Fabrication techniques solution blending

Another technique, known as the dry powder mixing method, has been employed by Cooper et al. to produce nanotube-reinforced polymethylmethacrylate (PMMA) composites [61]. Like most of the currently used fabrication methods for nanotube-based polymer composites, this technique is a combination of several protocols including solution-evaporation, sonication, kneading, and extrusion. More specifically, these workers used ultrasonic techniques to blend carbon nanotubes with PMMA particles, and the blend was later extruded to orient the nanotubes. Yang et al. [62] prepared small-scale batches of ABS nanocomposites without the use of solvents or ultrasonic techniques with good dispersion of the nanotubes. 

It has been indicated how interfacial morphology plays a crucial role in the transport properties of hybrid membranes, and conditions as close as possible to the ideal case must be achieved to ensure advanced separation performances. For this reason, several fabrication techniques have been developed to reduce as much as possible the influence of a nonideal interfacial morphology on the transport characteristics of the hybrid membranes. Among the most frequently used procedures there are solution blending, the sol-gel procedure, surface modification, and interfacial polymerization. In some cases a combination of these techniques is required to reach the best dispersion of the filler within the matrix. 

Since multiple electrical and optical functionality must be combined in the fabrication of an OLED, many workers have turned to the techniques of molecular self-assembly in order to optimize the microstructure of the materials used. In turn, such approaches necessitate the incorporation of additional chemical functionality into the molecules. For example, the successive dipping of a substrate into solutions of polyanion and polycation leads to the deposition of poly-ionic bilayers [59, 60]. Since the precursor form of PPV is cationic, this is a very appealing way to tailor its properties. Anionic polymers that have been studied include sulfonatcd polystyrene [59] and sulfonatcd polyanilinc 159, 60]. Thermal conversion of the precursor PPV then results in an electroluminescent blended polymer film. 

Purely physical polymer blends are most commonly prepared by either mechanical mixing (melt) or dissolution in a common solvent followed by casting and solvent removal. In this study, both techniques were used the latter method was more readily applicable for film formation in small-scale laboratory batches. It was recognized that certain morphological differences between melt- and solution-fabricated polymers are often observed these include phase inversions and distortions, especially with graft and block polymers. However, casual observation by optical and electron microscopy revealed no dramatic differences between the melt- and solution-cast films, and this cannot be readily explained. 

Wu, J., Liang, S., Dai, H. et al. (2010) Structure and properties of cellulose/chitin blended hydrogel membranes fabricated via a solution pre-gelation technique. Carbohydrate Polymers, 79(3), 677-684. 

NR composites and nanocomposites can be fabricated by three main techniques, namely latex compounding, solution mixing and melt blending. A variety of nanofillers, such as carbon black, silica, carbon nanotubes, graphene, calcium carbonate, organomodified clay, reclaimed rubber powder, recycled poly(ethylene terephthalate) powder, cellulose whiskers, starch nanocrystals, etc. have been used to reinforce NR composites and nanocomposites over the past two decades. In this chapter, we discuss the preparation and properties of NR composites and nanocomposites from the viewpoint of nanofillers. We divide nanofillers into four different types conventional fillers, natural fillers, metal or compound fillers and hybrid fillers, and the following discussion is based on this classification. 

A number of methods have frequently been employed in the production of nanocomposite materials. These include solution intercalation, melt intercalation, polymerization, sol-gel, deposition, magnetron sput-tering, laser, ultrasonication, supercritical fluid, etc. In PHA nanocomposite fabrication, solution intercalation and melt intercalation methods are the most widely explored procedures. However, use of in situ intercalative polymerization, supercritical fluids and electrospinning are shown to be promising and emerging techniques. The performance and quality of a nanocomposite depends on how well the nanofillers disperse or blend into the matrix. Therefore, these methods constitute different strategies to improve the composites thermo-mechanical and physico-chemical properties by enhancing efficient interactions between the nanofiller and the polymer matrices. 

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