Sorption behavior of four tropical woods using a dynamic vapor sorption standard analysis system

Abstract

Sorption behavior of four tropical woods coming from Cameroon is studied using a Dynamic Vapor Sorption-Intrinsic apparatus. Sorption isotherms at 20°C and 40°C of Triplochiton scleroxylon (obeche), Entandrophragma cylindricum (sapele), Sterculia rhinopetala (lotofa) and Terminalia superba (frake also called limba) are compared to those in the literature with methods using saturated salts for lotofa and frake with satisfactory results. Experimental values are fitted using two sorption isotherm models.Sorption hysteresis is greatest in sapele and least in frake. When temperature increases, differences in the hysteresis of sorption among the woods decreases. Hystereses of all studied woods ranged from 0,5 to 3%. Our studied woods have lower equilibrium moisture content probably caused by the higher values of extractives content. The water sorbed molecules on multilayer during both adsorption and desorption at 20°C and 40°C is greater in the case of frake and lower in the case of lotofa. The water sorbed molecules on multilayer of sapele is greater than those of obeche. The predominance of multilayer over monolayer of our woods is from 0,2 to 0,4 relative humidity in adsorption phase, and from 0,3 to 0,4 relative humidity in desorption phase.

An experimental and numerical study of moisture transport and moisture-induced strain in fast-grown Sitka spruce

“…The standard deviation associated with the moisture content measurement varied between 0,09 and 0,42%. Many models such as the Hailwood-Horrobin and GAB (Guggenheim-Andersen-de Boer) isotherms have been developed and utilised to describe the sorption behaviour of wood (Simpson 1973, Avramidis 1989, Sargent et al 2010, Simo-Tagne et al 2016. In this study, a 4 th order polynomial was found to have the best fit to the experimental data and is used to express the moisture content as a function of relative humidity at a temperature of 20°C (Equation 3).…”

“…This is primarily due to the similar cell wall structure within all species (Wadsö 1993). Many models have been created to determine the average equilibrium moisture content of timber as a function of the relative humidity and temperature (Hailwood and Horrobin 1946, Simpson 1973, Avramidis 1989, Sargent et al 2010, Simo-Tagne et al 2016, however, these models do not consider the moisture content hysteresis of timber during adsorption and desorption. Merakeb et al (2009) and Patera et al (2015) have investigated and modelled the influence of the hysteresis effect on moisture transport in timber.…”

Analysis of drying stresses in green-glued plywood of Bete (Mansonia Altissima) specie

“…In the literature, several authors conducted investigations concerning the mass transfer properties of wood (11) K D = K 0 exp(K 0w w), [25,26]. Concerning central Africa tropical woods, some results on species like sapelli (Entandrophragma cylindricum) and sipo (Entandrophragma utile) are available [27][28][29]. Such timber species present similar technological properties with Bete [30].…”

Experimental and numerical validation of hygrothermal transfer in brick wall

“…Otherwise, the sorption isotherms have an importance in the modeling of the drying to wetting process, determining the storage properties, and shelf‐life stability of materials 24‐26 . However, few works in the literature dealing with characterizing the properties of building materials have been performed and particularly on modeling the sorption isotherms of building materials.…”