Dehydration kinetics and glass transition of poly(acrylic acid)

Abstract The kinetics of dehydration and decarboxylation as well as the glass transition temperature as a function of anhydride content were measured for poly(acry1ic acid). It was found that the glass transition of PAA is of the order of 103°C and increases with increasing anhydride content, reaching an extrapolated value of 140°C for the pure linear anhydride. Anhydride formation is a firstsrder reaction, as is also decarboxylation, the latter being much slower than the former. The rate constants are for dehydration, k a = 2.5 × 10 9 exp {−26000/ RT }; for decarboxylation, k d = 2.9 × 10 8 exp {−27000/ RT }. Anhydride formation occurs primarily by an intramolecular process.