Preparation And Charaterization Of Bacterial Cellulose With High Flexibility

Due to the excellent physico-chemical and biological properties,Bacterial cellulose(BC)was widely used in preparation of a variety of composite materials,in order to expand the applications.The biodegradable and dispersion and stability in solution of oxidized cellulose is better than the cellulose,and the oxidized bacterial cellulose has lots of carboxyl that can react with vrious groups.In our study,firstly using the 2,2,6,6-tetramethyl-piperidine-1-oxyl radical(TEMPO)/NaBr/NaClO oxidation-mediated selectively oxidized the primary hydroxyl of BC.And the effects of dosage of NaCIO,temperature and the form of BC on carhoxyl content was investigated.The solidate oxidized BC(OBC)was characterized by FT-IR?13C-NMR?XRD?SEM?TA and DSC.1 g dray weight of BC beated-slurry,TEMPO 0.016 g,NaCIO 6 mmol,NaBr 0.1 g can obtained the higher carboxyl content(1.47 mmol/g)with reacting 12-18 h.FT-IR and 13C-NMR demonstrate that the C6 primary alcohol hydroxyl was selectively oxidized.XRD result shown that the craylstal form of oxidized bacterial cellulose is consistent with the BC,and the crystallinity of OBC(86.84%)is lower than the BC(90.57%).The TA and DSC characterized that the thermal stability of OBC is unconspicuously chang comparing with BC.Subsequently,a highly flexible nanocomposite membrane composed of graphene oxide(GO),polyetheramine(PEA D2000)and oxidized bacterial cellulose(OBC)with laminated structure was prepared using the vacuum-assisted self-assembly technique.The zeta potential demonstrated that the suspension of composites was stable without OBC,GO,and PEA aggregation.The surface and cross-section morphology of GO-PEA-OBC was observed by scanning electron microscope(SEM).The result indicated tant the GO-PEA-OBC nanocomposite film has three dimension nanonetwork structure and compacted and laminated layer-by-layer structure.The interaction between carboxyl groups of GO and OBC and amidogen of PEA D2000 were analyzed with Fourier transform infrared spectroscopy(FTIR)and 13C solid state nuclear magnetic resonance(NMR).As a crossing agent,PEA D2000 composites the GO on the nanonetwork of OBC by the amdie bond.And the X-ray diffractometry(XRD)was employed to characterize the crystallinity of the composites.The results show that the craylstal form of GO-PEA-OBC is consistent with the OBC,however the crystallinity of GO-PEA-OBC(98.76%)is higher than OBC(86.84%).The thermal stability of GO-PEA-OBC was analyzed through the TA and DSC which indicate that compared with OBC,the thermal stability of GO-PEA-OBC nanicomposite film has unconspicuously chang.Mechanical properties analysis was conducted with tensile testing.The tensile strength and elongation at break of GO-PEA-OBC nanocomposite obviously increased compared with OBC and GO-OBC...