Acrylonitrile butadiene styrene (ABS) (

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbol ...

(C₈H₈)_''x''·(C₄H₆)_''y''·(C₃H₃N)_''z'' is a common

thermoplastic A thermoplastic, or thermosoft plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Most thermoplastics have a high molecular weight. The polymer chains associate ...

polymer. Its glass transition temperature is approximately . ABS is amorphous and therefore has no true melting point. ABS is a

terpolymer In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are some ...

made by polymerizing

styrene Styrene () is an organic compound with the chemical formula C6H5CH=CH2. This derivative of benzene is a colorless oily liquid, although aged samples can appear yellowish. The compound evaporates easily and has a sweet smell, although high concen ...

and

acrylonitrile Acrylonitrile is an organic compound with the formula and the structure . It is a colorless, volatile liquid although commercial samples can be yellow due to impurities. It has a pungent odor of garlic or onions. In terms of its molecula ...

in the presence of polybutadiene. The proportions can vary from 15% to 35% acrylonitrile, 5% to 30%

butadiene 1,3-Butadiene () is the organic compound with the formula (CH2=CH)2. It is a colorless gas that is easily condensed to a liquid. It is important industrially as a precursor to synthetic rubber. The molecule can be viewed as the union of two vi ...

and 40% to 60% styrene. The result is a long chain of polybutadiene crisscrossed with shorter chains of poly(styrene-co-acrylonitrile). The nitrile groups from neighboring chains, being polar, attract each other and bind the chains together, making ABS stronger than pure polystyrene. The acrylonitrile also contributes chemical resistance, fatigue resistance, hardness, and rigidity, while increasing the heat deflection temperature. The styrene gives the plastic a shiny, impervious surface, as well as hardness, rigidity, and improved processing ease. The polybutadiene, a

rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, an ...

y substance, provides

toughness In materials science and metallurgy, toughness is the ability of a material to absorb energy and plastically deform without fracturing. For the majority of applications, ABS can be used between , as its mechanical properties vary with temperature.Plastic Properties of Acrylonitrile Butadiene Styrene (ABS)
. Small table of ABS properties towards the bottom. Retrieved 7 May 2010. The properties are created by rubber toughening, where fine particles of elastomer are distributed throughout the rigid matrix.

Properties

ABS provides favorable mechanical properties such as impact resistance, toughness, and rigidity when compared with other common polymers. A variety of modifications can be made to improve impact resistance, toughness, and heat resistance. The impact resistance can be amplified by increasing the proportions of polybutadiene in relation to styrene and also acrylonitrile, although this causes changes in other properties. Impact resistance does not fall off rapidly at lower temperatures. Stability under load is excellent with limited loads. Thus, by changing the proportions of its components, ABS can be prepared in different grades. Two major categories could be ABS for extrusion and ABS for injection molding, then high and medium impact resistance. Generally ABS would have useful characteristics within a temperature range from . The final properties will be influenced to some extent by the conditions under which the material is processed to the final product. For example, molding at a high temperature improves the gloss and heat resistance of the product whereas the highest impact resistance and strength are obtained by molding at low temperature. Fibers (usually glass fibers) and additives can be mixed in the

resin In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on n ...

pellets to make the final product strong and raise the maximum operating temperature as high as . Pigments can also be added, as the raw material's original color is translucent ivory to white. The aging characteristics of the polymers are largely influenced by the polybutadiene content, and it is normal to include antioxidants in the composition. Other factors include exposure to

ultraviolet radiation Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...

, which additives are also available to protect against. ABS polymers are resistant to aqueous acids, alkalis, concentrated

hydrochloric Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the digestiv ...

and phosphoric acids and animal, vegetable and mineral oils, but they are swollen by

glacial acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main component ...

, carbon tetrachloride and

aromatic In chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to satur ...

hydrocarbons and are attacked by concentrated sulfuric and nitric acids. They are soluble in

esters In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ar ...

, ketones (such as acetone), chloroform, and

ethylene dichloride The chemical compound 1,2-dichloroethane, commonly known as ethylene dichloride (EDC), is a chlorinated hydrocarbon. It is a colourless liquid with a chloroform-like odour. The most common use of 1,2-dichloroethane is in the production of vinyl ...

. They also offer poor resistance to chlorinated solvents, alcohols and aldehydes. Even though ABS plastics are used largely for mechanical purposes, they also have electrical properties that are fairly constant over a wide range of frequencies. These properties are little affected by temperature and atmospheric humidity in the acceptable operating range of temperatures.Harper C.A. (1975) ''Handbook of plastic and elastomers'', McGraw-Hill, New York, pp. 1–3, 1–62, 2–42, 3–1, ABS is flammable when it is exposed to high temperatures, such as those of a wood fire. It will melt and then boil, at which point the vapors burst into intense, hot flames. Since pure ABS contains no

halogens The halogens () are a group in the periodic table consisting of five or six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts). In the modern IUPAC nomenclature, this group i ...

, its combustion does not typically produce any

persistent organic pollutants Persistent organic pollutants (POPs), sometimes known as "forever chemicals", are organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes. They are toxic chemicals that adversel ...

, and the most toxic products of its combustion or pyrolysis are

carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...

and hydrogen cyanide. ABS is also damaged by sunlight. This caused one of the most widespread and expensive automobile recalls in US history due to the degradation of the seatbelt release buttons. ABS can be recycled, although it is not accepted by all recycling facilities. ABS is one of many types of thermoplastic with biomedical applications, with injection-molded components being easy to manufacture for single-use. It can be sterilized by gamma radiation or ethylene oxide (EtO).

Production

ABS is derived from

, and

. Acrylonitrile is a synthetic monomer produced from

propylene Propylene, also known as propene, is an unsaturated organic compound with the chemical formula CH3CH=CH2. It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. It is a colorless gas with a faint petro ...

and

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...

; butadiene is a petroleum hydrocarbon obtained from the C4 fraction of steam cracking; styrene monomer is made by

dehydrogenation In chemistry, dehydrogenation is a chemical reaction that involves the removal of hydrogen, usually from an organic molecule. It is the reverse of hydrogenation. Dehydrogenation is important, both as a useful reaction and a serious problem. At ...

ethylbenzene Ethylbenzene is an organic compound with the formula . It is a highly flammable, colorless liquid with an odor similar to that of gasoline. This monocyclic aromatic hydrocarbon is important in the petrochemical industry as an reaction intermedia ...

, a hydrocarbon obtained in the reaction of ethylene and

benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms ...

. According to the European plastic trade association PlasticsEurope, industrial production of of ABS resin in Europe uses an average of and is derived from

natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...

and

petroleum Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...

Machining

ABS is manufactured in a variety of grades, but for precision machining of ABS structural parts, it is recommended to use Machine Grade ABS. Machine Grade ABS is easily machined via standard machining techniques including; turning, drilling, milling, and sawing. ABS can be chemically affixed to itself and other like plastics.

Applications

ABS Printed Bell on Makerbot ThingOMatic

ABS was patented in 1948 and introduced to commercial markets by the Borg-Warner Corporation in 1954. ABS's light weight and ability to be

injection molded Injection moulding (U.S. spelling: injection molding) is a manufacturing process for producing parts by injecting molten material into a mould, or mold. Injection moulding can be performed with a host of materials mainly including metals (for ...

and extruded make it useful in manufacturing products such as drain-waste-vent (DWV) pipe systems. Musical instruments such as recorders, plastic

oboe The oboe ( ) is a type of double reed woodwind instrument. Oboes are usually made of wood, but may also be made of synthetic materials, such as plastic, resin, or hybrid composites. The most common oboe plays in the treble or soprano range. ...

s and clarinets, piano movements, and keyboard keycaps are commonly made out of ABS. Other uses include golf club heads (because of its good shock absorbance), automotive trim components, automotive bumper bars, binoculars, inhalers,

monocular A monocular is a compact refracting telescope used to magnify images of distant objects, typically using an optical prism to ensure an erect image, instead of using relay lenses like most telescopic sights. The volume and weight of a mono ...

nebulizer In medicine, a nebulizer (American English) or nebuliser (British English) is a drug delivery device used to administer medication in the form of a mist inhaled into the lungs. Nebulizers are commonly used for the treatment of asthma, cystic fibro ...

s, non-absorbable sutures, tendon prostheses, drug-delivery systems tracheal tubes, enclosures for electrical and electronic assemblies (such as

computer case A computer case, also known as a computer chassis, is the enclosure that contains most of the hardware of a personal computer. The components housed inside the case (such as the CPU, motherboard, memory, mass storage devices, power supply unit a ...

s), protective headgear, whitewater canoes, buffer edging for furniture and joinery panels, luggage and protective carrying cases, pen housings, and small kitchen appliances. Toys, including LEGO (Lego bricks have been made from ABS since 1958) and Kre-O bricks, are a common application. Household and consumer goods comprise the major applications of ABS. ABS plastic ground down to an average diameter of less than 1 micrometer is used as the colorant in some

tattoo ink Tattoo inks consist of pigments combined with a carrier, used in the process of tattooing to create a tattoo in the skin. These inks are also used for permanent makeup, a form of tattoo. Professional tattoo inks are available in many colors and ...

3D printing

When extruded into a filament, ABS plastic is a common material used in

3D printers 3D printing or additive manufacturing is the construction of a three-dimensional object from a CAD model or a digital 3D model. It can be done in a variety of processes in which material is deposited, joined or solidified under computer co ...

, as it is cheap, strong, has high stability and can be post-processed in various ways (sanding, painting, gluing, filling and chemical smoothing). When being used in a 3D printer, ABS is known to warp due to shrinkage that occurs while cooling during the printing process. The shrinking can be reduced by printing inside an enclosure on a heated print surface, using an adhesive such as a glue stick or hairspray to ensure the first layer of the print is well stuck to the print surface, or printing with a brim/raft at the base of the print to help increase adhesion to the print surface. ABS is only used in FFF/FDM 3D printers, as resin 3D printers can not melt plastic. Particular forms of ABS filaments are ABS-ESD (electrostatic discharge) and ABS-FR (fire resistant), which are used in particular for the production of electrostatically sensitive components and refractory prefabricated parts.

Hazard for humans

ABS is stable to decomposition under normal use and polymer processing conditions with exposure to

carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive subs ...

s well below workplace exposure limits. However, at higher temperatures at or above 400 °C (750 °F) ABS can decompose into its constituents:

(carcinogenic to humans),

(possibly carcinogenic to humans), and

(reasonably anticipated to be a human carcinogen).

Ultrafine particle Ultrafine particles (UFPs) are particulate matter of nanoscale size (less than 0.1 μm or 100 nm in diameter). Regulations do not exist for this size class of ambient air pollution particles, which are far smaller than the regulated PM10 and P ...

s (UFPs) may be produced at lower temperatures (such as in 3D Printing). Concerns have been raised regarding airborne UFP concentrations generated while 3D printing with ABS, as UFPs have been linked with adverse health effects, some of which may result from tissue obstruction in the kidneys, lungs, and intestines caused by a buildup of UFPs.

References

External links

Comparisons of many physical properties with other plastics

Comparison between ABS and PLA for 3D Printing
{{DEFAULTSORT:Acrylonitrile Butadiene Styrene Copolymers Plastics Thermoplastics Engineering plastic