Pyrolysis-evolved Gas-infrared Spectroscopy

Davidson [15] applied programmed pyrolysis - evolved gas IR spectroscopic techniques to determine whether for polymethylmethacrylate (PMMA) the evolution profiles of various pyrolysis gases against temperature were sufficiently distinctive to allow reliable identification of different types and to distinguish between different batches of the same type. The results showed that the different types and batches could be reliably identified. Reactions accounting for some of the compounds evolved 

The samples could be divided into two groups, those for which the methylmethacrylate (MMA) event peaked near 400 °C, and which had significant methanol and carbon dioxide profiles and those for which the MMA event peaked near 370 °C, and which yielded only traces of methanol and carbon dioxide. The former group contains those materials in which the crosslink is formed in a secondary condensation reaction, usually between two copolymer chains. In the latter group, crosslinks are formed in the addition polymerisation process by incorporation of polyfunctional vinyl compounds. 

The technique was tested on a series of samples. Positive identification was made in all cases. 

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