Wood and Paper Science & Technology Department, Faculty of Natural Resources, University of Tehran, Karaj, I.R. IRAN
Interest in research and development as well as utilization of Cellulose NanoFiber (CNF) has increased drastically over last decades. Therefore, surface chemical modification and improvement of CNF properties can open up new applications with giving new property while keeping its inherent properties. In this research, in order to enhance thermal stability of CNF cyanoethylation was carried out by acrylonitrile grafting at 60°C under alkaline condition. Degree of Substitution (DS) of cyanoethylated samples was calculated after determination of nitrogen content by Kjeldahl method. Moreover, the chemical structure of modified CNF was characterized with FT-IR spectroscopy and X-Ray Diffraction (XRD) pattern analyses. Thermal stability of modified CNF was then assessed by ThermoGravimetric Analysis (TGA) at three heating rate of 10ºC/min, 15ºC/min, and 20ºC/min under nitrogen atmosphere. Differential ThermoGravimetry (DTG) curves were plotted using TGA data and activation energies were calculated from experimental data. Results of nitrogen content measurements demonstrated DS=0.87 achievement. In addition, cyanoethylation of CNF was confirmed by FT-IR spectra analyses in comparison with control samples and detection of absorption band at 2250 cm-1 which is attributed to nitrile groups. Decrease in CNF crystalinity due to cyanoethylation was demonstrated by XRD analyses. Results of TGA also indicated high thermal stability of cyanoethylated CNF in comparison with unmodified CNF. Moreover, thermal decomposition of both untreated and cyanoethylated CNF occurred in one stage and increased with increasing heating rate. Also low activation energy was observed in cyanoethylated CNF than unmodified CNF. It seems that grafting of acrylonitrile to CNF can increase its utilization in special applications due to improving thermal stability and giving thermoplasticity because of playing role as internal plasticizer.