Charpy impact test of epoxy composites reinforced with untreated and mercerized mallow fibers

The mallow fiber (Urena lobate, linn) is demonstrating a great potential as reinforcement in polymer matrix composites. The difficulty in the use of the mallow, as in other natural lignocellulosic fibers (NLFs), is its hydrophilic compatibility with polymeric matrices that are typically hydrophobic. In order to improve the adhesion between the fiber surface and polymeric matrices, mallow fibers were subjected to mercerization treatment. In this work composites were produced with epoxy matrix reinforced with 30 vol% of mallow fibers, both untreated and mercerized. By means of XRD analysis it was verified the variation of crystallinity in fibers treated with different NaOH solutions as well as immersion times and agitation. After this XRD preliminary analysis, a treatment of 5% NaOH solution for 24h without agitation was selected. The objective was to compare the Charpy impact energy of composites specimens produced with untreated mallow fibers and treated for the higher crystallinity obtained after the selected mercerization. For the analysis of impact energy the Tukey test was applied from which it could be assured, with a confidence level of 95%, that the epoxy specimens reinforced with 30 vol% of untreated mallow fibers, had the best performance. (C) 2018 Brazilian Metallurgical, Materials and Mining Association. Published by Elsevier Editora Ltda.