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Behavior of Primary Radicals During Thermal Degradation of Poly(Methyl Methacrylate).


pdf icon Behavior of Primary Radicals During Thermal Degradation of Poly(Methyl Methacrylate). (530 K)
Kashiwagi, T.; Inabi, A.; Hamins, A.

Polymer Degradation and Stability, Vol. 26, 161-184, 1989.

Keywords:

polymethyl methacrylate; thermal degradation; radicals

Abstract:

The behavior of the primary radicals formed from the random scission of anionically polymerized poly(methyl methacrylate). PMMA, during thermal degradation is investigated by a theoretical and experimental study. The theoretically calculated relationship between the degree of polymerization and the conversion agrees well with the experimentally determined relationship if the random scission produces one polymer radical and one polymer molecule with an unsaturated bond at a chain end. It is proposed that the primary radical rearranges to form the polymer molecule with the unsaturated bond at a chain end. Two different degradation paths for this rearrangement are proposed via beta scisison at the C-C bond of the pendant group instead of beta scisison, as previously thought, at the backbond C-C bond. The products from the proposed degradation paths are CO, CO2, CH3OH, AND CH4. The products for anionically polymerized PMMA samples with three different values of initial molecular weight are measured by a mass spectrometer. The quantities of CO and CO2 are observed to decrease with an increase in initial molecular weight. This confirms that the two proposed degradation paths for the thermal degreadation of PMMA are quite plausible.