Effects of internal kinetic energy in the statistical theory of rubber elasticity

Abstract Conformations of statistical segment chains, that is, the set of segment orientations realized at a distance from the chain ends, as well as the kinetic energy of segments, are involved in the statistical model of the polymer chain system. Using this model, a plateau-like effect, called softening of the deformed rubber, occurs on the curve of the dependence of the tension force of the rubber sample on its elongation. This effect is not predicted based on a statistical model where only the orientations of the segments are considered. For further deformation a fast increase of that curve is observed. Both effects result from considering the kinetic energy of the chain segments.