Filler nanoparticles

Most of the reported inorganic fillers used to modify Nafion are composite where the inorganic particles (usually nanoparticles) are located in the membrane bulk. Most of them are prepared using the recast method, where the filler nanoparticles dispersed in a solvent are mixed with Nafion ionomer dispersion in the same solvent or a compatible one. The solution is cast on a Petri dish or a plane surface at high temperature to form the recast composite membrane. An alternative method adopted to prepare Nafion composites with silica [31, 32, 41, 95], functionalized silica [35], and zirconium and titanium phosphate [41], is the in situ sol-gel reaction method, schematized in Fig. 6.5. 

Polymer network chains, not the filler particle chains, are the main actors of reinforcement. The role of filler nanoparticles is passive in reinforcement. They produce field of forces influencing conformational changes of gradient layer chains. 

The progress in the oxidation of LDPE modified with maleic anhydride and alumina proceeds somewhat similar at various doses, because oxygen diffusion is hindered by filler nanoparticles [102]. The noticeable difference between pristine and modified LDPE consists of the presence of maleic anhydride, which interacts with molecular chains due to the electronegativity of oxygen atoms. The same radiation dose affects differently the dielectric behavior of the nanocomposites depending on the filler content. The dose of 50 kGy applied on LDPE-g-AM filled with 5 wt% nano-Al203 leads to a relative permittivity smaller than unfilled LDPE. y-Radiation can lead to a decrease in the dielectric losses of LDPE AI2O3 nanocomposites for properly chosen combination dose-fiUer content. 

On the basis of these considerations, the data listed in Tables 2 and 3 for the dense systems that have been simulated up to now and the corresponding data for other systems with intermediate compositions can be roughly predicted (for chains of 100 units with a random distribution of filler nanoparticles) as follows given the values of af and [Pg.124]

Additives used in flnai products - Fillers nanoparticles of Au, Pd, Cu, Ag ... 

In this contribution, a brirf review of selected results was presented on the elastic and viscoelastic behavior of amorphous polymer nanocomposites. The ovei-view was done in a simplified manner, in order to support its miderstaudability. Below the matrix Tg, a nanocomposite behaves like a two component system due to the low-entropy/low-mobility state of polymer matrix. Above the mati-ix Tg, the polymer chains near the nano-filler surface become perturbed in respect to their dynamics. These changes occurring on the molecular level cause severe effects observable on micro- and macroscopic levels. Due to the extensive nanofiller surface area, the filler nanoparticles are able to cause these effects even at a very low filler concentration. Interestingly, the immobilization phenomenon in polymers filled with high specific surface area fillers has already been addressed in the 60s by DiBenedetto [40], Lipatov [44,56] and others [39,43,45]. The cited authors interpreted the results properly although very poor computer simulation possibilities were available at that time. 

Yudin, V. E. and V. M. Svedichnyi. 2010. Effect of the structure and shape of filler nanoparticles on the physical properties of polyimide composites. Russian Journal of General Chemistry 80 (10) (November 26) 2157-2169. doi 10.1134/S1070363210100452. http //www.springerlink.coni/index/10.1134/S1070363210100452. 

Malzbender J. and de With G. (2002), Modification of the Mechanical Properties of a Sol-Gel Coating Using Silica Filler Nanoparticles , Adv. Eng. Mater., 4,296-300. 

The answers to these challenges are probably given by the fabrication of MMMs, in which the novel membrane materials are loaded in a host of polymeric membranes as filler nanoparticles. Thus, high processibilty of polymeric membranes is combined with high separation performance of filler materials. Usually, separation performance of MMMs is much improved compared with the host polymeric membrane, but the improvement is not as spectacular as expected from the novel membrane materials. A flux that is orders of magnitude higher than the host polymeric membrane has never been achieved by MMMs. 

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