1 ST BRAZILIAN CONFERENCE ON COMPOSITE MATERIALS - BCCM1 Natal-RN, July 16-19, 2012 1 THE EFFECTS OF CHEMICAL TREATMENT AND FIBRE ORIENTATION IN SISAL COMPOSITES Vieira, L.M.G. 1* , Santos, J.C. 1 , Sousa, S.S. 1 , Vieira, K. 2 , Mano, V. 2 , Christóforo, A.L. 1 , Panzera, T.H. 1 1 Department of Mechanical Engineering, UFSJ, São João Del Rei, Brazil 2 Department of Natural Science, UFSJ, São João Del Rei, Brazil. * Corresponding author (lucianomgv@yahoo.com.br) Abstract: Composite materials are designed to support axial, transverse, shear and combined loadings. The use of natural fibres such as coconut, banana, sisal, bamboo and others has been the focus of much research. The biocomposites present low density, high specific strength and attractive cost, besides the fact the fibres come from renewable sources and are biodegradable. The physic-mechanical properties are influenced by the percentage and orientation of fibres, and fibre-matrix interface. Chemical treatments, such as mercerization, acetylation, heat, have been investigated to improve the adhesion between natural fibres and matrix phase, This work investigates the effect of orientation of fibres and a chemical treatment in the flexural strength of biocomposites made of five unidirectional layers oriented such as, 0°/0°/0°/0°/0° and 0°/90°/0°/90°/0°. The results showed that the chemical treatment was able to enhance the interface adhesion. The composites fabricated as 0°/90°/0°/90°/0° showed a lower flexural strength compared to those composites laminated at 0°. Keywords: sisal, laminated composites, orientation, chemical treatment