8.1 Introduction

A reader who is unfamiliar with surface treatment of materials should begin by first reading Ch. 6 of this book. That chapter teaches the general considerations in the preparation of materials surfaces, including metals and plastics. The present chapter describes the common methods used for the preparation of specific plastic adherends. These procedures provide practical ways to obtain strong, reproducible adhesive bonds that readily fit in commercial processes. To add to the usefulness of this chapter, the authors have made liberal citation of commercial plastics when describing treatment techniques. It is difficult to describe surface preparation methods of specific plastics without identifying them; plastic manufacturers are the most frequent sources of basic preparation methods.

8.2 Thermoplastics

Thermoplastic surfaces, unlike thermosetting materials, ordinarily require physical or chemical modification to achieve acceptable bonding. This is especially true in the case of crystalline thermoplastics such as polyolefins (primarily polyethylene and polypropylene), linear polyesters, and fluoropolymers. Methods used to improve the bonding characteristics of these surfaces are described in Ch. 6.

Surface preparation methods are usually suggested for conventional bonding where an adhesive is applied to the bonding surfaces. Solvent cementing and thermal welding do not require chemical treatment of the plastic surface. As with metallic substrates, the effectiveness of the treatment imparted to plastics surfaces decreases with time. It is, therefore, important to carry out the priming or bonding steps as soon as possible after surface preparation.[1]