Nanocomposites nanofiber preparation

Nanocomposites were prepared by premixing PLA master batches, with both acetylated nanofibers and non-acetylated nanofibers. These master batches were eventually diluted to their final concentrations of 5% in the course of the extrusion. 

Fukuzumi H, Saito T, Iwata T et al (2008) Transparent and high gas barrier films of cellulose nanofibers prepared by TEMPO-mediated oxidation. Biomacromolecules 10 162-165 Garcia de Rodriguez NL, Thielemans W, Dulfesne A (2006) Sisal cellulose whiskers reinforced polyvinyl acetate nanocomposites. Cellulose 13 261-270 Gousse C, Chanzy H, Excoffier G et al (2002) Stable suspensions of partially silylated cellulose whiskers dispersed in organic solvents. Polymer 43 2645-2651 Gray DG (2008) Transcrystallization of polypropylene at cellulose nanocrystal surfaces. Cellulose 15 297-301... 

Saito T, Kimura S, Nishiyama Y et al (2007) Cellulose nanofibers prepared by TEMPO-mediated oxidation of native cellulose. Biomacromolecules 8 2485-2491 Sakurada I, Nukushina Y, Ito T (1962) Experimental determination of the elastic modulus of crystalline regions oriented polymers. J Polym Sci 57 651-660 Shimazaki Y, Miyazaki Y, Takezawa Y, Nogi M, Abe K, Ifuku S, Yano H (2007) Excellent thermal conductivity of transparent cellulose nanofiber/epoxy resin nanocomposites. Biomacromolecules 8 2976-2978... 

Jimenez, G. and Jana, S.C. (2007) Electrically conductive polymer nanocomposites of polymethylmethacrylate and carbon nanofibers prepared by chaotic mixing. Compos. PartAtAppl. Sd. Mam/f., 38,983. 

Jimenez, G. A. Jana, S. C. Eleetrically eonduetive polymer nanocomposites of polymethylmethacrylate and carbon nanofibers prepared by ehaotie mixing. Comp. Part A Appl. Sci. Manuf. 2007, 38, 983-93. 

Chitosan- and water-soluble chitosan-cellulose nanofiber nanocomposite films were prepared by a simple and green procedure based on casting water (or 1% acetic solutions) suspensions of chitosan with different contents of NFC (up to 60%), and BC (up to 40%). The transparency of the films obtained indicated that the dispersion of the NFC and BC into the chitosan matrices was quite good. The nanocomposite films prepared with BC showed higher transmittance than the corresponding films prepared with NFC, because of the higher purity of BC. 

Extrusion and impregnation, electrospinning, and multilayer films are other processes applicable for reinforced nanocomposites. Thus, preparation of cellulose whiskers reinforced with polylactic acid nanocomposites (by melt extrusion carried out by pumping the suspension of nanocrystals into the polymer melt during the extrusion process), using polyvinyl alcohol as a compatibilizer for the dispersion of cellulose whiskers within the polylactic acid matrix, was reported (de Menezes et al. 2009) bacterial cellulose whiskers incorporated into poly(oxyethylene) nanofibers by electrospinn to enhance the mechanical properties of electrospun fibers (Peresin et al. 2010) or the use of the layer-by-layer assembly technique, which maximizes the interaction between cellulose whiskers and a polar polymeric matrix (Bruno et al. 2009 Aulin et al. 2010), are some examples of nanocomposites reinforced by the last three methods. 

Prince, J.A., Singh, G., Rana, D., Matsuura, T., Anbharasi, V., Shanmugasundaram, T.S, 2012, Preparation and characterization of highly hydrophobic polyfvinylidene fluoride)-clay nanocomposite nanofiber membranes (PVDF-clay NNMs) for desalination using direct contact membrane distillation, JMemb Sci 397-398 80-86. 

The above polyolefin copolymers have also been used to prepare conventional composites and nanocomposites. However, similar to the case of polymer blends, not too many studies have been reported thus far. Recently, Kelarakis et al. (49) have mixed 10 wt% of surface-modified carbon nanofiber (MCNF) with propylene-ethylene random copolymer (propylene 84.3%). The MCNF acted as a nucleating agent for crystallization of the a-form of PP in the matrix. During deformation at room temperature, strain-induced crystallization took place, while the transformation from the 7-phase to a-phase also occurred for both unfilled and 10 wt% MCNF-filled samples. The tensile strength of the filled material was consistently higher than that of pure copolymer. These results are illustrated in Fig. 8.27. 

Nanofibers based on poly(vinyl alcohol) as the matrix, and nanocrystals of a-chitin (ca. 31 nm in width and ca. 549 nm in length) as the nanofiller were prepared by Junkasem et al. [51]. The average diameters of the electrospun fibers ranged between 175 and 218 nm. The addition of increasing amounts of the whiskers caused the crystallinity of poly(vinyl alcohol) within the nanocomposite materials to decrease and the glass transition temperature to increase. 

Graphene-polymer nanocomposites share with other nanocomposites the characteristic of remarkable improvements in properties and percolation thresholds at very low filler contents. Although the majority of research has focused on polymer nanocomposites based on layered materials of natural origin, such as an MMT type of layered silicate compounds or synthetic clay (layered double hydroxide), the electrical and thermal conductivity of clay minerals are quite poor [177]. To overcome these shortcomings, carbon-based nanofillers, such as CB, carbon nanotubes, carbon nanofibers, and graphite have been introduced to the preparation of polymer nanocomposites. Among these, carbon nanotubes have proven to be very effective as conductive fillers. An important drawback of them as nanofillers is their high production costs, which... 

Figure 7.17 SEM images of nanocomposites with hierarchial nanostructures prepared by electrospinning followed by calcination (a) V20s-Ta205 nanorods on Ti02 nanofibers, and (b) V2O5 nanorods on Si02 nanofibers. (Reprinted with permission from R. Ostermann et al. Nano Lett. 2006, 6, 1297. Copyright (2006) American Chemical Society.)...

Figure 4.7 SEM images of OD/PVP nanofibers (a) and OD/PVP with Ag nanocomposite (b), and TEM images of OD/PVP nanofibers (c) and OD/PVP with Ag nanocomposite (d). (Reprinted with permission from Synthetic Metals, Preparation of oligoaniline derivative/poly-vinylpyrolidone nanofibers containing silver nanoparticels by D. Chao, L. Cui, J. Zhang et al., 159, 537-540. Copyright (2009) Elsevier Ltd)...

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