Effect of Hydrolysis Time on the Properties of Cellulose Nanocrystals and Their Continuous Phase Separation Behavior
In this study,a series of bacterial cellulose nanocrystals(BCNC)were prepared by sulphuric acid hydrolysis,and the effects of acid hydrolysis time on the properties of BCNC and their continuous phase separation behaviour were investigated.The results showed that the length,diameter,and aspect ratio of the BCNC decreased gradually with the increase of acid hydrolysis time.When the mass fractions of the BCNC suspensions prepared at different acid hydrolysis time were all adjusted to 5.00%,the continuous phase separation only occurred in the BCNC suspension prepared by acid hydrolysis for 60 min.Meanwhile,the volume fraction of the anisotropic phase obtained from the second phase separation(BCNC60-2b)was significantly less than that of the anisotropic phase obtained from the first phase separation(BCNC60-1b).The properties of the BCNC fractions from isotropic and anisotropic phases differed significantly,with the length,diameter,as-pect ratio,Zeta potential absolute value,and crystallinity of the anisotropic phase BCNC being greater than those of the corresponding isotro-pic phase BCNC.Therefore,the self-assembly of the polydispersed BCNC particles was not random,but rather had different priorities,whereas the continuous phase separation could be used for BCNC grading.
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