- The first of the two parts that make up epoxy is the resin. The resin is a polymer whose structure includes unreacted epoxide units. Epoxides are chemical structures that are strained, so they are likely to react with compatible compounds, particularly those in hardeners.
- The second of the two parts that make up epoxy is the hardener. Hardeners are polyamine monomers, such as triethylenetetramine. The type of hardener that is used determines the working time of the epoxy, the viscosity of the epoxy, and the final properties of the hardened epoxy. The hardener is added to the resin at a specific ratio. The mixture is either stirred by hand or combined using a mixing nozzle to fully blend the two components before application.
- Compounds can be added to the basic epoxy materials to add additional properties to the final epoxy. Pigments can be added to create custom color epoxies. Plasticizers can be added to allow the epoxy blend to retain from flexibility. Silver can be added to an epoxy blend to allow it to be electrically conductive.
- When an epoxide resin and a hardener are combined in the right ratio, the material undergoes a chemical reaction. Covalent bonds are created between the resin and hardener molecules, resulting in a hard, interlinked epoxy material. This process is called curing. Some epoxies can be cured at ambient temperatures, but most epoxies cure faster and to a higher quality when exposed to an elevated temperature. Some epoxies cure when exposed to ultraviolet light.
- Epoxies are used for a wide variety of engineering and fabrication processes. They are combined with fiber materials such as fiberglass to create composite materials. Epoxies are often used for repairs of nearly any kind of material because of the strong bond that the epoxy provides. Frequently they are used for marine applications and other instances where waterproof surfaces or coatings are required. Epoxies are also widely used to create molds or models that are more durable than plaster or wax molds.They are generally excellent insulators, and are used to seal electronic components.
