Cross linkage effects

Chang MC, Ikoma T, Kikuchi M et al (2002) The cross-linkage effect of hydroxyapatite/collagen nanocomposites on a self organization phenomenon. J Mater Sd Mater Med 13 993-997... 

Various other chemical agents which by their nature are capable of producing cross-linkages between polymer chains effect the same changes in physical properties that are observed in sulfur vulcanization. One of the best known of these agents is sulfur monochloride, which readily combines with two molecules of an olefin (the mustard gas reaction). Applied to rubber, it induces vulcanization even at moderate temperatures, the probable structure of the cross-linkage being... 

Fig. 92.—Effects of flaws consisting of ends of primary molecules on the network structure. indicates a cross-linkage, O the terminus of a primary molecule, and signifies continuation of the network structure. ...

It is now an easy matter to express the total number Ve/2 of effective, or intrastructural, cross-linkages ]it will equal the actual number vl1 of cross-linkages less the threshold number, which may be taken as iV. Hence... 

Until recently s the last term in the brackets in Eq. (38) was given erroneously as (viFe/Fo)t 2. This error resulted from the use of incorrect elastic entropy and free energy expressions in which the InaJ term of Eq. (35) was omitted. This term takes account of the entropy of distribution of the effective cross-linkages over the volume Foq = F. 

Carmichael DJ, Dodd CM and Veis A (1977) The solubilization of bone and dentine collagens by pepsin. Effect of cross-linkages and non-collagen components. Biochim Biophys Acta 491, 177-192. 

Torchilin, V.P., Maksimenko, A.V., Smirnov, V.N., Berezin, I.V., Klibanov, A M. and Martinek, K. (1978) The principles of enzyme stabilization. 111. The effect of the length of intra-molecnlar cross-linkages on thermostabihty of enzymes. Biochim. Biophys. Acta, 522, 277-283. 

Polysaccharides that have been modified chemically, or altered physically, have been used as adsorbents for affinity chromatography. The modification of the structure of polysaccharides has been achieved by introducing cross-linkages between the chains of the polymer and bifunctional reagents. The alteration of the properties of polysaccharides by physical means can be effected by embedding the polysaccharide in a network of the support material. The molecular in-... 

Highly effective host molecules for metal ions have been designed with 2,9-bis(bro-momethyl)-l,10-phenanthroline (2) by the cross-linkage method [37]. By the reaction... 

Next, observe that in all of the cylindrical molecules nomenclated so far, the chains between the bridgehead atoms are "independent" i.e., there is no atom common to two or more chains between the bridgehead atoms. On the other hand, had there been such "cross-linkage" in three dimensional space then the "jump rope effect" between the individual chains would be... 

Resin Beads. The resin beads are prepared from commercially available Dowex 50W-X8, a sulfonic acid cation exchange resin. The 8% cross-linked resin was chosen because it does not shrink or expand excessively in acid-water systems and because it is readily available. Resin cross-linkage had no detectable effect on the final oxide products in the development test runs. The resin is hydraulically classified to produce a size fraction that is predominately 60-80 m in diameter. The classified resin is washed with 6 M HC1 to remove contaminants such as iron and rinsed thoroughly with water. 

Composition of Parent Pitch. Once the chemical composition of the carbonizing system moves away from the comparative simplicity of polynuclear aromatic hydrocarbons to that of industrial pitches, then the pyrolysis chemistry incorporates effects caused by the presence of heteroatoms (0, N and S) and alkyl and naphthenic groups. In general terms, the system becomes more Reactive creating higher concentrations of radicals detectable by ESR. This in turn, leads to enhanced cross-linkages and polymerization of molecular constituents of any mesophase which is formed, and this causes enhanced viscosity and a reduction in size of optical texture. 

Table 4-3. Effects of Increasing Cross-Linkage in Polystyrene or Phenolic Resins...

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