ABS properties
Chemical composition
Section titled “Chemical composition”ABS (acrylonitrile butadiene styrene) is an amorphous thermoplastic terpolymer with the general formula (C₈H₈)·(C₄H₆)·(C₃H₃N). The proportions of the monomers vary according to the grade, within the following typical ranges.
| Monomer | Percentage by weight |
|---|---|
| Styrene | 40 – 60 % |
| Acrylonitrile | 15 – 35 % |
| Butadiene | 5 – 30 % |
The structure consists of an elastomeric polybutadiene phase onto which styrene‑acrylonitrile (SAN) chains are grafted. Acrylonitrile provides chemical resistance, stiffness and hardness; styrene facilitates processability and surface gloss; butadiene provides toughness and ductility, even at low temperature.
Mechanical properties
Section titled “Mechanical properties”The mechanical values of ABS depend on the grade and the processing temperature. The table shows representative properties at 23 °C for a general-purpose grade.
| Property | SI Value | Imperial Value | Standard / Condition |
|---|---|---|---|
| Tensile strength | 48 MPa | 7.0 ksi | ASTM D638 |
| Tensile modulus | 2.34 GPa | 340 ksi | ASTM D638 |
| Flexural modulus | 2.7 GPa | 390 ksi | ASTM D790 |
| Elongation at break | 5 – 20 % | 5 – 20 % | ASTM D638 |
| Strain at yield | 3.2 % | 3.2 % | ASTM D638 |
| Notched Izod impact strength | 0.13 kJ/m (130 J/m) | 2.4 ft·lb/in | ASTM D256 |
| Surface hardness | RR 111 | RR 111 | Rockwell R |
Physical properties
Section titled “Physical properties”| Property | SI Value | Imperial Value |
|---|---|---|
| Density | 1.06 – 1.08 g/cm³ | 0.0383 – 0.0390 lb/in³ |
| Water absorption (24 h, 23 °C) | 0.3 % | 0.3 % |
| Linear thermal expansion coefficient | 12 × 10⁻⁵ /°C | 7.0 × 10⁻⁵ /°F |
| Flammability (UL94) | HB | HB |
| Limiting oxygen index | 19 % | 19 % |
Thermal properties
Section titled “Thermal properties”| Property | SI Value | Imperial Value |
|---|---|---|
| Maximum continuous service temperature | 70 °C | 158 °F |
| Glass transition temperature (Tg) | ~105 °C | ~221 °F |
| Heat deflection temperature (HDT) at 0.45 MPa (66 psi) | 112 °C | 234 °F |
| Heat deflection temperature (HDT) at 1.80 MPa (264 psi) | 104 °C | 219 °F |
| Thermal conductivity | 0.19 W/(m·K) | 1.35 Btu·in/(ft²·h·°F) |
| Specific heat | 1.42 kJ/(kg·K) | 0.34 Btu/(lb·°F) |
| Processing melting range | 250 – 285 °C | 482 – 545 °F |
Electrical properties
Section titled “Electrical properties”| Property | Value | Condition |
|---|---|---|
| Volume resistivity | 10¹⁶ Ω·cm | 23 °C, 50 % RH |
| Dielectric strength | 15 MV/m | Thickness 3 mm |
| Dielectric constant | 2.7 | 1 kHz |
| Dissipation factor | 0.008 | 1 kHz |
Chemical resistance
Section titled “Chemical resistance”Good resistance to:
- Dilute and concentrated aqueous acids (except concentrated sulfuric and nitric).
- Alkalis (sodium hydroxide, potassium hydroxide).
- Mineral, vegetable and animal oils.
Poor resistance (swelling or attack):
- Aromatic hydrocarbons (benzene, toluene).
- Halogenated hydrocarbons (carbon tetrachloride, chloroform).
- Ketones (acetone, methyl ethyl ketone).
- Esters and aldehydes.
- Glacial acetic acid.
- Alcohols (may cause stress cracking).
Applications by industry
Section titled “Applications by industry”- Automotive: bumpers, interior and exterior trim, mirror housings, ventilation grilles.
- Consumer goods: building blocks (LEGO®), appliance housings, vacuum cleaners, suitcases, musical instruments.
- Electronics and electrical: keyboards, monitor and computer housings, 3D printers (filament).
- Medical: prostheses, non‑absorbable sutures, tracheal tubes, inhalers.
- Construction: drainage, waste and vent (DWV) pipes.
- Other: golf club heads, binoculars, tattoo inks.
Comparison with similar materials
Section titled “Comparison with similar materials”| Property | ABS | PS | HIPS | PC |
|---|---|---|---|---|
| Density (g/cm³) | 1.06 – 1.08 | 1.05 | 1.04 | 1.20 |
| Tensile strength (MPa) | 48 | 45 | 25 | 65 |
| Izod impact strength (J/m) | 130 | 20 | 80 | 600 |
| HDT at 1.80 MPa (°C) | 104 | 95 | 85 | 130 |
ABS offers an optimal balance between impact resistance, stiffness and cost, surpassing polystyrene (PS) and high-impact polystyrene (HIPS) in thermal and chemical behavior. Polycarbonate (PC) offers higher impact resistance and service temperature, but at a higher cost.
Processing and molding
Section titled “Processing and molding”- Drying: 2 hours at 90 °C (recommended to remove surface moisture).
- Mold temperature: 40 – 80 °C.
- Injection melt temperature: 250 – 285 °C.
- Mold shrinkage: 0.5 %.
- Processing notes:
- Higher mold temperatures improve gloss and heat resistance.
- Lower mold temperatures favor maximum impact resistance.
- ABS is susceptible to degradation from excessive shear; low or medium compression screws are recommended.
Hazards and safety
Section titled “Hazards and safety”- At temperatures above 250 °C it decomposes releasing acrylonitrile, butadiene and styrene; some of these are classified as possible carcinogens.
- Combustion of ABS can generate hydrogen cyanide (HCN) and carbon monoxide (CO), which are highly toxic.
- During 3D printing or thermoforming it emits ultrafine particles (UFP) and volatile organic compounds (VOCs). Work must be carried out in ventilated spaces with appropriate filtration.
- Prolonged exposure to sunlight causes photodegradation, yellowing and loss of mechanical properties.
Frequently Asked Questions (FAQ)
Section titled “Frequently Asked Questions (FAQ)”What is the density of ABS?
Section titled “What is the density of ABS?”The density of ABS ranges between 1.06 and 1.08 g/cm³ (0.0383–0.0390 lb/in³), making it a lightweight yet rigid thermoplastic suitable for structural components not subjected to extreme loads.
What is the tensile strength of ABS?
Section titled “What is the tensile strength of ABS?”ABS has a typical tensile strength of 48 MPa (7.0 ksi) at room temperature. High-impact grades may show slightly lower values, while fiber-reinforced grades reach up to 60 MPa.
What is the maximum service temperature of ABS?
Section titled “What is the maximum service temperature of ABS?”It can be used continuously up to 70 °C (158 °F). Above this temperature, mechanical properties decrease significantly and the material begins to soften.
What is the heat deflection temperature (HDT) of ABS?
Section titled “What is the heat deflection temperature (HDT) of ABS?”The HDT of ABS is 104 °C (219 °F) under a load of 1.80 MPa and 112 °C (234 °F) under 0.45 MPa. This value determines the practical limit for applications requiring stiffness at high temperature.
Is ABS resistant to chemicals?
Section titled “Is ABS resistant to chemicals?”ABS resists dilute acids, bases and oils well, but is attacked by aromatic hydrocarbons, ketones, esters and chlorinated hydrocarbons. Contact with these solvents causes swelling and loss of mechanical strength.
How long should ABS be dried before processing?
Section titled “How long should ABS be dried before processing?”For most injection molding or extrusion processes, it is recommended to dry the granules at 90 °C for 2 hours. Insufficient drying can cause surface defects such as moisture marks or bubbles.
References
Section titled “References”- azom.com: https://www.azom.com/article.aspx?ArticleID=362
- engineeringtoolbox.com: https://www.engineeringtoolbox.com/physical-properties-thermoplastics-d_808.html
- steelnumber.com: https://www.steelnumber.com/en/steel_composition_eu.php?name_id=868