title: Size Determination of Porosity Inclusions in an Organic Solid Material by (1)H NMR Diffusion and SEM-FIB Experiments: The TATB Case.
abstract: An original approach has been presented to characterize the local geometry of pores containing protonated small molecule impurities in organic materials. It was here applied in TATB (1,3,5-triamino-2,4,6-trinitrobenzene) powder material to investigate the porosity able to enclose water molecules. The presence of such defects may have a significant impact on TATB-based compositions mechanical properties, efficiency, and shock sensitivity. Apparent self-diffusion coefficients measured on the low water signal residue were consistent with highly mobile species experiencing restricted diffusion in confined porosities. Applying the methodology commonly used for the characterization of porous systems, we could demonstrate for the first time that pores, with an average size in the 3-5 μm range, were already present in the native TATB powder before any formulation and that these pores were closed and filled with water/NH4Cl solutions. The presence of such macrocavities was further confirmed by analyzing the TATB 3D porous structure using the SEM-FIB dual-beam technique at the scale of particle fractions. Calculation of the pore volumes was performed to deduce pore size distributions assuming spherical cavities. A volume-weighted average size was calculated showing a satisfactory agreement with NMR results and a suitable complementarity of the two approaches.
authors.affiliation: CEA DAM le Ripault, F-37260 Monts, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Palmas
authors.affiliation: CEA DAM le Ripault, F-37260 Monts, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Botzanowski
authors.affiliation: CEA DAM le Ripault, F-37260 Monts, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Guerain
authors.affiliation: CEA DAM le Ripault, F-37260 Monts, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Forzy
authors.affiliation: CEA DAM le Ripault, F-37260 Monts, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Bruneton
authors.affiliation: CEA DAM le Ripault, F-37260 Monts, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Delrio