Correlation between characteristics of thermal and stress reversible deformations in solids with different structures

Abstract

The dependences of the coefficients of reversible thermal expansion on the tensile stress and the temperature dependences of the elastic modulus are measured for solids with different structures, such as a metal, rigid-chain oriented polymers, and a flexible-chain oriented polymer-poly(ethylene) in the devitrified state. For these materials, the elastic moduli differ by several orders of magnitude, whereas the thermal expansion coefficients can differ not only in magnitude but also in sign. It is found that, for a solid, the derivative of the thermal expansion coefficient with respect to the stress is close to the derivative of the reciprocal of the elastic modulus with respect to the temperature. The inference is made that these parameters do not depend on the specific features of the solids under investigation. Calculations are performed for several mechanisms of thermal and stress deformations of solids with different structures. The results of these calculations are in reasonable agreement with experimental data.