ABSTRACT
The search for new engineering materials that addresses ecological and environmental issues is generating renewed interest in utilisation of agricultural wastes to explore value-added application avenues. The aim of the study was to develop and characterise epoxy/borassus palm (Borassus aethiopum Mart.) leaf stalk fibre (BPLSF) reinforced composite to establish the potential of BPLSF as a reinforcement in epoxy, a thermosetting polymeric material, for maritime craft applications. Fibres were extracted from the stalk by water retting and treated with sodium hydroxide (NaOH) and natural latex coating. The fibre was characterised using Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy (SEM). The composites were produced by hand lay-up method, aligning the continuous fibres longitudinally. The composites produced were characterised by density evaluation and mechanical testing such as tensile, flexural, impact and hardness tests. Others included water absorption test, soil burial and natural weather exposure tests using weight gain or loss as criteria to evaluate the degradation of the composites. Dynamic mechanical analysis (DMA) was used to study the thermo-mechanical properties of the composites. SEM was used to study the impact fractured surfaces and water absorption specimen surfaces. Average fibre strengths of 1250 MPa, 1040 MPa and 820 MPa were obtained for untreated, alkali treated and latex treated fibres, respectively. The density results for untreated, alkali treated and latex treated fibre reinforced composites lie between 0.7967 g/cm3 and 1.0381 g/cm3, 0.8827 g/cm3 and 1.0498 g/cm3 and 0.9192 g/cm3 and 1.0786 g/cm3, respectively. Density decreased generally as fibre contents increased. Tensile test results showed a general increase in tensile strengths and moduli with increasing fibre contents. Epoxy exhibited tensile strength of 23.69 MPa compared to the composites having maximum tensile strengths at 25 wt. % fibre contents of 53.59 MPa for untreated, 55.74 MPa for alkali treated and 50.48 MPa for latex treated fibre reinforced composites. Corresponding tensile moduli for epoxy and composites at 25 wt. % fibre contents were 256.11 MPa, 1363.79 MPa, 1258.50 MPa and 1431.72 MPa, respectively. The morphological studies of impact fractured surfaces revealed brittle fracture for unreinforced matrix but ductile failure for the various composites. The water absorption tests showed a general increase in water absorption with increasing fibre content, the maximum water absorption at 25 wt% fibre contents were 51.3% for untreated, 19.4% for alkali treated, and 50.2% for latex treated fibre reinforced composites in river water; while in distilled water, lower values for epoxy and all composites were obtained compared to those in river water. Morphological study of water absorption sample surfaces revealed fibre debonding for untreated fibre and loss of surface integrity for latex coated fibre-reinforced composites. DMA results showed a decrease in storage and loss modulus with increasing fibre content, tangent delta reduced with fibre content. It was concluded that BPLSF is a potential reinforcement for epoxy matrix and may be beneficial in complementing/replacing the man-made fibre.