Unveiling the thermal kinetics and scissoring mechanism of neolatry polyethylene/reduced graphite oxide nanocomposites

Abstract

The present study focuses on thermal degradation mechanism of low density polyethylene (LDPE)/reduced graphite oxide (rGO) nanocomposites prepared by solvent cast method with an implication of its kinetics modelling. Graphite oxide (GO) was reduced under solvothermal conditions, using sodium borohydride and 0.1, 1.0, 3.0 and 5.0wt% of rGO was incorporated into LDPE. Thermogravimetric analysis (TGA) was used to determine the decomposition kinetics of the nanocomposites at different heating rates of 1, 5, 10 and 20°C/min. The maximum activation energy (Ea) calculated using Kissinger (K) and Flynn-Wall-Ozawa (FWO) models were noted to be 321.80 and 335.01kJ/mol respectively at nanocomposite with 3wt% rGO content. Also, the correlation coefficient (r2) in FWO models was higher than 0.95, confirming a single-step decomposition in the nanocomposites. TGA coupled with gas chromatography (GC) and mass spectroscopy (MS) was employed to separate the evolved compounds into alkane, alkene and aromatic groups. Interestingly, pravastatin, a useful gaseous compound was detected at 370°C and other toxic gases were evolved at degradation temperature ∼460°C and above. Our findings on kinetics behaviour and degradation mechanism emphasize on the thermal cracking characteristic of the LDPE/rGO nanocomposites, which can be utilized to extract useful gaseous components for pharmaceutical application.