Cable-like structure

While the formation of the nanoribbons can be explained in terms of a crystallization process that leads to these structures on solid surfaces, the formation of the nanocables and nanowires is not so straightforward. The origin of the cable-like structures thus became a topic of interest. They could either arise by a crystallization process when a homogeneous solution of 12 is dried on a surface, or these superstructures could be preformed in solution and act as seeds for the subsequent growth of cables. 

The carbon black in semiconductive shields is composed of complex aggregates (clusters) that are grape-like structures of very small primary particles in the 10 to 70 nanometer size range (see Carbon, carbon black). The optimum concentration of carbon black is a compromise between conductivity and processibility and can vary from about 30 to 60 parts per hundred of polymer (phr) depending on the black. If the black concentration is higher than 60 phr for most blacks, the compound is no longer easily extruded into a thin continuous layer on the cable and its physical properties are sacrificed. Ionic contaminants in carbon black may produce tree channels in the insulation close to the conductor shield. 

The cell-permeable inhibitors induce dramatic changes in cell morphology. These have been documented in several cell types (see Hirano etal., 1992). In 3T3 fibroblasts the changes involve a reorganization of F-actin and its gradual aggregation into a ball-like structure that is connected to the nucleus via cables of intermediate filaments. Several proteins are phosphorylated, but of the major cytoskeletal proteins only vimentin and myosin were identified (Chartier et al., 1991 Hirano and Hartshorne, 1993). It is not known if these extensive changes occur in smooth muscle cells. 

As mentioned above, metal/CPs with core-sheath structure can be prepared by the template method. However, the approach based on the template technique is complicated and non-economical because of the need to remove the templates. In fact, metal/CPs with core-sheath structure can be fabricated via a one-step chemical polymerization [83-87]. Niu and co-workers demonstrated that Au/PANI coaxial nanocables could also be fabricated by the redox reaction between chloroauric acid and aniline in the presence of d-CSA [85]. In that case, CSA acted not only as a dopant, but also as a surfactant or a soft template. In addition to Ag/PPy and Au/PANI nanocables, cable-like Au/poly(3,4-ethylenedioxythiophene) (PEDOT) nanostructures have been synthesized in the absence of any surfactant or stabilizer through one-step interfadal polymerization of EDOT dissolved in dichloromethane solvent and HAuCl dissolved in water [86]. Microscopy studies showed (Figure 13.6) that the outer and inner diameters of Au/PEDOT nanocables were aroimd 50 and 30 nm, respectively. 

Kaolin or clay, its more common name, is a naturally occurring mineral with the chemical formula Al Si, 0, (OH)5. It has a plate-like structure, and is refined and treated for specific uses, the largest of which is the paper industry. Metakaolin, produced by the dehydroxylation of kaolin, is often used to improve the electrical properties of PVC wire and cable compounds. At loadings of about 30 weight percent of the resin in a wire and cable PVC formulation, a doubling of the volume resistivity can be achieved. 

The severity of corrosion interaction will depend on the density of the stray current discharged at any point on the secondary structure. This may be assessed by measuring the changes in structure/soil potential due to the application of the protection current. Potential tests should be concentrated on the portions of pipe or cable which are close to the structure to be cathodic-ally protected, where the potential change is likely to be more positive. 

In the energy domain, new and efficient uses in gas lines, electric cable ducts and the like, will promote surface stabilization and endurance as well as complex stress capability of various extruded or cast systems. Such reactants as acetylene terminated polymers have yielded cross-linked cured, networks of exceptional density and durability. A diimide dianhydride combined with (3) ethynylaniline yields an acetylene terminated tetraimide. On further polymerization at 250°C, the cross-linked structure derived can be used continuously at about 230°C. When this is combined with polymer carbon fibers or filaments, an exceedingly refractory and tough binder is produced. 

The main function of metal deactivators (MD) is to retard efficiently metal-catalyzed oxidation of polymers. Polymer contact with metals occur widely, for example, when certain fillers, reinforcements, and pigments are added to polymers, and, more importantly when polymers, such as polyolefins and PVC, are used as insulation materials for copper wires and power cables (copper is a pro-oxidant since it accelerates the decomposition of hydroperoxides to free radicals, which initiate polymer oxidation). The deactivators are normally poly functional chelating compounds with ligands containing atoms like N, O, S, and P (e.g., see Table 1, AOs 33 and 34) that can chelate with metals and decrease their catalytic activity. Depending on their chemical structures, many metal deactivators also function by other antioxidant mechanisms, e.g., AO 33 contains the hindered phenol moiety and would also function as CB-D antioxidants. 

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