Thermal stabilization of polyamide 11 by phenolic antioxidants

Abstract

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 °C). The effect of several phenol concentrations (up to about 0.4%) on kinetic curves for imide build-up, 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.