• Epoxy resins are a reaction product between an epichlorohydyrin molecule and (in the case of Bis A resin, the FRP industry standard) phenol and acetone reaction molecule. Other materials can become part of the reaction yielding Bis F resin, Novolac resins, and multifunctional resins. For the purpose of describing CPD systems, Bis A resin is the most commonly used.

• The reacted product is high in viscosity (thicker) and can either undergo further reaction processes to yield a lower viscosity resin or diluted with a reactive diluent to lower the viscosity.

• Epoxy resins are often modified with other products to improve some measured property of the end use system such as toughness or tensile properties.

• Epoxy resins and their additives contribute to the viscosity of the system, shrink values, and the amount of the fillers and diluents will impact both physical and handling properties of the resin system.

• Epoxy resins are part of a two component thermoset plastic that requires an epoxy hardener to determine the majority of the handling and physical property base.

• Use of several variations of unmodified and modified epoxy resins with the same epoxy hardener will yield some variation in property measurements, however, the epoxy hardener is the primary factor in the base property measurements.

• In the FRP industry, epoxy hardeners must hold consistent to stated viscosity and have a very low water content (ppm) to be effective as a system with any hardener.

Epoxy Hardeners: What Are They?

• Epoxy hardeners "join" with the epoxy resin, greatly contributing to the ultimate properties of the cured resin system. Hardeners are not catalysts. Catalysts promote reactions but do not chemically become part of the finished product.

• Epoxy hardeners provide three foundations for handling characteristics:

• Epoxy hardeners provide five foundations for physical properties:

• The performance of Epoxy Hardeners are influenced by five chemical characteristics:

Viscosity of the epoxy resin

• The performance of Epoxy Hardeners are influenced by five physical characteristics:

Process Used in making the part

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