Hybrid glass/Kevlar fiber reinforced phenolic matrix composites: Thermal degradation and flammability studies

Abstract In the present work, bio‐based phenolic matrix composites (PMCs) were fabricated by reinforcing them with bi‐directional glass fiber mats, bi‐directional Kevlar fiber mats, and their hybrid combinations. Both fiber mats were treated with (3‐glycidyloxypropyl) trimethoxysilane (GPTMS) to enhance fiber‐to‐matrix adhesion. Subsequently, the fibers were coated with a phenolic binder made from a mixture of phenol‐hexamine‐based novolac (N) resin and cardanol‐hexamine‐based benzoxazine (Bz) resin. Then the layers of binder‐coated fibers were compressed using a hot press molding machine at 200°C to cure the resins. The developed composites were subjected to thermogravimetric analysis (TGA) and UL‐94 V flammability test. The glass fiber (GF‐NBz) and Kevlar fiber (KF‐NBz) reinforced PMCs show an overall mass loss of ~18.5% and 66% at 850°C. Whereas the hybrid GF/KF fiber‐reinforced PMCs exhibit balanced properties of improved thermal stability and higher char yield. The flammability test results show both pure and hybrid samples exhibited a V‐0 rating. Based on these observations, the combination of glass fiber and Kevlar fiber‐reinforced PMCs may be suitable for automotive applications, such as dashboards, and door panels, with improved performance and fire safety. Highlights Glass and Kevlar/phenolic and their hybrids were developed using hot press. Fibers coated by (3‐glycidyloxypropyl) trimethoxysilane to enhance bonding. GF/KF composites exhibited balanced properties in thermal property. The pure and hybrid samples achieved a V‐0 rating under UL‐94 V test.