(Invited) Novel Fullerene-Based Stabilizer and Its Behavior during Thermal Decomposition of Nitrocellulose

Abstract

Propellants are composed of a large number of high-energy components and used widely in rocket and ammunition[ 1,2]. The interaction between components could lead to deterioration of propellants during long-term storage. The main energy components of propellants, such as nitrocellulose and nitroglycerin, decompose slowly while releasing nitrogen oxides[ 3-5]. Traditional stabilizers, such as diphenylamine (DPA), N,N ’-dimethyl-N,N ’-diphenylurea (C2), and N,N'-Dimethyldiphenylurea (AKⅡ), are added into propellants to restrain the autocatalytic decomposition of nitrocellulose[6,7]. However, these traditional stabilizers are consumed immediately at high-temperature or high-pressure environments that do not satisfy the increasing demands of weapon systems for wide temperature range and strict environmental requirement. Moreover, these stabilizers are not environmentally friendly because of the toxicity of the secondary derivatives[ 8,9]. Therefore, it is important to design a new stabilizer that will not deteriorate even under strict conditions. A novel highly functional fullerene derivative, C60-DBTMP, is successfully designed to obtain high performance stabilizers. The thermal stability of this novel fullerene-based stabilizer is investigated by methyl violet test, vacuum stability test, and constant temperature TG were shown in Table 1. The results indicate that C60-DBTMP has good compatibility with nitrocellulose, and the stability is found to be more superiority than other traditional stabilizers (DPA, C2, AKⅡ). Further thermal analysis showed that C60-DBTMP interact with the decomposition products during the thermal decomposition of nitrocellulose, which changed the decomposition mechanism of nitrocellulose at the initial stage of thermal decomposition from self-accelerating catalytic model to non-autocatalytic reaction model. The stabilization mechanism is also investigated in detail, the electron spin resonance (ESR) test showed that the nitroxide radicals scavenging efficiency of C60-DBTMP is 73.39%, and effectively inhibit the acidity change caused by the thermal decomposition of nitrocellulose, which provided a precondition for the thermal stability of nitrocellulose. The results showed that C60-PhO(PhOMe)4 can react with nitric oxide and nitric due to the conjugate structure of the carbon cage and the electron affinity of substituent is considered. The consumption process of C60-DBTMP is found to follow the pseudo-first-order kinetics. Our study demonstrated the potential application of this highly functionalized fullerene derivative as a stabilizer for nitrocellulose and provided a new strategy for designing high-performance stabilizers.Table 1 The test date of vacuum stability test, isothermal TG and methyl violet test Samples S-1 S-2 S-3 S-4 S-5 Stabilizers — DPA C2 AKⅡ C60-DBTMP The time used for weightloss of 1%/min 7.2914.11 15.60 17.10 18.09 The gas volume per unit mass/mL·g−1 4.67 2.79 1.73 1.65 1.19 Time/min 58 75 95 99 129 Storage for 5 h Non-burning and non-exploding Figure 1. The synthesis of C60-DBTMP, and the interruption and re-scanning curves of (a) S-1 and (b) S-5, (c) α-T of S-1 and S-5, (d) Plots of theoretical and experimental y(α), and the ESR spectra of NO-Fe(DETC)2 in different concentrations of (e) AKⅡ and (f) C60-DBTMP. Acknowledgement This work was supported by the financial support received from the Frontier Innovation Project of Military Commission Science and Technology Commission(project no. 19-163-13-ZT-002-004-04), and the China Academy of Engineering Physics (project no. 18zh0080), and the Project of State Key Laboratory of Environment-friendly Energy Materials, Southwest University of Science and Technology (project no. 19fksy04).