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 degrees 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 degrees 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.