Studies On Preparation And Properties Of Bamboo Hemicellulose/Graphene Oxide Composite Films

With the increasing shortages of petrochemical resources and the deterioration of environmental pollution,the demand for green renewable resource was increased.In particular,the functional composites materials manufactured from cellulose,lignin and hemicellulose extracted from agricultural and forestry biomass waste.It provided a theory for the application of biomass-based materials in biomedicine,tissue engineering scaffolds,flexible electronic devices and absorbent materials.In this study,quaternized and carboxymethyl hemicelluloses were successfully prepared from bamboo by etherification modification.A series of functional composite films based on the hemicelluloses derivative were successfully prepared by vacuum filtration and casting with graphene oxide of two-dimensional structure as reinforcing phase,which provided a theoretical basis for high-valued utilization of bamboo hemicelluloses.The main conclusions were as follows:(1)Quaternized and carboxymethyl hemicelluloses were prepared from bamboo by etherification.The obtained modified hemicelluloses were characterized by FT-IR,1H-NMR and GPC.The results of FT-IR,1H-NMR and GPC showed that the modification was successfully.In addition,graphene oxide was synthesized by improved Hummer's method.The results of FT-IR,XRD,XPS,TEM and Raman showed that the preparation was successfully,and the content of oxygen element reached 30.51%.The crystal plane spacing of(001)reached 0.769 nm,which made it possible to combine with the modified hemicellulose.(2)The humidity sensitivity hybrid films were prepared by one-step vacuum filtration method from the quaternized hemicelluloses and graphene oxide.The obtained films were investigated by SEM,XRD,FT-IR and DMA,and the relationships between humidity sensitivity and structure of hybrid films were also detected.The results showed that the mechanical properties of the hybrid films were improved significantly by adding graphene oxide compared with the pure quaternized hemicelluloses film.When the mass fraction of graphene oxide was 4.8%,the mechanical properties of the hybrid film were best with the stress and strain at break of 43.83 MPa and 4.52%,respectively.In addition,the hybrid films could respond to humidity quickly,which showed that it has high mechanical strength at low humidity environment with the decreasing of the mechanical strength at high humidity environment.The shape of the hybrid films could be changed and curled in seconds under different humidity conditions,which was mainly caused by the non-uniform internal stress caused by the entering of water molecules to the composite system.This humidity sensitive hybrid films would have a certain application potential in humidity threshold switch,humidity sensor and other fields.(3)The carboxymethyl hemicelluloses/chitosan/graphene oxide composite films were prepared by casting method.The relationships between structure and properties of composite films were investigated by SEM,AFM,XRD,FT-IR,DMA and TGA.The results showed that the mechanical properties of the composite films were improved obviously by adding graphene oxide.When the mass fraction of graphene oxide was 0.5%the mechanical properties of composite film were the best.In addition,the oxygen resistances of the composite films were increased greatly with the addition of graphene oxide.This was mainly due to that graphene oxide could absorbed the energy through slipping between layers and prevented the passage of gases effectively in the composite system.Furthermore,the composite film exhibited excellent anti-ultraviolet ability,and the ultraviolet transmittance in the UV-B and UV-C regions was 0.These results provided a theoretical basis for the application of composite film materials in packaging materials and coating materials.