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

Abstract

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.

Molecular Mechanism of Surface Melting of Polyamide12 as Elucidated by Synchrotron Radiation X-ray Scattering and 1H Spin Diffusion NMR

“…Limited by the spin–lattice relaxation time T 1 , the equilibrium state is not always possible with the long t m value, generally less than 1s for semicrystalline polymers. , It is thus convenient to use t normalm s , 0 , the intercept of the first slope with the x axis, using the equivalence between the ratio t m s t m bolds , bold0 and the volume fraction of the sink phase φ . In our experiment, the sink phase is the dispersed rigid component.…”

“…57,64 It is thus convenient to use t m s,0 , the intercept of the first slope with the x axis, using the equivalence between the ratio and the volume fraction of the sink phase φ. 59 In our experiment, the sink phase is the dispersed rigid component. Note that eqs 11 and 12 cannot independently calculate the size of RAF.…”

The irreversible thermal expansion of an energetic material

“…The microstructure is highly idealized, in the form of TATB grains and a uniform thickness of binder layers as well. The presence of reduced molecular mobility binder layers in the vicinity of TATB grain surfaces is likely, although the recent work of Parisse et al (2019) suggests that their thickness might be small with respect to binder layer thickness. Moreover, the temperature dependence of the yield stress was considered as the most prominent feature of the binder behavior, such that thermal expansion and strain rate and pressure dependence of the yield stress have been neglected.…”