Degradation of poly(vinyl butyral) and its stabilization by bases

This paper describes the effect of several bases, including sodium hydroxide, calcium hydroxide, barium hydroxide and hexamine ((CH₂)₆N₄) on thermal stability of poly(vinyl butyral) (PVB). The characterization techniques used were visual colour comparison, thermogravimetric analysis (TG), infra-red spectroscopy, and UV-vis absorption spectra. Visual colour comparison and TG results showed that some acids or other substances that were easily oxidised into acids caused the degradation of PVB. However, PVB could be stabilized to different degrees by adding various bases. The infra-red spectra and UV-vis absorption spectra revealed that during the thermal degradation of PVB mixed with barium hydroxide and hexamine separately, the bases prevented the opening of the cyclic acetal ring and the production of conjugated groups which could cause the colour change.