STUDY OF THE THERMAL-DEGRADATION OF POLY(N-VINYL-2-PYRROLIDONE) BY THERMOGRAVIMETRY-FTIR

The thermal degradation of poly(N-vinyl-2-pyrrolidone) (PVP) was studi ed by dynamic thermogravimetric analysis (TGA) in the range 200-600-de grees-C under nitrogen and oxygen atmospheres at various heating rates . The apparent activation energy of the degradative process was determ ined by the application of kinetic treatments, giving an average value of 242 kj/mol in N2, whereas in the presence of oxygen, two trends ma y be considered: At relatively low temperatures (200-400-degrees-C) an d degrees of conversion, alpha, lower than 0.5, we obtained an average value of 199 kj/mol, whereas in the temperature interval 400-600-degr ees-C with degrees of conversion higher than 0.5, the value of E(a) wa s 306 kj/mol. Isothermal experiments carried out in N2 in the interval 350-400-degrees-C gave an average value of E(a) = 231 kj/mol, in good agreement with that obtained from dynamic treatments. The FTIR spectr a of the volatile compounds evolved in degradation experiments carried out in N2 as well as in the presence of oxygen suggest that PVP is th ermally degraded, predominantly, by the release of the pyrrolidone sid e group and the subsequent decomposition of polyenic sequences. (C) 19 93 John Wiley & Sons, Inc.