Green synthesis of CuO nanoparticles using Malva sylvestris leaf extract with different copper precursors and their effect on nitrocellulose thermal behavior

Abstract

In this work, we have synthesized copper oxide nanoparticles (CuO NPs) by a precipitation method using leaf extract of Malva sylvestris as a stabilizing agent and three different copper precursors. The obtained CuO NPs have been characterized in detail by X-ray diffraction, ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and scanning electron microscopy. The as-prepared CuO NPs present the same pure chemical composition and belong to a monoclinic crystalline phase, with a spherical shape and crystallite diameter in the range of 19–26 nm, according to their precursors. Based on the differential scanning calorimetry (DSC) analyses performed at different heating rates, the thermal behavior of pure nitrocellulose (NC) and NC-CuO NPs composites has been investigated using four integral isoconversional kinetic methods. The obtained results show that, whatever the precursor, CuO NPs could be safely used as a catalyst for NC. Moreover, the added nanocatalysts could reduce the activation energy and slightly decrease the peak temperature. Finally, the thermal decomposition process of both NC and NC-CuO composites determined with Kissinger–Akahira–Sunose and Flynn–Wall–Ozawa) models, respectively, is classified as R2, contracting cylinder $$g \, \left( \alpha \right) \, = 1 - (1 - \alpha )^{\frac{1}{2}}$$ , whereas that of Trache–Abdelaziz–Siwani integral model is ascribed to F1/3 and F3/4 chemical reaction $$g \, \left( \alpha \right) \, = 1 - (1 - \alpha )^{\frac{2}{3}}$$ .