We performed dynamic mechanical analysis (DMA) on nitrocellulose (NC) plasticized by an insensitive plasticizer N-butyl-N-(2-nitroxy-ethyl)nitramine (Bu-NENA). NC/Bu-NENA blend shows two mechanical relaxation processes in the temperature ranges of − 50 to − 40 °C and 30 ~ 40 °C, and their variations with deformation frequencies were studied. To explore further the effect of temperature on relaxation, the binary mixture model of NC/Bu-NENA was constructed, and molecular dynamic simulations were conducted. The simulated mean square displacements (MSD) show abrupt increase in the temperature range of − 50 to − 40 °C and 30 ~ 40 °C, which are consistent with those of the two relaxation processes observed in the DMA curves. Moreover, the free volume (V_free) and torsion energy obtained from molecular dynamic simulations exhibit distinct increase at the temperature above 30 °C and − 50 °C respectively, reflecting the sudden enhancements on the mobility of polymer chain elements and the rotation of molecular bonds. Furthermore, the radial distribution function (RDF) associated with the intermolecular interactions reveals that the intensities of both hydrogen bond and van der Waals forces decrease with the increase of temperature, which is responsible for the decrease of storage modulus at high temperature. These computational and experimental studies reveal guidance to strengthening the NC base propellants in broad temperature range.

我们对由不敏感的增塑剂 N-丁基-N-(2-nitrooxy-ethyl)nitroamine (Bu-NENA) 增塑的硝化纤维素 (NC) 进行了动态力学分析 (DMA)。NC/Bu-NENA 共混物在 - 50 至 - 40 °C 和 30 ~ 40 °C 的温度范围内显示出两种机械松弛过程，并研究了它们随变形频率的变化。为了进一步探索温度对弛豫的影响，构建了NC/Bu-NENA的二元混合模型，并进行了分子动力学模拟。模拟的均方位移 (MSD) 在 - 50 至 - 40 °C 和 30 ~ 40 °C 的温度范围内显示突然增加，这与 DMA 曲线中观察到的两个弛豫过程一致。此外，自由体积（V _free) 和从分子动力学模拟中获得的扭转能分别在高于 30 °C 和 - 50 °C 的温度下表现出明显的增加，反映了聚合物链元素的流动性和分子键的旋转的突然增强。此外，与分子间相互作用相关的径向分布函数（RDF）表明氢键和范德华力的强度都随着温度的升高而降低，这是高温下储能模量降低的原因。这些计算和实验研究揭示了在宽温度范围内加强 NC 基础推进剂的指导。