If the evaporative rates of the solvents used are too high due to excessive volatility of the solvent, crazing or blushing often results. In terms of synthesis, cyclohexanol can be oxidized to provide cyclohexanone, which is usually accomplished by the reaction of sodium dichromate and an acid source. This is true because the final joint consists solely of the parent plastic, with no other adhesive or solvent material present. Solvent-cemented joints are less sensitive to thermal cycling than joints bonded with conventional adhesives and are as resistant to degrading environments as the parent plastic. These additions of polymer aid in gap filling, accelerate setting, and reduce shrinkage and internal stresses. Many thermoplastic resins are easier to join effectively by solvent cementing than by conventional adhesive bonding and mixtures of solvents give better results than individual solvents.
After evaporation of the solvent, the resin itself acts as the adhesive. The process involves small amounts of the plastic to be dissolved in the solvents forming bodied cements. In this process, thermoplastics, usually amorphous or low crystallinity, are softened by the application of a suitable solvent, or mixture of solvents, and then pressed together to affect a bond. This process of cementing is the simplest and most economical method of joining thermoplastics.
This chapter provides an account of the process of solvent cementing of plastics.