Effect of rheological properties of dissolved cellulose/microfibrillated cellulose blend suspensions on film forming

Soluble soybean polysaccharide/nano zinc oxide antimicrobial nanocomposite films reinforced with microfibrillated cellulose

Nanocomposite films of soluble soybean polysaccharide (SSPS)/nano zinc oxide (nZnO) reinforced with microfibrillated cellulose (MFC) were developed by solvent casting method. The structure, optical, barrier, thermal, surface wettability, mechanical properties and antimicrobial activity of the SSPS/MFC, SSPS/nZnO and SSPS/nZnO/MFC nanocomposite films were evaluated. Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectra indicated interactions between SSPS and the nano-fillers. The nanocomposite films containing MFC showed improved tensile strength, stiffness, ultraviolet (UV) light barrier property, thermal stability and water resistance when compared with the neat SSPS film. The nZnO-incorporated nanocomposite films exhibited good antimicrobial activity against E. coli and B. subtlis. Overall, the MFC-reinforced SSPS/nZnO nanocomposite films possessed desirable characteristics to be considered as potential candidates for antimicrobial packaging and biomedical applications.

Gelation of cellulose-NaOH solutions in the presence of cellulose fibers

It is well known that when cellulose is dissolved in aqueous NaOH-based solvent, solutions are gelling with increasing time and temperature. The goal of this work was to understand if the presence of non-dissolved cellulose fibers influences gelation behavior of the whole system. One of the motivations is to control gelation when making all-cellulose composites with short fibers dispersed in cellulose-NaOH-water solutions. Gelation kinetics of cellulose(dissolving pulp)-NaOH-water solutions with added softwood kraft fibers were investigated using dynamic rheology. Fiber concentration, dissolving pulp degree of polymerization and solution temperature were varied. In all cases the addition of kraft fibers accelerates gelation and increases modulus at gel point while the presence of "inert" carbon fibers does not influence solution gelation kinetics. It was suggested that acceleration of gelation and reinforcement of cellulose gels is due to the interactions between dissolved and non-dissolved cellulose.

Effects of Ball Milling Processes on the Microstructure and Rheological Properties of Microcrystalline Cellulose as a Sustainable Polymer Additive

To investigate the effect of ball mill treatment of microcrystalline cellulose (MCC) on the rheological properties of MCC-polymer suspension, the structure and physicochemical characteristics of ground samples with different milling time and the rheological behaviors of MCC-starch suspensions were determined and comprehensively analyzed. During the ball milling process, MCC underwent a morphological transformation from rod-like to spherical shape under the combined effect of breakage and an agglomeration regime. The particle size and crystallinity index of MCC exhibited an exponential declining trend with ball milling time. All of the milled MCC samples presented a crystalline cellulose Iβ structure whereas the MCC mechanically treated in a shorter time had better thermal stability. Rheological measurements of starch/MCC suspensions indicated that all the blended paste exhibited shear thinning behavior and ‘weak’ elastic gel-like viscoelastic properties over the whole investigated range owing to the formation of entangled network structure. The rheological behavior of starch/MCC pastes was strongly dependent on milling time and concentration of MCC samples. The increase in milling time of MCC samples resulted in the loss of rheological properties of starch/MCC pastes, where the size of the MCC playing a dominant role in affecting the properties of composite suspension. In addition, a possible network within starch/MCC suspensions was proposed.

Tetracycline hydrochloride loaded regenerated cellulose composite membranes with controlled release and efficient antibacterial performance

Fabrication of cellulose based composites with controlled release and efficient antibacterial performances is of general interest in biomedical areas.