Biological treatment of nitrocellulose: investigation on structural and thermodynamic properties

Abstract Biological method is a sustainable method for various waste polymers treatment due to green, low-cost, mild condition and simple operation. In this study, a novel biological method to process nitrocellulose (NC) to obtain NC with low nitrogen via nitrate ester removal using fungal Chaetomium elatum was proposed. With the extension of time (6 d), the N% of NC declined continuously from 13.06% to 11.71%. Structure properties were investigated by Fourier-transform infrared spectroscopy (FTIR), and Laser Raman co-focal microspectrometry (Raman), which showed the intensity of energetical groups (O-NO2, -NO2) decreased. Most importantly, the thermal decomposition properties were performed using Thermogravimetric analysis (TG) and Differential scanning calorimetry (DSC) analysis, where the kinetic parameters of thermal decomposition reaction with DSC were calculated by three traditional methods: Friedman-Reich-Levi, Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose. It indicated that the weight-loss ratio of bio-treated NC decreased from 86.33% to 66.20% and the activation energy (Ea) increased first and then reduced as the increase of denitrification time, which demonstrating thermostability of bio-treated NC was enhanced. Hence, this structure exploration and thermodynamic analysis provide new method for further investigation of the mechanism of the biological denitrification process and the assessment safety of bio-treated NC.