Preparation And Electrical Sensing Properties Of Cellulose Matrix Composites

Cellulose is a natural polymer compound that widely exists in nature,has good biocompatibility,and is a green resource that is friendly to the environment.Due to the existence of many active hydroxyl groups in the molecular structure of cellulose,it is easy to modify and prepare different types of derivatives,and can be used as a matrix or reinforcing material to composite with other materials to prepare functional materials.In this paper,low-substituted water-soluble cellulose acetate(WSCA)and graphene oxide(GO)are used as raw materials to prepare composite membrane materials and aerogel materials.The structural properties of the material and aerogel materials were studied,and the conclusions were as follows:(1)Using a simple composite method,a highly sensitive reduced graphene oxide/cellulose acetate composite moisture-sensitive film material was prepared.Using WSCA as the humidity sensing layer and reduced graphene oxide(r GO)as the resistive transduction layer,the prepared r GO/WSCA composite membrane has the advantages of low cost,green environmental protection,fast response speed,high signal intensity,and low hysteresis.The composite film has certain mechanical strength and high thermal stability,can be bent and folded arbitrarily,and the maximum tensile stress can reach 205 MPa.In a 97%relative humidity environment,the maximum response of the thin film sensor can reach 140%,and a stable moisture absorption-dehumidification cycle can be performed in the relative humidity range of22%to 97%.These features provide a reference for making portable and wearable humidity sensors.(2)In view of the problem of sheet stacking in the reduction process of graphene oxide,the preparation method of the humidity-sensitive composite film was improved in the experiment,using the amphiphilic group of the WSCA molecule,in which the hydrophilic hydroxyl group was combined with the oxygen-containing functional group of the GO sheet,the hydrophobic-CH₃ group was combined with the hydrophobic C skeleton of the GO sheet,and WSCA was used as the dispersant in the GO reduction system to prepare the r GO/WSCA composite film by the"first mixing"method.The moisture-sensitive composite film prepared by the improved method has greatly improved mechanical properties,heat resistance,moisture-sensitivity and electrical conductivity of the film.The tensile stress is increased to a maximum of 297MPa,an increase of 92 MPa,and the maximum response value of the humidity sensor is increased to 240.7%,and it can also monitor the breathing frequency of the human body in different states,broadening the application field.(3)Two kinds of r GO/WSCA carbon aerogels were prepared by hydrothermal method at 180°C and chemical static method at 95°C,respectively,which were used as electrode materials for the preparation of supercapacitors,and their electrical properties were tested and compared.Both cellulose and graphene aerogels have a 3D network structure,and the performance of the gel is the best when WSCA:GO=3:7.The specific capacitances of the aerogel materials prepared by the two methods at 1 A g^-1 are respectively For 215 F g^-1,319.7 F g^-1.By comparison,the 95°C chemical reduction method is superior to the 180°C hydrothermal reduction method,and the addition of WSCA effectively increases the area for electron storage and transport,which can be used as a green and sustainable carbon precursor in the field of energy storage.