Also known as DGEBA, it is the acronym of Bisphenol A diglycidyl ether and constitutes the smallest compound in many types of epoxy resins.
Materials made of two or more constituent materials combined to enhance performance and durability. The composite part has enhanced performance characteristics which are different from the individual components. Epoxies are often used as matrix resins for composites to strengthen and reinforce other materials such as steel, concrete, marble, glass or carbon fibres and widely used in wind farms, water pipes, automotive components and many other products.
In chemistry, a process involving an energy-intensive reaction which cross-links polymer chains, usually aimed at creating hardened (thermoset) substances. Epoxies are created by curing epoxy resins with other substances called hardeners, or by reacting with themselves through a process known as catalytic homo-polymerisation.
An organic compound containing two carbon atoms and one oxygen atom, connected to two alkyl or aryl groups. Epoxy resins always contain at least two epoxide groups. Epoxide content is used to determine the amount of hardeners needed to cure the epoxy resin. In common language, epoxides are often referred to simply as epoxies.
Epoxy or epoxies
Epoxies are the resulting product of a chemical reaction called ‘curing’, which involves reacting epoxy resins with other chemicals known as ‘hardeners’. Together they create epoxy plastics. However, as resins are the most important component of epoxy polymers, in everyday common language the term ‘epoxy resins’ is often used to refer to the end cured product as well as to the uncured resin. Epoxy is also often used to indicate an epoxide group, which is the reactive functional component found in epoxy resins.
Epoxy resins are a class of prepolymers and polymers containing more than one epoxide group. The vast majority of epoxy resins are petroleum derivatives produced through industrial processing. Today, hundreds of epoxy resins are available, the most common produced from epichlorohydrin and Bisphenol A. They are also known as polyepoxides and are often used to designate cured epoxies, also called epoxy or epoxy polymer.
Multiple chemical components are needed to develop the end product epoxy polymer. Epoxies are made available to consumers as two-component systems, comprising an epoxy resin and a hardener. More complex, industrial systems can include multiple resins and other components.
They are the substances used to ‘cure’ epoxy resins to transform them into epoxy polymers. The most common hardeners for epoxy resins are amines, acids, acid anhydrides, phenols, alcohols and thiols.
Some epoxy resins are cured using a process of catalytic homo-polymerisation, in which the epoxy resins are cross-reacted with themselves rather than with other chemicals. This process involves ring opening of the epoxide group using acid or base catalysts.
Low and high molecular weight
The molecular mass of an element, depending on the sum of the mass of each atom multiplied by the number of atoms of the element in the molecular formula. Epoxy resins’ molecular weight (MW) ranges from low MW – a honey-like fluid at room temperature – to high MW –taking a more solid, crystalline form. Low and high molecular weight epoxies have different uses. The former are used in casting, coating and gap-filling glues, while the latter are usually found as base resins in paints and lacquers.
A large class of substances with a molecular structure composed of smaller molecules called monomers which are covalently bonded together. In the case of epoxies, cross-linking epoxy resin (polymers or prepolymers) to create epoxies forms a thermosetting polymer with significant mechanical properties and high resistance to various media. See also thermosetting polymer.
Solvent-free coatings applied electrostatically and subsequently heated to form a protective layer over many objects for consumer or industrial use. Many epoxy-based powder coatings are used as ‘functional’ coatings to protect appliances such as ovens, fridges and washing machines to protect them from damage resulting from transport or installation or strong chemicals which may damage them internally or externally during cleaning.
See epoxy resin.
Polymers cured through heat-intensive reactions acquiring an irreversible solid or viscous state. Cured thermosetting polymers are called thermosets. All epoxy polymers are thermoset by nature, i.e. they cannot be reprocessed, like e.g. polyolefin thermoplastics, once they have undergone curing.
Waterborne Cathodic Electro Deposition (CED)
An epoxy-based coating which helps prevent rust and corrosion on metal parts used for example in vehicle bodies. The process to apply such technology involves a thin anti-corrosive coating as a primer onto metal parts and is now standard throughout the automotive industry.