Preparation of Nitrocellulose by Homogeneous Esterification of Cellulose Based on Ionic Liquids

The industrial nitrification system of preparing nitrocellulose (NC) adopts nitric and sulfuric mixed acid, which generates a large amount of waste acid and by-products, and requires a laborious procedure for the stability treatment. In this study, a novel method was developed for the preparation of NC. NC with a nitrogen content of 12.62 % was prepared in 15 min by homogeneous esterification of cellulose based on [Bmim]Cl (1-butyl-3-methylimidazolium chloride). The samples were characterized by FT-IR, XRD, Raman, XPS, TG-DSC, GPC, SEM, and elemental analysis. In addition, the activation energy (Ea) was calculated according to the Kissinger method. The burning rate and chemical stability of samples were also tested. The results showed that the NC had 3D honeycomb structure with pores of 200-300 nm diameter, uniform distribution of nitrogen elements, nitrogen content of 12.62 %, and minimum polydispersity index (PDI) of 1.55. The heat of decomposition (Q(dec)) released by the samples was increased by 141 J/g, the Ea decreased by 16.4 %, and the burning rate increased by 40.5 % when compared with commercially available NC12.6%. The chemical stability was very well only after water cooking. Compared with the conventional method, this method doesn't use sulfuric acid, generates less waste acid, and doesn't produce by-products such as sulfate esters. The procedure of stability treatment was also very effortless. The costs could also be reduced by the recycling of ionic liquids.

Automated summary

A novel method was developed for the preparation of nitrocellulose (NC) with a nitrogen content of 12.62% using [Bmim]Cl (1-butyl-3-methylimidazolium chloride) as a catalyst, which only required 15 minutes of reaction time. The samples exhibited a 3D honeycomb structure, uniform distribution of nitrogen elements, and a smaller polydispersity index. Compared with commercially available NC12.6%, the samples showed higher burning rate and better chemical stability.