Moisture Absorption and Its Effects on the Mechanical Properties of Biopolymers Reinforced by Curauá Fiber and Montmorillonite Clay: A Transient Experimental Evaluation
Gustavo Henrique de Almeida Barbalho, J.J. Silva Nascimento, Lucineide Balbino da Silva, João M. P. Q. Delgado, Anderson Ferreira Vilela, Joseane F. Pereira, Ivonete B. Santos, Márcia Ramos Luíz, Larissa da Silva Santos Pinheiro, Adriano Rodrigues da Silva, Roberto Mendonça Faria, Francisco Samuel Chaves, Antônio Gilson Barbosa de Lima
Abstract
Biocomposites are defined as eco-friendly materials from an environmental point of view. Because of the importance of this class of materials, their study is important, especially in moist and heated conditions. In this sense, this work aims to evaluate the transient behavior of moisture absorption and mechanical performance of biocomposites composed of a matrix of high-density biopolyethylene (originated from ethanol produced from sugarcane) filled with curauá vegetable fiber and organophilic montmorillonite clay. For this purpose, dry biocomposites filled with organophilic montmorillonite clay and curauá fiber (1, 3, and 5 wt.%) were prepared using a hand lay-up technique and subjected to moisture absorption and mechanical (flexural and impact tests) characterizations at different times. The experiments were carried out at water bath temperatures of 30 °C and 70 °C. The results have proven the strong influence of chemical composition and temperature on the moisture absorption behavior of biocomposites across time. For a higher percentage of reinforcement on the polymeric matrix, a higher moisture migration rate was verified, reaching a higher hygroscopic equilibrium condition at 16.9% for 5 wt.% of curauá fiber and 10.25% for 5 wt.% of montmorillonite clay particles. In contrast, the mechanical properties of all of the biocomposites were strongly reduced with an increasing moisture content, especially at higher fiber content and water bath temperature conditions. The innovative aspects of this research are related to the study of a new material and its transient mechanical behavior in dry and wet conditions.