9.1 Introduction

Generally, it is not necessary to completely understand the ingredients in an adhesive formulation or the manufacturer's reasoning behind the specific formulation. One can often select a commercial adhesive based on functional properties, curing procedures, and other relevant information that are supplied by the adhesive manufacturer. However, a knowledge of the common materials used in formulating adhesives, and compositional techniques used to solve common application problems are especially important to anyone engaged in developing adhesive systems. A general knowledge of these factors is also important to the casual adhesive user so that he or she can more easily converse with the adhesive manufacturer regarding modifications that may be required or regarding certain characteristics of the adhesive system.

This chapter is intended to provide a very basic understanding of the components that are commonly used in adhesive formulation. The relationship between these materials and the properties exhibited by the adhesive system are explained. The customary techniques used to overcome several everyday problems are also discussed. These techniques include formulation processes and materials to control flow, extend temperature range, improve toughness, match thermal expansion coefficients, reduce shrinkage, increase tack, and modify electrical or thermal conductivity.

9.2 Adhesive Composition

Modern-day adhesives are often fairly complex formulations of components that perform specialty functions. Very few polymers are used without the addition of some modifying substance such as plasticizer, tackifier, or inert filler. The selection of the actual ingredients will depend on the end-properties required, the application and processing requirements, and the overall...