A comprehensive thermal characterization of the various stereoregular polymethacylic acid (PMMA) was conducted via mass spectrometry and thermal analysis. The results showed that no glass transition occurred in the range from 30℃ to 200℃of these polymers was observed. Maximun water evolution
due to anhydride formation
and carbon dioxide evolution
due to decarboxylation
occurred at-245℃℃
respectively
in syndiotactic PMAA
but only water evolution at -185℃ in isotactic PMAA. The relationship between the thermal stability and stereoregula-rity of PMAA was discussed. The activation energy of the dehydration was obtained.