Influence of chemical modifications on water-sorption and mechanical properties of Agave fibres

Because of their good mechanical properties and low density, natural fibres are more and more considered as reinforcement in composite materials. In this work, to improve the adhesion between a polyester matrix (unsaturated polyester resin) and Agave (Agave Americana L.) fibres and to increase their moisture resistance, chemical surface treatments have been performed on the fibres. These different treatments were performed with acetic anhydride (Ac), styrene (S), acrylic acid (AA) and maleic anhydride (MA). The modified Agave fibres were characterized by means of infrared spectroscopy, surface energy, and microscopic analysis. The effect of these treatments on water sorption was investigated by using a gravimetric static equilibrium method. Water sorption isotherms have been deduced from kinetic data. The Park model based on the three sorption modes: Langmuir, Henry’s law, and clustering, was successfully used to simulate the experimental sorption data. It was found that the chemical treatments used reduced the overall water uptake of the Agave fibres. In particular, the acetylation treatment allows to significantly increase the moisture resistance of these fibres. The mechanical properties of the treated fibres were analyzed from tensile tests. The tensile modulus, the breaking strength and the breaking strain depend on the chemical treatment used.