Viscosity of copolymers

Viscosimetric studies of organotin copolymer solutions allow the changes in the shape of the macromolecules to be followed as a function of the electrostatic charge. From the plot of the intrinsic viscosity of copolymers in DMFA solution against the degree of dilution it is seen that increasing dilution results in a rise of viscosity, probably due to an extension of macromolecular chains accompanied by conformational transformations. Naturally, this rise in viscosity with dilution cannot proceed infinitely since a coiled chain cannot be extended more than a completely extended chain conformation, due to intramolecular repulsion. 

Viscosity of copolymer solutions decreases by, at most, 3 percent when electrolyte concentration changes from 0 to 0.342 M sodium chloride or 2.45 x 10 M calcium chloride. Viscosity of hydrolyzed polymer solutions decreases exponentially with increasing electrolyte concentration in water. 

The reaction proceeding was also monitored by viscosity increase of synthesized copolymers. It was found that viscosity of copolymers and the hydride polyaddition degree increase with temperature rise to 70 - 90°C. In hydride polyaddition of a, -dihydridedimethylsiloxane to divinylorganotricyclodecasiloxane, conversion of =Si-H bond increases with temperature as follows from 85% (70°C) to 95% (90°C). Figure 7 shows time dependence of =Si-H concentration (%) decrease for various temperatures. 

Table 5. Molecular masses and characteristic viscosities of copolymer 3 fractions (Table 1, structure I) at different temperatures...

Figure 3. Effect of copolymer concentration on the apparent viscosity of copolymers of acrylamide with octylacrylamide in 0,342 M NaCl at 25 °C and a shear rate of 1.28 s. ...

Different compositions of HA were copolymerised with siloxane monomer (SL) and the feed ratio of copolymers (M1/M2) varied from 0.2 to 5. The elemental viscosities of copolymers were 0.55, 0.63 and 0.34 dl/g, respectively (in 2-methoxyethanol at 25 "C), indicating that polymerisation had occurred. The amount of HA in the... 

Note also that characteristic viscosities of copolymers obtained at the end of the reaction at copolymerisation of monomeric systems of various compositions increase with the molar part of MMA in the initial monomeric mixture [70]. Molecular masses of copolymers obtained must increase in the same direction. This result also fully corresponds to a change of the copolymerisation gel-effect intensity as the initial composition of the monomeric couple studied changes [69, 70]. 

The shear rate at typical open-hole completions is approximately 2,000 sec l at an injection rate of 600 bbl/day the shear rate in the reservoir is approximately 20 sec at a reservoir rate of 1 foot/day. The viscosity of copolymer B at the wellbore condition is approximately 44 percent of the viscosity at a typical laboratory shear condition of 7.3 sec" this value was obtained from extrapolation along curve B for the 80/20 mix in Figure 4. Mechanical degradation of the copolymers under shear, as measured by viscosity loss, in field (Wilmington) and laboratory (4) inves-... 

Figure 1. Viscosities of Copolymers Prepared for Study, at 50% Solids in Water.

Addition of sodium, potassium, calcium, ammonium, etc., bases to aqueous solutions of Gantrez AN resins leads to two viscosity peaks, corresponding to 1 and 2 mole equivalents of base. The interpolymers are precipitated by Ca ions and other heavy, polyvalent metal cations, beyond 0.7 mole equivalents. With ammonium hydroxide, peaks tend to be observed at about 1 and 3 mole equivalents of base. Ionic interactions in aqueous solutions of Gantrez AN polyelectrolytes and polycarboxylates, electrophoretic mobility and viscosity of copolymer salts, counterion binding properties, etc., have received substantial <659,672.700-702,1100) polyelectrolyte salt sol-... 

Copolymer composition, cis/trans ratio of the double bonds, and inherent viscosities of copolymers obtained at varying conversions using different monomer mixtures [37] are presented in Table 1. It is evident from a comparison of the molar ratios of the monomers and the monomeric units in the chain that the reactivity of lower cycloolelins is considerably higher. Although the trans content of the copolymers is not in all cases as high as in homopolymers made with the same catalyst, all copolymers, even those that are... 

Fig. 7.6. Elfect of NaCl concentration on Brookfield viscosity of copolymer RFA-18 at various concentrations...

The polymerization is carried out at temperatures of 0—80°C in 1—5 h at a soHds concentration of 6—12%. The polymerization is terminated by neutralizing agents such as calcium hydroxide, calcium oxide, calcium carbonate, or lithium hydroxide. Inherent viscosities of 2-4 dL/g are obtained at 3,4 -dianiinodiphenyl ether contents of 35—50 mol %. Because of the introduction of nonlinearity into the PPT chain by the inclusion of 3,4 -dianiinodiphenyl ether kinks, the copolymer shows improved tractabiUty and may be wet or dry jet-wet spun from the polymerization solvent. The fibers are best coagulated in an aqueous equiUbrium bath containing less than 50 vol % of polymerization solvent and from 35 to 50% of calcium chloride or magnesium chloride. 

Melt Viscosity. As shown in Tables 2 and 3, the melt viscosity of an acid copolymer increases dramatically as the fraction of neutralization is increased. The relationship for sodium ionomers is shown in Figure 4 (6). Melt viscosities for a series of sodium ionomers derived from an ethylene—3.5 mol % methacrylic acid polymer show that the increase is most pronounced at low shear rates and that the ionomers become increasingly non-Newtonian with increasing neutralization (9). The activation energy for viscous flow has been reported to be somewhat higher in ionomers than in related acidic... 

In low sohds muds, vinyl acetate—maleic anhydride copolymers were once used to extend or enhance the viscosity of bentonite suspensions (141). This function is largely performed by polyacrylamides. The vinyl acetate—maleic anhydride copolymers can also have a flocculating effect on drill sohds. Concentrations generally are quite low (0.14—0.57 kg/m (0.05—0.2 Ib/bbl)). 

The dilute solution properties of copolymers are similar to those of the homopolymer. The intrinsic viscosity—molecular weight relationship for a VDC—AN copolymer (9 wt % AN) is [77] = 1.06 x 10 (83). The characteristic ratio is 8.8 for this copolymer. 

In early hterature, the molecular weights of PVDC and VDC copolymers were characterized by the absolute viscosity of a 2 wt % solution in (9-dichlorobenzene at 140°C. The exact correlation between this viscosity value and molecular weight is not known. Gel-permeation chromatography is the... 

Vinylidene Chloride Copolymer Foams. Low density, fine-celled VDC copolymer foams can be made by extmsion of a mixture of vinylidene chloride copolymer and a blowing agent at 120—150°C (190). The formulation must contain heat stabilizers, and the extmsion equipment must be made of noncatalytic metals to prevent accelerated decomposition of the polymer. The low melt viscosity of the VDC copolymer formulation limits the size of the foam sheet that can be extmded. 

The use of poly(vinyl acetate) or copolymer emulsions eliminates the need for expensive, flammable, odorous, or toxic solvents and the need for the recovery of such solvents. They are easy to apply and the equipment is easy to clean with water, if done promptly. Emulsions also offer the advantage of high sohds content with fluidity, siace the viscosity of emulsions are iadependent of the molecular weight of the resia iu the particles. 

Specifications and Standards. Typical specifications of the commercially available emulsions are tabulated in Table 11. However, there are exceptions to the ranges given. For example, most emulsions contain 55—56 wt % soHds but some are available at 46—47 wt % with viscosities of 10 15 mPa-s(=cP), and others at 59 wt % soHds with viscosities of 200 4500 mPa-s. Specialty copolymer emulsions are available containing 72 wt % sohds and viscosities under 2000 mPa-s (139). 

Using this equation, the approximate (T — T ) value required for a film of a thermoplastic copolymer to be dry-to-touch, ie, to have a viscosity of 10 mPa-s(=cP), can be estimated (3,4). The calculated (T — T ) for this viscosity is 54°C, which, for a film to be dry-to-touch at 25°C, corresponds to a T value of —29 "C. The calculated T necessary for block resistance at 1.4 kg/cm for two seconds and 25°C, ie, rj = 10 ° mPa(=cP), is 4°C. Because the universal constants in the WLF equation are only approximations, the T values are estimates of the T requited. However, if parameters such as the mass per area appHed for blocking were larger, the time longer, or the test temperature higher, the T of the coating would also have to be higher. 

The analysis of the main properties of aqueous solutions of polyacrylamide and copolymers of acrylamide has been reviewed [4,5]. The main characteristics of aqueous solutions of polyacrylamide is viscosity. The viscosity of aqueous solutions increases with concentration and molecular weight of polyacrylamide and decreases with increasing temperature. The relationship between the intrinsic viscosity [q]) in cmVg and the molecular weight for polyacrylamide follows the Mark-Houwink equations ... 

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