STUDIES OF THERMAL TRANSITION BEHAVIOR IN PLASTICIZED POLY(VINYL BUTYRAL-CO-VINYL ALCOHOL) WITH SOLID-STATE NMR AND THERMAL-ANALYSIS TECHNIQUES

Samples of plasticized poly(vinyl butyral-co-vinyl alcohol) (PVB) are found to exhibit multiple thermal transitions as observed by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). Arrhenius plots using DSC and DMA data suggest that two of the transitions are glass-type ones. Variable temperature solid-state C-13-NMR experiments show a temperature-dependent line-broadening pattern for all PVB backbone carbons with maximum broadening at 55-degrees-C or at about 50-degrees-C above the second-order-type transitions alpha, and alpha-2 as measured by DSC. Using Arrhenius plots, the NMR transition is found to best correlate with alpha-1, which is consistent with glass transition behavior. The solid-state NMR spectra also show that vinyl alcohol tacticity remains unresolved up to a temperature of about 95-degrees-C, beyond which line narrowing begins to occur. High-temperature thermal transitions are also observed by DSC and DMA, which suggest that the onset of motion involving vinyl alcohol sequences may be responsible for these transitions.