Impact of quercetin concentration on the thermal stability of ultra high molecular weight polyethylene: a thermogravimetric study

The impact of quercetin concentration (0.1–1.0 wt%) on the thermal stability of Ultra high molecular weight polyethylene (UHMWPE), in temperature region 50–600 °C, at 5 °C/min is examined by utilizing the thermogravimetric (TGA/DTA) technique. The activation energies of these thermograms are determined by utilizing the model fitting kinetic method (Coats and Redfern). Through this, 0.4 wt% is found to be the optimum quercetin concentration. UHMWPE sample at optimized quercetin concentration is further subjected to three other heating rates (10, 15 and 20 °C), in same temperature region. The complexities involved in thermal decomposition are resolved by using the deconvolution technique, adopting a bi-Gaussian asymmetric function. Activation energies of these deconvoluted peaks, obtained through Starink and Friedman kinetic models, follow a similar trend. By utilizing activation energy, a random nucleation reaction mechanism involved in thermal decomposition is identified. Finally, the pre-exponential factor, change in entropy (Δ S ), change in enthalpy (Δ H ) and change in Gibbs free energy (Δ G ) are determined.