SANS OF POLYMER NETWORKS UNDER DEFORMATION

Small Angle Neutron Scattering investigations into the microscopic deformation of chains in uniaxially strained polymer networks are presented. The structure factor S(q) of a single chain inside the network topology is a perfect descriptor to discriminate between current theories of rubber elasticity. The experimental data are succesfully interpreted in terms of a mean-field tube model which describes the confinement of chains due to the chemical crosslinking and chain entanglements by an effective tube which is anisotropic and depends on strain non-affinely as . Different length scales in the rubber are studied and a transition from affine to phantom-like behaviour of chain deformation is found for decreasing lengths of the investigated part of the chain. Applications to block copolymers with different architectures as well to the field of filled elastomers are summarized.