The understanding and the simulation of stabilized polyamide oxidation is a significant stake for users and producers. The present work aims at proposing the first kinetic model for thermal oxidation of polyamide 11 films stabilized by phenols.Three hindered phenols are investigated: Irganox 1098, 1010 and 245 at concentration range between 0.05 and 0.5 % wt., and the thickness of the corresponding polyamide 11 films is about 100 �m. Accelerated agings are performed between 90 and 165 �C. Carbonyl build-up, investigated by FTIR, do not bring out induction period as usually observed for stabilized PE, but the curves display a complex shape: after a fast increase, the carbonyl build-up reaches a plateau of which level and length depend on phenol concentration before another increase (figure 1a). Phenols reduce yellowing kinetics, determined by UV-Vis spectroscopy. However, the relationship between carbonyl concentration and the absorbance at 280 nm (which is our discoloration index) remains similar for stabilized and unstabilized PA11. The investigation of molar mass changes by size exclusion chromatography points out an increase of molar weight during the plateau assigned to a post-polycondensation process (figure 1b). These results will be discussed in the light of a PA11 kinetic model in which phenol stabilization mechanism is implemented.

Toward the kinetic modeling of thermal oxidation of polyamide 11 film stabilized by hindered phenols

248th National Meeting (2014)

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