Effect on physical properties of variations in a two-part epoxy resin system

Formulation of proprietary epoxy compositions has become a common practice for many manufacturers of cast epoxy parts. Two common techniques applied are the batch approach and the two component of `A´ and `B´ approach. In the former all the components are blended together and immediately transferred into the molds. In the latter technique the complete formulation is divided into two parts: the `A´ side usually composed of the epoxy resin and a portion of the filler, and the `B´ side composed of the rest of the filler, the hardener, and the catalyst. The advantage of this latter approach is that the `A´ and `B´ divisions usually have a long if not indefinite pot life. Thus large batches of `A´ and `B´ can be mixed individually and at the desired moment stoichiometric portions of the `A´ and `B´ master batches drawn off, blended together, and transferred into the molds.