Study On Depositing SiO₂ Nanoparticles On The Surface Of Jute Fibers Via Hydrothermal Method And Its Reinforced Polypropylene Composites

In recent years,jute fiber reinforced polypropylene?PP?composites have been gradually applied in electronics,automobile,aviation and construction fields due to their advantages of light weight,low cost,low production energy consumption and biodegradability.However,due to the poor interfacial compatibility between jute fiber and PP,the reinforcing effect of jute fiber can not be fully exerted,and the mechanical properties of the composites were much lower than expected.Therefore,SiO₂ nanoparticles were deposited on the surface of jute fibers via hydrothermal method to improve the interface property of jute fiber/PP composites.Jute fibers were treated with alkali treatment and acid/alkali treatment,respectively,and the surface morphology,chemical composition,crystallinity and polarity of jute fibers before and after treatment were tested and analyzed.The results showed that both alkali treatment and acid/alkali treatment could effectively remove the low-strength colloid from the surface of jute fibers,which exposed a large number of grooves and increased the surface roughness of jute fibers.Meanwhile,the degree of freedom of orderly arrangement of cellulose in jute fiber was increased due to the removal of amorphous colloid,the crystallinity of jute fiber was increased accordingly.The acid/alkali treatment was able to more thoroughly remove the colloid from the surface of jute fiber than the alkali treatment,which could avoid the generation of interfacial voids due to the volatilization of the colloid during the preparation of the jute fiber/PP composites.SiO₂ nanoparticles were deposited on the surface of the acid/alkali pretreated jute fiber via hydrothermal method using tetraethoxysilane?TEOS?as the silicon source under the catalysis of ammonia.The effects of hydrothermal process parameters and pretreatment methods on the surface morphology and mechanical properties of jute fiber were studied.Afterwards,the optimal hydrothermal process parameters for the deposition of nano-SiO₂ on the surface of jute fiber were determined.When the amount of jute fiber was 0.1g,the concentration of TEOS was 0.05M,the concentration of ammonia was 0.55M,the reation temperature was 100°C,and the deposition time was 6h,the deposition amount of SiO₂ nanoparticles on the surface of jute fiber was 4.29%,the averge particle size was 65±2nm,and SiO₂ nanoparticles of this size could fill in the surface defects of the jute fibers to a large extent,hence the comprehensive performance of the jute fiber was the best.Finally,based on the experimental results,the deposition mechanism of SiO₂ nanoparticles on the surface of jute fibers was proposed.The composites were fabricated by the lamination molding method using the nano-SiO₂deposited jute fibers as the reinforcement and PP as the matrix,in which the content of jute fiber was35wt%,and the mechanical properties and interface properties of the composites were analyzed to investigate the effects of SiO₂ nanoparticles on the interface properties of composites..The results showed that compared with the untreated jute fiber/PP composites,the tensile strength,flexural strength and impact strength of the nano-SiO₂ deposited jute fiber/PP composites were enhanced by29.89%,35.22%and 25.65%,respectively,and the water absorption capacity was decreased by35.06%.What's more,the fracture morphology of the composites indicated the nano-SiO₂ deposited jute fibers were tightly bonded to PP,and a large amount of PP was adhered to the surface of the jute fiber.These behaviors demonstrated that the deposition of nano-SiO₂ on the surface of acid/alkali pretreated jute fiber by hydrothermal method could effectively improve the interfacial compatibility between jute fibers and PP.