Cellulose nanofibers properties

Ifuku, S., Nogi, M., Abe, K, Handa, K., Nakatsubo, F., Yano, H. Surface modification of bacterial cellulose nanofibers for property enhancement of optically transparent composites dependence on acetyl-group DS. Biomacromolecules 8, 1973-1978 (2007)... 

Cellulose nanofibers from different sources have showed remarkable characteristics as reinforcement material for optically transparent composites [160, 161], Iwamoto et al. [160] prepared optically transparent composites of transparent acrylic resin reinforced with cellulose nanofibers extracted from wood pulp fibers by fibrillation process. They showed that cellulose nanofiber-reinforced composites are able to retain the transparency of the matrix resin even at high fiber content (up to70 % wt). The aggregation of cellulose nanofibers also contributes to a significant improvement in the thermal expansion properties of plastics. 

The research on cellulose nanofibers and nanocomposites has been reviewed (23). Some mechanical properties of cellulose in comparison to other engineering materials are given in Table 5.7. 

The effect of chemical modification of cellulose nanofibers on the properties of PLA nanocomposites has been investigated (44). Ac-etylated nanofibers, with a degree of substitution 1.07, were isolated from acetylated kenaf fibers by a mechanical procedure. The acet-ylated nanofibers were found to be more hydrophobic. Both crystallinity and thermal stability of acetylated nanofibers were lower in comparison to the non-acetylated nanofibers. 

Biodegradable polyester-based composites have been extensively studied for use in medical applications owing to their biocompatible and degradable properties in the human body. The major reported examples in biomedical products are fracture-fixation devices, such as sutures, screws, micro titration plates, and delivery systems [77]. Cellulosic nanofiber reinforced PLA composite materials... 

Kowalczyk, M., Piorkowska, E, Kulpinski, P., and Piacella, M. (2011) Mechanical and thermal properties of PLA composites with cellulose nanofibers and standard size fibers. Composites Part A, 42 (10), 1509—1514. 

All-cellulosic based composite films can be prepared from either isotropic or anisotropic cellulosic derivatives solutions. However, these composites cannot compete with mechanical properties of cellulose nanofiber reinforced composites. Pioneering studies reported by Favier et al. [35, 36], showed that small amounts of cellulose tunicate whiskers resulted in dramatic improvements in modulus above the glass transititMi temperature of an amorphous polymer matrix, due to the percolation of the cellulose nanofibers. Also recently, a completely new route to cellulose-based composites was proposed by Nishino and Arimoto [37], Soy-keabkaew et al. [38—40], They focused on approaches following self-reinforcing polymer concepts [41, 42] to create composites that often outperform traditional nanofiber reinforced composites [38,40],... 

The use of cellulosic nanofibers in the productiOTi of all-cellulosic based composites can greatly improve the mechanical performance of these composites. With these nanofibers and a cellulosic anisotropic matrix a synergy between the percolation of the nanofibers and its matrix-induced orientation can lead to composites with enhanced mechanical properties. 

Jonoobi, M., Harun, J., Mathew, A. R, Oksman, K. (2010). Mechanical properties of cellulose nanofiber (CNF) reinforced polylactic aeid (PLA) prepared by twin screw extrusion. (12), 1742-1747. 

The development of new polymeric materials based on cellulose nanofibers and other polysaccharides is a pronrising strategy within the context of new sustainable and environmental-friendly materials. As exemplified in this brief review, the properties of these materials suggest that they could be successfully applied in such areas as packaging materials, particularly because bacterial cellulose is beconring a progressively more available raw material at reasonable price. 

Other biopolymers useful for synthesis of nanocomposites include (i) gelatin—a water-soluble protein obtained by extracting collagen liom animal skin and bones and thermal denaturation. (ii) PHB—a natural product of biosynthesis performed by bacteria in nature, (iii) Chitosan—a natural polymer widely found in exoskeletons of crustaceans and insects, as well as in the cell walls of microorganisms (Maiti et al. 2003 Zheng et al. 2002 Takegawa et al. 2010). Moreover, the mechanical and water vapor barrier properties of chitosan-based nanocomposites with cellulose nanofibers could be enhanced. 

Hietala M, Mathew AP, Oksman K (2013) Bionanocomposites of thermoplastic starch and cellulose nanofibers manufactured using twin-screw extrusion. Eur Polym J 49 950-956 Hoover R, Hughes T, Chung HJ, Liu Q (2010) Composition, molecular structure, properties and modification of pulse starches a review. Food Res Int 43 399-413 Hotza D (1997) Colagem de Folhas Ceramicas. Tape Casting Ceramica 159-166 Huneault MA, Li H (2012) Preparation and properties of extruded thermoplastic starch/polymer blends. J Appl Polym Sci 126 96-108... 

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