Influnce of in situ depositing size-controlled nano-SiO2 particles on the mechanical and surface properties of jute fibers

Jute fibers with high crystallinity, high specific strength, and biodegradability were extensively applied as reinforcements for advanced polymer composites. However, the surface flaws of jute fibers not only affected its properties, but also formed the interface voids between jute fibers and polymer matrix. In this work, the surface flaws of jute fibers were successfully filled up by depositing sizecontrolled nano-SiO2 particles via the sol-gel technique. In order to enhance the combination between the nano-SiO2 particles and jute fibers, the carboxyl groups were introduced onto the fiber surface by the carboxymethylated pre-treatment. The nano-SiO2 particles were chemically deposited as confirmed by infrared spectroscopic analysis. The deposition amount and particle size of nano-SiO2 on the surface of jute fibers during nucleation and growth process were manipulated by selecting the tetraethylorthosilicate (TEOS) concentration. The results showed that the surface flaws of jute fibers could be filled up by nano-SiO2 particles (80 nm-90 nm) with the TEOS concentration of 0.21 mol/L. The presence of nano-SiO2 particles contributed to the significant enhancement on the surface free energy and tensile strength of jute fibers. Compared with carboxymethylated fibers, the surface free energy and tensile strength of nano-SiO2 deposited fibers were increased by 17.8% and 20.9%, respectively. This was expected to be contributed to the improvement of surface properties of nano- SiO2 deposited fibers. Moreover, the possible depositing mechanism of nano-SiO2 particles onto the surface of jute fibers was proposed and schematically demonstrated.