Study On The Preparation Of High-strength Cellulose Fiber And Its Anti-ultraviolet Performance

Cellulose is the most productive renewable resource in the world.With the depletion of petroleum resources,the development of cellulose as raw material for the preparation of various high-performance materials has good prospects.Using cellulose as raw material to prepare high-performance and high-strength fibers can replace some synthetic polymer fibers,greatly alleviating the pressure of energy.The high stability,good spinnability and recyclability of DMAc/LiCl cellulose dissolution system make it a good choice for dissolving cellulose.However,the mechanical properties of cellulose prepared by DMAc/LiCl solution system are poor due to its amorphous micro-structure.In order to overcome this shortcoming,high strength cellulose fibers were prepared by chemical crosslinking method and induced crystallization method respectively.The details are as follows:Chemical crosslinking method is to dissolve the crosslinking agent to benzyl dichloride in cellulose solution to form homogeneous solution,scrape it into a film,and then immerse it in NaOH solution to complete crosslinking.The effects of reaction conditions such as the amount of cross-linking agent(molar ratio),reaction time and NaOH concentration on the tensile strength of cellulose cross-linking films were studied by orthogonal design.The optimum reaction conditions were obtained:the amount of cross-linking agent was 1:0.125(-OH:-Cl),the concentration of NaOH was 0.1 mol/L and the reaction time was 3 h.FTIR,XPS,XRD and SEM were used to characterize the cross-linking and the effect of cross-linking conditions on the structure of cellulose films.The tensile strength,ultraviolet resistance and thermal stability of cellulose films were also characterized.The cross-linked regenerated cellulose fibers were prepared according to the above optimal conditions,and the surface structure,mechanical properties and ultraviolet resistance of the fibers were characterized.The results showed that the surface of cross-linked cellulose fibers became rough and the breaking strength reached 2.13 cN/dtex,which was 2.3 times higher than that of non-cross-linked fibers;the breaking elongation reached 31.92%,which was 1.3 times higher;and the cross-linked fibers had certain ultraviolet resistance.Cellulose composite fibers were prepared by induction crystallization.Firstly,1,7-dibromoheptane and cyanobiphenyl were synthesized by reaction of 1,7-dibromoheptane and cyanobiphenyl with acetonitrile at 80 C for 8 h,and then the nucleating agent was synthesized by reaction of the intermediate with N-methylimidazole at 80 C for 6 h.Cellulose composite film was prepared by adding nucleating agent to cellulose solution.The effect of nucleating agent on the crystallization behavior of cellulose composite films was investigated by POM and DSC.The structure of cellulose composite films was characterized by FTIR,XRD and SEM.At the same time,the mechanical properties and ultraviolet resistance of cellulose composite films were characterized.The results showed that induced crystallization could improve the mechanical properties and ultraviolet resistance of cellulose materials.Cellulose composite fibers were prepared by adding nucleating agent into cellulose spinning solution and inducing cellulose to form small crystals by controlling the temperature of coagulation bath temperature and air bath temperature.The results showed that the breaking strength of the modified fibers reached 0.89 cN/dtex,increased by 37.3%,the elongation at break increased by 109%,and had some anti-ultraviolet properties.