Nano-cellulose whiskers

Pandey, J. K., Chua, W. S, Kima, C. S., Leeb, C. S., and Ahn, S. H. (2009). Bio-nano reinforcement of environ mentally degradable polymer matrix by cellulose whiskers from grass,... 

Gauthier, C. (1995). Nano-composite materials from latex and cellulose whiskers, 6, 351-355. 

An attempt to use a recently patented concept (Dispersed Nano-Objects Protective Encapsulation—DOPE process) intended to disperse carbon nanotubes in polymeric matrices was reported. Physically cross-linked alginate capsules were successfully formed in the presence of either cellulose whiskers or microfibrillated cellulose [153]. The resulting capsules were extruded with a thermoplastic material. Another possible processing technique of nanocomposites using cellu-losic nanoparticles in the dry state present in the filtration of the aqueous suspension to obtain a film or dried mat of particles followed by immersion in a... 

In-situ intercalative polymerization of layered silicates is perhaps the best example of reactive molding of nanocomposites today. In-situ interactive polymerization of layered silicates, which was discussed above, can be achieved either with thermosetting matrices, such as polyurethane and epoxy, or with thermoplastic systems, such as nylon-6 [4, 23]. A general requirement for reactive molding of nanocomposites is that the particulate phase of a PNC is compatible with the monomer phase of the reactive molding system, which acts as a polymerizable solvent This makes it possible to achieve and maintain a fine dispersion of the particulate phase in the monomer during matrix consolidation, resulting in excellent particle distribution in the final PNC. Above, it was noted that the hydroxylated surface of cellulose makes it reactive to isocyanate. Cellulose whiskers may therefore represent the ideal particulate phase for a nano-RIM process. For this to be achieved, the whisker-polyurethane system needs to be better characterized, so that the RIM process can be adapted to fabrication of cellulose whisker PNCs. 

In addition to conventional vegetal cellulose fibers (Figure 1 A), other forms of cellulose have been assessed in the last few years. The use of micro and nano-cellulose fibers, namely whiskers, obtained from a marine species (Samir, 2005), bacterial cellulose produced by some bacterial strains (Pecoraro, 2008) as well as micro- or nano-fibrillated cellulose prepared by mechanical, enzymatic or chemical treatments of the vegetal fibers (Nakagaito, 2004), for the development of high performance composite materials is attracting researchers from diverse fields (Dufresne, 2008 Lee, 2009), as the addition of very modest amounts of nano fibers leads to new composite materials with superior mechanical properties and new functionalities (Klemm, 2009) when compared with their conventional cellulose fibers counterparts. 

A Transmission Electron Microscope (TEM) observation was performed using a Philips CM30 to study the morphology of cellulose nanowhiskers. One droplet of 1% suspension was put on a Cu-Grid covered with a thin carbon film. To enhance contrast in TEM, the nano-saized whiskers were negatively stained in a 2 wt% solution of uranyl acetate (a heavy metal salt) in de-ionized water for one min. 

Abdullayev E, Joshi A, Wei W, Zhao Y, Lvov Y (2012) Enlargement of halloysite clay nanotube lumen by selective etehing of aluminum oxide. ACS Nano 6(8) 7216-7226 Alexandre M, Dubois P (2000) Polymer-layered silicate nanocomposites preparation, properties and uses of a new class of materials. Mater Sci Eng R Rep 28(1-2) 1-63 Aice A, Earle MJ, Katdare SP, Rodriguez H, Seddon KR (2007) Phase equilibria of mixtures of mutually immiscible ionie liquids. Fluid Phase Equilib 261(l-2) 427 33 Azizi Samir MAS, Alloin F, Dufresne A (2005) Review of recent research into cellulosic whiskers, their properties and their application in nanocomposite field. Biomacromolecules 6(2) 612-626... 

Pandey JK, Ahn SH, Lee CS, Mohanty AK, Misra M (2010) Recent advances in the application of natural fiber based composites. Macromol Mater Eng 295 975-989 Pandey JK, Chu WS, Kim CS, Lee CS, Ahn SH (2009) Bio-nano reinforcement of environmentally degradable polymer matrix by cellulose whiskers from grass. Compos B 40 676-680... 

Nanocrystalline cellulose (NCC), cellulose nanocrystals (CNC), crystallites, rodlike cellulose microcrystals, cellulose whiskers (CW) or cellulose nano whiskers (CNW) 2-20 100-600 10-100... 

A new type of biobased material was synthesized from cellulose nano whiskers (CW) and furfuryl alcohol by employing in-situ polymerization method to produce polyfur-furyl alcohol (PFA)/cellulose nanocomposites without the use of solvents or surfactants. Furfuryl alcohol (FA) played a dual role, serving both as an effective dispersant for the cellulose whisker (CW) and as the matrix precursor for the in-situ polymerization. The filler, CW also served multiple functions, by first catalyzing the polymerization of FA, and then acting as an effective matrix modifier, increasing the thermal stability of the consolidated PFA nanocomposite. The polymerization was catalyzed by sulfonic acid residues at the CW surface left over from the whisker preparation [67]. 

G. Siaueira, J. Bras, and A. Dufresne, Cellulose whiskers versus microfibrils Influence of the nature of the nanoparticle and its surface functionahzation on the thermal and mechanical properties of nano composites. Biomacromolecules 10(2), 425-432 (2009). 

Li, Y., H. F. Ren, and A. J. Ragauskas. 2010. Rigid polyurethane foam reinforced with cellulose whiskers Synthesis and characterization. Nano-Micro Lett. 2 89-94. 

The cellulose based materials that are used as nano-reinforcements are cellulose nanocrystals (i.e. whiskers and nanospheres), nanofibrillated cellulose, regenerated cellulose nanoparticles and electrospun nanofibers. A wide range of polymer matrices have been used to form cellulose nanocomposites. Synthetic polymers such as polypropylene, poly(vinyl chloride) (PVC) [102], waterborne epoxy [103], waterborne polyurethane [104], polyurethane [105], poly-(styrene-co-butyl acrylate) [106], poly(oxyethylene) [107], polysiloxanes [108], polysulfonates [109], cellulose acetate butyrate [110,111], poly(caprolactone) [112], poly(viny 1 alcohol) [113] and poly (vinyl acetate) [114]. Different biopolymers such as starch-based... 

In this chapter we have reviewed some of the most important characteristics of cellulose and cellulose based blends, composites and nanocomposites. The intrinsic properties of cellulose such as its remarkable mechanical properties have promoted its use as a reinforcement material for different composites. It has been showed that cellulose is a material with a defined hierarchy that tends to form fibrillar elements such as elementary fibrils, micro fibrils, and macro fibers. Physical and chemical processes allow us to obtain different scale cellulose reinforcements. Macro fibers, such as lignocellulosic fibers of sisal, jute, cabuya, etc. are used for the production of composites, whereas nano-sized fibers, such as whiskers or bacterial cellulose fibers are used to produce nanocomposites. Given that cellulose can be used to obtain macro- and nano-reinforcements, it can be used as raw material for the production of several composites and nanocomposites with many different applications. The understanding of the characteristics and properties of cellulose is important for the development of novel composites and nanocomposites with new applications. 

Abstract Nature is gifted with several nanomaterials which could be obtained from different animal and plant sources. Cellulose, chitin and starch are abundant, natural, renewable and biodegradable polymers. By intelligent processing techniques they could be used as classical nano reinforcing fillers in polymers i.e., composites. They are often called whiskers. 

Mikkonen, K.S., Mathew, A.P., Pirkkalainen, K., Serimaa, R., Xu, C., Willfor, S., Oksman, K., Tenkanen, M. Glucomannan composite films with cellulose nano whiskers. Cellulose 17, 69-81 (2010)... 

Abstract Biopolymers are expected to be an alternative for conventional plastics due to the limited resources and soaring petroleum price which will restrict the use of petroleum based plastics in the near future. PLA has attracted the attention of polymer scientist recently as a potential biopolymer to substitute the conventional petroleum based plastics. The chapter aims to highlight on the recent developments in preparation and characterization of PLA blends (biodegradable and non-biodegradable blends), PLA composites (natural fiber and mineral fillers) and PLA nanocomposites (PLA/montmorillonite, PLA/carbon nanotubes and PLA/cellulose nano whiskers). 

As a result of their diverse architecture, different descriptors such as whiskers, nanowhiskers, cellulose nanocrystals, nano-crystalline cellulose, monocrystals or microcrystallites are used in literature to describe crystalline rod-like nanoparticles (Eichhom et al, 2010 Frone et al, 2011 Khalil et al, 2012), while terms such as microfibrils, microfibrillated cellulose or nanofibrillated cellulose are used to describe cellulosic nanoparticles that are obtained as a result of mechanical shearing disintegration process (Siqueira et al, 2010 Siqueira et al, 2011). In this paper, sources, isolation, property and applications of natural cellulose fibers are reviewed. 

The extraction of cellulose nanociystals or CNCs (also called (nano-/ micro-)crystallites, whiskers, nanorods, and nanowires ) was first demonstrated in 1952 using acid hydrolysis of cellulose fibres. However, interest in the technique remained low until 1992, when their chiral... 

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