Chapter 8 - Epoxies

Abstract

Epoxies are an important class of polymers and provide a basis for numerous composites. They can be easily deposited as coatings in the liquid state and then solidified by cross-linking. We discuss the starting materials for making epoxies, including cashew nut shell liquid, and their viscosities. We explain the chemistries of epoxies, including those based on bisphenol A, bisphenol F, novolacs, peracids, and hydantoins. We define important properties of polymers, including brittleness B and flexibility Y. We list properties of a number of epoxies, including their heat deflection temperatures, flexural strength, flexural modulus, compressive strength, tensile strength, tensile elongation at break, Izod impact strength, electrical conductivity, hardness, thermal conductivity, and thermal expansivity. We discuss property modifiers including fillers and processing procedures. We explain gelation and vitrification. We discuss differential scanning calorimetry, thermomechanical analysis, dynamic mechanical analysis, thermally stimulated depolarization, and their uses in location of the glass transition regions. Epoxies find application as coatings, electrical and electronic insulation, adhesives, castings in medicine and dentistry, corrosion protectants, fiber optics sheathing, and flooring. A violin was constructed using a graphite/epoxy composite.