Extraction process optimization of Juncus plant fibers for its use in a green composite

In the context of the development of green building materials using plant fibers, this research has focused on the characterization of natural fibers extracted from Juncus plant, commonly called Juncus. A well-known chemical extraction method was applied here for the first time at our knowledge to the Juncus plant, in order to obtain better mechanical characteristics (tensile strength and elastic modulus) and better surface morphology. Therefore, a chemical treatment with alkalization through various factors such as temperature, NaOH concentration (alkalizing agent), presence or not of sodium dithionite Na2S2O4 (for reducing lignin) and sodium hypochlorite NaOCl (chlorine bleach delignification agent) was performed. This study aims to determine the effects of different chemical treatments applied to the fiber extraction of Juncus stem, on the change in fiber diameter, surface state morphology, density, tensile strength and elastic modulus. As one of the Juncus fiber treatments considered in this work, the cold alkali-treatment did not give good results in terms of delignification of the Juncus fibers (There is always non-cellulosic products on the treated fiber) and low values of tensile stress and modulus of elasticity. The treatment with a solution of 8% NaOH, sodium hypochlorite and sodium dithionite at hot temperature present the best result due to the effective delignification of the fibers which has allowed reaching highest tensile strength and highest elastic modulus.