Effect of chemical treatments of Alfa (Stipa tenacissima) fibres on water-sorption properties

Natural fibres have prooved to be an excellent reinforcers in composite materials. Since many years, for economic and environmental reasons, there has been an increasing interest in using plant fibres in composite systems. However, the main disadvantage of the natural fibres being used as reinforcers is their hydrophilic nature, therefore, the ageing of composite materials can be pronounced because of the diffusion of water molecules leading to a swelling effect. Moreover, the adhesion between natural fibres and the polymer matrix is insufficient. In this work, various chemical surface treatments have been performed on the Alfa (Stipa tenacissima) fibre. These different treatments involve acetylation (Ac), with the help of chemicals such as styrene (S), acrylic acid (AA) and maleic anhydride (MA). The treatment effects on the fibres have been characterized by means of infrared spectroscopy, surface energy, and microscopy analysis. A detailed investigation on the water sorption characteristics of Alfa fibres has been carried out. It was found that treatments reduced the overall water uptake of Alfa fibres. In particular styrene treatment allows to increase significantly moisture resistance of these fibres.