Non-Fickian Moisture Absorption in Vegetable Fiber Reinforced Polymer Composites: The Effect of the Mass Diffusivity

Abstract

This article aims to study the non-Fickian water absorption process in vegetable fiber-reinforced polymer composite using the Langmuir-type model, evaluating the influence of mass diffusivity on the process. The numerical solutions of the governing equations were obtained using the finite-volume method. Transient results of the local and average moisture content, free and entrapped water molecules concentration considering the constant diffusivity and as a function of the average and local moisture content were presented and analyzed. It was observed that the mass diffusivity effectively influences the water absorption behavior, especially in the initial time of the process, where higher differences in the water migration rates into the material are found. The largest free and entrapped water molecule concentration gradients were found close to the composite surface, especially when considering constant mass diffusivity.

Mechanism of Moisture Adsorption In Plant Fibers Surface-Modified With Glycerol Evaluated By LF-NMR Relaxation Technique

“…Effect of glycerol on the water state of plant bers 2D LF-NMR relaxation spectra re ect the change of water state and distribution (Melo et al, 2021) in the plant bers caused by glycerol during the water vapor adsorption, SR-CPMG sequence was applied to capture 2D T 1 -T 2 maps of the samples. Three main water states in plant bers could be distinguished clearly, according to T 2 .…”

Research of cycloaliphatic epoxy resin and silicone rubber composite insulator interface based on four‐electrode system and temperature rise model

“…The test conditions are consistent with the artificial ageing test in section 2.2, the quality changes are recorded regularly, and the results are shown in Figure 4. Fick and Langmuir models describe the water diffusion process in the material [21, 22]. By fitting with Fick and Langmuir models, the saturated water absorption m ∞ and diffusion coefficient D of the sheath are obtained.…”

Mechanism of moisture adsorption in plant fibers surface-modified with glycerol evaluated by LF-NMR relaxation technique

“…Effect of glycerol on the water state of the plant fibers 2D LF-NMR relaxation spectra reflect the change of water state and distribution (Melo et al, 2021) in the plant fibers caused by glycerol during the water vapor adsorption, SR-CPMG sequence was applied to capture 2D T 1 -T 2 maps of the samples. Three main water states in the plant fibers could be distinguished clearly, according to the relaxation time of T 2 .…”

“…Water adsorption capability of the plant fibers is closely related to their properties, such as mechanical strength (Perrier et al 2017;Ridzuan et al 2016), physicochemical resistance (Varara et al, 2018), bacterial inhibition capability (Popescu et al 2014), hydrolysis (Jiang et al 2021) and pyrolysis performance (Sun et al 2019). Therefore, the water adsorption behaviour on plant fibers is importantly correlated to their wide applications, such as fields of paper-making (Modaressi and Garnier 2002), bio-energy (Emerson et al 2018;Sotannde et al 2020), bio-degradation (Gheorghita et al 2020), functional materials (Hachem et al 2020;Melo et al 2021), pharmaceutics, cosmetics, textile and tobacco industries (Sun et al 2019).…”