Nanocellulose dispersion

Zhou et al. [53] studied the effect of nanocellulose isolation techniques on the quality of nanocellulose and its performance in reinforced nanocomposites. They employed three different techniques including acid hydrolysis (AH), TEMPO-mediated oxidation (TMO) and ultrasonica-tion (US) to isolate nanocellulose from microcrystalline cellulose (MCC) and to evaluate the quality of nanocellulose and the reinforcing ability of these nanocelluloses in PVA matrices. The characterization of nanocellulose indicated that nanocellulose with higher aspect ratio, surface charge (-47 mV) and yields (37%) was obtained by TMO treatment, while acid hydrolysis treatment resulted in higher crystallinity index (88.1 %) and better size dispersion. 

Nanocelluloses isolated from AH technique have individual crystallites and disperse uniformly showing needle-shaped structures (namely nanocrystals), with diameters of 30-40 nm and lengths of 200-400 nm, while the TMO-derived nanocelluloses are interconnected webs showing nanofibrils with diameters of 40-80 nm and lengths ranging from 200 nm to several micrometers, having a wide range of aspect ratio. 

Both the TMO-derived and AH-derived nanocelluloses could homogeneously disperse in the PVA matrixes. The TMO/PVA films were better than AH/PVA films for tensile modulus and strength but were lower for elongation. The thermal behavior of the PVA nanocomposite films was more highly improved with addition of TMO-derived nanofibrils. It has been found that because of the mild reaction condition, the environmentally friendly attribute, the good quality of resulted nanofibrils and the superior properties of the final reinforced nanocomposites, the TMO technique has significant potential in the field of composite reinforcement. 

The incorporation of nanocellulose into a polypropylene matrix is very challenging and at the same time very promising due to the large market for natural polymers as a reinforcement agent, mainly for the automotive industry. This chapter describes the work done aiming to disperse and incorporate nanocellulose from several sources into a polypropylene matrix. 

There have also been some investigations into the properties of nanocellulose from wood, which has an amazing waterstorage capacity, similar to BC. A dispersion of... 

Potential of nanocellulose has been established as the next generation renewable reinforcement for the production of renewable high performance biocomposites by the researchers. The tensile modulus and strength of most cellulose nanocomposites has been reported hnearly with the tensile modulus and strength of the cellulose nanopaper structures. Uniform dispersion of individual cellulose nanofibres in the polymer matrix may improve the composite properties [54]. In last few decades... 

Lemahieu L, Bras J, Tiquet P, Augier S, Dufresne A. Extrusion of nanocellulose-reinforced nanocomposites using the dispersed nano-objects protective encapsulation (DOPE) process. Macromol Mater Eng 2011 296 984-991. 

Figure 12.8 shows the morphological features of cellulose, NC, NC/PVA, and AMO-P(AA-co-AMPS)-g-NC/PVA. Cellulose seems to be fibrous in nature, while, NC looks fluffy and behaves like a gel, which may be due to the increased hydrophi-licity. This gel structure is suitable for the drug delivery vehicles. NC/PVA combines both the nature of NC and PVA. Nanocellulose fibers appear to be dispersed in the PVA matrix. AMO-P(AA-c<9-AMPS)-g-NC/PVA clearly indicates the drug loading and the polymers adhered on the surface of the NC/PVA composite. 

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