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Epoxy

physical science Maturity 11-13 Next article →

Epoxy refers to a family of reactive components or their final, cured products. These materials belong to a class of polymers known as polyepoxides.

Epoxide generic
Epoxide generic

They are defined by the presence of epoxide functional groups. The IUPAC name for this specific group is an oxirane. Epoxy is essential because it can form thermosetting polymers. These materials possess excellent mechanical properties. They also show high resistance to both heat and chemicals. This makes them incredibly versatile for many industrial uses.

To turn liquid resin into a solid, a process called curing must occur. This happens through a reaction known as cross-linking.

VernetzteEpoxidharze
VernetzteEpoxidharze

In this process, the epoxy resin reacts with various co-reactants. These co-reactants are called hardeners or curatives. Common hardeners include polyfunctional amines, acids, phenols, alcohols, and thiols. During curing, these molecules link together to form a dense, three-dimensional network. This network is what gives the finished product its strength and stability.

There are several distinct types of epoxy resins used in manufacturing. The most common type is based on bisphenol A.

Diglycidether
Diglycidether

When epichlorohydrin reacts with bisphenol A, it creates bisphenol A diglycidyl ether, or BADGE. These resins can exist in different physical states. A product with only a few repeat units is a viscous, clear liquid called liquid epoxy resin. If the product has more repeating units, it becomes a colorless solid at room temperature. Other types include novolaks, which are produced by reacting phenol with methanal. These resins often have very high cross-link density. This results in high temperature resistance but low mechanical flexibility.

Another category is aliphatic epoxy resins. These include cycloaliphatic epoxides and epoxidized vegetable oils.

Synthesis epoxide peracid
Synthesis epoxide peracid

Cycloaliphatic epoxides contain aliphatic rings and lack chlorine. This absence of chlorine leads to low viscosity and good weather resistance. However, they polymerize slowly at room temperature. They usually require heat or UV light to trigger the reaction. Epoxidized vegetable oils are made by reacting unsaturated fatty acids with peracids. These oils have very low viscosities. They are often used as secondary plasticizers in PVC products.

History shows how these materials were gradually developed by scientists. Paul Schlack of Germany first reported and patented the condensation of epoxides and amines in 1934.

FiveMinEpoxy
FiveMinEpoxy

Later, in 1943, Pierre Castan discovered the use of bisphenol A-based epoxy resins. His work was licensed by the Swiss company Ciba, Ltd. This company became one of the three largest epoxy producers in the world. In 1946, Sylvan Greenlee of the Devoe & Raynolds Company patented another resin. This resin was derived from both bisphenol A and epichlorohydrin.

Epoxy is used in a massive range of modern applications. It serves as a protective coating for metals and as a component in composites.

Titan epoxy
Titan epoxy

In the electronics industry, it is vital for protecting delicate parts. It is used for computer chips on boards, LEDs, and high-tension electrical insulators.

Hybridcircuit
Hybridcircuit

You might even find it inside a pocket calculator to cover central components.

Citizen se-733 int 1ac
Citizen se-733 int 1ac

It is also used in manufacturing paintbrushes and fiber-reinforced plastics. Because it is so strong, it is used in high-performance items like surfboards.

Understanding epoxy requires looking at its chemical measurements. A key value is the epoxy value, which relates to the epoxide group content. This is expressed as the epoxide equivalent weight. This is the ratio between the monomer's molecular weight and the number of epoxide groups. Scientists use this number to calculate exactly how much hardener is needed for curing. Using the correct stoichiometric amount of hardener is necessary to achieve the best physical properties. This precision ensures the material reaches its full strength and durability.

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🖼️ Images & Media (14)
File:FiveMinEpoxy.jpg
FiveMinEpoxy.jpg
File:Epoxide generic.svg
Epoxide generic.svg
File:Synthesis epoxide Epichlorohydrin.svg
Synthesis epoxide Epichlorohydrin.svg
File:Synthesis epoxide peracid.svg
Synthesis epoxide peracid.svg
File:Diglycidether.svg
Diglycidether.svg
File:Synthesis Bisphenol A diglycidyl ether higher Mw.svg
Synthesis Bisphenol A diglycidyl ether...
File:Epoxy prepolymer chemical structure.png
Epoxy prepolymer chemical structure.png
File:Epoxyphenol-Novolak.svg
Epoxyphenol-Novolak.svg
File:Diepoxyester.svg
Diepoxyester.svg
File:VernetzteEpoxidharze.svg
VernetzteEpoxidharze.svg
File:N1,N1'-(ethane-1,2-diyl)bis(ethane-1,2-diamine) 200.svg
N1,N1'-(ethane-1,2-diyl)bis(ethane-1,2-dia...
File:Titan epoxy.jpg
Titan epoxy.jpg

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