Performance of layered birnessite-type manganese oxide in the thermal-catalytic degradation of polyamide 6

Abstract

The nature and the extent of degradation of polyamide 6 (PA6) in the presence of layered birnessite-type manganese oxide (LMO) were analysed by thermogravimetric analysis under static air atmosphere at several heating rates between 5 degrees C/min and 20 degrees C/min. The samples were characterized using infrared (IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), N-2 gas adsorption-desorption and thermal analysis (TA) techniques. XRD and DTA results for LMO showed that the oxidative transformation of MnO2 was occured on heating from 300 degrees C to 500 degrees C. The IR spectra of Mn-O band proved the covalent character of oxygen bonding to the metal ions of the surface. The addition of LMO caused the change in the crystalline phase of PA6 from predominantly alpha at to largely gamma phase. The activation energy for degradation estimated by Kissinger method for PA6 and 10 wt.% LMO/PA6 composite were found to be 213 and 118 kJ/mol in static air atmosphere, respectively. The experimental results revealed that the addition of 10 wt.% LMO decreased the thermal stability in static air of PA6 by about 80 degrees C. (c) 2012 Elsevier B.V. All rights reserved.