Reaction pathways and kinetic analysis of PVB thermal degradation using TG/FT-IR

Poly(vinyl butyral) (PVB) was thermally degraded in a thermogravimetry (TG) in nitrogen atmosphere. Evolving gases during PVB degradation were continuously analyzed with an FT-IR instrument. The main products identified were butyraldehyde, 2-butenal, butanoic acid, acetic acid, 2,5-dihydrofuran, and butanol. The IR spectra of mixture gases were resolved on the basis of the spectrum of pure species. The intensity of IR absorbance for each species was recorded as a function of temperature, and the temperature-dependent quantitative information for each species was calculated and used to evaluate the kinetic parameters. Activation energy and preexponential factors were evaluated for each species under the assumption of a parallel degradation mechanism and first-order kinetics. In addition to this detailed analysis, the polymer weight loss information measured by TG was used to determine the overall kinetic parameters. Results showed that activation energy obtained by both methods was consistent.