Nanocellulose types

Currently, five kinds of nanocellulose are known CNP, ANP, NFC, BNC, and CNY. These nanocellulose types have unique features, such as small dimensions, a variety of shapes and enhanced specific surface, high sorption and absorption ability, high thermal stability, and high resistance to dilute solutions of acids and alkalis, organic solvents, proteolytic enzymes, antioxidants, and some other TAS. The specific features open new, promising application areas, particularly in various branches of care and cure, such as hygiene, cosmetics, pharmaceutics, medicine, etc. 

Relatively speaking, NFCs are considered more ductile as compared to CNCs and can be applied as a more useful template for further functionalization [46]. For the systematic comparative study, the Halpin-Kardos and Ouali models were applied to simulate the modulus of the nanocomposites and, as predicted, the experimental values showed good agreements. Therefore, on the basis of type of nanocellulose, systematic comparative study can help to develop the criteria for selecting the proper nanocellulose as a biobased nanoreinforcement material in polymer nanocomposites [45]. Therefore, these nanocellulose types such as CNCs and NFCs have attracted a great interest in the field of industrial and biomedical applications. Therefore, CNCs are often referred to as microcrystals, whiskers, nanocrystals, nanoparticles, and microcrystallites. Hereafter, for convenience, they will be called "cellulose nanocrystals" (CNCs). 

As described before, one type of nanocellulose is formed directly as the result of biosynthesis of special bacteria. A very pure product with subsequently reported important properties is formed that necessitates challenging biosynthesis/biotechnological handling and the development of large-scale production. 

There have been numerous investigations into the subsequent modification of bacterial and wood nanocelluloses. The additives range from other polysaccharides, albuminoids such as gelatine, different types of monomers and synthetic polymers, to metals, metal oxides, and inorganic fibers. On the... 

The second chapter by Dieter Klemm, Dieter Schumann, Hans-Peter Schmauder, and coworkers focuses on the recent knowledge of cellulosics characterized by a property-determining supramolecular nanofiber structure. Topics in this interdisciplinary contribution are the types of nanocelluloses and their use in technical membranes and composites as well as in the development of medical devices, in veterinary medicine, and in cosmetics. 

Fig. 4 Structure and properties of nanocellulose, (a) Hierarchical assembly of cellulose molecules into cellulosic fibers. Adapted, with permission, from [131]. Copyright 2012 Elsevier, (b) Proposed mechanism of formation of CNF cross-linked with metal cations. Reproduced, with permission, from [132]. Copyright 2013 American Chtanical Society, (c) Effect of the type of metal cation on the frequency-dependent storage modulus of CNF hydrogels, probed by dynamic frequency sweeps (25 °C) at a strain rate of 0.5 %. Adapted, with permission, from [132]. Copyright 2013 American Chemical Society, (d) Polarization optical microscopy photograph of a biphasic 8.78 % (w/w) CNC suspension. Adapted, with permission, from [133]. Copyright 1996 American Chemical Society, (e) Polarization optical microscopy photograph of a CNC suspension. Scale bar. 200 pm. Reproduced, with permission, from [134]. Copyright 2000 Amaiean Chemical Society...

Nanofibers are generally produced from polymers which deviate from the conventional fiber-forming type of materials, and so it may be apprehended that the scope of use of these nanofibers may be far beyond the use of standard fibers, microfibers or fibrous materials. The bottom-up method modifies the fibers at a molecular or supramolecular level of fragmentation and transforms them into a polymer/polymer blend before the formation of fibers, which gives them new, specific properties favorable from a practical point of view. Nanocellulose fibers possess optimized product properties and target-directed development, quantification of eco-efficiency and sustainability factors. 

There are four types of nanocellulose depending on their fabrication method bacterial cellulose, electrospun cellulose, microfibrillated cellulose (MFC) and whiskers of cellulose (nanorods). Bacterial cellulose is a nanomaterial derived from plant material by bacterial action in the presence of oxygen. Various strains of Acetobacter species [82,83] can be used to produce cellulose, although strains of pseudomonas, Achrobacter, Alcaligene, Aerobacter and Azotobacter [84] can also be used. The bacterial cellulose... 

Kose and Kondo studied tbe size effects of cellulose nanofibres on the crystallization behaviour of PLA. They discovered that the smaller size of cellulose nanofibres on tbe nanoscale does not necessarily make a better nucleating agent for PLA. Table 9.1 summarizes the Avrami kinetic parameters for the isothermal crystallization of the PLA and PLA biocomposites with different types of nanocelluloses as compared to PLA composites with talc and nanoclay. With the addition of unmodified and silylated CNCs as nucleating agents, the t 2 value increases with increasing T similar to that of nanoclay and com starch, but opposite to that of talc. Comparing the... 

Literature shows that nanocellulose diaphragms of about 20 microns thickness were obtained by dehydration and compression in a suitable matrix. Advantages of these types of cellulosic diaphragms were that they allows the sound going through at the same speed as the diaphragms made of aluminum or titanium (Jonas and Farah 1998 Iguchi et al. 2000). In these types of headphones, sounds can be heard very clearly and bass notes are remarkably deep (Fig. 1). 

Nanocellulose and its derivatives can be processed into different forms. Bacterial celulose is one such important type of nanocellulose. It has been processed into nanofibers for different applications. Figure 1.8 shows the different applications of cellulose acetate nanofibers [51]. Chapters 2 and 4 discuss the different perspectives of bacterial cellulose-based materials and their different applications. In these chapters the authors discuss in detail a vast collection of BC nanocomposites prepared using different polymer matrices such as natural polymers and thermoplastic matrices. In addition to this,... 

Among the various types of nanofillers, nanocellulose is gaining importance due to its renewable nature, ecofriendliness and low cost. Several research works are now being carried out incorporating nanocellulose as filler in different polymer matrices to develop new products with enhanced properties at a lower cost. 

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