Energy balance in networks simply elongated at constant temperature

Summary Mechanical and thermal energy exchange in isothermal simple elongation experiments on various rubbers observed by Godovsky can fully be described by means of implicit relations which are defining the thermo-elastic properties of van der Waals networks up to highest elongations. Global and local properties in the molecular networks are shown to be uniquely related thus manifesting indirectly the existence of a Gibbs-function.Symbols f force per unit unstrained area - f_s,f_e entropy- or enthalpy component of the deformational stress - N density of crosslinks - k Boltzmann's constant - T absolute temperature - L₀ fiducial length - <²> actual mean-square end-to-end distance - <₀> mean-square end-to-end distance of the equivalent free chains - () deformation function - D=/ derivative of() - strain parameter - _m maximum strain - a₁,a₂ interaction — van der Waals parameters - linear coefficient of thermal expansion - linear coefficient of compressibility - V₀ volume in the unstrained state of the rubber - h_K⁽ⁱ⁾,s_K⁽ⁱ⁾ specific enthalpy and entropy of the internal freedom (K)