Organic cross-linked

The general properties of the resins are much as to be expected. They have very good heat resistance but are mechanically much weaker than the corresponding organic cross-linked materials. This weakness may be ascribed to the tendency of the polymers to form ring structures with consequent low cross-linking efficiency and also to the low intermolecular forces. 

It is necessary to remember that as well as organic cross-links, elements such as boron, silicon and calcium cross-link all the major external proteins and saccharides even in the walls of prokaryotes. Many of the cross-linking binding sites are of oxidised side chains of biopolymers. As described in Section 8.10, certain of these elements form mineral deposits but now these minerals are frequently found inside the multi-cellular organisms. Here, we see a great difference between the chemo-types of plants and animals. The acidity of the extracellular fluids of plants differs from the neutral fluid of animals. It is not possible to precipitate calcium carbonates (shells) or phosphates (bones) in plants due to the weak acid character of these anions (see Table 8.12). Plants therefore precipitate silica and calcium... 

These steps are typical for most of the synthetic elastomers. The use of sulfur for vulcanization is common for the production of most elastomers. Magnesium and zinc oxides are often used for the cross-linking of polychloroprene (CR). Saturated materials such as EPM and fluoroelastomers are cross-linked using typical organic cross-linking agents such as peroxides. 

Recently Richardson and Richardson (1987) have designed a protein that is intended to adopt an antiparallel /3-barrel structure similar to that of an immunoglobulin VL domain (Fig. 22). To aid in the chemical synthesis of the molecule, the protein was designed as a homodimer of two identical chains connected by an organic cross-linking moiety. The model for the designed protein is highly symmetrical (Fig. 22), with a 2-fold rotational... 

C. Poriel, Y. Ferrand, P. Le Maux, J. Rault-Berthelot, G. Simonneaux, Organic cross-linked electropolymers as supported oxidation catalysts Poly((tetrakis(9,9 -spirobifluorenyl)porphyrin) manganese) films, Inorg. Chem. 43 (2004) 5086. 

Eollowing several observations leading to the easy formation of well-organized cross-linked lattices with simple clusters [59,68], including dimers [69], we became... 

Collagen content, organization, cross-linking and ratio of types 1 to III change with age and in various disease conditions including myocardial ischemia and infarction, hypertension and hypertrophy... 

The Lemaire research group has performed pioneering studies in this area. For example, enantioselective hydride-transfer reaction has been investigated using a catalytic rhodium complex incorporated into an organic cross-linked... 

Different chemical strategies can be devised in order to get an organic cross-linked NLO active system. 

Kosonen H et al. Self-organized cross-linked phenolic thermosets Thermal and dynamic mechanical properties of novolac/block copolymer blends. Polymer 2001 42(23) 9481-9486. 

Jacob, S., Poinsignon, C., and Popall, M. (2005) Inorganic-organic hybrid protonic polymeric materials for fuel cells based on polycondensed and organically cross-linked sulfonyl- and styrene-... 

Infrared and Raman spectroscopy are powerful tools in the elucidation of the ionic conductivity/ionic association relationship in PE systems. This sort of spectroscopic analysis usually involves the examination of diagnostic bands of the host polymer and of the anion. In the case of the organic/ inorganic hybrid matrices incorporating organic cross-links (e.g. di-ureasils), this study must also include the analysis of the bands characteristic of these functional groups (i.e. urea groups). 

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