RUBBER ELASTICITY AND INHOMOGENEITIES IN CROSS-LINK DENSITY

This paper discusses the effects of network defects, such as weak inhomogeneities in the cross-link density. The appearance of inhomogeneities of the cross-link density in space during rubber fabrication is an obvious problem. We ask the question what is the effect of such inhomogeneities on the free energy of the sample, i.e. the mechanical stress-strain relation (this contains macroscopic information), and on the neutron scattering form factor, i.e. the microscopic information. We show there is only a marginal effect on the free energy of the sample. Essentially there is no change in the deformation dependence and in the modulus of the free energy. We predict a strong effect on the neutron scattering of a given inhomogeneous sample.