The incorporation of nanoparticles (NPs) into polymer matrices can significantly improve the mechanical performance of polymer nanocomposites (PNCs), whose origin remains largely elusive. Molecular overstraining or strain amplification has been invoked in the past to explain the modulus enhancement of PNCs. However, both the presence and the absence of molecular overstraining have been reported in PNCs, leaving the origin of the high mechanical strength of PNCs highly controversial. In this contribution, we quantify the molecular anisotropy of deformed PNCs through a combination of small-angle neutron scattering (SANS) and rheology. Our results show clearly that molecular deformation of the matrix polymer dominates the stress of PNCs, while no enhanced structural anisotropy has been found. We will discuss the detailed mechanisms of the mechanical reinforcement and the origin of the lack of molecular overstraining in the talk.

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

ACS Spring Meeting 2021

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