Thermal stability of maleic acid-vinyl acetate copolymer in aqueous solution: Size exclusion chromatography analysis

Sodium maleate-vinyl acetate (NaM-VA) and maleic acid-vinyl acetate (MAc-VA) copolymers were synthesized and characterized and their aqueous solutions were kept at 25 and 100 degrees C. The molecular weight (Mw) of the copolymers was measured after different times of storage by size exclusion chromatography, and IR spectra were recorded. At 100 degrees C, NaM-VA showed a continuous decrease of MW, which can occur due to the chain breaking and/or chemical modification, while for MAc-VA copolymer a decrease was observed, followed by an increase of the apparent MW. This difference of behavior was attributed to some interchain chemical reactions. The decrease in the molecular weight of the two copolymers at 25 degrees C was found to be less important than at 100 degrees C.