Cross-linldng

G(scission) = G(S) = Number of polymer chain scissions per 100 eV absorbed. G(cross-linldng) = G(X) = Number of polymer cross-link sites per 100 eV absorbed. 

I.4.2.2. Cross-linldng of Polymers Among applications of nitrile oxides, cross-linking of polymers is of main importance. Both nucleophilic addition and 1,3-dipolar cycloaddition are the pertinent reactions. 

Formaldehyde cross-linldng of vvhoie cells (if required)... 

To elucidate the mechanism of cross-linldng in CMS, pulse radiolysis studies (98) and low-temperature electron spin resonance (ESR) studies (99)... 

Conditions Activator, 1.5% HNO3 (72%) (oven-dry basis) cross-linldng agent, 7% (oven-dry basis), composed of 60% ammonium lignosulfonate, 25% furfuryl alcohol, and 15% maleic anhydride target density, 0.65 g/cm bonding, 7 min at 177 °C with 9-11% moisture content of the material. 

Curdlan gel formation is heat dependent. This polysaccharide is not soluble in water, but when an aqueous suspension is heated it becomes dear at about 54°C. Furdier heating leads to gel fonnation. The gels are stable over a wide range of pH (3 to 95) and do not melt at temperatures below 100°C. Curdlan gels are formed by cross-linldng, involvii conformational ordering of the exopolysaccharide molecules to give a triple helical structure. 

MacryUc. [Ivax Ind tries] Self-cross-linldng acrylate emulsion shrinkt e and abrasion improver. 

Some ingenious strategies have been reported fw the site-specific cross-linldng of oligonucleotide strands. Oligodeoxyribonucleotides containing thymidine residues in which the N-3-... 

The curves plotted in Figure 4 are from equation 1 with = 3 and 4. The curve for four cross-linldng sites per mole is in very good agreement with the chemical estimate of the number of pendant hydrophobes. 

N number of cross-linldng sites per unit volume... 

The viscosity of the copolymer-surfactant solution depends upon the nature and extent of association of the hydrophobic blocks (27). Figure 2 illustrates the possibilities. If no surfactant is present (top of Figure 2), the hydrophobic blocks can associate intermolecularly, intramolecularly, or a combination of both. If the system is swamped with surfactant (middle of Figure 2), each hydrophobic block is completely solvated by surfactant so that there is no cross-linldng. As heat, electrolyte, or other additives affect the number and aggregation number of micelles, various amounts of inter-molecular or intramolecular cross-linldng are produced (bottom of Figure... 

This chapter describes ionic cross-linldng of the HASE thickener with zinc oxide or zinc ammonium complexes to improve early blister resistance. Zinc ammonium complexes have been used in ammonia-removable latex floor polishes for decades. Paint formulations containing zinc oxide have benefits but are prone to sporadic viscosity instability, which sometimes cannot be predicted by standard laboratory tests. However, many paint manufacturers have learned how to successfully stabilize these zinc oxide-containing latex paints. 

Organometallic Complexes in Macroporous Polymers. Fluently the catalytic activity of two or more organometallic complexes in equilibrium is due only to one species. The composition, as we have seen frrom spectroscopic studies, depends on the degree of functionalization of die polymer, the degree of cross-linldng, and the... 

In a very elegant study involving site-directed cross-linldng of the receptor Tar, Milligan and Koshland [503] have demonstrated that the MCPs are homodimers (Figure 13). The dimers appear to be the... 

For both filopods and lamellipods/pseudopods, stimulated actin polymerization directly under the membrane is thought to provide the driving force producing the protrusion [21,40,169,173]. Thus the regulation of the location of actin polymerization and the cross-linldng between actin filaments is critical for coordinating chemotactic responses. 

When photosensitizers such as benzophenone are added to polymer, absorption of ultraviolet radiation results in excitation of the sensitizer followed by hydrogen abstraction fi-om the polymer to yield radical sites (Equation 1.39) available for cross-linking by combination reactions. Copolymers of vinyl esters and fluorinated monomers that can be cross-linked by ultraviolet radiation have been developed for use as weather-resistant wood coatings. In this application, the vinyl ester constitutes about 10% of the copolymer and benzophenone is added as a photosensitizer. The vinyl ester polymer also undergoes a-cleavage reaction (Equation 1.40) with subsequent cross-linldng. 

Gamma Irradiation Cross-Linldng, Anal. Chem. 59 134 (1987). 

In an elastomer (rubber), the macromolecules are cross-linked. The cross-linldng degree is moderate so that elastomers can be stretched easily. A transparent elastomer widely used in microfluidics is the sdicOTie rubber polydimethyl-siloxane (PDMS). 

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