Perturbation-correlation moving-window 2D correlation analysis of temperature-dependent infrared spectra of a poly(vinyl alcohol) film

Temperature-dependent infrared (IR) spectra of a poly(vinyl alcohol) (PVA) film were analyzed by perturbation-correlation moving-window two-dimensional (PCMW2D) correlation spectroscopy. The PCMW2D correlation analysis revealed that there are two characteristic bands in the O–H stretching region, though only one broad feature is found in the original IR spectra. These two bands were assigned to bulk hydroxyl group on the PVA chain with hydrogen bonds, which appears at a lower wavenumber region, and residual hydroxyl group induced by thermal degradation, which appears at a higher wavenumber region. The lower wavenumber band changes below the melt temperature of PVA, while the higher wavenumber band changes above the melt temperature. Spectral variations in the C–H deformation bands region and those in the CO stretching bands region were also discussed from the results of the PCMW2D correlation analysis.