ABS is heavily used in engineering applications and consumer products from home appliances and everyday household items to automotive parts and electronics housings. It has become one of the most indispensable materials in both industrial manufacturing and daily life. This article will explore what ABS plastic is, how to fabricate it, and its applications.
Overview of ABS Plastic
ABS, short for Acrylonitrile Butadiene Styrene) is a high-performance thermoplastic engineering plastic, commonly known as ABS resin. It combines excellent strength, outstanding toughness, and easy processability, making it one of the most widely produced and broadly used polymers today.
ABS effectively brings together the best properties of polystyrene (PS), styrene-acrylonitrile copolymer (SAN), and butadiene rubber (BS), delivering a well-balanced mix of toughness, rigidity, and hardness with impressive overall mechanical performance. Chemically, it’s a terpolymer made from 3 monomers: acrylonitrile (A), butadiene (B), and styrene (S).
Thanks to its versatile and well-rounded properties, ABS can be shaped using a variety of common processing methods such as injection molding, extrusion, blow molding, and calendering. It also lends itself well to secondary operations like CNC machining, bonding, painting, vacuum metallization, and more.
Properties of ABS Materials
ABS is a pale yellow, granular or powdery opaque resin. It is non-toxic, odorless, lightweight, with a relative density of 1.04~1.07. It exhibits outstanding impact resistance, good low-temperature performance and chemical resistance, excellent dimensional stability, high surface gloss, and ease of painting and coloring. Its disadvantages include flammability, low heat distortion temperature, and poor weather resistance. The table below shows the typical properties of different grades of ABS resin.
| Item | General-Purpose | Medium-Impact | High-Impact | Heat-Resistant | Electroplating Grade |
| Density | 1.02~1.06 | 1.04~1.05 | 1.02~1.04 | 1.04~1.06 | 1.04~1.06 |
| Tensile Strength, MPa | 33~52 | 41~47 | 33~44 | 41~52 | 38~44 |
| Elongation, % | 10–20 | 15–50 | 15–70 | 5–20 | 10–30 |
| Flexural Strength, MPa | 68–87 | 68–80 | 55–68 | 68–90 | 69–80 |
| Flexural Modulus, GPa | 2.0–2.6 | 2.2–2.5 | 1.8–2.2 | 2.1–2.8 | 2.3–2.7 |
| Izod Impact Strength (23℃), (J/m) | 105–215 | 215–375 | 375–440 | 120–320 | 265–375 |
| Rockwell Hardness (R) | 100–110 | 95–105 | 88–100 | 100–112 | 103–110 |
| Heat Distortion Temperature (4.82MPa)/℃ | 87–96 | 89–96 | 91–100 | 105–121 | 95–100 |
| Coefficient of Linear Expansion, 10⁻⁵ /℃ | 7.0–8.8 | 7.8–8.8 | 9.5–11.0 | 6.4–9.3 | 6.5–7.0 |
Mechanical Properties
ABS resin has excellent impact strength: high-impact grades can reach up to 400J/m at room temperature, and remain above 120J/m even at -40℃. It is a heterogeneous two-phase system, with the resin as the continuous phase and rubber as the dispersed phase (rubber particles dispersed in the resin matrix). Its superior impact resistance is attributed to rubber particles absorbing external impact energy and inhibiting crack propagation. Impact performance correlates with rubber content, grafting ratio, and particle size.
ABS resin has good wear resistance. Although not suitable for self-lubricating materials, its excellent dimensional stability makes it applicable for medium-load bearings.
Thermal Properties
The heat distortion temperature of ABS resin is approximately 93℃ under 1.82MPa load, increasing by 6–10℃ after annealing. Due to its amorphous structure, it exhibits a stable stress-temperature effect: reducing the load from 1.82MPa to 0.45MPa only increases the heat distortion temperature by 4–8℃. Heat-resistant grades can reach up to 115℃. The brittle temperature is -7℃, and it retains considerable strength at -40℃. The service temperature range is -40–100℃. The coefficient of linear expansion ranges from 6.4×10⁻⁵ ℃ to 11.0×10⁻⁵ ℃(one of the lowest among thermoplastics). Thermal stability is relatively low for engineering plastics: decomposition occurs at 260℃, releasing toxic volatile substances. ABS is flammable and non-self-extinguishing.
Electrical Properties
ABS resin has good electrical insulation over a wide frequency range, with minimal influence from temperature or humidity. Electrical performance data are shown in the table below.
| Item | 60Hz | 10³Hz | 10⁶Hz |
| Dielectric Constant (23℃) | 3.73–4.01 | 2.75–2.96 | 2.44–2.85 |
| Dielectric Loss Tangent (23℃) | 0.004–0.007 | 0.006–0.008 | 0.008–0.010 |
| Volume Resistivity, Ω·cm | (1.05~3.60)×1016 | (1.05~3.60)×1016 | (1.05~3.60)×1016 |
| Arc Resistance, S | 66–82 | 66–82 | 66-82 |
| Dielectric Strength, (kV/mm) | 14–15 | 14–15 | 14–15 |
Chemical Resistance
ABS resin has good chemical resistance: nitrile groups in its molecular structure make it nearly inert to dilute acids, dilute bases, and salts. It is soluble in ketones, aldehydes, esters, and chlorinated hydrocarbons; insoluble in most alcohols (but softens in methanol after hours); and swells upon prolonged contact with hydrocarbon solvents. Like most plastics, ABS undergoes stress cracking when exposed to chemical reagents (e.g., acetic acid, vegetable oils) under stress. The table below shows mass changes and appearance variations after long-term immersion in selected chemicals.
| Chemical Name | Mass Change Rate, % | Mass Change Rate, % | Appearance Change |
| 30d | 365d | ||
| Cyclohexane | +0.03 | +0.51 | Slight Swelling |
| Refined Turpentine | +0.19 | +0.31 | — |
| 10% Citric Acid | +0.62 | +0.74 | Brownish |
| 6% Chromic Acid | +0.58 | +0.71 | Brownish |
| 2.5% Calcium Chloride | +0.61 | +0.77 | — |
| 2.5% Silver Nitrate | +0.67 | +0.84 | — |
| 4% Sodium Fluoride | +0.53 | +0.59 | — |
| 10% Ammonium Nitrate | +0.50 | +0.57 | — |
| 10% Sodium Carbonate | +0.56 | +0.65 | — |
| 3% Potassium Chloride | +0.64 | +0.78 | — |
| Saturated Ammonium Chloride | +0.35 | +0.39 | — |
| 10% Copper Nitrate | +0.64 | +0.76 | — |
| Ethylene Glycol | +0.63 | +0.15 | — |
| 3% Hydrogen Peroxide Solution | +0.69 | +1.03 | Yellowing |
| Saturated Sodium Bisulfite Solution | +10.95 | +6.70 | Amber |
| Methanol | +4.50 (2d) | +26~+28 | Swelling, Whitening |
| 12% Acetic Acid | +0.69 | +0.75 | Swelling, Whitening |
Fabrications of ABS Plastic
ABS is an amorphous polymer with no distinct melting point. It begins to decompose above 260℃, so molding temperatures are typically controlled below 250℃. ABS melt has moderate viscosity: lower flowability than polyamide but higher than polycarbonate, with faster cooling and solidification.
Pre-Drying
ABS has high water absorption due to polar nitrile groups. It must be pre-dried to a moisture content <0.1% before processing. Common methods: circulating air drying (70–80℃, >4h) or oven drying (80–100℃, 2h, material thickness <50mm).
Injection Molding
Injection molding of ABS typically uses a screw-type injection machine. Screws should be single-flighted, equal-pitch, tapered, fully threaded, with a non-return valve; L/D ratio of 20, compression ratio of 2.0–2.5. Nozzle types: open or extended (avoid self-locking nozzles to prevent reduced flow or discoloration).
Injection temperatures are higher for heat-resistant and electroplating grades (to improve melt flow or plating performance), and lower for general-purpose and high-impact grades (to prevent decomposition or mechanical property degradation).
Injection pressures are higher for thin-walled, long-flow, small-gate parts or heat-resistant/flame-retardant grades, and lower for thick-walled, large-gate parts. Holding pressure should be moderate to minimize residual stress.
| Items | General-type ABS | Impact-resistant ABS | Heat-resistant ABS | Electroplated ABS |
| Screw Speed, r/min | 30–60 | 30–60 | 30–60 | 20–60 |
| Nozzle Temperature, ℃ | 180–190 | 190–200 | 190–200 | 190–210 |
| Barrel Temperature, Rear Zone, ℃ | 180–200 | 180–200 | 190–200 | 200–210 |
| Barrel Temperature, Middle Zone, ℃ | 210–230 | 210–230 | 220–240 | 230–250 |
| Barrel Temperature, Front Zone, ℃ | 200–210 | 200–210 | 200–220 | 210–230 |
| Mold Temperature, ℃ | 50–70 | 50–80 | 60–85 | 40–80 |
| Injection Pressure /MPa | 70–90 | 70–120 | 85–120 | 70–120 |
| Holding Pressure /MPa | 50–70 | 50–70 | 50–80 | 50–70 |
| Injection Time, s | 3–5 | 3–5 | 3–5 | 1–4 |
| Holding Time, s | 15–30 | 15–30 | 15–30 | 20–50 |
| Cooling Time, s | 15–30 | 15–30 | 15–30 | 15–30 |
| Total Cycle, s | 40–70 | 40–70 | 40–70 | 40–90 |
Extrusion Molding
Extrusion molding of ABS uses a general-purpose single-screw extruder with an L/D of 18 to 20 and a compression ratio of 2.5 to 3.0. Both gradual and abrupt compression screws are suitable. ABS melt has moderate flowability, so no screw cooling is required. Extrusion produces profiles such as pipes, rods, and sheets.
| Pipe Outer Diameter/mm | 32.5 | Screw Speed, r/min | 10.5 |
| Pipe Inner Diameter/mm | 25.5 | Die Inner Diameter, mm | 33 |
| Barrel Temperature, Feed Zone /℃ | 160–165 | Straight Section Length, m | 50 |
| Barrel Temperature, Compression Zone /℃ | 170–175 | Draw Ratio | 1.02 |
| Metering Zone | 175–180 | Sizing Sleeve Inner Diameter, mm | 33 |
| Die Temperature/℃ | 175–180 | Cooling Sleeve Length, mm | 250 |
| Die Land Temperature/℃ | 190–195 | Distance from Vacuum Sizing Sleeve to Diem, m | 25 |
| Mandrel Outer Diameter/mm | 26 |
Extrusion Conditions for ABS Rods
| Rod Diameter, mm | 90 | Die Temperature, ℃ | 150–160 |
| Barrel Temperature, Feed Zone, ℃ | 160–170 | Sizing Temperature, ℃ | 55–60 |
| Barrel Temperature, Compression Zone, ℃ | 170–175 | Screw Speed, r/min | 11–14 |
| Barrel Temperature, Metering Zone, ℃ | 175–180 | Extrusion Speed, m/min | 22–25 |
| Die Land Temperature, ℃ | 170–180 |
Foam Molding
ABS foam is mostly produced via chemical foaming using blowing agents (e.g., azodicarbonamide) compounded into the resin. Two molding methods are used:
Injection Molding: Foamed ABS uses a screw-type injection machine (superior to plunger types for uniform density/performance). A valve is installed at the nozzle to prevent leakage of gas-containing melt. Unlike conventional injection molding, foamed melt expands in the mold to fill the cavity before cooling, eliminating the need for high injection pressure. Barrel temperatures are lower in the feed zone and higher near the nozzle: rear of 145–160℃, middle of 170–185℃, and front of 190–200℃.
Extrusion Molding: Foamed ABS grades are extruded into sheets, rods, and pipes. Unlike conventional extrusion, gas-melt mixture moves through the barrel, requiring precise temperature control to balance resin melting and blowing agent decomposition. Barrel temperature and extrusion speed affect appearance and density.
| Extruder L/D | 22 | Zone 4 Temperature/℃ | 170 |
| Zone 1, Barrel Temperature (Hopper Side)/℃ | 133 | Zone 5 Temperature/℃ | 180 |
| Zone 2, Barrel Temperature (Hopper Side)/℃ | 160 | Zone 6 Temperature/℃ | 157 |
| Zone 3, Barrel Temperature (Hopper Side)/℃ | 164 | Screw Speed/(r·min⁻¹) | 25 |
Key properties of foamed ABS products include:
- Can be produced as high-density structural components or low-density lightweight parts;
- Combines light weight and rigidity while maintaining mechanical strength.
- Sandwich structures (foamed core + thin ABS skin) offer equivalent rigidity to solid ABS at lower weight;
- Excellent thermal insulation and sound absorption;
- Unique wood-grain surface pattern;
- Lower water absorption than wood;
- Easy processing into sheets, pipes, and rods;
- Shorter cycle times for thick-walled parts compared to solid ABS;
- Paintable and colorable;
- Machinable (cutting, drilling, bonding) like wood.
| Density /(g/cm³) | 0.69 | Compressive Modulus /MPa | 353 |
| Tensile Strength /MPa | 14.0 | Izod Impact Strength /(kJ/m²) | |
| Elongation /% | 24.6 | Notched | 5.5 |
| Tensile Modulus /MPa | 300 | Unnotched | 13.6 |
| Flexural Strength /MPa | 20.0 | Water Absorption /% | 0.35 |
| Flexural Modulus /MPa | 723 | Thermal Conductivity/[W/(m·℃)] | 0.01 |
| Compressive Strength /MPa | 12.6 | — | — |
Applications of Foamed ABS plastic include:
- Lightweight structural materials: vehicle control panels, engine covers, ship doors, containers, etc.;
- Building materials: wall panels, ceiling tiles, drain pipes, thermal insulation pipes;
- Wood substitutes: furniture, piano components, handles, and markers (similar in appearance/density to wood, but superior in water/corrosion resistance, with customizable surface patterns, coloring, and molding).
Electroplating
Electroplating uses electroplating-grade ABS resin. Key steps include: roughening, sensitization, activation, reduction/degelation, electroless plating, and electroplating.
Roughening: Improves surface hydrophilicity and roughness to ensure coating adhesion. Chemical etching is the primary method. High-chromate formulations yield the best adhesion.
Sensitization: Adsorbs Sn²⁺ (reducing agent) onto the roughened surface to reduce Ag⁺/Pd²⁺ to catalytic Ag/Pd during activation. The table below lists sensitization solutions and conditions.
| Stannous Chloride | 10–30 | 2–5 |
| Hydrochloric Acid | 40–50 | 2–5 |
| Sensitization Temperature/℃ | 20–25 | 20–25 |
| Sensitization Time/min | 3–5 | 3–10 |
Activation: Forms catalytic noble metal nuclei to initiate electroless plating. It is divided into ionic activation and colloidal activation (combining sensitization and activation). The table below shows colloidal palladium activation formulations and conditions.
Reduction: After ionic activation, reduction improves catalytic activity, accelerates electroless plating, and removes residual activator to prevent bath decomposition. After colloidal palladium activation, degelation removes Sn²⁺ hydrolysate layers to expose Pd nuclei (immersion in 36% HCl at 35–45℃ for 1–3min).
Electroless Plating and Electroplating: After reduction/degelation, ABS undergoes electroless plating and electroplating.
Electroless Ni/Cu coatings can be directly electroplated. For better thermal shock resistance, copper plating is preferred (coefficient of linear expansion close to ABS, extending outdoor service life). Copper coatings can be colored or plated with other metals, most commonly nickel/chromium (Ni/Cr).
Application Fields of ABS Resin
Household Appliances and Electronic Components
Household Appliances: The largest and most promising application field for ABS, including casings and internal components of TVs, tape recorders, washing machines, refrigerators, record players, telephones, vacuum cleaners, air conditioners, lamps, electric fans, etc.
Electronic Components: Used for antenna sockets, coil bobbins, terminal blocks, converters, speakers, connectors, etc.
Automotive
Interior Components: Instrument panels, instrument cluster housings, A-pillars, air vents, control boxes, door liners, toolboxes, regulator handles, switches, knobs, steering column covers, steering wheels, horn covers, conduits, etc.
Exterior Components: Mudguards, armrests, grilles, lamp shades, ventilation covers, wheel covers, brackets, louvers, nameplates, rear spoilers, bumper guards, mirror frames, etc.
Machinery
Used for machinery casings and general components: motor housings, instrument boxes, water tank shells, battery tanks, gears, bearings, pump impellers, handles, bolts, covers, bushings, fasteners, etc.
Office Equipment
Excellent impact resistance, rigidity, dimensional stability, and moldability make ABS an ideal material for office equipment casings, including fax machines, copiers, typewriters, computers, and monitors. Flame-retardant grades are typically used due to fire safety requirements.
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