The Joule Effect

Abstract

Abstract With reference to a paper by Gleichentheil and Neumann on “The Gough-Joule Effect in Vulcanizates,” we should like to call attention to the similarity between the results reported in their paper and the earlier work reported by Wiegand and Snyder entitled “The Rubber Pendulum, the Joule Effect and the Dynamic Stress-Strain Curve.” The latter authors analyzed from a thermodynamic point of view the rubber stress-strain curve as affected by temperature. As a result of this analysis the stress-strain curve was divided into three groups, Region A, Region B and Region C. Each region was characterized by different trends as regards the Joule effect and internal energy changes. The following description is taken from the original paper: “Region A, The Steel Spring.—This region, extending to approximately 300 per cent elongation for the conditions in the experiments described, is characterized by the comparative absence of heat transfers . … little or no Joule effect.” “Region B, The Gas (and the Crystal).—In region B the region of the Joule effect . … there is the maximum of heat evolution. It should be noted that Region B extends from approximately 300 per cent elongation to 700 per cent elongation. “Region C, The Friction Member.—This region is characterized by the almost entire absence of reversible effects. The Joule effect has disappeared. There is no evolution of heat….“