Casting method composites

Immobilization of the bilayer membranes as thin solid films is required when the bilayer membranes are used as novel functional materials. Casting method is a simple way to immobilize the bilayer membrane on a solid support from an aqueous solution by drying. Polymer film is easily prepared when the cast film of polymerizable bilayer membrane is polymerized. A free standing polymer film prepared by photo polymerization of the cast film of diacetylene amphiphiles was reported by O Brien and co-workers [34]. Composition with macromolecular materials is another way of polymer film preparation. Bilayer membranes are immobilized as polymer composites by the following physical methods ... 

Liu, C. and Martin, G. R. 1990. Ion-transporting composite membranes III. Selectivity and rate of ion transport in Nafion-impregnated Gore-Tex membranes by a high-temperature solution casting method. Journal of the Electrochemical Society 137 3114-3120. 

Neat ADN contains crystals shaped as needles or flakes. No method for re-crystallizing ADN to give more uniformly-shaped crystals has been reported. The ill-shaped crystals limit the amount of ADN in cast-cured compositions due to high viscosity. The only solution to this problem is to reshape the ADN crystals to be more regular. Since the melting point is not directly associated with decomposition, it is possible to use a method whereby ADN is melted. 

Perhaps the most common method for preparing polymer-nanotube composites has been to mix the nanotubes and polymer in a suitable solvent before evaporating the solvent to form a composite film. One of the benefits of the solution casting method is that agitation of the nanotube powder in a solvent facilitates nanotube de-aggregation and dispersion. Almost all solution processing methods are variations on a general theme which can be summarized in three major steps ... 

Chen et al. (67) reported the use of trifluoroacetic acid (TFA) as a cosolvent with tetrahydrofuran (THF) to improve dispersion and processability of the nanocomposites. They prepared MWCNT-PMMA composite films with varying CNT content by solvent casting method using 10 vol % TFA as a co-solvent with tetrahydrofuran (THF). SEM and optical microscopy revealed a good dispersion of nanotubes in solvent and PMMA. The composites showed low percolation... 

At present the progress in the pressure casting method as applied to aminoplasts involves the automation of control for the casting process, as well as the elimination of the hardening of the composition melt in the distribution gates. 

Several polymer/polyelectrolyte-nanocrystal hybrid devices have been fabricated seeking to exploit the electro and photoluminescent properties of such material [179-188]. Device fabrication in all these cases is by low-cost self-assembly based techniques. These devices utilize thin films of these hybrids obtained either by multilayer deposition or drop/spin casting methods. Thus, solar cells have been made from poly(2-hexylthiophene)-CdSe nanorod multilayers, lasers from drop cast films of CdSe-titania composites and an infrared emitter from multilayers... 

Fabrication of a thin film composite membrane is typically a more expensive route to reverse osmosis membranes because it involves a two-step process versus the one-step nature of the phase inversion film casting method. However, it offers the possibility of each individual layer being tailor-made for maximum performance. The semipermeable coating can be optimized for water flux and solute rejection characteristics. The microporous sublayer can be optimized for porosity, compression resistance and strength. Both layers can be optimized for chemical resistance. In nearly all thin film composite reverse osmosis membranes, the chemical composition of the surface barrier layer is radically different from the chemical composition of the microporous sublayer. This is a common result of the thin film composite approach. 

Figure 4. Shear elastic modulus of composites filled with varying amounts of SPC, DSF, SSF, SPI, or CB, The samples were prepared by a casting method. Measured at 0.05% strain, 0.16 Hz, and 140 °C.

Figure II. Stress-strain behaviors at ambient conditions, (a) DSF composites (b) SPI composites (c) SPC composites (d) CB composites. Wt% of filler is indicated on each curve. The samples were prepared by the casting method. (Reproduced from reference 16.)... 

Figure 14. The 8 cycle of strain sweep experiments at 140 °C and 1 Hz. (a) 30/70 DSF/SB composite (b) 20/80 DSF/SB composite (c) 30/70 SPI/SB composite (d) 20/80 SPI/SB composite. The samples were prepared by the casting method. Solid lines are the fit from the Kraus model. (Reproducedfrom reference 16.)...

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