Thermal stabilization of polyamide 11 by phenolic antioxidants

This paper addresses the effect of hindered phenols (mainly Irganox 1098 with a few comparisons with other phenolic antioxidants) on the stabilization of polyamide 11 aged at several temperatures (90-165 degrees C). The effect of several phenol concentrations (up to about 0.4%) on kinetic curves for imide buildup, yellowing, and molar mass changes (in association with embrittlement) was investigated. Phenols significantly contribute to yellowing, even at low imide concentrations. When they are used at high concentrations, a post-polycondensation reaction becomes predominant at earlier exposure times, thus increasing molar mass and significantly delaying embrittlement. (C) 2020 Elsevier Ltd. All rights reserved.