Chemical compatibility of energetic metal complexes with polymers by thermal analytical techniques

Energetic metal complexes have been established to be effective combustion catalyst for energetic composites and propellants with improved performance. Chemical compatibility is an important aspect in the development of novel energetic composites which are related to safe processing, handling, and storage. In the present paper, the compatibility of energetic metal complexes [Zn(atrz)(DNBA)₂(H₂O)₂]_n (complex 1) and [Cd(atrz)(DNBA)₂(H₂O)₂]_n (complex 2) with Viton A and epoxy resin as polymer binder are studied by thermal analytical techniques. The compatibility was studied through vacuum stability test (VST), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) according to standardization agreement (STANAG) 4147 method. Furthermore, physicochemical methods including powder X-ray diffraction (PXRD) and Fourier transform infrared spectroscopy (FTIR) are used to support the thermal analytical methods. The VST results indicate that the volume of gases evolved for complex 1/Viton A, complex 1/epoxy resin, complex 2/Viton A, and complex 2/epoxy resin is found to be 0.545 mL/g, 0.86 mL/g, 0.403 mL/g, and 0.884 mL/g, respectively, indicating high compatibility with one another. According to the STANAG 4147 criteria, the DSC/DTG data demonstrate that the difference in T_max is less than 2 °C for all the admixtures, suggesting that the polymer binders under investigation are compatible with complexes. TG results demonstrate that the mass loss difference is less than 4 % for all admixtures, indicating good compatibility. The essential additional information offered by the supplementary non-thermal FTIR and PXRD techniques confirm that no reaction occurs between metal complex and polymer. SEM micrographs exhibit that metal complex crystals are embedded in the polymer matrix.