Study of the thermal degradation of poly(<i>N</i>‐vinyl‐2‐pyrrolidone) by thermogravimetry–FTIR

Abstract

Abstract The thermal degradation of poly( N ‐vinyl‐2‐pyrrolidone) (PVP) was studied by dynamic thermogravimetric analysis (TGA) in the range 200–600°C under nitrogen and oxygen atmospheres at various heating rates. The apparent activation energy of the degradative process was determined by the application of kinetic treatments, giving an average value of 242 kj/mol in N 2 , whereas in the presence of oxygen, two trends may be considered: At relatively low temperatures (200–400°C) and degrees of conversion, α, lower than 0.5, we obtained an average value of 199 kj/mol, whereas in the temperature interval 400–600°C with degrees of conversion higher than 0.5, the value of E a was 306 kj/mol. Isothermal experiments carried out in N 2 in the interval 350–400°C gave an average value of E a = 231 kj/mol, in good agreement with that obtained from dynamic treatments. The FTIR spectra of the volatile compounds evolved in degradation experiments carried out in N 2 as well as in the presence of oxygen suggest that PVP is thermally degraded, predominantly, by the release of the pyrrolidone side group and the subsequent decomposition of polyenic sequences. © 1993 John Wiley &amp; Sons, Inc.