In this work, the properties of baobab/sisal fibre reinforced low density polyethylene hybrid composites were studied. The effect of fibre loading and fibre treatment with varying sodium hydroxide (NaOH)concentration on the composite properties was investigated. The developed composites were characterized for tensile strength, modulus of elasticity (MOE), elongation at break, hardness and impact strength.Analysis of the results showed that, for the monolithic composite,10 wt% baobab fibre loading had the bestmechanical property compared to other baobab fibre loadings, with tensile strength and MOEof 8.28 MPa and 127 MParespectively.The result ofNaOH treatment showed that 8 wt% treated fibre composite exhibited the best tensile strength, MOE, impact strength and the least percentage water absorption of 14.54 MPa, 245 MPa, 4.4 J/mm2 and 1.8% respectively.On hybridization with sisal, it was observed that the100% sisal fibre composite exhibited higher tensile strength and MOEof 12.47 MPa, 262.85 MPa, and the least percentage water absorption capacity of 0.37% but for both the hybrid were higher than the monolithic composite. The result of the NaOH treated hybrid composite showed that 6 wt% NaOH treated sisal/baobab fibre exhibited the best tensile strength, MOE and percentage water absorption of 17.08 MPa, 279.40 MPa, and 0.18% respectively which were higher than that of the monolithic sisal fibre reinforced composites. The fourier transforms infrared spectroscopy (FT-IR) analysis of untreated and treated baobab fibre showed that there was reduction in the hemicelluloses in the NaOH treated baobab fibres as indicated by the band at2277–2274 cm-1representing C=O stretching of hemicelluloses. The scanning electron microscope (SEM) analysis showed that composite produced from untreated fibre had more cracks and voids, possibly due topoor interaction between the fibre and low density polyethylene matrix, resulting in lower mechanical properties.The composite have properties whichsuggest their suitability for application in deck boards, dash board, rear seat barriers and guardrails systemsto replace the hardwood and metals currently used hence, preserving the environment.

Composites are multifunctional material systems that provide characteristics not obtainable from any discrete materials. They are cohesive structures made by physically combining two or more compatible materials, different in composition and characteristics and sometimes in form (Prankash et al., 2009). These materials consist of the matrix and reinforcement (Mohiniet al., 2011). The constituents can be wholly natural or synthetic and sometimes the combination of the two.

Synthetic-based fibre composites are commercially appealing because they can be used to develop products with known properties to meet a variety of diverse applications. However, these materials represent an environmental liability both in production and upon disposal. In the past years, growing environmental pollution has called for the use of natural materials for different applications. This has been influenced by the ever increasing demand for newer, stiffer, recyclable, fire repellant, less expensive and yet lighter-weight materials in fields such as aerospace, transportation, construction and packaging industries (Duigou et al., 2008). Meanwhile, natural fibres reinforced polymer composites represent an opportunity to partially minimize on the environmental impacts by integrating biodegradable fibres such as flax, hemp, sisal, and wood particles in place of synthetic fibres such as glass, carbon or steel in composite materials production (Alabi, 2011).