Molecular Motion in Viscous DGEBA with Nanoparticles as Seen by Quasi-Elastic Neutron Scattering

Pure and filled epoxies are widely used in industry. Nanocomposites especially are affected by interphase regions where properties deviate from bulk. The study of molecular mobility in epoxy monomers is a first step to understanding the molecular dynamics in nanocomposites and their effect on crosslinking in epoxy networks. Here, quasi-elastic neutron scattering is used to disentangle the molecular motions of monomeric diglycidylether of Bisphenol A (DGEBA) and a suspension of zeolite nanoparticles in DGEBA on a timescale from 2 ps to 5.5 ns. Regarding molecular transport of DGEBA inside the suspension, the particles have no impact on the faster rotational motions. A combination of neutron time-of-flight and backscattering spectroscopy reveals a pronounced hindrance of DGEBA molecular dynamics on/in the zeolite particles along with a new type of molecular motion occurring on intermediate timescales. That localized motion is attributed to jump diffusion motions, emanating from interphase effects at the zeolite particles.