Reduction Of Graphene Oxide And Study On Preparation And Thermal Conductivity Of Nanocellulose Composites

Based on the rapid development of science and technology,the trend of miniaturization and high integration of electronic products is increasingly prominent,and amounts of heat will inevitably be generated during using.If heat is not released in time and effectively,its service life and efficiency will be greatly affected.At the same time,electronic products also put forward the requirements of light-weight,high-strength and good thermal conductivity for heat dissipation materials.Therefore,thermally conductive polymer composites can meet its requirements.In this thesis,composite film with excellent thermal conductivity was prepared by filling graphene and carbon nanotubes(CNTs)with nano-cellulose(NFC)as the matrix.The specific research contents are as follows:1.Graphene oxide(GO)was prepared by using natural graphite as raw material by the improved Hummers method,and then GO was treated by vitamin C(VC)reduction,thermal reduction and solvothermal reduction(VC as reducing agent)methods and reduced graphene oxide(RGO)was obtained.FT-IR and X-ray photoelectron spectroscopy(XPS)showed that solvothermal reduction method had the most obvious weakening strength on the oxygen-containing groups in GO.Raman spectroscopy showed that after the solvothermal reduction,the value of I_D/I_G did not be increased,defects(vacancies,voids,etc)were effectively repaired by the removal of oxygen-containing groups,and the degree of graphitization of RGO was increased.The elemental analysis showed more intuitively that after solvothermal reduction,the O content of RGO was decreased from 50.06%to 13.72%,and the C/O value was increased from 0.90 to 6.29.2.Waste larch paper pulp was as raw material,NFC was prepared by TEMPO oxidation method and mechanical treatment.NFC/RGO thermally conductive composite film was obtain by the recombination of NFC and RGO.SEM showed that after NFC was filled by RGO,the gaps between NFC/RGO composite film were reduced and the compactness was significantly improved.FT-IR showed that carboxylated NFC was successfully prepared,and hydrogen bonds were formed between NFC and RGO.The mechanical properties showed that the tensile strength of NFC/RGO composite film was 86.29 Mpa,which was 38.2%higher than that of NFC film.TG showed that the initial pyrolysis temperature and the maximum pyrolysis rate temperature of NFC/RGO composites were respectively 206?and 305?,which were 21?and 23?higher than NFC,respectively.The total mass loss of composites was 6.0%lower than that of NFC,and its thermal stability was higher than that of NFC.Thermal conductivity showed that NFC/RGO composite film was5.82 W/(m·K),which was increased by 3.22 times compared with NFC film.3.NFC/CNTs@RGO thermally conductive composite film was prepared by the combination of CNTs and RGO to synergistically enhance NFC.SEM showed that when the ratio of RGO and CNTs was 6:9,the interlaminar voidage of NFC/CNTs@RGO composite film was the lowest.The mechanical properties showed that the maximum tensile strength of NFC/CNTs@RGO composite film was 105.29MPa.Thermal conductivity showed that the maximum value of NFC/CNTs@RGO composite film was 11.26 W/(m·K).