Polymerization nanocomposites

The rheological properties of insitu polymerized nanocomposites with end-tethered polymer chains were first described by Krisnamoorti and Giannelis [33]. The flow behavior of PCL- and Nylon 6-based nanocomposites differed extremely from that of the corresponding neat matrices, whereas the thermorheological properties of the nanocomposites were entirely determined by the behavior of the matrices [33]. The slope of G (co) and G"(co) versus flxco is much smaller than 2 and 1, respectively. Values of 2 and 1 are expected for linear mono-dispersed polymer melts, and the large deviation, especially in the presence of a very small amount of layered silicate loading, may be due to the formation of a network structure in the molten... 

Both the high-temperature and reverse selective polymeric nanocomposite membranes are being investigated on a laboratory scale. 

Keywords polyamides solid-state polymerization nanocomposites FTIR catalysis. 

Simultaneous evaporation of metal with organic and inorganic substances followed by vapor deposition on a substrate allows the production of composite films containing M nanoparticles stabilized in various dielectric matrices [2, 28]. The use of monomer molecules in this process polymerizing during deposition or as a result of the subsequent reactions yields polymeric nanocomposite films with metal inclusions [2, 3, 28, 37]. The new low-temperature synthesis of polymeric nanocomposite films has been elaborated recently. This synthesis is based on the deposition of M/SC and monomers vapors at temperature 80 K followed by low-temperature solid-state polymerization of obtained films in conditions of frozen thermal movement of molecules (cryochemical synthesis) [2], This synthesis has important features, which will be considered further. 

Utracki, L. A., Sepehr, M., and Boccaleri, E. Synthetic, layered nanoparticles for polymeric nanocomposites (PNCs). Polym. Adv. Technol. 2007,18, 1-37. 

Joshi, M. and Butola, B. S., Polymeric nanocomposites—polyhedral oligomeric silsesquioxanes (POSS) as hybrid nanofiller, J. Macromol. Sci., Polym. Rev. (2004), C44, 389M10. 

Utracki, L. A. Clay-Containing Polymeric Nanocomposites, RAPRA Tech. Ltd., Shawbury, Shrewsbury, Shropshire, U.K., 2004, p. 496. 

Recently, new approaches on flame retardancy deal often with nanofillers and in this section some examples of improvements of fire behavior of polymeric foams obtained by use of nanoclays or nanofibers will be shown. Much more details on flame retardancy of polymeric nanocomposite may be found elsewhere as for example in the book edited by A. B. Morgan and C. A. Wilkie105 or in scientific review.106 Polymer nanocomposites have enhanced char formation and showed significant decrease of PHRR and peak of mass loss rate (PMLR). In most cases the carbonaceous char yield was limited to few weight %, due to the low level of clays addition, and consequently the total HRR was not affected significantly. Hence, for polymer nanocomposites alone, where no additional flame-retardant is used, once the nanocomposite ignites, it burns slowly but does not self-extinguish... 

POROUS POLYMERIC NANOCOMPOSITES FILLED WITH CHEMICALLY MODIFIED FUMED SILICAS... 

Historically, polysiloxane elastomers have been reinforced with micron scale particles such as amorphous inorganic silica to form polysiloxane microcomposites. However, with the continued growth of new fields such as soft nanolithography, flexible polymer electronics and biomedical implant technology, there is an ever increasing demand for polysiloxane materials with better defined, improved and novel physical, chemical and mechanical properties. In line with these trends, researchers have turned towards the development of polysiloxane nanocomposites systems which incorporate a heterogeneous second phase on the nanometer scale. Over the last decade, there has been much interest in polymeric nanocomposite materials and the reader is directed towards the reviews by Alexandre and Dubois (4) or Joshi and Bhupendra (5) on the subject. 

These interesting POSS features, briefly mentioned above, have motivated this work to critically review recent developments in the syntheses of POSS polymer materials to form POSS nanocomposites. The work further examines the properties of POSS nanobuilding blocks that can otherwise be used for developing polymeric nanocomposites. In particular, the syntheses of POSS cages, monomers containing POSS cages, POSS-dendrimers cores, POSS-containing polymers and POSS nanocomposites are covered in details. It should be emphasized that the assessment of the relationship between the... 

Effect of Fed 3 on Polymerization/Nanocomposite Formation in N-Vinylcarbazole-MMT System... 

Table4. Some typical data for ANI-MMT [(NH4)2S208] polymerization/nanocomposite formation system...

MMT polymerization/nanocomposite formation system addition of FeCl3 increased the percentage loading of PNVC in the composite. 

The first All-Russia Scientific and Technical Conference Nanostructures in polymers and polymeric nanocomposites (the Kabardino-Balkarian State University, Nalchik, Russia, June, 2-5 2007) ... 

H.-J. GLASEL, F. BAUER, E. HARTMANN, R. MEHNERT, H. MOBUS, V. PTATSCHEK, Radiation-cured polymeric nanocomposites of enhanced surface-mechanical properties , NIM-B, (2003)... 

Polymeric nanocomposites are a class of relatively new materials with ample potential applications. Products with commercial applications appeared during the last decade [1], and much industrial and academic interest has been created. Reports on the manufacture of nanocomposites include those made with polyamides [2-5], polyolefins [6-9], polystyrene (PS) and PS copolymers [10, 11], ethylene vinyl alcohol [12-15], acrylics [16-18], polyesters [19, 20], polycarbonate [21, 22], liquid crystalline polymers [8, 23-25], fluoropolymers [26-28], thermoset resins [29-31], polyurethanes [32-37], ethylene-propylene oxide [38], vinyl carbazole [39, 40], polydiacethylene [41], and polyimides (Pis) [42], among others. 

The processing of polymeric nanocomposites based on PET and a clay, MMT, was analyzed elsewhere [45]. The clay was chemically modified with a quaternary ammonium salt, and this was subsequently incorporated into the polymer using maleic anhydride (MAH) and pentaerythritol (PENTA) as compatibilizing agents. 

The radiation technique is widely used for the production of nanostructured polymer-containing materials such as polymeric nanocomposites and nanogels (Sharif et al. 2007, Ulanski and Rosiak 1999). The radiation processing of these materials is accompanied by various radiation-induced processes (polymerization, cross-linking, degradation of polymeric chains, etc.) (Chmielewski et al. 2005). 

Polymeric nanocomposites are an important class of new emerging nanomaterials that exhibits remarkable improvanents of material properties compared with conventional micro- and macrocomposite materials. The small dimension of the filler particles and, accordingly, large surface of the phase separation give the final product characteristics, which considerably exceed traditional ones at minimal filler concentration (Mikitaev et al. 2008). The formation of the polymeric nanocomposite may be represented as the process of filling of the free space in disperse phase with polymer in the form of melt or solution or with monomer followed by its in situ polymerization by chemical or radiation influence on the formed composite structure. The scheme of the polymeric nanocomposite synthesis under radiation is shown in Figure 18.5. 

The radiation synthesis of polymeric nanocomposites is one of the promising technologies in the production of polymeric nanomaterials (Taleb et al. 2012). Along with the polymerization of monomers in situ (Liu et al. 2001, Meszaros and Czvikovszky 2007), radiation-induced cross-linking leads to the reinforcement of the available polymeric matrix owing to additional bond formation both between polymer chains of the matrix (Glhsel et al. 2003, Sharif et al. 2007) and between the polymer matrix and filler particles (KrkljeS et al. 2007, Planes et al. 2010). It is a very useful technique to improve the thermal stability, stress crack resistance, solvent resistance, and... 

FIGURE 18.5 Schematic view of the radiation-induced formation of polymeric nanocomposites. 

Radiation methods occupy an important place in the production and investigation of new functional materials, devices, and systems of nanometer size (ion-track membranes, polymeric nanocomposites, 3D nanostructures, metal nanoparticles, carbon nanostructures, etc.). The recent trend towards electronic miniaturization places at the forefront the problem of fabrication of semiconductor nanostructures, which is possible only with the use of radiation lithographic methods. The radiation modification of graphene can play a key role in the development of a new generation of industrial microchips based on graphene transistors, which will lead to a sharp increase in the operation speed and recording density of modem computer and communication systems. 

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