Transferência de calor e de massa em materiais compósitos poliméricos reforçados por fibras vegetais: modelagem avançada e simulação.

Abstract

Composite materials are of great importance for engineering, since they possess certain properties not obtained by their constituent materials individually. Polymeric composites reinforced by vegetable fibers, for instance, have low density, higher availability and deformability, low cost and biodegradability as advantages. However, the hydrophilic nature of vegetable fibers negatively affects the mechanical properties of these composites. Thus, it is essential to predict the dynamics of moisture absorption and heating, and their effects on the mechanical properties of these composites. The aim of this work is to study the moisture absorption (Langmuir model) and heat transfer (Fourier law) in polymeric composites reinforced by vegetable fibers using a three-dimensional and transient approach. The analytical (Laplace Transform method) and numerical (Finite Volume Method) solutions of the governing equations are presented and analyzed. Results of concentrations of free and entrapped solute, moisture content, temperature and average moisture content obtained within the material at different instants of the process are presented and analyzed. It has been found that the gradients of molecule concentrations (free and entrapped) are higher on the surface of the material and how higher the concentration of free solute, will be higher the concentration of solute entrapped within the material at any time. In addition, it was observed that the geometric effect and the physical parameters of the Langmuir Model directly influence the kinetics and distribution of the mass properties.