Preparation Of Cellulose Nanofibrils/Aluminum Nitride Composite And Their Thermal Conductivity

Cellulose,as a rich natural resource on the earth,it is environmentally friendly and has a wide range of sources.Due to its low cost,easy processing,low thermal expansion coefficient,optical transparency,light weight,good mechanical properties,high specific surface area,biodegradability and chemical surface modifiability,cellulose nanofibrils(CNF)prepared from lignocellulosic biomass has gained increasing attention.However,CNF has some shortcomings in thermal stability and thermal conductivity,which limits its application as a thermal management material in electronic cooling substrates.In this paper,CNF was prepared from bagasse pulp by xylanase pretreatment assisted mechanical method.The thermal stability and thermal degradation of CNF were studied,CNF/A1N composites were prepared,and the effects of AIN on the thermal conductivity of CNF-based composites,and the effects of AIN modification on the thermal conductivity of composites were studied.The preparation of CNF smaller than 100 nm was prepared by using a xylanase pretreated bagasse slurry assisted ultrafine grinder.Unbleached bagasse pulp was treated with different doses of xylanase and samples were taken at different stages of the milling stage.By comparing the thermogravimetric analysis,it is found that the CNF produced by the puree has higher thermal stability than the CNF after the enzyme treatment,and the thermal stability decreases with the increase of the enzyme dosage.Besides,the presence of hemicellulose and lignin in the puree contribute to the thermal stability of the CNFCNF/A1N composites were fabricated by assembling CNF as a polymer substrate and AIN nanosheets by a simple vacuum filtration method.The interaction between CNF and AIN nanosheets was studied,and the effect of AIN content on the properties of the composites was discussed.The electronic components made of the composite exhibit excellent thermal conductivity,thermal stability and mechanical flexibility.The in-plane thermal conductivity of the composite film with 25 wt.%AIN is 4.20 W/mK.The addition of AIN improves the thermal stability of nanocomposites.The interaction between CNF and TAIN nanosheets was studied,and the effect of TAIN content on the properties of the composites was discussed.Silane improves the dispersion of AIN nanosheets in CNF matrix,and leads to the generation of covalent bonds between them so that improve the mechanical properties of the composite films.The function of silane reduces the phonon scattering between AIN nanosheets and CNF matrix interface,and then the composite film exhibits excellent thermal conductivity.The in-plane thermal conductivity of the composite film reaches 5.11 W/mK when the TAIN content is 25%.In this paper,CNF was prepared by using bagasse pulp as a raw material,and CNF shows good mechanical properties,good reconfiguration,excellent dispersion and so on.The composite film with high thermal conductivity and mechanical:flexibility was prepared by vacuum filtration with AIN.The thermal conductivity of the composite film reaches 5.11 W/mK.As a thermal management material,it is expected to be used as a flexible electronic component,and that further expands the application range of cellulose in the flexible electronics market.