Study On Regenerated Cellulose Nanocomposites Construction And Process Rheology Properties

This paper mainly studies the construction of high performance regenerated cellulose nanocomposites in acetate two-component cellulose solvent.Firstly,the rheological properties such as viscoelasticity,complex modulus and viscous flow activation energy of the system were investigated to reveal the structural changes of the cellulose solution after adding other components.The results show that when the water content in the cellulose solution is less than 4wt.%,the system remains in a solution state.In this range,the increase of water content will cause the viscosity of the system to decrease slightly from 298 Pa s of cellulose stock solution to about 202 Pa s.Continued increase in water content will cause the solution to gel,the viscosity of the aqueous 6 wt.%cellulose solution sharply increases to about 2000 Pa s,the modulus intersection is greatly advanced from 12 Hz to 7 Hz,and the gel of the solution The state is not thermally reversible.The effect of the solution on the change of the nature of the solution after adding ethanol to the solution is mainly similar to water,and the dilution effect is mainly exhibited at a low addition amount,and the gelation tendency occurs at a high addition amount.Dimethyl sulfoxide and N,N-dimethylacetamide can be miscible with the cellulose solution after addition.The addition of such a polar aprotic solution only causes the cellulose solution to be diluted,and the viscosity of the system after adding 50 wt.%of dimethyl sulfoxide.The drop was drastically reduced to about 30 Pa s,confirming that the decrease in the electrolyte component content in the system did not cause cellulose precipitation or solution gelation.Based on the conclusion that dimethyl sulfoxide and N,N-dimethylacetamide are added without changing the dissolution state of cellulose in the solution,nanocellulose is selected as the reinforcing phase,and the nanocellulose dispersion is prepared by using dimethyl sulfoxide as the dispersion medium.The cellulose solution was mixed to obtain a whole cellulose mixture containing dissolved cellulose and dispersed nanocellulose,and a whole cellulose composite fiber was prepared by a dry-wet spinning method.The results show that the whole cellulose composite fiber is a composite material containing a plurality of cellulose crystal forms,and no phase interface exists between the nanocellulose and the regenerated cellulose as a reinforcing phase in the scanning electron microscope image.The addition of nanocellulose improves the thermal stability and mechanical properties of the fiber.The tensile strength of the regenerated cellulose fiber containing 2.5wt.%of nanocellulose is 302.4Mpa.The mechanical properties of the fiber continue to increase with the addition amount,and the nanofibers are contained.The 10.Owt.%whole cellulose composite fiber has the highest tensile strength and the tensile strength can reach 403.7Mpa.The preparation conditions of regenerated cellulose aerogel under composite solvent were studied.The results show that the solid content of 4wt.%and the aerogel porosity and specific surface area obtained by supercritical drying method are ideal.A whole cellulose composite aerogel is prepared on the basis of a whole cellulose mixture.The physical structure,chemical structure,mechanical properties and thermal insulation properties of the whole cellulose aerogel were characterized.The results show that the whole cellulose aerogel has a typical porous structure,and the aerogel containing 7.5wt.%nanocellulose has a specific surface area of 274 m3/g compared with 324m3/g of pure regenerated cellulose aerogel.The hydroxylated carbon nanotubes were used as the reinforcing phase,and the acetate/dimethyl sulfoxide was used as the dispersion.The amphiphilicity of the acetate in the solvent was used to disperse the carbon nanotubes to prepare the hydroxylated carbon nanotubes/recycled fibers.Composite fiber.Studies have shown that the dispersed particle size of hydroxylated carbon nanotubes is about 1-5?m at 2.5wt.%,and the undifferentiated carbon nanotubes have a particle size of about 15-20?m.The dispersibility of hydroxylated carbon nanotubes is better than that.Modified carbon nanotubes.The characterization and analysis of the composition,structure and properties of the composite cellulose showed that there is a hydrogen bond interaction between the hydroxylated carbon nanotubes and the cellulose.The addition of carbon nanotubes improves the crystallinity and thermal stability of the regenerated cellulose fibers.Properties and mechanical properties,the composite fiber with 5wt.%carbon nanotubes has a tensile strength of up to 390.7Mpa.Using isophorone diisocyanate as a crosslinking agent,the hydroxylated carbon nanotubes are crosslinked with nanocellulose crystals to obtain a carbon nanotube-nanocellulose composite(CNT-CNC),and the chemical structure of the composite is carried out.The analysis showed that the carbon-nitrogen bond characteristic peak at 285.6 eV appeared in the XPS spectrum of the cross-linked carbon nanotubes and nanocellulose,indicating that there is a chemical bond between the two,and the XRD data proves that there is no cross-linking reaction.Destroy the crystal structure of carbon nanotubes and nanocellulose.Then,the CNT-CNC nanocomposite was dispersed as a reinforcing phase in N,N-dimethylacetamide.The dispersion was mixed with the cellulose solution,and the composite fiber was prepared by dry-wet method.The physical morphology of the composite fiber was studied.Chemical structure and mechanical properties.The results show that the composite material has further improved properties compared with the pure carbon nanotube CNT-CNC nanocomposite and the regenerated cellulose matrix.and the composite fiber containing 10wt.%CNT-CNC nanocomposite.The tensile strength can reach 425.3Mpa.