Solutions, polymer formation

Polymerization of acrylamide is usually performed in aqueous solutions. The principal factors that determine popularity of this polymerization technique are a high rate of polymer formation and the possibility to obtain a polymer with a large molecular weight. The reason for a specific effect produced by water upon acrylamide polymerization lies in protonation of the macroradical, leading to localization of an unpaired electron, which leads to an increase in the reactivity of the macroradical ... 

Uranyl Nitrate Influence on Polymer Growth. The effect of a solute such as uranyl nitrate on this polymer formation is so complex that the net effect on the polymer growth rate cannot be predicted. Experimentally, it is observed that the rates of growth at given initial HNO3 concentration are always slower in the presence of as indicated by the solid curve in... 

Reflux Experiments. More recent efforts have been directed at a quantitative evaluation of those parameters that affect polymer growth, namely acidity, plutonium concentration, temperature, and reflux action. The last is an interesting example to illustrate since the admission of low acid condensates or diluents to a Pu(IV) solution causes some polymer formation even when the bulk solution is otherwise acidic enough to prevent any measurable degree of hydrolysis. 

This untimely polymer formation is understood to be caused by the very rapid hydrolysis and aggregation of monomeric Pu(IV) species (at the region of condensate reentry into the hot plutonium solution) to produce hydrous polymers that are not readily depolymerized. At high temperatures such as found under reflux conditions, the polymer rapidly ages through the conversion of hydroxyl- to oxo-bridges ... 

Frumkin, 169 for zinc, 92, 100 tabulated, 101 zinc-solutions, and, 92 Potential step method, in polymer formation, 386... 

Quantum chemical calculations, 172 Quantum chemical method, calculations of the adsorption of water by, 172 Quantum mechanical calculations for the metal-solution interface (Kripsonsov), 174 and water adsorption, 76 Quartz crystal micro-balance, used for electronically conducting polymer formation, 578... 

In reversible polymerization, the critical concentration is equal to the equilibrium dissociation constant for polymer formation. This parameter is therefore independent of the number of polymers in solution. Confirmation comes from smdying reversible polymerization of ADP-actin when sonic vibration is applied to a solution of F-ADP-actin filaments at equilibrium with G-ADP monomers, no change is observed in the proportion of G- and F-actin (Carlier et al., 1985). Therefore, the only effect of sonic vibration is to increase the number of filaments without affecting the rates of monomer association to and dissociation from filament ends. 

Solution Polymer of length / is formed by the reaction of any two molecules whose lengths sum to /. It is consumed when it reacts with any molecule. The batch rate equation governing the formation of polymer of length I is... 

Overall goal of this work was to maximize the amount of information obtained from chromatographic analysis of latex solutions. More specific aims were (1) measure amounts of unreacted monomers, as one measure of conversion, (2) determine amount of polymer, as a second measure of conversion, (3) estimate chemical composition of the polymer formed, and (4) look for evidence of grafting (in the AN/M polymerization) as evidenced by detection of insoluble polymer formation. 

CDCI3 solution the formation of the monochlorolau-rate was observed [251]. Despite the fact that 119Sn is a reasonable sensitive NMR nucleus (Table 5.14) 119Sn 1-NMR activity applied to polymer additives is quite limited. 

Polymer formation is still observed with some sterically hindered thiolates, 2,4,6-Ao-propyl thiophenolate, and 2,4,6-trimethyl thiophenolate complexes have been studied. They can be synthesized by the reaction of Zn[N(SiMe3)2]2 with the appropriate arene chalcogenol. With the least steric bulk, the trimethyl derivative forms coordination polymers that can only be dissolved in strongly coordinating solvents. The iso-propyl derivative is more soluble forming oligomers in solution. 1... 

Viscosity Behavior. The polymeric nature of triorganotin fluorides dissolved in nonpolar solvents is outlined in the introduction. As a result of the transient polymer formation, these solutions exhibit nonlinear concentration vs. viscosity curves. 

At the end of the above reaction sequence Pu(OH)4 precipitates out - Katz and Seaborg (11) have calculated the solubility product as 7 x 10-56. Polymer formation is a rapid process when the Pu4+ solution is adjusted to contain 0.4 x 10 4m to 1.2 x 10 2m in 0.1m HN03,40% of the plutonium polymerised within the first 30 minutes and within 60 minutes 55 % had polymerised. 

The polymer yield increased with the current density at the constant electricity, although the molecular weight of the obtained polymer remained constant. The polymerization rate was related to the current density on the electrode, i.e. the concentration of the activated phenol. When the reaction solution was vigorously stirred, the polymer formation was much suppressed and yield of the dipheno-quinone through C-C coupling increased. This result suggests that the polymerization occurs on the surface region of electrode or within the diffusion layer on electrode. 

When the contribution of polymerization inside the particles increases, the rate of graft polymer formation decreases because it is due to the polymerization in solution, and the curve of log GPavail versus log X has slope less than 1. But as long as the curve of log GPavan versus log X remains in the QmM-Qmi zone, the condition for the particles to remain monodisperse will be fulfilled. If the curve doesn t become... 

It is recommended that a reslurry of crude OSL in an organic solvent or 10% aqueous salt (e.g., NaHCOa) solution be performed to remove low-molecular-weight (mono-functional) species, waxes, and carbohydrates. This purification leads to an improvement in OSL reactivity and contributes to the usefulness of OSL as a PF resin extender or PF copolymer raw material. It is presumed that extraneous removed materials in the crude lignin react with formaldehyde but do not lead to productive cross-linking polymer formation. 

With some ions the extent of polymer formation is high, even in acidic solution, e.g. vanadium(V) can exist as a polyvanadate ion, Vio0286. ... 

The aqueous chemistry of molybdenum and tungsten is complicated by polymer formation in acid solution and reduction potential data are not known with certainty. The acid-solution chemistry of molybdenum is summarized in Table 7.17. 

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