Submit Manuscript | http://medcraveonline.com Abbreviations: Mag, magnetite; PAni, polyaniline; APS, am- monium persulfate; FTIR, fourier transformed infrared; TGA, thermal gravimetric analysis; PVA, poly (vinyl alcohol); PP, poly propylene Introduction Cementitious composite is one of the most widely used construction materials in the world because its abundant resources, strong adaptability and mature production process. 1 Despite cementitious matrices present good compression strength, they are brittle and usually break when suffer some strain caused by tensile effort. Aiming to overpass this problem some fbers can be used as reinforcement, being the most commonly used fbers of steel, glass, poly (vinyl alcohol) (PVA), polypropylene (PP) and carbon. 2 However, vegetable fbers, also named lignocellulosic fbers, has been used for this application due to their biodegradability, abundance, considering they are from renewable sources, low cost and low health risk. As disadvantage the vegetable fbers present low adhesion on the cementitious matrix, high water absorption by the fber and low durability in alkaline media, related to the hemicelluloses and lignin degradation followed by fbers mineralization. 3 The mechanical properties of a vegetable fber-reinforced composite depend on many parameters, such as fber strength, modulus, fber length and orientation, in addition to the fber-matrix interfacial bond strength. A strong fber-matrix interface bond is critical for high mechanical properties of the composites. A good interfacial bond is required for effective stress transfer from the matrix to the fber whereby maximum utilization of the fber strength in the composite is achieved. Modifcation to the fber also improves resistance to moisture induced degradation of the interface and the composite properties. In addition, factors like processing conditions/ techniques have signifcant infuence on the mechanical properties of fber reinforced composites. 4 To achieve the desired properties, mainly to improve the adhesion between the fbers with the cementitious matrix, some surface treatments have been studied. 5–8 In this work, mango seed fbers surface were chemically modifed by the coating of a magnetite layer and a double coating of polyaniline layer and magnetite layer. The mango seed fber was chosen because they are very abundant in Brazil and their industrial process produces from 30 to 40% of wastes, which means thousands of waste tons per year. 9 The mango seed fber was obtained from a simple washing and fltering process after the extraction of the fruit pulp. This surface modifcation aimed to get better the fber/matrix adhesion as well as to promote a chemical protection of the fber. The fbers, before and after the surface modifcations, were characterized by FTIR and TGA, to make sure the effciency of surface modifcation. After that, the fbers were used as fller in a cementitious matrix and their mechanical resistance was tested by compression evaluation. The fbers presence has improved the compression resistance of all composites; however the double coated fber presented similar young’s modulus than natural fber, but associated the chemical protection on the fber. Materials and methods Materials Mango seed fbers were extracted from some fruits collected straightly from a mangoes tree. The fruit extract was removed leaving the fbers. They were washed and dried to be used. All used reactants in the modifcations are P.A. and they were supplied by Vetec. The used water was in house distillated. MOJ Poly Sci. 2017;1(5):178‒181. 178 © 2017 Moura et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and build upon your work non-commercially. Mango seed fbers surface chemical modifcation applied as mechanical reinforcement in cementitious composites Volume 1 Issue 5 - 2017 Moura BR, 1 Oliveira GE, 2 Toledo Filho RD, 2 Souza FG 1,2 1 Instituto de Macromoléculas, Universidade Federal do Rio de Janeiro(IMA/UFRJ), Brazil 2 Programa de Engenharia Civil, Universidade Federal do Rio de Janeiro(PEC /COPPE/UFRJ), Brazil Correspondence: Oliveira GE, Programa de Engenharia Civil, Universidade Federal do Rio de Janeiro(PEC / COPPE/UFRJ), Av. Horácio de Macedo, 2030, I-110, Cidade Universitária, Rio de Janeiro-RJ, Brazil, Fax 21941-590, Email geizaesperandio@gmail.com Received: October 28, 2017 | Published: November 29, 2017 Abstract As well known, the fibers can be used as mechanical reinforcement fillers in the composites. In the specific case of vegetable fibers in cementitious matrices, there are some concerns about low adhesion on the matrix, high water absorption by the fiber and low durability in alkaline media, which can be improved by some chemical treatments on the fiber surface. This present work aim to evaluate a single coating of a magnetite layer and a double coating of polyaniline layer and magnetite layer on the mango seed fiber surface. These coating aimed to get better the fiber/matrix adhesion as well as to promote a chemical protection of the fiber. The natural and coated mango seed fibers were characterized by FTIR and TGA, to evaluate the coating process result. The morphology of the composites presents no change using natural or coated fibers. The mechanical properties of the composites containing the fibers, natural and coated, were determined by compression tests. The fibers presence, independent on the surface treatment, got better the all composites mechanical properties. On the other hand, the composite with 0.5% of double coated fibers had similar young’s modulus than natural fiber, associated the chemical protection on the fiber. Keywords: mango seed fiber, chemical modification, magnetite, polyaniline, mechanical reinforcement MOJ Polymer Science Research Article Open Access