Nanoparticle agglomeration state

Jiang. J.K., Oberdorster, G., and Biswas, P., Characterization of size, surface charge, and agglomeration state of nanoparticle dispersions for toxicological studies, J. Nanopart. Res., 11, 77, 2009. 

Stabilization studies have also been carried out with other metal oxide nanoparticles. Due to the demanding requirements as to transparency and homogeneity of nanocomposites for optical applications, which are greatly determined by the agglomeration state of the... 

As shown in Fig. 8.11, an excellent agreement was achieved between the two sizing techniques moreover the electrochemical sizing technique was foimd to present a number of advantages over NTA, which can suffer from drawbacks commonly associated with optical sizing techniques such as the inabihty to measure the agglomeration state of non-spherical nanoparticles without performing a... 

Morphology evolution is thus found to be dependent on the processing technique applied to disperse the nanoparticles. The latex-blended and prevulcanized nanocomposites show predominant exfoliation with some intercalation, especially in uncured and prevulcanized samples. In conventionally cured but latex-blended nanocomposites, realignment of NA particles is visible, with a greater tendency of NA platelets towards agglomeration. In solid state mixing, the dispersion is still poorer. XRD studies also corroborate the above observations. 

The species H, ejq, and OH" are very reactive. Both H and e-, are strong reducing agents with redox potentials of (H+/H )=-2.3 Vnhe and E° (H20/e-,)=-2.87 V he. respectively. Therefore, both can reduce metal ions present in the solution to a state of zero valence. This process takes place through the direct reaction of the metal ion with either H" or e-, in the case of monovalent ions. In contrast, the reduction of multivalent metal ions in aqueous solutions is a multistep process where atoms in unusual valence states are initially formed. This initial reduction is followed by further reduction and agglomeration until a stable nanoparticle is obtained (Belloni et al. 1998). 

The preparation of nanomaterials can be classified into three main approaches according to the states of the reactants nsed Uqnid-phase, solid-phase, and gas-phase method [14,15]. One of the most popular methods in both laboratory and indnstry at present is the Uqnid-phase method. In the preparation of nanoparticles by the Uqnid-phase method, drying is an indispensable unit operation. Nanoparticles tend to agglomerate and properties of nanoparticles are adversely affected if we do not choose appropriate drying methods. So to assnre that nanoparticles are weU dispersed during drying is a vital requirement in the preparation of snch products. 

The strategy of top down is considered traditional for powders fabrication. Nanoparticles are the product of milling of large pieces of any material. The grinding process may also be accompanied by chemical and phase transformations. Theoretically, any substance can be crushed or converted to a vapor state and then condensed. However the problems of impurities, control of particle size distribution and the properties of agglomerates still remain open. 

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