Experimental study of water-sorption and desorption of several varieties of oil palm mesocarp fibers

Abstract

The availability and mechanical performance of palm nut mesocarp fibers make them a serious alternative to synthetic fibers for certain textile and composite applications. However, their use can be limited by the lack of knowledge of the process of water absorption and moisture recovery of these fibers as well as the mechanisms of desorption. This work highlights the porous character of palm nut mesocarp fibers (OPMF) by SEM analysis; this character is amplified by NaOH treatment. X-ray diffraction, Thermogravimetric Analysis and Infrared spectrometry of OPMF are also performed. The study of the drying kinetics of OPMF shows that the desorption model of Verna et al. best describes their drying process at three desorption isotherms (60, 70 and 80 °C). The diffusion coefficient is lower for the interior fibers than the exterior ones at all isotherms. The activation energy of the outer Tenera fibers (21.3 kJ/mol) is twice that of the Dura variety (10.2 kJ/mol). Moisture uptake is about 10% for Dura and inner Tenera varieties and 7% for outer Tenera fibers while water uptake is about 160% for Dura and Tenera varieties and 114% for outer Tenera fibers. The models of Sikame et al. and Mohsenin best describe the water and moisture uptake kinetics of OPMF. The moisture diffusion coefficient varies from 2.31 × 10−12 m2/s to 5.26 × 10−12 m2/s while the water diffusion coefficient varies from 3.32 × 10−10 m2/s for external Tenera fibers to 4.85 × 10−10 m2/s for internal Tenera fibers. There is great versatility between the water and moisture diffusion parameters from one variety of OPMF to another as well as within the same variety between external and internal fibers.