Effect of Temperature–Humidity Control During Pre‐Drying on Properties of Single‐Base Gun Propellant and Solvent‐Removal Kinetics

ABSTRACT Solvent removal is a critical step in manufacturing single‐base gun propellants. Temperature–humidity control during pre‐drying strongly governs solvent‐removal efficiency and affects product performance. Here, we investigate the coupled effects of temperature and relative humidity (RH) on pre‐drying kinetics, microstructure, and performance, with a focus on process optimization. A two‐factor, three‐level full‐factorial design was used to conduct convective hot‐air drying experiments under various temperature and humidity conditions. The residual solvent content within the propellant particles was measured using gas chromatography and gravimetric methods. Data analysis was performed using nonlinear least squares regression combined with five classical semi‐empirical kinetic models. The effective diffusion coefficients and drying activation energies were calculated using the slope method. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were employed to investigate the impact of different pre‐drying conditions on the thermal stability of the samples, while the impact strength was evaluated using a drop weight impact tester. The results revealed that the optimal pre‐drying conditions for single‐base gun propellants were 35°C and 85% relative humidity. Under these conditions, the sample exhibited a moderate drying rate in the early stage, with an effective diffusion coefficient of 1.35 × 10 − 1 1 m 2 ·s − 1 and a low residual solvent content of 3.05%. Additionally, the sample preserved an open and connected mesoporous network without surface crusting and maintained thermal stability and mechanical strength, yielding the best overall drying performance. This study provides basic theoretical and experimental support for optimizing the solvent removal process and enhancing the quality and consistency of single‐base gun propellants.