High-performance glass fiber composites based on cashew nutshell liquid–derived benzoxazine and novolac resins

Cashew Nutshell Liquid (CNSL) is a versatile phenolic source for synthesizing high-performance thermosetting resins, such as benzoxazine and novolac. This study reports the development and characterization of bio-based composites reinforced with glass fibers (GF), utilizing CNSL-derived matrices as sustainable alternatives to conventional epoxy resins. Two distinct systems were synthesized and characterized via FTIR and DSC to evaluate their curing behavior. The resulting composites, prepared by hot pressing, were investigated through TGA, DMA, tensile testing, and SEM. Thermal analysis revealed that CNSL-modified systems, particularly the CNSL-a/GF and CNSL-nov/DGEBA/GF formulations, exhibited superior thermal stability with higher degradation temperatures and char yields compared to neat DGEBA/GF. DMA results indicated a significant increase in storage modulus and glass transition temperature ( T g ), reflecting robust polymer–fiber interfacial adhesion. Morphological analysis via SEM confirmed enhanced matrix–fiber cohesion and a reduction in interfacial defects. Overall, the CNSL-a matrix demonstrated exceptional potential for high-performance structural applications, while the CNSL-nov/DGEBA/GF blend emerged as a viable sustainable, maintaining both thermal and mechanical integrity.