TYPES OF POTTING COMPOUNDS 

2-9.1 TYPES OF POTTING COMPOUNDS 

There are three major types of potting compounds: epoxy resin formulations, polyurethane formulations, and room temperature vulcanizing (RTV) silicone rubber compounds; also some less frequently used types, such as polystyrene and unsaturated polyester formulations. There are literally hundreds, and perhaps thousands, of possible formulations of potting compounds commercially available with a resulting wide range of physical, thermal, and electrical properties. Table 2-6, which lists properties of some typical potting compounds, should be utilized therefore only in a very general way, particularly in the case of the epoxy resin compounds. It is usually a relatively simple matter to select a potting compound having the required thermal and electrical properties for a potting application. The major problems involved in achieving a satisfactory potted connection are those which can be classified as problems of adhesion. The problems can be narrowed even further by considering that adhesion to the metallic components of the connection are relatively easily resolved, thus leaving the adhesive bonds between the potting compound and wire or cable insulation orjacket materials as the most critical. 

2-9.2 POTTING - DESIGN CRITERIA Some suggestions which should be considered in the design of potted wire and cable terminations are the following: 2—9.2.1 Surface Preparation a. Rely upon the advice of the potting compound supplier with regard to surface preparation and priming. 

b. In the case of bonding TFE or FEP, either sodium-etch the area to be bonded or use wires having a bondable coating. c. In the case of polyethylene, some method of oxidizing the surface is usually required. The simplest method is that of "flame-treating". d. Once having prepared the surfaces to be bonded, keep them clean. 

source : https://apps.dtic.mil/sti/tr/pdf/AD0865109.pdf