Spectral and thermal studies on the synthesis and catalyzed oligomerization of novel cardanol-based benzoxazines

The aim of this study was to synthesize novel cardanol-based benzoxazines, using different primary amines, and evaluate their influences on the synthesis and polymerization process. The monomers were characterized using NMR (H-1 and C-13), FT-IR, DSC and TGA. It was demonstrated how the amines structures influence on the stability of the oxazine ring, which relates to the onset polymerization temperature (T-e). Aniline-type benzoxazines provided higher T-e than aliphatic ones. Since at this elevate temperature (230e295 degrees C) the alkyl chain of cardanol could degrade, the use of a new catalyst was also evaluated, showing the innocuous MgCl2 as an efficient alternative. The polymerization of these monomers with MgCl2 (1%) were studied using FT-IR, DSC and GPC, showing that under mild temperatures it is possible to obtain polybenzoxazines completely soluble and with high polydispersity. (C) 2016 Elsevier Ltd. All rights reserved.