Mechanical reinforcement of polymer nanocomposites at large deformation: new insights from small-angle neutron scattering and rheology*

Incorporation of nanoparticles (NPs) into polymer matrices can significantly improve the mechanical performance of polymer nanocomposites (PNCs). Despite the wide recognition of the nano-reinforcement effect in PNCs, the molecular origin of this phenomenon remains largely elusive. Although molecular overstraining or strain amplification has often been invoked to explain the modulus enhancement of PNCs, a rigorous examination of the presence of molecular overstraining is still missing. In this contribution, we quantify the structural anisotropy of the PNCs at deformation through small-angle neutron scattering (SANS). While molecular deformation of the matrix polymer dominates the stress of PNCs, quantitative analyses of SANS spectra reveal no enhanced structural anisotropy in the PNCs compared with the pristine polymers under the same deformation conditions. These detailed mechanisms of the lack of molecular overstraining will be discussed in the talk.