Synthesis of cellulose nitrates from Miscanthus × giganteus var. KAMIS cellulose obtained under pilot production conditions

Abstract

The work is devoted to the study of a novel national raw material resource Miscanthus × Giganteus var. KAMIS, which is positioned as one of the most promising natural sources for obtaining high-quality cellulose for the purpose of its further chemical functionalisation. A batch of technical cellulose isolated from raw materials under pilot production conditions using the nitric acid method having a cellulose content of 50.2% was characterized by high α-cellulose mass fraction (92.8%) and degree of polymerisation (1200) values. On the basis of the pilot batch of technical cellulose, a sample of cellulose nitrates offering basic functional properties was obtained: mass fraction of nitrogen – 11.18%; viscosity – 48 MPa·s; solubility – 94%. The synthesised sample is characterized by extremely high solubility in acetone, confirming the production of cellulose nitric acid esters, and a high yield of 150%. IR-Fourier spectroscopy was used to identify the main functional groups in the experimental batch of technical cellulose (3384, 2902, 1639, 1428, 1370, 1319, 1161, 700–500 cm-1) and in a sample of cellulose nitrates (1659, 1278, 834, 746, 683 cm-1). Acorresponding affiliation to cellulose and cellulose nitric acid esters was established. The structural and morphological features of the fibres of the experimental batch of technical cellulose and a sample of cellulose nitrates were characterised using scanning electron microscopy. Combined methods of thermogravimetric and differential thermal analyses were used to establish high initial temperature (197 °C) and specific heat of decomposition (6.92 kJ/g) values at the beginning of intensive decomposition. The obtained results substantiate the possibility to chemically functionalise cellulose isolated from a new alternative source into cellulose nitric acid esters with satisfactory functional properties.