Hardening or Curing Agent

The binder system of a plastic encapsulant consists of an epoxy resin, a hardener or curing agent, and an accelerating catalyst system. The conversion of epoxies from the Hquid (thermoplastic) state to tough, hard, thermoset soHds is accompHshed by the addition of chemically active compounds known as curing agents. Flame retardants (qv), usually in the form of halogens, are added to the epoxy resin backbone because epoxy resins are inherently flammable. 

Transformation of epoxy resins, which are viscous liquids or thermoplastic solids, into network polymers is a result of interaction with alkali or acid substances by means of to polyaddition and ionic polymerization mechanisms.10 A resin solidified by to the polyaddition mechanism, is a block copolymer consisting of alternating blocks of resin and a hardener or curing agent. A resin solidified by the ionic mechanism is a homopolymer. Molecules of both resin and hardener contain more than one active group. That is why block copolymer formation is a result of multiple reactions between an epoxy resin and a curing agent.11... 

The adhesive should be a two-part epoxy comprising resin and hardener components. The resin will normally be based on the diglycidyl ether of bisphenol A or bisphenol F or a blend of the two. The hardener, or curing agent, will normally be from the polyamine group, since these tend to result in adhesives with better resistance to moisture than have the polyamides and are likely to... 

In the process technology of conventional polymer-modified mortars using epoxy resin, the use of a hardener or curing agent has been considered indispensable for the hardening of the epoxy resin. Recently, Ohama et al. noticed that the hardening of epoxy resin occurs in the presence of alkalis in cement mortar as shown in Fig. and conducted a... 

Catalysts are called reactive hardeners or curing agents and become bound to the polymer by opening the epoxide linkage. When the hardener is an amine, the reaction is... 

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