Polypropylene stabilization by hindered phenols - Kinetic aspects

This article deals with polypropylene stabilization by hindered 2,6-di-tert-butylphenols. Two aspects are mainly considered: the influence of stabilizer structure, of its concentration and temperature on induction period duration through a literature compilation completed by results obtained on PP samples stabilized by Irganox 1010 in conditions in which physical loss was negligible. Results show that the induction period duration is almost proportional to the phenol concentration and that the proportionality ratio is almost independent of the stabilizer structure in the investigated phenol family. A unique set of kinetic parameters can be therefore used to model the kinetic behaviour of all the family members. The kinetic approach can be more or less complex depending on the number of secondary processes taken into account. The results of simulations indicate that a two steps process allows generation of a kinetic behaviour in good agreement with experimental trends regarding effects of both stabilizer concentration and temperature on induction time.