Development of heating elements based on conductive polymer composites for electrofusion welding of plastics

Conductive polymer composites have been developed based on high-density polyethylene filled with carbon black (HDPE-CB), capable of generating heat when an electric voltage is applied. For each voltage value, the composite reached a constant value of equilibrium temperature, which obeyed a quadratic dependence on voltage and a linear dependence on electric power. The possibility of using such composites as heating elements (HE) for electrofusion welding of polyethylene adherents was evaluated in two modes, ''hard'', when high voltage was applied for a short welding time, and ''soft'', in which a stepwise regime of the applied voltage and a longer welding time were used. The latter provided a stronger welded joint. Using HE based on the HDPE-CB composites for welding of butt and lap joints of the polymer materials enabled to obtain welded joints with high strength.