Bacterial cellulose nanofibrils

Table 6.6 The mechanical properties of natural fibres modified with bacterial cellulose nanofibrils...

Zhijiang et al. reported an improvement in the mechanical properties of a PHB nanocomposite made of bacterial cellulose nanofibrils that was prepared by the solution casting method. In addition, they found that the nanocomposite showed better biocompatibility and mechanical properties than pure PHB based on cell-adhesion analysis using Chinese hamster lung (CHL) fibroblast cells and stress strain tests, respectively. In comparison to pure PHB, the nanocomposite of PHB/bacterial cellulose was observed to exhibit about a 202% increase in tensile stress and a 2.2-fold increase in elongation to break, respectively (Figure 5.3). ... 

Few examples of nanocomposites in which the cellulosic nanostructure is used in biobased thermosets can be also foimd. Due to the fact that these environment friendly composites suffer from several limitations, such as low mechanical properties due to low strength in reinforcement plus inadequate interfacial strength, and that cellulose nanostructures have been shown to have significant potential as a reinforcement, the possibility of using cellulose nanofibers as reinforcements in a bio-derived resin was revised. In Masoodi et al. [200], cellulose nanofibers were used as reinforcements in the forms of layered films, while in Lee et al. [201] the stability of the gas-soybean oil foam templates and the mechanical properties of the polymer nanocomposite foams are enhanced upon the addition of bacterial cellulose nanofibrils. Other examples of biobased thermosets containing cellulosic nanoreinforcements are the work of Shibata [202] in which the use of a biobased epoxy was revised, and systems in which cellulose nanocrystals are incorporated in biobased polyurethanes [203,204], Few examples exist also in the literature on the polymerization of furfuryl alcohol in presence of CNR [205,206] in these papers, the authors established the feasibility of producing furfuryl... 

Zhijiang C, Guang Y. Optical nanocomposites prepared by incorporating bacterial cellulose nanofibrils into poly(3-hydroxybutyrate). Mater Lett 2011 65 182-4. 

In Figure 1 we see bacterial cellulose that has been grown by Haigler in the presence of dissolved carboxymethyl cellulose (CMC), which inhibits the aggregation of the most elementary fibrils into the ribbons that are usually observed without the CMC. The most subelementary nanofibrils in Figure 1 are of the order of... 

CNY is manufactured by means of electrospinning technology (Doshi and Reneker, 1995). The natural nanofibrils of bacterial cellulose are produced by several species of bacteria, for example, G. xylinus. The biosynthesized long and thin elementary nanofibrils of bacterial cellulose are aggregated to microfibrils forming a network filled with water. 

A brief overview of composite materials based on cellulose fibers (vegetal cellulose, bacterial cellulose and nanofibrillated cellulose) with other natural polymers such as chitosan and starch will be presented. 

Nanocellulose can broadly be defined as a set of particles having at least one dimension in nanoscale obtained by different mechanical/chemical, or only chemical, or acid-hydrolysis methods. According to a survey of the literature, there is no standardized nomenclature for cellulose-based nanoparticles, while various terms have been used to describe a particular set of cellulose nanoparticles. Because of inconsistency in use of these terms, there are some particle types depending on source materials of cellulose and method of extraction. However, depending on their aspect ratio, nanocelluloses have already been characterized with different terms like microfibrillated cellulose (MFC-diameter 10-100 nm) [34], nanofibrillated cellulose (NFC-diameter 4-20 nm) [35], CNCs (CNCs-diameter 3-5 nm) [34, 36], tunicate CNCs (t-CNCs-diameter 20 nm) [34, 37], algae cellulose particles (AC-diameter 20 nm) [38,39], bacterial cellulose particles (BC-diameter 6-50 nm) [40, 41]. It can commonly be called "nanocellulose,"... 

Orts et al. [17] investigated composites of wheat or potato starch blended with pectin and reinforced with cellulose nanofibrils extracted from cotton, softwood, or bacterial cellulose. Mechanical and thermal properties of composites produced by casting and extrusion (extruded under a low and high shear mode) were evaluated. The addition of cellulose microfibrils to starch had a significant effect on mechanical properties at low concentrations. For example. Young s modulus of wheat starch nanocomposites reinforced with cotton nanofibrils increased by five times with the addition of only 2.1 wt% of nanofibrils (see Table 11.1). 

Kojima Y, Tonouchi N, Tsuchida T, YoshinagaF, Yamada Y (1998) The characterization of acetic acid bacteria efficiently producing bacterial cellulose liom sucrose the proposal of Acetobacter xylinum subsp. nonacetoxidans subsp. nov. Biosd Biotechnol Biochem 62 185-187 Kose R, Sunagawa N, Yoshida M, Tajima K (2013) One step production of nanofibrillated bacterial cellulose (NFBC) from waste glycerol using Glulconacetobacter intermedius NED-01. Cellulose 20 2971-2979... 

A device specific capacitance of 32.4 F was achieved, based on dry weight of 20.8 mg of both electrodes [112]. The effect of paper substrates on the capacitive performance of PPy-cellulose nanofibrils has been investigated [113]. Similarly, there has been some investigations on cellulose nanofibril aerogel-PPy composites for use as supercapacitor electrodes [114]. In addition, cellulose nanofibrils derived from a bacterial source has been used for making of PAn composites [115, 116]. 

In isolated celluloses, the elementary nanofibrils are abrogated in microfibrillar bundles with lateral size of 20-40 nm, and such bundles can form lamellas and layers of the cell wall of cellulose fibers, as well as ribbons of bacterial cellulose (loelovich, 2008 Klemm, 2005). 

Figure 1. (A) Visual and SEM micrographs of vegetal cellulose, (B) nanofibrillated, and (C) bacterial...

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