Polyaniline and magnetite on curaua fibers for molecular interface improvement with a cement matrix

Abstract

Modifications were used in the natural fibers, aiming for a more outstanding adhesion between vegetable fibers and cement-based matrices. As a reinforcement load, improvements in dimensional stability (due to high hydrophilicity) and compatibility between both phases are necessary. In this work, reinforcement fibers were developed from hornified curaua fibers (HF) modified with polyaniline (HF-PAni), magnetite (HF-Mag), and both (HF-PAni/Mag). The obtained materials were tested on adhesion compatibility with the Portland cement matrix through the fiber's pullout test and microstructural analysis. The modified fibers were analyzed by infrared spectrometry (FTIR), water retention value (WRV%), Scanning Electron Microscopy coupled with X-ray Dispersive Energy (SEM-EDS), Direct Traction, Electrical Resistivity, and Magnetic Force. The last two analyses are due to each surface modification specific properties. The water retention value results show a reduction in the water absorption capability for all the treated fibers, indicating a gain in dimensional stability, especially for the PAni covering samples, due to the waterproofing of the fiber promoted by the hydrophobic polymer. Furthermore, the mechanical results of the HF-PAni sample showed good tensile strength responses. With the coating of the hybrid HF-PAni/Mag, the pullout test results indicate a significant improvement in fiber-matrix adhesion, resulting in a 40% increase in the adhesion stress compared to hornified fiber (HF).