AbstractBiocomposites were prepared with rice husk flour (RHF) (raw and alkali-treated) in a recycled polymer blend (RPB) using a co-rotating twin screw extruder. Modifications to the composite were carried out through fibre surface treatment with 4 wt.% sodium hydroxide (NaOH) and 3 wt.% maleic anhydride polyethylene (MAPE) coupling agent. Fourier transform infrared (FTIR) analyses of raw and NaOH-treated RHF were performed. The effects of the interfacial modification (MAPE or/and NaOH) and filler loading (50 to 80 wt.%) on the mechanical, physical, and morphological properties were investigated. Improvements in the tensile strength and Young's modulus as well as reduction in water absorption and water loss were observed for raw RHF composites incorporated with MAPE. Alkalisation of fibres resulted only in an enhancement in elongation and impact strength. The composite with 70 wt.% RHF modified with only MAPE exhibited the highest tensile strength and modulus, 22.2 and 711.6 MPa, respectively. The general trend of the composite results exhibited some decrease in water absorption and water loss from untreated RHF composites with only MAPE modification as compared to the NaOH-treated composite, although a rougher surface for the treated fibres was revealed in SEM images.