5.1 Processing of PTFE

There is a distinct difference between the processing methods used for PTFE and those used for the remaining fluoroplastics. The reason for that is the extremely high melt viscosity of PTFE, which does not allow the degree of flow required for the melt processing methods used for most thermoplastics. Thus, depending on the form of the resin, PTFE is processed by different methods. Granular resins are processed by methods that are similar to those used in powder metallurgy or by ram extrusion. Each of these methods requires a specific grade of resin. Fine powders are processed in the form of a paste prepared by mixing the resin with a hydrocarbon lubricant. Aqueous dispersions are processed by methods, such as dipping, coating, impregnation, casting, and so on. The remaining fluoroplastics are essentially processed by melt-processing methods, such as extrusion, injection moulding, film casting, blown film extrusion, and so on. More detailed discussion of individual methods is given in the following sections.