Theoretical studies on the plasticizing effect of DIANP on NC with various esterification degrees

To investigate the plasticizing effect of DIANP (1,5-diazido-3-nitrazapentane) on NC (nitrocellulose), four NC with different esterification degrees (N% of 7.22 (NC1), 9.50 (NC2), 10.36 (NC3), and 12.04 (NC4)) as well as the binary mixtures DIANP/NC with the mass ratio of 1:3 were constructed and investigated by molecular dynamic (MD) simulations with the COMPASS force field. For comparison, NG (nitroglycerin) and NG/NC mixtures with the mass ratio of 1:3 were also simulated. The miscibility of the mixtures was determined using the solubility parameters. The solubility parameters obtained from the MD simulations were in reasonable agreements with the experimental data. The mechanical properties, i.e. elastic coefficients, modulus, Cauchy pressure, Poisson’s ratio, etc., were predicted and the results show both NG and DIANP can effectively improve the mechanical properties of NC. The higher the temperature is, the better the mechanical properties are. For the NC with higher N%, DIANP has better plasticizing effects than the conventional plasticizer NG, while the situation is on the contrary for the NC with lower N%. The better mechanical properties of DIANP/NC4 are related with the larger binding energy and stronger intermolecular interactions. The hydrogen bonding interactions between NC4 and DIANP mainly come from the interactions between the H1 of NC and the N2 and N5 of DIANP.