INTRODUCTION

Composite materials owe their very existence to adhesion between resin matrix and reinforcement. However, despite the general applicability of much of this Chapter to this aspect of adhesion, the intention is to focus interest on the more demanding problem of ‘structural’ adhesion as an alternative means of joining composite components together to facilitate ease of fabrication from standard components. A number of excellent general guides as well as more detailed texts, cover the basic principles and these have been drawn on, and supplemented where appropriate by reference to recent research papers.

Nature of Polymeric Adhesion

Although adhesives of animal, vegetable or mineral origin have been in use by man for millennia, it has only been in the last 50 years that the development of synthetic resins have accelerated to a point where there is now a bewildering array of adhesives available, many of sufficient potential strength to be labelled ‘structural’, compatible with almost all possible adherents. Choosing the right adhesive depends on chemical, design and fabrication considerations grafted onto a basic understanding of the nature of adhesion itself.

Bonding depends for its success on the forces which exist at the molecular level between the adherent and adhesive and within the adhesive itself. It follows that to achieve a successful bond requires that:

1. a) the molecules of the adhesive come into intimate contact with those in the surface of the adherent

2. b) this adhesive contact is not lost for any reason over time

3. c) the cohesive strength of the adhesive material is adequate to sustain the mechanical strains imposed on the joint. This should include not only consideration of static and dynamic loading but also temperature and creep properties