Moisture Absorption in Polymer Composites Reinforced with Vegetable Fiber: A Three-Dimensional Investigation via Langmuir Model.

Brito Brito,Neto Neto,Queiroz Queiroz,Lima Lima,Santos Santos,Tavares Tavares,Correia Correia

doi:10.3390/polym11111847

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https://doi.org/10.3390/polym11111847

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Abstract

This work aims to study numerically the moisture absorption in polymer composite reinforced with vegetable fibers using the Langmuir model which considers the existence of free and entrapped water molecules inside the material. A three-dimensional and transient modeling for describing the water absorption process inside the composite and its numerical solution via finite volume method were presented and discussed. Application has been made for polymer composites reinforced with sisal fiber. Emphasis was given to the effect of the layer thickness of fluid close to the wall of the composite in the progress of water migration. Results of the free and entrapped solute (water) concentration, local moisture content and average moisture content, at different times of process, and inside the composite were presented and analyzed. It was verified that concentration gradients of the molecules (free and entrapped) are higher in the material surface, at any time of the process, and concentration of free solute is greater than the concentration of entrapped solute. It was verified that the water layer thickness surrounding the composite strongly affects the moisture absorption rate.

Highlights

IntroductionComposite is a material consisting of two or more insoluble materials, which are combined to create a useful engineering material having some properties not obtained by the constituents taken separately [1].The main purpose to manufacture composite materials is to obtain a new material with increased properties, mainly from the mechanical point of view (mechanical resistance) and low weight [2].Among the different types of composite materials, we can cite those which are reinforced with particles, reinforced with fibers (high length/diameter ratio) and those structural (combination of composites and homogeneous materials whose properties depend on the geometric designs of the structural elements).Polymers 2019, 11, 1847; doi:10.3390/polym11111847 www.mdpi.com/journal/polymersFibers are efficient reinforcements whose main function is to support the loads transmitted by the matrix
Composite is a material consisting of two or more insoluble materials, which are combined to create a useful engineering material having some properties not obtained by the constituents taken separately [1].The main purpose to manufacture composite materials is to obtain a new material with increased properties, mainly from the mechanical point of view and low weight [2].Among the different types of composite materials, we can cite those which are reinforced with particles, reinforced with fibers and those structural.Polymers 2019, 11, 1847; doi:10.3390/polym11111847 www.mdpi.com/journal/polymersFibers are efficient reinforcements whose main function is to support the loads transmitted by the matrix
Concerning the types of fibrous reinforcements, which may be used in the composites, the vegetable fiber stands out

Summary

Introduction

Composite is a material consisting of two or more insoluble materials, which are combined to create a useful engineering material having some properties not obtained by the constituents taken separately [1].The main purpose to manufacture composite materials is to obtain a new material with increased properties, mainly from the mechanical point of view (mechanical resistance) and low weight [2].Among the different types of composite materials, we can cite those which are reinforced with particles, reinforced with fibers (high length/diameter ratio) and those structural (combination of composites and homogeneous materials whose properties depend on the geometric designs of the structural elements).Polymers 2019, 11, 1847; doi:10.3390/polym11111847 www.mdpi.com/journal/polymersFibers are efficient reinforcements whose main function is to support the loads transmitted by the matrix. The main purpose to manufacture composite materials is to obtain a new material with increased properties, mainly from the mechanical point of view (mechanical resistance) and low weight [2]. Among the different types of composite materials, we can cite those which are reinforced with particles, reinforced with fibers (high length/diameter ratio) and those structural (combination of composites and homogeneous materials whose properties depend on the geometric designs of the structural elements). Fibers are efficient reinforcements whose main function is to support the loads transmitted by the matrix. The functions of the matrix are to join and guide the fibers, to transmit and distribute the mechanical stress, and to protect them from mechanical damage, such as abrasion and environmental degradation [3].

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