Development of chopped glass fiber composites with difunctional benzoxazine and bio-based phthalonitrile copolymer: A study of mechanical and thermomechanical properties

The randomly-oriented glass fibers (GF) reinforced composites with Bisphenol A–amine based benzoxazine (BA-a) and bio-based eugenol-based phthalonitrile (EPN) copolymer were developed by an isothermal compression molding technique. The silane coupling agent-treated GF (TGF) reinforced composites showed much better impact strength as compared to as-received GF reinforced composites. A rise of 95.2 MPa, 5.5GPa, 69.1 MPa, and 2.5GPa in flexural strength, flexural modulus, tensile strength, and Young's modulus were observed, respectively. The DMA results confirmed that the storage modulus ( E' ) and glass transition temperature ( T g ) were gradually increased and the damping factor decreased as the TGF reinforcement was raised from 0 to 40 wt%. E' and T g values were 3.09 GPa and 27°C, respectively, higher than the recorded values for the neat copolymer. The 40 wt% TGF reinforced poly(BA-a/EPN) composite showed the maximum thermal stability values of 475.4, 507.3°C, and 75.43% for T 5 , T 10 , and Y c , respectively. The LOI values confirm that the TGF/copolymer composites have self-extinguishing properties.