Dehydration kinetics and glass transition of poly(acrylic acid)

Abstract

AbstractThe 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, ka = 2.5 × 109 exp {−26000/RT}; for decarboxylation, kd = 2.9 × 108 exp {−27000/RT}. Anhydride formation occurs primarily by an intramolecular process.