ABS Plastic

 

ABS Plastic -

            ABS stands for the Acrylonitrile Butadiene Styrene. Chemical formula of ABS is (C₈H₈)x·​(C₄H₆)y·​(C₃H₃N)z   

            It is common thermoplastic polymer. ABS is amorphous and therefore has no true melting point. It is a terpolymer (i.e. made up of three monomers). It is blended copolymers of styrene- acrylonitrile (70:30) and butadiene-acrylonitrile (65:35). 

            The ABS is stronger than pure polystyrene because the nitrile functional groups from neighboring chains, being polar, attract each other and holds the chains together. 

            The properties of chemical resistance, hardness, and rigidity in ABS are due to the acrylonitrile. The acrylonitrile also contribute for increasing the heat deflection temperature. The styrene provides the plastic a shiny, impervious (i.e. not allowing fluid to pass through) surface, as well as hardness, rigidity, and improved processing ease. The polybutadiene, offers toughness and ductility at low temperatures.

            Majorly the ABS can be used between -20 to 80 °C (−4 to 176 °F), as its mechanical properties fluctuate with change in temperature.

            The ABS shows properties like impact resistance, toughness, and rigidity in comparison with other common polymers. A variety of modifications can be made to improve the certain properties of ABS. For example, the impact resistance can be amplified by increasing the amounts of polybutadiene with respect to styrene. Therefore, by varying the extent of its monomers, ABS can be easily modified in different grades.

Two major types of ABS are 
        1) ABS for extrusion 
        2) ABS for injection molding

Extrusion is a technique where molten polymer is forced through a die and is used to produce components of a fixed cross-sectional area such as tubes and rods.

            ABS polymers are resistant to aqueous acids, alkalis, concentrated hydrochloric and phosphoric acids and animal, vegetable and mineral oils, however, they are swollen by glacial acetic acid, carbon tetrachloride and aromatic hydrocarbons and are attacked by concentrated sulfuric and nitric acids. They are soluble in esters, ketones (such as acetone), chloroform, and ethylene dichloride. They also offer poor resistance to chlorinated solvents, alcohols and aldehydes.

            ABS is flammable when it is exposed to high temperatures. At very high temperature, it will melt and then boil, at this stage the vapors burst into intense and hot flames.

            ABS is also get damaged by exposure to sunlight. ABS can be recycled. The biomedical applications of ABS is in manufacturing of disposable injection-molded components. These ABS made biomedical devices can be sterilized very easily by gamma radiation or ethylene oxide. When extruded into a filament, ABS plastic is a common material utilized in 3D printers.

 

References – 

1) Harper C.A. (1975) Handbook of plastic and elastomers, McGraw-Hill, New York, ISBN 0070266816

2) Peters, Edward N., "Plastics: Thermoplastics, Thermosets, and Elastomers", Handbook of Materials Selection, New York: John Wiley & Sons, Inc.