Physicomechanical, water absorption and thermal properties and morphology of Paederia foetida fiber–Al₂O₃ powder hybrid‐reinforced epoxy composites

Abstract

Hybridization of natural fibers with ceramic materials for reinforcing composites allows to optimize properties of these materials. For this reason, the present study aims to investigate physical, mechanical, water absorption, swelling and thermal properties as well as morphological characteristics of the hybrid Paederia foetida fibers–alumina powder (PFs/Al2O3) reinforced epoxy composite. Epoxy resin served as the matrix, while Paederia foetida fibers (PFs) and alumina powder (Al2O3) were employed as reinforcement. Five types of composites were fabricated using the hot‐pressing technique. The corresponding ratios of PFs:Al2O3 volume fractions considered here were 0%:40% (SFA), 10%:30% (SFB), 20%:20% (SFC), 30%:10% (SFD), and 40:0% (SFE), respectively. The results reveal that the density of the hybrid PFs/Al2O3 composites decreased for increasing volume fractions of PFs: from 2.173 g/cm3 of SFA composite to 1.042 g/cm3 of SFE composite. The highest values of tensile strength (i.e. 49.085 MPa), tensile elastic modulus (i.e. 1.431GPa) and impact strength (24 kJ/m2) were obtained for the SFD composite material with 30% volume fraction of PFs and 10% volume fraction of Al2O3: this happened because interface bonds between PFs, Al2O3and Epoxy phases achieved their optimal configuration. Overall, mechanical properties of hybrid PFs‐Al2O3 reinforced epoxy composites were superior over those of the composites reinforced only by PF fibers or only by Al2O3 powder. Water absorption and swellability reached their maximum values at the steady state occurring after tested samples remained immersed in the water for 820 h. The SFE composite reinforced only by PFs presented the highest water absorption and swelling (i.e. 6.034% and 5.81%, respectively) while for all other hybrid composites (e.g. SFD, SFC and SFB) these two quantities remained below 5%. Density and volume fraction of voids of hybrid PFs‐Al2O3 reinforced composites were consistent with the corresponding properties of the composites reinforced only by Al2O3 or PFs. The SFD composite was also the most thermally stable material. SEM observations of fractured surfaces indicated that the microstructure of PFs‐Al2O3 reinforced epoxy composites presents several voids, fiber pullouts and transverse fibers, which concur to optimize the mechanical response of the composite material. Remarkably, the SFD composite material was highly competitive with the most recently developed hybrid composites employing natural reinforcements.This article is protected by copyright. All rights reserved.