Thermal stability and degradation mechanisms of poly(acrylic acid) and its salts: Part 1—Poly(acrylic acid)

The thermal degradation of poly(acrylic acid) has been studied using thermal volatilisation analysis (TVA) and thermogravimetry (TG). The degradation studies were carried out using two approaches. Programmed heating was carried out at 10°/min to temperatures from 170 to 500°C and the polymer was also heated isothermally at 210°C for different times, under TVA conditions. Quantitative measurements of the main product fractions have been made. The gaseous, volatile liquid and cold ring fraction (CRF) products from the TVA degradation have been analysed by IR, MS and GC-MS techniques. The polymer yields water and carbon dioxide as major products. The degraded polymer develops anhydride ring structures in the chain as a result of a dehydration process. At higher degradation temperatures, chain fragments with anhydride rings and/or acid groups are formed, together with various minor volatile products. The mechanism of degradation is discussed.