Modelling of the Water Absorption Kinetics and Determination of the Water Diffusion Coefficient in the Pith ofRaffia viniferaof Bandjoun, Cameroon

Abstract

The present work focuses on the study of the water absorption phenomenon through the pith of Raffia vinifera along the stem. The water absorption kinetics was studied experimentally by the gravimetric method with the discontinuous control of the sampling mass at temperature of 30 ∘ C. The samples of 70 mm × 8 mm × 4 mm were taken from twelve sampling zones of the stem of Raffia vinifera. The result shows that the percentage of water absorption of the pith of Raffia vinifera increases from the periphery to the center in the radial position and from the base to the leaves in the longitudinal position. Fick's second law was adopted for the study of the water diffusion. Eleven models were tested for the modelling of the water absorption kinetics and the model of Sikame Tagne (2014) is the optimal model. The diffusion coefficients of two stages were determined by the solution of the Fick equation in the twelve sampling zones described by Sikame Tagne et al. (2014). The diffusion coefficients decreased from the center to the periphery in the radial position and from the base to the leaves in the longitudinal position.

Ageing of autoclaved epoxy/flax composites: Effects on water absorption, porosity and flexural behaviour

“…Figure 14 A 52% variation is obtained between the transverse and longitudinal composites after 4 days of saturation. The water penetration is easier along the direction of the cross-section of the fibres [39,40] because more porosity is present there than along their peripherical surface. Transverse prismatic samples feature a better percolation of water because of the presence of a larger number of fibres cross-sections, in comparison to the longitudinal samples.…”

“…Transverse prismatic samples feature a better percolation of water because of the presence of a larger number of fibres cross-sections, in comparison to the longitudinal samples. Mbou et al [40] investigated the water diffusion from the pith of Raffia vinifera by Fick's second law. The diffusion coefficients decrease from the centre to the periphery in the radial position, while the water absorption increases from the periphery to the centre in the radial position.…”

Quantum Tunneling Hygrometer with Temperature Stabilized Nanometer Gap

“…Since sensor dynamics is heavily dependent on the diffusion of water vapor molecules into the polyimide patch causing expansion of the polymer, the dynamic response of the absorption cycle of the sensor can therefore by mathematically described using a modified version of Fick's second law [26]. Fick's law of diffusion has been extensively used to describe the diffusion process and to experimentally determine diffusion constant of various substances.…”

Swelling and Shrinking Behavior of Modified Starch Biopolymer with Iron Oxide

“…The C 0 is the initial concentration of biopolymer and C 1 is the after weight gain/loss after solution absorption/desorption. [45][46][47]…”

“…For Figure 3b, the complex of the iron oxide and starch composite has the appearance of characteristics major peaks at 10. 47 [52,53] The biopolymer has 18 nm average crystalline grain size. The average grain size has been calculated by the Scherrer Debby Formula.…”