Styrene-acrylonitrile resin
Encyclopedia
Styrene acrylonitrile resin is a copolymer plastic
consisting of styrene and acrylonitrile
. It is also known as SAN. It is widely used in place of polystyrene
owing to its greater thermal resistance. The chains of the polymer show alternating repeat unit
s of styrene and acrylonitrile
, and it is a copolymer.
The relative composition is typically between 70 and 80% styrene and 20 to 30% acrylonitrile. Larger acrylonitrile content improves mechanical properties and chemical resistance, but also adds a yellow tint to the normally transparent plastic.
. Like polystyrene itself, it is optically transparent and brittle in mechanical behavior. The copolymer has a glass transition temperature greater than 100°C owing to the acrylonitrile
units in the chain, thus making the material resistant to boiling water. Uses include food containers, kitchenware, computer products, packaging material, battery
cases and plastic optical fiber
s. It is structurally related to ABS
plastic, where polybutadiene
is colpolymerised with SAN to give a much tougher material. The rubber chains form separate phases which are 10-20 micrometers in diameter. When the product is stressed, crazing
from the particles helps to increase the strength of the polymer. The method of rubber toughening
has been used to strengthen other polymers such as PMMA and nylon
.
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...
consisting of styrene and acrylonitrile
Acrylonitrile
Acrylonitrile is the chemical compound with the formula C3H3N. This pungent-smelling colorless liquid often appears yellow due to impurities. It is an important monomer for the manufacture of useful plastics. In terms of its molecular structure, it consists of a vinyl group linked to a nitrile...
. It is also known as SAN. It is widely used in place of polystyrene
Polystyrene
Polystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...
owing to its greater thermal resistance. The chains of the polymer show alternating repeat unit
Repeat unit
An essential concept which defines polymer structure, the repeat unit or repeating unit is a part of a polymer chain whose repetition would produce the complete polymer by linking the repeat units together successively along the chain, like the beads of a necklace.A repeat unit is sometimes called...
s of styrene and acrylonitrile
Acrylonitrile
Acrylonitrile is the chemical compound with the formula C3H3N. This pungent-smelling colorless liquid often appears yellow due to impurities. It is an important monomer for the manufacture of useful plastics. In terms of its molecular structure, it consists of a vinyl group linked to a nitrile...
, and it is a copolymer.
The relative composition is typically between 70 and 80% styrene and 20 to 30% acrylonitrile. Larger acrylonitrile content improves mechanical properties and chemical resistance, but also adds a yellow tint to the normally transparent plastic.
Properties
SAN is similar in use to polystyrenePolystyrene
Polystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...
. Like polystyrene itself, it is optically transparent and brittle in mechanical behavior. The copolymer has a glass transition temperature greater than 100°C owing to the acrylonitrile
Acrylonitrile
Acrylonitrile is the chemical compound with the formula C3H3N. This pungent-smelling colorless liquid often appears yellow due to impurities. It is an important monomer for the manufacture of useful plastics. In terms of its molecular structure, it consists of a vinyl group linked to a nitrile...
units in the chain, thus making the material resistant to boiling water. Uses include food containers, kitchenware, computer products, packaging material, battery
Battery (electricity)
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...
cases and plastic optical fiber
Plastic optical fiber
Plastic optical fiber is an optical fiber which is made out of plastic. Traditionally PMMA is the core material, and fluorinated polymers are the cladding material...
s. It is structurally related to ABS
Acrylonitrile butadiene styrene
Acrylonitrile butadiene styrene is a common thermoplastic. Its melting point is approximately 105 °C ....
plastic, where polybutadiene
Polybutadiene
Polybutadiene is a synthetic rubber that is a polymer formed from the polymerization process of the monomer 1,3-butadiene.It has a high resistance to wear and is used especially in the manufacture of tires, which consumes about 70% of the production...
is colpolymerised with SAN to give a much tougher material. The rubber chains form separate phases which are 10-20 micrometers in diameter. When the product is stressed, crazing
Crazing
Crazing is a network of fine cracks on the surface of a material, for example in a glaze layer.Crazing is a phenomenon that frequently precedes fracture in some glassy thermoplastic polymers. Crazing occurs in regions of high hydrostatic tension, or in regions of very localized yielding, which...
from the particles helps to increase the strength of the polymer. The method of rubber toughening
Rubber toughening
Many thermoplastics such as polystyrene and PMMA are brittle when stressed, a property which limits applications. A good way of strengthening such polymers is to copolymerise elastomeric chains during manufacture...
has been used to strengthen other polymers such as PMMA and nylon
Nylon
Nylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station...
.