Abstract
This communication relates to the heating of plastic materials of. a semiconducting nature by passing electricity through them. In particular, it relates to the vulcanization of rubber and rubberlike materials, including Neoprene, with heat generated by the conduction of an electric current and, similarly, it relates to the heat treatment of thermosetting plastics by conduction of an electric current. It is well known that all electrical conductors are heated to some extent by the passage of an electric current. This heating is a direct consequence of internal resistance. The effect so obtained is proportional to the electrical energy absorbed, and is expressed by the equation: power=I2R, in which I is the current in amperes between two points and R is the corresponding resistance in ohms. The unit of power is the watt. Others have used electrical means of heating unvulcanized rubber, but the disclosures differ fundamentally from this proposal. For example, Neerlye coils a steel ribbon and an uncured rubber belt in a spiral and heats the coil by passing electricity through the steel. Newton claims vulcanization by abeam of electrons from a cathode ray tube. The most significant disclosure is by Dufour. This claims the “process for the vulcanization of rubber characterized by the feature that the rubber to be heat-treated is arranged as a dielectric between the electrodes of an electric condenser to which there is applied a high frequency alternating current of a periodicity of several million cycles per second”. This patent is characterized by utilization of high-frequency fields of the order of several megacycles per second. Further, it is not required in induction curing with high-frequency current that the electrodes be in actual mechanical contact with the rubber. Induction curing is facilitated when the material to be heated has both a high power factor and a high dielectric constant, but high electrical conductivity of appreciable amount is not essential to the application of the method.
STUDIES IN HYPERTHERMIA INDUCED BY THE HIGH FREQUENCY ELECTRIC CURRENT
