The influence of mechanical properties on the surface tracking of polyester resin

Net tracking and dry arc tests were conducted to evaluate the effect of mechanical properties on the surface tracking of polyester resin. The material chosen for investigation was a clear casting polyester resin, whose mechanical properties could be systematically modified by the progressive plasticization of the material through the addition of controlled amounts of a plasticizing polyester resin. The erosion and tracking resistance of polyester resin appear to be influenced by the mechanical properties of the material. As the tensile strength and fracture toughness of the material are reduced by plasticization, the rate of erosion of material from the surface under dry conditions and the rate of tracking under wet conditions are both increased. These effects may not, however, be as a direct consequence of the mechanical weakening of the material but may come about indirectly as a result of changes in internal strain.<>