Home – Home – Jornals – Chemistry for Sustainable Development 2007 number 1

Thermal oxidative degradation of poyacroleinoximes that have been obtained by condensation of polyacroleins that contain as much as 80 % of aldehyde groups, with hydroxylamine has been studied. In response to differential thermal and isothermal analysis as well as to IR and mass spectrometry, it has been demonstrated that the process of thermal oxidative degradation of poyacroleinoximes to a large measure depends on their heating rate and to a lesser degree, on the molecular mass and on the structure of polymers. It has been found that dehydration of oxime groups and N-hydroxy piperidine cycles is observed in a temperature range from 120 to 250 ^oC at the heating rate up to 4 ^oC/min (on evidence of DTGA, as well as based on the results that have been received in the study of thermal oxidative and thermal degradation under the isothermal regime at 170 and 190 ^oC), which gives rise to acrylonitrile units in the macromolecules, these units being capable to intra- and intermolecular cross-linking. Thus, heat treatment of poyacroleinoximes at 190 ^oC under the isothermal regime may yield heat resistant polymers. With increased heating rates for poyacroleinoximes, being as large as 5 ^oC/min and higher, the destruction becomes complicated even at 170 ^oC due to oxidizing detachment of lateral groups that make up the macromolecules of polymers, probably, at the expense of a chain process initiated by nitroxyl radicals. This yields a hydrocarbon polymeric residue that contains conjugated -С=С- bonds in the macrochain and that is burnt down in a temperature range of 400-600 ^oC.