Mechanical and thermomechanical behaviour of agro-waste almond shell biochar filler interlaced chemically treated flax fibre vinyl ester composites

Biofibre and filler are used to develop environmental friendly products for the automotive, marine, construction, and other structural industries. Employing chemical treatments on natural fibres and adding micro/nanofillers can enhance the properties of hybrid polymer composites. This study investigated the effects of chemical treatments of flax fibre and biochar filler loading on the mechanical and thermomechanical characteristics of hybrid composites. The hand layup technique was used to make biochar-filled polymer laminates with a weight percentage of 0 to 15%. The alkaline-treated flax fibre with 10% biochar interlaced composite (ALTBC10C) showed higher tensile, bending, and impact strengths of 71.5 MPa, 79.5 MPa, and 7.99 J. ALTBC10C has a 36.5% higher tensile strength than untreated UTBC10C due to increased adhesion of the matrix and reinforcements. Similarly, the ALTBC10C interlaced biochar composite exhibited a higher storage modulus (6907.08 MPa) and a higher loss modulus (768.12 MPa). The UTBC10C composite shown the highest tan delta value (0.941), while the ALTC composite revealed the lowest tan delta value (0.542) due to the porous structure of the biochar filler.