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Carbon-based network solids

Covalent network solids Atoms such as carbon and silicon, which can form multiple covalent bonds, are able to form covalent network solids. In Chapter 7, you learned how the structures of graphite and diamond give those solid allotropes of carbon different properties. Figure 13-20 shows the covalent network structure of quartz. Based on its structure, will quartz have properties similar to diamond or graphite ... [Pg.402]

Khalkhal and Carreau (2011) examined the linear viscoelastic properties as well as the evolution of the stmcture in multiwall carbon nanotube-epoxy suspensions at different concentration under the influence of flow history and temperature. Initially, based on the frequency sweep measurements, the critical concentration in which the storage and loss moduli shows a transition from liquid-like to solid-like behavior at low angular frequencies was found to be about 2 wt%. This transition indicates the formation of a percolated carbon nanotube network. Consequently, 2 wt% was considered as the rheological percolation threshold. The appearance of an apparent yield stress, at about 2 wt% and higher concentration in the steady shear measurements performed from the low shear of 0.01 s to high shear of 100 s confirmed the formation of a percolated network (Fig. 7.9). The authors used the Herschel-Bulkley model to estimate the apparent yield stress. As a result they showed that the apparent yield stress scales with concentration as Xy (Khalkhal and Carreau 2011). [Pg.751]

Template-based synthesis involves the fabrication of the desired material within the pores or channels of a nanoporous template. A template may be defined as a central structure within which a network forms in such a way that removal of the template creates a filled cavity with morphological and/or stereochemical features related to those of the template. Track-etch membranes, porous alumina, and other nanoporous structures have been characterized as templates. Electrochemical and electroless depositions, chemical polymerization, sol-gel deposition, and chemical vapor deposition have been presented as major template synthetic strategies. Template-based synthesis can be used to prepare nanostructures of conductive polymers, metals, metal oxides, semiconductors, carbons, and other solid matter... [Pg.397]

In the case of PSCSs when x > 0.1, most of the products were found soluble and were converted into the corresponding PCS at 450 °C, under atmospheric pressure. These spinnable PCS were transformed into SiC-based materials with ceramic yields very close to those of Yajima ( 60 %). PSCSs of formula (MeRSi),.j-(HR SiCH2SiR H)j also were prepared in order to appreciate the influence of R and R on the carbon content of the ceramic. Otherwise, multinuclear solid state NMR studies indicated that the network was first built around silicon atoms (formation of SiC4) then, at higher temperature, aroimd carbon atoms (formation of CSi4). [Pg.710]

Activated carbons were the first adsorbents to be developed. As stated in previous sections, activated carbons are produced from a solid carbonaceous based material, which is non-graphitic and non-graphitizable, and has an initial isotropic structure. The precursor is transformed or activated by means of medium to high temperature treatments, which remove solid mass, and at the same time, create pores where the removed mass was previously located. The common properties of activated carbons and other kinds of carbon adsorbents is their well developed pore network, and the similar ways in which they are... [Pg.12]


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Carbon bases

Carbon network

Carbon-based

Carbon-based networks

Network solids

Solid carbon

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