Matrix chain deformation in reinforced networks: a SANS approach

A small-angle neutron scattering (SANS) investigation of matrix chain defor mation in an especially designed composite model system fora filled rubber- elastic network is presented. SANS experiments on the structure of polyisop rene homopolymer chains introduced into a well-microphase-separated tribloc k polyisoprene-polystyrene-polyisoprene (PI-PS-PI) system of the ABA type a re reported. Use is made of the phase- and composition-matching techniques. The data are described in terms of the scattering behavior of the correspo nding pure polyisoprene network at larger microscopic than macroscopic stra ins. The results confirm the model for the strain enhancement in reinforced networks and give the first direct microscopic insights into the mechanism s of reinforcement. A complementary small-angle X-ray scattering (SAXS) stu dy yields all relevant geometrical parameters of the model filler and its d etailed behavior under strain.