Preparation And Characterization Of Modified Bacterial Celluloses And Their Reinforced Thermoplastic Starch Biopolymers

In this study,BCPEG-MAH fibers which were preparation by disperesing and modifying Bacterial Cellulose(BC)fibers were added to thermoplastic starch(TPS)resins forreinforcement.From the result of the Transmittance analysis it could be found that transmittance value of(BCUrea)125-2.5 specimens reaches a minimum of 18.40%.The FTIR spectra showed that PEG-g-MAH specimens appear characteristic absorption peaks which are respectively corresponding to the C=C bending vibration,C=C stretching vibration,-O-C=O stretching vibration,-COOH stretching vibration and-OH stretching vibration at the peaks of 675cm-1,1643cm-1,1745cm-1,1718cm-1/3050cm-1 and 3460cm-1.BCPEG-g-MAH fibers specimens appeared characteristic absorption peaks which are respectively corresponding to the C = C bending vibration,C = C stretching vibration,and-O-C = O stretching vibration at the peaks of 678cm-1,1645cm-1 and 1743cm-1.Typical reticulated rodlike feature was observed for both original and oxidized BC nanofiber specimens from the SEM analysis.From the result of TEM analysis it could be found that after oxidation by NaIO4 solutions,the translucent impurities original present in between BC nanofibers were removed and the oxidized BC nanofibers are significantly thinner than original BC.After being modified by PEG-MAH,some translucent resins were found attaching on the surface of the BC nanofibers.From the SEM analysis it could be found that after being plasticized and gelatinized by the high temperature and strong mechanical forces for a long time,the natural crystalline structure of corn starch molecules were disappeared.From the result of DSC thermal analysis of the TPS and TPS100BCx series specimens,it could be found a wide range but weak endothermic peak which is corresponding VH-type of starch crystallization melting.It's worth noting that the wide range but weak endothermic peak of TPS 100BCPEG-g-MAHx series specimens increase as as their BCPEG-g-MAH contents increase.WAXD pattern of corn starch specimens appears four obvious diffraction peaks which are corresponding to the typical A-type crystallization.The original A-type crystallization peaks of starch disappear and only a weak diffraction peaks corresponding to the VH-type crystallization peaks appear in the TPS specimens.Obviously there are three diffraction peaks corresponding to the typical cellulose I crystallization in the WAXD pattern of BC fiber specimens.WAXD pattern of TPS100BCx series specimens not finding any characteristic diffraction peak which is corresponding to the cellulose I crystallization;WAXD pattern of TPS100BCMAH-PEGX series specimens appears characteristic diffraction peaks which are corresponding to the cellulose II crystallization;The intensity of diffraction peaks corresponding to VH-type starch crystallization of TPS100BCMAH-PEGX series specimens slightly increased as as their BCPEG-g-MAH fibers contents increased.The tensile strength(?f)and elongation at break(?f)values of TPS100BCx and TPS100BCPEG-g-MAHx series specimens reach a 19.2MPa/9.1%and 20.8MPa/10.1%maximal value respectively as their BC/BCPEG-g-MAH contents approach the optimal value.