 3D Printing: High-strength, high-heat-resistant printing materials

PC/ABS is one of the most widely used engineering plastic alloys, covering almost all mid-to-high-end fields.
Automotive Applications

 

Automotive industry is the largest application area for PC/ABS. Instrument panels are a hallmark application of PC/ABS—it has better heat resistance than ABS, better processing than PC, lower cost than pure PC, a perfect balance of rigidity and toughness to meet instrument panel requirements. New energy vehicles have driven growth in demand for flame-retardant grade PC/ABS (charging guns, battery components, etc.).
Electronic and Electrical Applications

 

Consumer electronics is the second largest application of PC/ABS. Laptop casings are a classic application of PC/ABS – high-flow grades can achieve wall thicknesses below 1.0mm while maintaining sufficient strength and impact resistance, at a much lower cost than magnesium-aluminum alloys.
Home Appliance Applications

Other Applications

Simulation modeling of PC/ABS is similar to that of ABS, but its performance is closer to PC, requiring consideration of rate dependence and temperature sensitivity.
Rate Dependence: Yield strength of PC/ABS increases with strain rate (significantly more so than ABS, but less so than PC). Rate-dependent constitutive models are recommended for dynamic simulations such as collisions and drops. Temperature Sensitivity: Performance of PC/ABS varies with temperature. Simulations in high-temperature environments need to consider effect of temperature on modulus and strength. Isotropic: Unfilled PC/ABS is an isotropic material, simplifying modeling and eliminating need to consider fiber orientation. Internal Stress Influence: Internal stress of PC/ABS is smaller than that of pure PC, but it still exists. High-precision simulations (especially stress cracking analysis) need to consider residual molding stress.

Failure modes of PC/ABS fall between those of PC and ABS, with stress cracking and aging being main problems.
Stress Cracking

 

Problem: Under combined action of stress and chemical media, PC/ABS products develop streaks and cracks. Better than pure PC, but worse than ABS, it remains one of the most common failure modes for PC/ABS.
Common Scenarios: Cracking after contact with alcohol, detergents, or lubricants; long-term cracking due to assembly stress; spontaneous cracking due to internal stress.
Solution:

Impact Fracture
Problem: Fracture under impact load. PC/ABS has much better impact toughness than ABS, but slightly lower than pure PC, and it still becomes brittle at low temperatures.
Common Scenarios: Drop impact, low-temperature impact, stone impact.
Solution:

Heat Deformation / High-Temperature Failure
Problem: Deformation and strength reduction at high temperatures. PC/ABS has better heat resistance than ABS, but lower than pure PC. Common scenarios: Car interior exposed to direct sunlight, high temperatures near headlight housings, and overheating of electronic components.
Solution:

Aging/Yellowing
Problem: Under prolonged UV exposure, PC/ABS yellows, becomes brittle, and its performance deteriorates. Both butadiene phase in ABS and benzene ring in PC are sensitive to UV radiation.
Common scenarios: Outdoor use, direct sunlight, and prolonged high-temperature environments.
Solution:

Development Trends
Low VOC/Low Odor PC/ABS: Meets environmental protection requirements for automotive interiors, reducing volatile organic compounds. Paint-Free PC/ABS: Special color powders and pearlescent effects replace painting, reducing costs and protecting the environment. High Flow PC/ABS: Thinner walls and lighter weight, suitable for consumer electronics and automotive lightweighting. High Heat Resistance PC/ABS: Heat resistance is continuously improving, some approaching level of pure PC. Halogen-Free Flame Retardant PC/ABS: Environmentally friendly flame retardant, ultra-thin flame retardant (V-0 @ 0.8mm), high flow flame retardant. Chemical Resistant PC/ABS: Improves stress cracking resistance and solvent resistance, expanding application areas. Electroplating Grade PC/ABS: Higher coating adhesion, better appearance, and more environmentally friendly processes. PC/ABS Alloy Upgrades: New alloys such as PC/PBT, PC/ASA, and PC/PMMA, with customized performance. Glass Fiber Reinforced PC/ABS: Higher rigidity and higher heat resistance, replacing metal structural parts. Recycling PC/ABS: Advances in chemical and physical recycling technologies have led to increased closed-loop recycling.