The temperature dependence of network forces in rubber‐like materials

Abstract

AbstractIn the simplest model of rubber‐like materials only two kinds of forces are assumed: network forces with identical temperature dependence, and liquid forces which. are isotropic. For this simple model the relation between the temperature dependence of the network forces and that of the observed elastic force is calculated. When the elastic equation of the network is of the classical one term type, the well‐known equation of Flory, Ciferri and Hoeve is found without using assumptions about the physical meaning of the front factor in the elastic equation. When the elastic equation of the network is of the Mooney‐Rivlin type with two terms, the difference between the temperature dependence of the observed forces and of the network forces is found to depend on the ratio of the coefficients in the Mooney‐Rivlin equation and on the elongation. The effect of the internal pressure is to add a factor to this term. The conclusion is that detailed knowledge about the network forces is needed in order to establish the value of the correction term for thermal expansion in the equation for the temperature dependence of the elastic force in the material.