Properties of Cellulose Nanofibers

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],... 

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. 

Takagi, H. and Asano, A. (2008) Effects of processing conditions on flexural properties of cellulose nanofiber reinforced green composites. Composites Part A, 39 (4), 685-689. 

The main properties of cellulose nanofibers are its high strength compared to other natural and synthetic fibers, in addition to the birefringence and biodegradability characteristics. 

High-tenacity fibers have been demonstrated by dry-jet wet-spinning of anisotropic solutions of cellulose triacetate, but a product has not yet been commercialized [113,114], Nanofiber composites have been demonstrated by electro-spinning dilute cellulose acetate and triacetate solutions. These composites have exceptionally high specific surface area, and exciting new applications are envisioned [115], There are many new specialty applications, and research is continually finding new applications that take advantage of the unique balance of properties of cellulose acetate [107,109,110,116],... 

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. 

Zimmermann T, Pdhler E, Schwaller P (2005) Mechanical and morphological properties of cellulose fibril reinforced nanocomposites. Adv Eng Mater 7 1156-1161 Zoppe JO, Peresin MS, Habibi Y et al (2009) Reinforcing poly(8-caprolactone) nanofibers with cellulose nanocrystals. ACS Appl Mater Interfaces 1 1996-2004... 

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. 

Effect of Cellulose Nanofiber Toward Mechanical Properties... 

In a novel application of BC, Grande et al. (2009) added starch to the culture medium of cellulose-producing bacteria in order to introduce the granules into the forming network of cellulose which allowed the preservation of the natural ordered structure of cellulose nanofibers. Microscopic analysis revealed that starch acted as a matrix which filled the voids in the BC network. Using MCF as reinforcement, the nanocomposites showed considerable improvement in mechanical properties. 

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