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Research on the hygroscopic behavior of NC is essential because it affects the mechanical properties, combustion properties, and safe storage of NC‐based products. In this study, Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and scanning electron microscopy (SEM) are used to characterize the chemical structure, crystal structure, and microscopic morphology of NC, respectively. The moisture adsorption isotherms of NC fibers with different nitrogen content are determined by dynamic vapor sorption (DVS) and fitted with Hailwood‐Horrobin (H−H) and Guggenheim‐Anderson‐de Boer (GAB) models. The specific surface area and surface energy of NC are also measured by inverse gas chromatography (IGC). The results show that as the nitrogen content of NC increases, the intensity of the −OH characteristic absorption peak is weakened, the crystallinity does not change much, the number of cracks and pores on the NC fiber surface increases, and the equilibrium moisture content (EMC) of the NC decreases in general. In addition, the fitting results based on the H−H and GAB models show that, under low humidity conditions, the EMC value of NC is determined by the adsorbed water content of the monolayer, which is mainly related to the −OH content in NC. However, with the increase of humidity, the EMC value of NC is gradually determined by the multilayer adsorbed water content, which is influenced by both the nitrogen content and the fiber cleavage structure. Meanwhile, the IGC results show that the surface energy of the NC consists mainly of the dispersive surface energy (values >46 mJ m−2), with the specific surface energy contributing approximately 25 mJ m−2. The total surface energy of NC and the bonding strength between NC molecules and water molecules decrease with increasing nitrogen content. [ABSTRACT FROM AUTHOR]

In order to study the numerical variation law of the internal ballistic overload of the guided projectile under different coated mixed charge structures, and to provide a basis for the development of a new type of high muzzle velocity and low overload propellant charge design, taking a large-caliber suppressed artillery as the simulation object, the layered combustion model of the coated propellant was established by using the one-dimensional two-phase flow theory, and the lace 37-hole nitroguanidine propellant was used as the main charge (MC) and lace 19-hole nitroguanidine coated propellant as auxiliary charge (B). The effects of mixed charges with different charge mass, different mixing ratios and different coating layer thicknesses on the internal ballistic overload value were studied by simulation calculation. The research results show that the increase of the total charge mass will increase the overload impact of the guided projectile and the muzzle velocity of the projectile ; with the increase of the thickness of the coating layer and the proportion of the coated propellant in the mixed charge ratios, the longitudinal overload and the muzzle velocity of the projectile in the chamber of the guided projectile will be decreased to a certain extent and the time point when the maximum overload occurs will be delayed; under the structure of the coated mixed charge, the influence of the proportion of coated propellant in different mixed charge ratios and the coating layer thickness of coated propellant on the launch overload of the guided projectile is greater than the muzzle velocity of the projectile, and the effect of reducing the firing overload in the chamber by increasing the proportion of coated propellant in different mixed charge ratios is the most significant.