Enhancing energetic features of HTPB binder through nitro-functionalization and nitrocellulose doping

This study presents a double modification strategy to enhance hydroxyl‑terminated polybutadiene (HTPB) properties as an energetic binder. HTPB was chemically nitrated to obtain nitro-HTPB (NHTPB), then blended with nitrocellulose (NC) at different ratios of 10%, 30%, and 50%. The morphological evaluation revealed a uniform NC dispersion within a smooth binder surface. Fourier-transform infrared spectroscopy confirmed successful nitration and homogeneous NC incorporation. As the NC content increases, the enhancement in density, thermal stability, and combustion behavior becomes more pronounced for which the best performance is observed at 50% NC—where NHTPB density increased by approximately 46.72% compared to the pure HTPB. Differential scanning calorimetry analysis revealed a 28 °C shift to higher temperatures for the glass transition, while the thermogravimetric Analysis indicated a lower onset decomposition temperature, accompanied by a 13% reduction in residual mass. Kinetic analysis, performed using an isoconversional method, showed a 19.52% and 30.05% decrease in activation energy for the first and second decomposition stages, respectively, compared to pure HTPB. This reduction is attributed to the catalytic effect of nitrate groups, although the effect diminished slightly with increasing NC content. The impact and friction sensitivity tests confirm that 30% of the NC doping level provides the optimal compromise between safety, handling, storage, and energetic performance for effective propellant applications.