Hansen Solubility Parameters of Nitrocellulose and Application toward Printable Energetics

While there have been many studies on the use of various solvents for processing nitrocellulose (NC), the optimization of these solvents and/or solvent mixtures has not been studied, particularly for the application of additive manufacturing (AM) of energetic materials. To optimize the printability of NC, Hansen solubility parameters (HSPs) of both 12.2% and 13.4% nitrogen content NCs were assessed via broad-spectrum dispersion testing in 17 solvents (acetone, dimethyl sulfoxide, dimethyl formamide, ethanol, methanol, isopropyl alcohol, m-cresol, toluene, xylene, ethyl acetate, ethyl lactate, diethyl ether, chloroform, acetonitrile, diethylene glycol, formamide, and cyclohexane) and a specific binary solvent gradient dispersion method. From the HSPs, solvents were selected for the dispersion of both 12.2 and 13.4% NCs and subsequent printing of these solutions via direct ink write (DIW). For 12.2% NC and 13.4% NC, successful prints were achieved with a solvent/antisolvent mixture of acetone/isopropyl alcohol (IPA) at 30/70 and 80/20 vol %, respectively. The use of HSPs not only indicate that there are multiple solvent mixtures available for the optimal printability of various grades of NC, but also HSPs may be used for the future processing of NC for various applications.