Bio-composites of rice husk and saw dust reinforced bio-benzoxazine/epoxy hybridized matrices: Thermal, mechanical, electrical resistance and acoustic absorption properties

Abstract

The prime objective of the present work is developing cost competitive, less thermal conductive, electrical resistive, hydrophobic and acoustic insulation sustainable hybrid green composite materials using the hybrid bio-benzoxazines/epoxy matrix and bio-waste products. In this context, cardanol-melamine (C-m) and cardanol-aniline (C-a) based benzoxazines were synthesised using melamine, aniline and paraformaldehyde separately. The synthesized bio-benzoxazines were blended with (0:100 and 50:50 wt%) of bisphenol-A epoxy resin (DGEBA) and reinforced separately with rice husk and saw dust to obtain corresponding bio-composites for acoustic insulation applications. The breakthrough achieved in the present work is the cardanol benzoxazine is made in the form of hybrid matrix with epoxy resin, which cures significantly at lower temperature of 105 °C in the absence of any curatives. The specimens of composites prepared have been characterized for their thermal, mechanical, electrical resistance and acoustic insulation behaviour by different analytical methods. Among the composites, poly(50 wt% C-m/50 wt% Ep) based composites possess better composites than others. The tensile strength of the rice husk and saw dust reinforced poly(50 wt% C-m/50 wt% Ep) composites were observed at 7.5 and 7.1 MPa. The thermal resistivity of the rice husk and saw dust reinforced poly(50 wt% C-m/50 wt% Ep) composites were observed at 0.1 M2 k/w and 0.08 M2 k/w and roughness (Ra) were noticed at 5.1 and 5.6 µm. The electrical surface resistance of the rice husk and saw dust reinforced poly(50 wt% C-m/50 wt% Ep) composites were ascertained at 1.27 × 1010 Ω/sq and 7.29 × 109 Ω/sq. Data obtained from acoustic studies, it was observed that the highest value of sound absorption coefficient of 6400 Hz was noticed for composite specimens developed using both rice husk and saw dust reinforced with hybridized polymer composites.