Effect of alkaline treatment on the physical and mechanical properties of borassus flabellifer leaf fiber.

The treatment method of natural fiber is one of the factors that influences its properties. There are several reports on sodium hydroxide (NaOH) treatment of many natural fiber. Though there are works on NaOH treatment of the fruits fiber, however, works on Borassus flabellifer Leaf fiber (BFLF) is sparsely reported. Hence no report on the optimum conditions for sodium hydroxide treatment of Borassus Flabellifer Leaf fiber. Therefore, this study aimed at establishing the optimum concentration and time for alkaline treatment on the properties of BFLF. The fiber extraction was carried out using water retting method for 24 h. Experimental design was carried out using Design Expert 12.0 adopting Central composite design in response surface methodology. NaOH concentration of 0–5 wt% and time of 1–12 h were used as the independent variables. The responses were water absorption, elongation (%), modulus of elasticity and tensile strength. The surface morphology of the fiber was studied using scanning electron microscope (SEM) and the functional group changes established using Fourier transform infrared (FTIR) spectroscopy to indicate effect of NaOH treatment (FTIR) spectroscopy to show the functional group changes due to NaOH treatment. The optimum concentration and treatment time was established as 2 wt% NaOH and 4 h, respectively, with corresponding responses of water absorption, tensile strength, modulus of elasticity and elongation (%) were 2.07%, 977.378 MPa, 6971.02 MPa, 5.178%, respectively. Using these optimum treatment conditions of time and NaOH concentration, the responses were validated to be 1.88%, 920.019 MPa, 6943.73 MPa, 4.99 mm having a desirability of 0.963. The SEM revealed rough surfaces and increased porosity for the treated fiber compared to the untreated. The FTIR spectra showed reduction in peaks representing lignin at wavelength of 3321.1 cm−1 to 3306.1 cm−1, which indicated that the NaOH treatment resulted to decrease in lignin in the fiber. The properties of the BFLF obtained at the optimum treatment conditions were within range of other fibers used in composite materials development, hence, BFLF treated at these conditions is suitable for composite development. [ABSTRACT FROM AUTHOR]