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• CNC with similar molecular structure and composition to NC can be used in propellant. • Civilian nitrocellulose can further plasticize high-nitrogen nitrocellulose. • The thermal stability of CNC based-propellant was enhanced and presented stable combustion behavior. Developing binders for propellants with balanced mechanical and energy properties is important and challenging. Herein, high-viscosity civilian nitrocotton (CNC) was used as reinforcing binder to prepare CNC-based propellant by solvent method. The influence of viscosity and content of CNC on mechanical properties, thermal stability, and combustion performance of propellants was investigated. The plasticizing process of nitrocellulose fibers can be well described by swelling mass changes and has a strong correlation with mechanical properties. The impact test combined with morphology observation by scanning electron microscope (SEM) and evaluation about matrix, fiber, and structure systems revealed that the subsidiary plasticizing mechanism of CNC and the homogeneous system of CNC-based propellant play the dominant role in enhancement of macroscopic mechanical properties. Besides, the structure of propellant was investigated using FTIR, XRD, and Raman, which indicated that propellant containing CNC exerting similar structure with NC-based propellant. Moreover, the analysis of thermal decomposition kinetics demonstrated that the introduction of CNC could further enhance the thermal stability of propellant, like the increased activation energy. Finally, the study of combustion performance demonstrated that CNC-based propellant can burn steadily, and energy out-put was further enhanced as compared with NC propellant. Therefore, this design and adjustment for the introduction of CNC in propellant could provide fundamental theory and data support for the development of CNC in propellants. [ABSTRACT FROM AUTHOR]

[Display omitted] • A high-energy & high-strength NQ propellant was obtained by integrated of reinforcement nanofiller CNFs. • NQ propellant molecular model was pioneered constructed and its structural–functional relationship was studied as well. • Thermal decomposition dynamics of NQ propellant modified by CNFs was synthetically studied by liner fitting and iso -conversional methods. • An impressive enhancement mechanism was proposal deeply to explain the evident increased mechanical strength of NQ propellant with CNFs. High-energy propellant always encounters deficient mechanical properties and unstable combustion behavior under low temperature, leading to difficulties in subsequent use. Herein, the reinforcement filler carbon nanofibers (CNFs) were pioneered introduced into nitroguanidine propulsion, meanwhile, the molecular model and structure–function relationship of high-solid content propellant system was constructed. A sequence of characterizations manifested that CNFs were integrated well in propulsion system. The result of mechanical properties demonstrated that anti-impact strength increased with the increase content of CNFs in propellant, and a proper content range from 0.25 % to 1.0 % exerted better mechanical strength than that of high content under different temperature conditions. A "wire-tie" structure acting bridging effect that exhibit buffer exoenergic effect in terms of the enhancement mechanism was proposal as well, combing the theoretical calculated interaction of nitroguanidine (NQ) and nitrocellulose/nitroglycerin (NC/NG). Additionally, the analysis of thermal decomposition kinetic of propellant by conventional iso -conversional rate methods demonstrated that the addition of CNFs can could furtherly reduce the activation energy of NQ-GP, which is accord with the result of linear fitting methods. It also demonstrated that the thermal decomposition behavior of propellant was influenced by different high-pressure conditions and CNFs content, including T p and heat-release. Additionally, propellant integrated with CNFs burning steadily under different temperatures, and the burning rate coefficient and burning pressure exponent of propellant could be also flexible tuned with proper content of CNFs. Hence, the presented study highly broadens the application scope of reinforcement nanofiller, and will be potential of value to the community development in high-energy and high strength gun propulsion in aspect of combining experimental and theoretical calculation. [ABSTRACT FROM AUTHOR]

In the domain of energetic materials (EMs), the high-energy and high-strength propellants are always what are the scientists pursuing to satisfy the great demands of fast development and replacement for artillery. Recently, the emerging of cellulose nanofibers (CNFs) has attracted great interests since its extraordinary performances like biocompatibility, carbon-neutral nature, tailorable surface chemistry, and unprecedented mechanical properties. Inspired by the fascinating high strengthen of CNFs, this study prepared a kind of energetic hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX)@CNFs composites firstly, and then applied them in conventional double-based gun propellant (GP) to study its energy, combustion and mechanical, and sensitivity performances. The results of the mechanical properties demonstrated that the impact strength of RDX@CNFs-GP with different content of CNFs was improved by 34.9-104.7%, 7.1-39.4%, 14.4-51.2% under the condition of low, room and high temperature, the compression strength was improved by 8.6-49.5%, 4.3-45.9%, 6.2-47.8%, while the tensile strength was improved by 0.6-21.2%, 7.0-19.5%, 9.0-26.0%, respectively. Moreover, the impact and electrostatic spark sensitivities have also been increased by 21.8% and 61.8% in terms of the maximum value and exert favorable desensitization effect compared with blank sample. Notably, the propellant added with CNFs could burn steadily without anomalous combustion behavior, and the energy level of the RDX@CNFs-2.0%-GP (1180.70 J/g) maintain relative close value to that of RDX@CNFs-0%-GP (1184.84 J/g) with regard to the gunpowder impetus. Lastly, the enhancement mechanism of the CNFs in GP was discussed and proposal. Hence, this present work could potentially provide fundamental theory and data support for the development of CNFs in high-strength and high energy propellants. [ABSTRACT FROM AUTHOR]