Cardanol-capped main-chain benzoxazine oligomers for resin transfer molding

Main-chain benzoxazine oligomers can be phenol-capped now. In this article, cardanol, a renewable phenol extracted from agricultural byproduct, is designed as the capping agent for the oligomers. Benefiting from the long alkyl chain of cardanol, the oligomers possess good pro-cessability to satisfy resin transfer molding without adding any diluents. The structures of the oligomers are verified by Fourier transform infrared spectroscopy, H-1 and C-13 nuclear magnetic resonance spectroscopy. The molecular weight and distribution have been measured by size exclusion chromatography. The thermal properties, including glass transition temperature, coefficient of thermal expansion, thermal stability and char yield, are characterized and discussed in this study.