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 symbols, ...

(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 The glass–liquid transition, or glass transition, is the gradual and reversible transition in amorphous materials (or in amorphous regions within semicrystalline materials) from a hard and relatively brittle "glassy" state into a viscous or ru ...

temperature is approximately . ABS is

amorphous In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid, glassy solid) is a solid that lacks the long-range order that is characteristic of a crystal. Etymology The term comes from the Greek language, Gr ...

and therefore has no true melting point. ABS is a terpolymer made by polymerizing styrene 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 v ...

and 40% to 60% styrene. The result is a long chain of polybutadiene crisscrossed with shorter chains of poly(styrene-co-acrylonitrile). The

nitrile In organic chemistry, a nitrile is any organic compound that has a functional group. The prefix '' cyano-'' is used interchangeably with the term ''nitrile'' in industrial literature. Nitriles are found in many useful compounds, including me ...

groups from neighboring chains, being polar, attract each other and bind the chains together, making ABS stronger than pure

polystyrene Polystyrene (PS) is a synthetic polymer made from monomers of the Aromatic hydrocarbon, aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin pe ...

. 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, and ...

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 nat ...

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

antioxidant Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubrica ...

s in the composition. Other factors include exposure to ultraviolet radiation, which additives are also available to protect against. ABS polymers are resistant to aqueous acids, alkalis, concentrated hydrochloric and phosphoric acids and animal, vegetable and mineral oils, but they are swollen by glacial acetic acid, 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 Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...

and nitric acids. They are soluble in esters,

ketones In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double b ...

(such as acetone), chloroform, and ethylene dichloride. They also offer poor resistance to chlorinated solvents,

alcohols In chemistry, an alcohol is a type of organic compound that carries at least one hydroxyl () functional group bound to a saturated carbon atom. The term ''alcohol'' originally referred to the primary alcohol ethanol (ethyl alcohol), which is ...

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, its combustion does not typically produce any persistent organic pollutants, 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 simpl ...

and

hydrogen cyanide Hydrogen cyanide, sometimes called prussic acid, is a chemical compound with the formula HCN and structure . It is a colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at . HCN is produced on a ...

. 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 styrene. 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 ...

; butadiene is a petroleum hydrocarbon obtained from the C4 fraction of

steam cracking Steam cracking is a petrochemical process in which saturated hydrocarbons are broken down into smaller, often unsaturated, hydrocarbons. It is the principal industrial method for producing the lighter alkenes (or commonly olefins), including et ...

; 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. A ...

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 interme ...

, a hydrocarbon obtained in the reaction of

ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). 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 carbon d ...

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

clarinet The clarinet is a musical instrument in the woodwind family. The instrument has a nearly cylindrical bore and a flared bell, and uses a single reed to produce sound. Clarinets comprise a family of instruments of differing sizes and pitch ...

s, 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 Binoculars or field glasses are two refracting telescopes mounted side-by-side and aligned to point in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. Most binoculars are sized to be held ...

, inhalers, monoculars, nebulizers, non-absorbable sutures, tendon prostheses, drug-delivery systems tracheal tubes, enclosures for electrical and electronic assemblies (such as computer cases), 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 ( , ; stylized as LEGO) is a line of plastic construction toys that are manufactured by The Lego Group, a privately held company based in Billund, Denmark. The company's flagship product, Lego, consists of variously colored interlocki ...

(Lego bricks have been made from ABS since 1958) and

Kre-O KRE-O is a line of construction toys (similar to Lego and Mega Bloks) manufactured by South Korea-based Oxford and marketed by Hasbro. Kre-O was released in stores in Fall 2011. The name ''Kre-O'' comes from the Latin word ''creo'', which means ...

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 Micrometer can mean: * Micrometer (device), used for accurate measurements by means of a calibrated screw * American spelling of micrometre The micrometre ( international spelling as used by the International Bureau of Weights and Measures; ...

is used as the colorant in some tattoo inks.

3D printing

When extruded into a filament, ABS plastic is a common material used in 3D printers, 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 sub ...

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 styrene (reasonably anticipated to be a human carcinogen). Ultrafine particles (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