Comparison of the structural and physical properties of nitrocellulose plasticized by N-butyl-N-(2-nitroxy-ethyl)...

We performed experimental studies on the effects of N-butyl-N-(2-nitroxy-ethyl) nitramine (Bu-NENA) and nitroglycerin (NG) on the plasticization of nitrocellulose (NC). The tensile strength and elongation at break of NC/Bu-NENA measured at -40 °C show increments of about 23% and 33% respectively, compared with those of NC/NG, suggesting that Bu-NENA has a higher plasticizing efficiency than NG. Scanning electron microscope (SEM) observation reveals that NC shows better miscibility with Bu-NENA than NG, which was further evidenced by the mesoscopic morphologies derived from mesodynamics simulations. Furthermore, molecular dynamic simulations were conducted to explore the mechanical strengthening mechanism of plasticizers. The simulation results such as free volume (Vfree), binding energy (Ebind) and radial distribution function (RDF) were obtained. NC/Bu-NENA shows a 28% improvement in Vfree compared to NC/NG, suggesting that Bu-NENA molecules demonstrate higher mobility in NC matrix. The larger Ebind of NC/Bu-NENA than NC/NG indicates the stronger interaction between NC and Bu-NENA. Furthermore, g(r) values correlated to the atom pair interaction determined from RDF curves reveal that NC/Bu-NENA shows higher intensities of both hydrogen bond and van der waal force than those of NC/NG blend. These computational and experimental studies reveal great potential in design and fabricating low vulnerable insensitive propellants.