Degree of neutralization

Paste rosin sizes are supplied as viscous pastes containing 60—80% solids. These sizes may contain unmodified or fortified rosin that has reacted (ie, been fortified) with either maleic anhydride [108-31-6] or fumaric acid [110-17-8] (see Fig. 3). In either case, the unmodified or fortified rosin is treated with aqueous alkaH so that the degree of neutralization, ie, saponification, varies from 75—100% depending on the physical state desired for the commercial product. Before use, the paste size must be converted to a stable, dilute rosin size emulsion by careful sequential dilution with warm water foUowed by cold water, with good agitation. 

An empirical formula, where 0 < m < 3rt can be written to describe overall PAG composition. The degree of neutralization of... 

The rate constants decreased with increasing degree of neutralization of the polymers. 

They found that the rates for NABS increased as the degree of neutralization (a) was lowered and a maximum in the k—a plot appeared near a = 0.6. For DNPA, such an enhancing effect was not detected. 

Wittwer and Zollinger (1954) determined the neutralization curves of aqueous solutions of diazonium salts under standard conditions of ionic strength, etc., and found that the acidity depended on the degree of neutralization in a manner different to that expected for a dibasic acid. The curve obtained did not exhibit two steps with an intermediate region of a few pH units in which the monobasic acid is stable, as is the case, for instance, with oxalic acid (Fig. 5-1). On the contrary, there was only one step, but it extended over two equivalents of base per diazonium ion. 

A carboxymethyl derivative of dextran has been prepared in order to study the effect of charge density, concentration, degree of neutralization. 

Fig. 137.—Equilibrium swelling ratio qm of poly-(methacrylic acid) gels prepared by copolymerizing methacrylic acid with 1, 2, and 4 percent (upper, middle, and lower curves, respectively) of divinylbenzene plotted against degree of neutralization i with sodium hydroxide. (Katchalsky, Lifson, and Eisenberg. )...

When the degree of neutralization is small the charge on the polyion and the number of counterions will also be small and the majority of counterions will be free. As the degree of neutralization, a, increases, the polyion charge, Q, will increase. This observation follows from the following equations ... 

Figure 4.8 Cylindrical and spherical hydration regions around poly(acrylic acid) at various degrees of neutralization (or charge densities). Based on Ikegami (1964).

Although all divalent ions precipitate PAA when the degree of dissociation, a, approaches 10, there are differences when a = 0-25 (Figure 4.11). Small amounts of barium and calcium ions precipitate PAA at this low a value, whereas magnesium ions do not. These differences are not to be attributed to differences in the amounts of counterions bound, for condensation theory (Section 4.2.3) predicts that all divalent counterions are bound to polyanions to the same extent (Imai, 1961). Therefore, differences must arise from differences in solubility between the various polyacrylates. At low degrees of neutralization barium polyacrylate has low solubility, while magnesium polyacrylate is very soluble. This is related to the extent of disruption of hydration regions as cations are bound to polyions. 

Apart from the kind of components used in preparing microgels from EUP and comonomers, the yield essentially depends on the composition of the reactive components, on the water/monomer ratio, the W/M (serum ratio), the degree of neutralization of the EUP [91] and on the concentration of electrolytes. 

The [nri] of microgel solutions decreases with increasing degree of neutralization of the carboxyl acid groups of the EUP (Fig. 19) because the emulsifier concentration increases and, accordingly, the micelles or microemulsion droplets become smaller. In this case an external emulsifier poly(oxymethylene) octylphenyl ether was added to insure complete solubilization over the whole range of neutralization. 

Fig. 27. Relation between the degree of neutralization and the mole fraction of dodecyl hydrogen maleate (DHM) in the copolymerization with S [131].(DHM/S in reaction mixture 0.133). 

The frequency of the symmetric stretch does not vary with degree of neutralization for hydrated membranes, which was attributed to the shielding of sulfonate anions from the electrostatic field of the Na+ ions. 

In this work, we have chosen several systems stabilized through hydrogen bonds. The homopolymer is a polybase, i.e. PEO, PVME or PVP, and the copolymer is polyacrylic acid with various degrees of neutralization a, in which the acrylates are the non active groups. Complex formation is studied by potentiometry (because complexation induces a variation of the solution pH) and by viscometry and polarized luminescence which respectively give information about the macroscopic and local structure of the complex in solution. The influence of parameters such as the degree of neutralization of PAA a, the concentration ratio r - [polybase]/[PAA], the concentration and the molecular weight of polymers is examined. 

In Figure 1 the pH is plotted versus concentration ratio r, for the PAA-670 000 / PEO-100 000 system and for various degrees of neutralization of the PAA a, determined by the ammount of NaOH added. For all the experimental points the concentration of PAA in polymer units is constant and equal to 0.02 unit mol/1. 

Figure 1. pH change versus concentration ratio, r [PE0]/[PAA], for various degrees of neutralization, a. 

As expected, when the degree of neutralization of PAA is 0%, the specific viscosity falls rapidly with addition of polybase. For degrees of neutralization 3 and 6% we also get viscosity curves characteristic of a compact complex formation. For the values of a higher than 10% the linear variation is due to the addition of PEO without complex formation. These results agree with the potentiome-tric ones for instance in both cases no point characteristic of a fixed stoichiometry is observed. 

Similar curves are obtained for lower concentrations in polymers, but a very different behaviour is observed with the same system at higher concentration (five times higher), see Figure 5. For a degree of neutralization 0% the curve is typical of the formation of a compact complex. For a values higher than the limit one, a 15% and 20%, there is no indication of complex formation. But for a between 0 and we observe a very important increase in viscosity, especially for a 6% and 10%. 

The gain in viscosity also depends on the nature of polymers. Mixtures of particularly high viscosity are obtained with the system PAA-800 OOO/PVP-900 000. For a PAA degree of neutralization of 10% a gain in viscosity of six hundred is reached (Figure 7). The value of a at the maximum of g is 10% for the PAA/PVP system whereas it is 5% for the PAA/PEO couple. 

The complexation power of the three polybases towards PAA was easily estimated from potentiometric results PVP > PVME > PEO. The mean stoichiometry of the polymer complex depends on the degree of neutralization of the polyacid, a. 

From circular dichroism, it appears that for pectins with a degree of neutralization (a ) of over 0.4, a specific interaction with calcium occurs... 

This result is directly proportional to the minimum number of carboxylic acid sites required to form a stable junction zone on polymers. The number of calcium cations bound must also be directly related to the stability of the junction and its thermoreversibility. Finally, it must be also pointed out that it is not the pH, but the degree of neutralization, a, which controls calcium binding. 

Figure 1. Normalized ellipticity at 210 nm as a function of the degree of neutralization (o ) for (1) sodium form of oligogalacturonates and polygalac-turonate (2) calcium form of galacturonates (O DP2, A DP4, DP5), (3) calcium form of the polygalacturonate (Ae taken as reference is the ellipticity of acid forms for each product open = sodium form filled = calcium form.)...

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