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.