Molecular weights of thermally degraded polymethyl methacrylate

Victor E. Hart
1956 Journal of research of the National Bureau of Standards  
Molecular weights of polymer residues from the thermal degradation in vacuum of two polymethyl methacrylate samples, one polymerized with benzoyl peroxid e and the other without an y initiator, have been obtained over wide extents of degradation at various constant temperatures. A linear relation, dependent upon the temperature but i ndependent of rate of volatilization and rate of change of l /M w , is found when log R is plotted against l /M w • (R = ratio of residue weight to original
more » ... n weight, and .Mw= weight-average molecular weight. ) The results are explained on the basis of a free-radical chain-reaction mechanism in which intermolecular chai n transfer (activation e nergy = 29 kilocalories) is the primary, or perhaps the sole, cause of the molecular-weight decrease.
doi:10.6028/jres.056.009 fatcat:24lrkenetfecpp3gxxemke4skq