The Thermal Performance Study Of Cellulose-based Nanocomposites

In this paper,reduction of graphene oxide?RGO?nanosheets were stably dispersed in water directly in the presence of montmorillonite?MMT?nanoplatelets and cellulose nanofibers?CNFs?.This could be attributed to the steric hindrance of CNFs and the repulsion between different charges which exist in RGO nanosheets,MMT nanoplatelets and CNFs.Taking advantage of these stable hybrids,the films with unique microstructure have been fabricated successfully via vacuum filtration.For the highly oriented layer structures,the films have been given high thermal stability and good flexibility.Meanwhile,because of the excellent electrical property of RGO nanosheets and the dielectric property of MMT nanoplatelets,there are lots of micro-capacitors in the film which has unique microstructure,and these micro-capacitors can impart the film high dielectric constant and relatively low dielectric loss.Carboxymethyl cellulose is an important derivative of cellulose.There are many carboxymethyl groups in their molecules,so it's possible to add the different positive ions to CMC,such as Li⁺,Na⁺,K⁺,NH₄⁺and so on.While these ions will react with the intermediate products during the pyrolyzation and combustion,which will influence the thermal and combustion performances.In this paper,different CMC were studied by TG and MCC to find how the different degrees of substitute and positive ions influence the thermal and combustion performances.We found that metal carboxymethylcellulose produce more residual than other CMC,which can provide a good protection to avoid pyrolysis and burning.For CMC-NH₄,with the temperature increasing,the weight of CMC-NH₄ decreases badly,for it's easy to take off the ammonia and release gas.On the other hand,the gas will take away the heat and protect the CMC,though there is little residual.Nano-SiO₂ and CNFs are important nanofillers to improve the nanocomposite performances.For nano-SiO₂,the existence of nano-SiO₂ will improve the nanocomposites'heat resistance and reduce PHRR and THR.But for mechanical properties,nano-SiO₂ will result in deterioration on mechanical properties badly.To solve the problem,we put CNFs in the nanocomposite too,for CNFs is a good nanofillers to enhance nanocomposites'mechanical properties.And we found that,when both CNFs and nano-SiO₂ were in the nanocomposite films,the tensile strength and elongation at break of nanocomposite films improved greatly.So this phenomenon can give us a new way to prepare nanocomposite with excellent performance.