Question

epoxy resins and adhesives generally consists of two components, describe both components.

Answer 1

answer

Epoxy resins

are thermosetting polymer resins where all the resin molecule contains one or more epoxide groups. The chemistry can be adjusted to perfect the molecular weightor viscosity as required by the end use. There are two primary types of epoxies, glycidyl epoxy and non-glycidyl. Glycidyl epoxy resins can be further defined as either glycidyl-amine, glycidyl ester, or glycidyl ether. Non-glycidyl epoxy resins are either aliphatic or cyclo aliphatic resins.

One of the most common glycidyl epoxy resins is created using Bisphenol-A and is synthesized in a reaction with epichlorohydrin. The other frequently used type of epoxy is known as novolac based epoxy resin.

Epoxy resins are cured with the addition of a curing agent, which is commonly called a hardener. Perhaps the most common type of curing agent is amine based. Unlike in polyester or vinyl ester resins where the resin is catalyzed with a small (1-3%) addition of a catalyst, epoxy resins usually require the addition of the curing agent at a much higher ratio of resin to hardener, often 1:1 or 2:1.

As mentioned, the properties of epoxy can be altered and tweaked to fit the desired need. Epoxy resin can be "toughened" with the addition of thermoplastic polymers.

Multi-component adhesives

harden by mixing two or more components which chemically react. This reaction causes polymers to cross-link into acrylics, urethanes, and epoxies - See thermosetting polymers.

There are several commercial combinations of multi-component adhesives in use in industry. Some of these combinations are:

• Polyester resin – polyurethane resin
• Polyols – polyurethane resin
• Acrylic polymers – polyurethane resins

The individual components of a multi-component adhesive are not adhesive by nature. The individual components react with each other after being mixed and show full adhesion only on curing. The multi-component resins can be either solvent-based or solvent-less. The solvents present in the adhesives are a medium for the polyester or the polyurethane resin. The solvent is dried during the curing process.

One-part

One-part adhesives harden via a chemical reaction with an external energy source, such as radiation, heat, and moisture.

Ultraviolet (UV) light curing adhesives, also known as light curing materials (LCM), have become popular within the manufacturing sector due to their rapid curing time and strong bond strength. Light curing adhesives can cure in as little as a second and many formulations can bond dissimilar substrates (materials) and withstand harsh temperatures. These qualities make UV curing adhesives essential to the manufacturing of items in many industrial markets such as electronics, telecommunications, medical, aerospace, glass, and optical. Unlike traditional adhesives, UV light curing adhesives not only bond materials together but they can also be used to seal and coat products. They are generally acrylic-based.

Heat curing adhesives consist of a pre-made mixture of two or more components. When heat is applied the components react and cross-link. This type of adhesive includes thermoset epoxies, urethanes, and polyimides.