Structure and Properties of Chain Branched Nitrocellulose

Nitrocellulose (NC) with a semi-rigid polymer chain is one of the typical traditional cellulose derivatives. Optimization of its mechanical properties is of great significance for improving the performance of NC-based propellants. The nitrate glycerol ether cellulose (NGEC) was prepared by introducing glycerol onto the unreacted, free hydroxyl groups on NC through a three-step process (alkalization, etherification, and nitration). The effects of both the nitration process and the degree of etherification on the NGEC nitrogen content were qualitatively explored. By adding NGEC into modified double-base propellant, a standard engine grain with a diameter of 50 mm was produced by adsorption, granulation, and screw extrusion. The heat of explosion, and other physical properties of NGEC were characterized and the variation in mechanical properties and performance after storage for 6 years was investigated. The results indicated that the sensitivity was improved, and the stability was slightly decreased on increasing the nitrogen content of NGEC. Compared with NC containing similar nitrogen levels, NGEC exhibited a slightly higher heat of explosion, similar compatibility, and lower sensitivity. Additionally, the solubility of NGEC in ethanol/ether exceeded 99.7%. Through branched-chain chemical modification, the glycerol ether played a significant role in achieving internal plasticization among the cellulose chains.