Cross Unking

The crystal stmcture of ramsdeUite [12032-73-4] is similar to that of P Mn02 except that double chains of MnO octahedra are cross-Unked to adjacent double chains through the sharing of oxygen atoms located at the corners. RamsdeUite and pyrolusite are the only manganese dioxide phases where the composition approaches the stoichiometric Mn02 formula. Heating ramsdeUite to 250°C transforms it to pyrolusite. 

Dicyclopentadiene is also polymerized with tungsten-based catalysts. Because the polymerization reaction produces heavily cross-Unked resins, the polymers are manufactured in a reaction injection mol ding (RIM) process, in which all catalyst components and resin modifiers are slurried in two batches of the monomer. The first batch contains the catalyst (a mixture of WCl and WOCl, nonylphenol, acetylacetone, additives, and fillers the second batch contains the co-catalyst (a combination of an alkyl aluminum compound and a Lewis base such as ether), antioxidants, and elastomeric fillers (qv) for better moldabihty (50). Mixing two Uquids in a mold results in a rapid polymerization reaction. Its rate is controlled by the ratio between the co-catalyst and the Lewis base. Depending on the catalyst composition, solidification time of the reaction mixture can vary from two seconds to an hour. Similar catalyst systems are used for polymerization of norbomene and for norbomene copolymerization with ethyhdenenorbomene. 

The emulsion technique is convenient when the drug is particularly sensitive to certain parameters connected to the spray-drying. The emulsion technique may be associated to cross-Unking or other treatments of the microspheres. The following examples are self-explanatory. 

In summary, the attributes of the elastomer that contribute to the enhanced impact strength of a plastic in plastic mbber blend include the type of mbber, plastic to mbber ratio, particle size, particle size distribution, cross-Unk density, and degree of grafting, if any. Molecular weight and molecular weight distribution of the plastic also exert some influence. For example, for high-impact PS, the optimal molecular weight of PS is between 170,000 and 220,000. The dispersity index is... 

The objective of recent DSM studies was to develop new EPM-based elastomers that have improved oil resistance. The idea was to develop such products by chemical modification of EPM copolymers using highly polar graft monomers, such as maleic anhydride (MA), and, optionally, by reacting these EPM-g-MA polymers with other chemicals as a way to (cross-Unk and) further enhance the polarity of the products. It is expected that the enhanced polarity will eventually lead to improved oil resistance of the final (cross-Unked) products, ft is noted that the EPM copolymers with extremely high MA graft levels as employed in this study are not commercially available. 

Assumption in the new model that there is hardly any or no chemical cross-Unks in the SH layer, only makes the changeable and deformable characteristics of the SH layer possible. This assumption has almost been verified experimentally. 

Cross-Unking Since cross-Unks provide constraints against chain portions being moved apart by incoming liquid molecules, swelling is reduced by high cross-linked levels. 

Presence of photosensitive groups is an essence for a polymer to get cross-Unked by light energy (UV or visible). 

Product yield The yield of an irradiation process [39] can be defined as the amount of a particular reaction (cross-Unking, degradation, gas formation, formation of unsaturation, etc.) produced per 100 eV of absorbed energy. It is expressed as the G value, for example. 

DM and DAc of various pectin fractions except those of OHSP (due to deesterification during extraction) are summarized in Table 5. The DM of WSP of conventionally canned carrots did not significantly differ from that of fresh carrots,while in the presence of CaCk a considerable increase was observed. This increment can be ascribed to cross-Unking of water soluble-low methylated... 

Static leak-off experiments with borate-crosslinked and zirconate-cross-Unked hydroxypropylguar fluids showed practically the same leak-off coefficients [1883]. An investigation of the stress-sensitive properties showed that zirconate filter-cakes have viscoelastic properties, but borate filter-cakes are merely elastic. Noncrosslinked fluids show no filter-cake-type behavior for a large range of core permeabilities, but rather a viscous flow dependent on porous medium characteristics. 

Most of the methods of synthesis reported above present some limitations and constraints lack of solubility for polycationic phosphorus-containing dendrimers from generation 3 [2], dendrimers of weak molecular weight [4], difficulties to overcome cross Unking reactions [6], possibility only to incorporate phosphorus groups on the surface of dendrimers [3], etc. 

From carbodiimide cross Unking experiments it has been suggested that Lysl87 of cytochrome f becomes attached to Asp44 of plastocyanin [152]. 

Felby, C., Hassingboe, J. and Lund, M. (2002). Pilot-scale production of fibreboards made by laccase oxidized wood fibers board properties and evidence for cross-Unking of lignin. Enzyme and Microbial Technology, 31(6), 736-741. 

Novolac on heating with formaldehyde undergoes cross Unking to form an Infusible solid mass called bakelite. It is used for making combs, phonograph records, electricai switches and handles of various utensils. 

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