Preparation And Of Cellulose Based Carbon Aerogels And Its Pressure Sensitive Properties Study

Cellulose has attracted much attention due to its renewable,sustainable,biodegradable,non-toxic properties,and high strength and stiffness.It has a good prospect of high value utilization,such as carbon aerogel preparation raw material.Carbon aerogels have attracted much attention in the research of wearable devices due to their low density,flexibility,electrical conductivity and chemical inertia.Carbon aerogels for wearable use need to have excellent mechanical properties and high sensitivity,while carbon aerogels prepared from nanocellulose have poor properties.In order to improve the properties of carbon aerogels,this paper designs the microstructure of carbon aerogels with special layer structure.The structure forming mechanism of carbon aerogel and its mechanical,electrical properties were studied.A strategy of using lignin as carbon welding was proposed,in which the carbonized nanocellulose was welded together by lignin to reduce its polycondensation during carbonization,so as to maintain the special layered structure of carbon aerogel.Carbon aerogels have high mechanical and electrical properties because of the special layered structure.The specific results are as follows,?1?the carbon welding formed by the addition of lignin makes the CNC welded together,which hinders the fracture and deformation of CNC during the carbonization process.?2?when the mass ratio between CNC and lignin in the dispersion was 1:0.4,the carbon aerogel obtained had better mechanical properties.The carbon aerogel prepared under this condition has super compressibility,elasticity and fatigue resistance,and can withstand 99%extreme strain.Through the 50%strain for 1000 cycles,the height retention rate is 98%,and after the deformation of 30%for 10000 cycles,the height retention rate is 100%.?3?carbon aerogel has a stable current response and can feel the tiny pressure generated by 3?L water droplets,with a sensitivity up to 172.738k Pa^-1.The carbon aerogel can be used to detect the fingers bending and human pulse.Nanocellulose,GO and lignin were mixed in a certain proportion into a dispersion solution,and carbon aerogel was prepared by directional freezing and carbonization.The growth direction of ice crystals was designed by directional freezing to make the prepared carbon aerogel have a special layered structure,and the interaction between the layers of carbon aerogel was increased by lignin.After the microstructure design and the support of cellulose to the layered structure,the carbon aerogel has excellent performance.The results are as follows,?1?CNC can reduce the re-accumulation of GO in the annealing process,and serve as a carrier to maintain the structure and morphology of the carbon aerogel and enhance the formation of the carbon aerogel skeleton.?2?The carbon aerogels prepared with CNC,GO and lignin as raw materials through directional freezing and carbonization had a good layered wavy structure,while the carbon aerogels prepared with GO and lignin as raw materials had a disordered structure.The CNC-GO-Lignin carbon aerogel with layered ordered structure quickly recovered 92%of its original height after a complete compression,while the disordered structure of GO-Lignin carbon aerogel had poor mechanical properties and was directly ulcerated after compression without elasticity.?3?CNC-GO/Lignin carbon aerogel has excellent elasticity,compressibility and fatigue resistance.It can withstand 99%of extreme strain.CNC-GO-lignin carbon aerogel has good current response and sensitivity.The sensitivity was as high as 190.94 k Pa^-1 at the small pressure?6Pa.The strain sensitivity of the carbon aerogel was 16.17 GF in the small strain range of 5%.The carbon aerogel has good sensitivity to detect the weak signals such as water droplets and human pulse.