Epoxy resins are extremely versatile materials that offer a variety of benefits. They have excellent tensile, flexural and compressive strength, are resistant to many chemicals and can withstand harsh environmental conditions such as salt water, sunlight, oil, gasoline and solvents.
They can be poured in various thicknesses and tinted to create a range of colors. Some epoxy, such as ArtResin and Industrial Clear, are even food-safe when cured, making them great for crafting art, home decor and jewellery.
What is epoxy?
Epoxy resin is a versatile material that has become a favorite among artists, crafters, and woodworkers. It is used to create beautiful glossy finishes on artwork, DIY jewelry, trays, coasters, and more. It is also used as an adhesive and sealant for various materials. Resin has many uses and can be found in almost any home improvement store.
Epoxies are a broad class of cross-linkable polymers that are characterized by the presence of oxirane rings. These rings contain oxygen and carbon atoms that are bonded to other atoms of the polymer through a variety of methods. The resulting polymer is often rigid and thermosetting. The final epoxy formulations may also contain a range of additives such as fillers, catalyst hardeners, and pigments.
Different classes of epoxies are distinguished by the number of rings in the phenol-containing molecules and the way they are bonded together during the curing process. Glycidyl epoxy resins are characterized by the addition of a glycidyl functional group to the oxirane ring. This group helps to improve the chemical resistance of the epoxy resins.
Rigid epoxies are usually cured by heat, although some can be air-cured. They are considered fully cured when they no longer dent when pressed with a point or edge. Many epoxies require prolonged cure times and manufacturers’ curing schedules should be followed carefully to avoid failure or damage.
How is epoxy made?
Epoxy, renowned for its exceptional durability and bonding strength, serves a multitude of applications with remarkable resilience against heat, water, and chemicals. Its ability to bond dissimilar materials like metals, woods, glass, and stone, coupled with high creep resistance and corrosion resistance, makes it an ideal choice for protective coatings and structural reinforcements.
Derived from petrochemicals such as epichlorohydrin and bisphenol A (BPA), epoxies polymerize into robust three-dimensional lattices, imparting unparalleled strength and longevity. Formulated with additives, they can achieve specialized properties such as flame resistance and electrical insulation.
With diverse formulations tailored to specific needs, epoxies are available as one-component systems that require no catalyst and cure efficiently at lower temperatures. Alternatively, two-component epoxies offer enhanced strength but involve mixing resin and hardener in precise ratios.
What are the main properties of epoxy?
Epoxy resins are one of the most versatile adhesive materials available. They are durable, strong and can withstand high levels of wear and tear. They can be used to coat a variety of surfaces including wood, metal, concrete and glass.
The main properties of epoxy resin include high tensile strength, compressive strength and resistance to corrosion, chemicals and weather elements. They also have excellent adhesion to a wide range of substrates including metal, glass, fabric and wood.
In addition, epoxies are often admixed for specific properties such as flame resistance or electrical insulation (via fluorinated and brominated bisphenol A). These admixtures have a negative effect on the Tg.
Typical epoxies are formulated through the glycidylation of polyols or aliphatic alcohols to create diluents. These diluents are then mixed with curing agents or catalytic hardeners. Once the combination is mixed and poured, a polymerization reaction takes place to form a rigid and durable material.
Some epoxy resins are free of volatile organic compounds or VOCs. These types are typically safe to use and require no respirator. Other epoxies are cured with aromatic amines and epichlorohydrin. This results in novolacs with a high level of functionality. The most common novolacs are epoxycresol novolac (ECN) and tetraglycidyl p-aminophenol / N,N,N’,N’-trimethylolpropane tetraglycidyl amine (EPN). These are considered high performance epoxies as they provide good chemical and oxidation resistance and low-medium viscosities at room temperature.
What are the main types of epoxy?
Epoxy resins are multi-component materials. They contain both a liquid epoxy resin and an activator hardener, which need to be proportionately mixed together for use. This usually requires a measuring system to ensure the correct quantity of each component is used. Other components can include fillers, stabilisers, anti-foaming agents and reactive diluents. Other additives can be included to modify specific epoxy properties including viscosity, thermal stability and chemical resistance.
Epoxies are very versatile and can be poured in a wide range of thicknesses, tinted for a colour and finished with a matt or glossy finish. They can be bonded to most surfaces including fabric, wood, glass, metal and concrete. They also work well as protective coatings and are commonly used in industrial applications such as protecting steel structures from corrosion.
The main types of epoxy resin are classified by a number of properties such as the functionality level, the type and the number of phenol rings. They are also divided into glycidyl and non-glycidyl varieties with sub-categories of glycidyl ethers, glycidyl esters and glycidyl amines. Other categories include aliphatic and cyclo-aliphatic. The most important commercial epoxy resins are bisphenol A diglycidyl ethers (DGEBA), with other bisphenols such as diethylene glycol bisphenol A and tetrabromobisphenol A showing promise for higher performance and broader application. The glycidyl varieties have lower viscosity than other types and can be used in colder temperatures.
