Flame retardant and anti-corrosion behaviour of sustainable composites from Aerva lanata ash and cardanol-based benzoxazine

A new monomer of bi-functional benzoxazine was synthesized using cardanol (C) and p-phenylenediamine (ppda) under suitable experimental conditions. The curing behaviour of C-ppda benzoxazine monomer was studied by DSC analysis and Tp of C-ppda benzoxazine was found to be 237°C. Further, benzoxazine monomer was reinforced with varying weight percentages (5, 10 and 15 wt%) of bio-ash derived from Aerva lanata (AL-ash) to obtain hybrid composites. TGA data infer that AL-ash reinforced benzoxazine composites possess an excellent thermal stability and flame retardant behaviour. The morphology of AL-ash and cardanol based benzoxazine composites was analysed using FESEM. The FESEM results infer the homogeneous distribution of AL-ash in composites. Energy dispersive X-ray (EDX) spectroscopy analysis was used to determine the elemental composition of AL-ash used for preparation of composites. The value of water contact angle of poly(C-ppda) was found to be 148°. Data obtained from corrosion studies indicated that mild steel specimen coated with benzoxazine matrix and specimen coated with bio-ash reinforced benzoxazine composites exhibit an excellent resistance towards corrosion. The bio-ash reinforced composites of cardanol based benzoxazine can be used in the form of sealants, encapsulants, adhesives, coatings and matrices in microelectronics and automobile applications under high thermal and moist environmental conditions.