Binder and Interphase Microstructure in a Composite Material Characterized by Scanning Electron Microscopy and NMR Spin Diffusion Experiments

1H NMR spin diffusion is shown to advantageously complement scanning electron microscopy (SEM) observations for the characterization of polymer structuring in composite materials. It is here demonstrated on a material containing a few percent of polymer binder and a crystalline organic/inorganic mixture as reinforcement. In SEM observations, polymer accumulations are seen. However, the polymer is also expected to fill small porosities and thin layers at the interface of particles to ensure the cohesion and the mechanical properties of the assembly. In most cases, this polymer structuring is invisible considering the resolution and contrast achieved by SEM on such material. It is thus investigated taking advantage of the two‐step decay of nuclear magnetic resonance spin diffusion curves. Average thickness values of 30 and 188 nm are estimated for the interphase and the overall polymer, respectively. Such structural information improves the knowledge of structure/property relationships and provides better understanding of material properties and making processes. The structuring of the binder in a polymer‐based composite is addressed by nuclear magnetic resonance spin diffusion to complement SEM observations. A particular interest is given to the second decay of the diffusion curve, which turns out to characterize the interphase between binder and reinforcement.