Polymer carboxyl content

There have been other approaches to obtaining rubber/metal adhesion besides primers or additives consisting of phenolics or epoxies plus halogenated elastomers. For example, carboxylated polymers (olefins and diolefins copolymerized with acrylic acid monomers) have shown excellent adhesion to metals. Very little carboxyl is necessary, and polymers with carboxyl contents as low as 0.1% show good adhesion when laminated to bare steel. When these materials possess... 

Hydrolysis of amide groups to carboxylate is a major cause of instability in acrylamide-based polymers, especially at alkaline pH and high temperatures. The performance of oil-recovery polymers may be adversely affected by excessive hydrolysis, which can promote precipitation from sea water solution. This work has studied the effects of the sodium salts of acrylic acid and AMPS, 2-acrylamido-2-methylpropanesulfonic acid, as comonomers, on the rate of hydrolysis of polyacrylamides in alkaline solution at high temperatures. Copolymers were prepared containing from 0-53 mole % of the anionic comonomers, and hydrolyzed in aqueous solution at pH 8.5 at 90°C, 108°C and 120°C. The extent of hydrolysis was measured by a conductometric method, analyzing for the total carboxylate content. 

The extent of hydrolysis of the copolymers was determined by conductometric titration. The increase in carboxylate content was determined by difference, before and after hydrolysis. (The AMPS content of the polymers, where measured, was determined by colloid titration with poly [diallyl dimethyl ammonium chloride].)... 

The c-spectrum shows more carboxylic content (ketonic absorbance at 1716 cm l), meaning that the prestrain has enhanced the photodegradation of the polymer. 

According to Scheme 12, the alkaline peeling of cellulose should continue until the entire polymer is degraded. However, cellulose dissolves partially, but not completely, in hot alkali, and this remaining polysaccharide contains an increased carboxyl content.Thus, a second reaction is occurring that competes with the step-wise, peeling procedure. 

We seek to determine an effective fixed-charge density which influences ion uptake and transport. This may be different from an analytical determination of total carboxyl content because some groups may not be in swollen regions of the polymer and so may not... 

Viscosity measurements on a series of CPSs having the same polymerization degree but different carboxyl contents have provided clear evidence for self-association in solutions. Figure 30 shows the reduced viscosities in butanone and THF (2 mg/ml) at 30.0 °C as a function of carboxyl content. When the carboxyl content is below 3.4 mol%, the reduced viscosity decreases as carboxyl groups are introduced into the CPS. This behavior reflects the constriction of polymer... 

Several kinds of chain extenders that permit rapid production of poly (ethylene terephthalate) of high molecular weight and low carboxyl content have been found. The composition, molecular-weight distribution, and chemical properties of poly (ethylene terephthalate) obtained by this chain-extender method are quite similar to those of the polymer obtained by the conventional method, except for a lower carboxyl content. 

Incorporation of carboxyl groups in vinyl polymers (J) and polyolefins (1, 7) improves the adhesion of these polymers to various materials. However, many of these carboxylated polymers, particularly the carboxylated polyolefins, have limited solubility in volatile, lacquer-type solvents such as butyl acetate or methyl ethyl ketone and thus are limited in their ability to improve the adhesion of coatings applied from solvents. Carboxylated polyesters that are soluble in these solvents can be prepared. We were therefore interested in determining the effects of structure and carboxyl content on the adhesion of coatings of various classes of polymers blended with carboxylated polyesters. 

Table II shows the effect of the carboxyl content on the adhesive characteristics of PMDA-extended polyesters in blends with K-l polycarbonate [4,4 - (2-norbomylidene) diphenol polycarbonate] (VIII), cellulose acetate butyrate, and poly (vinyl chloride). K-l polycarbonate is an experimental polymer which, like cellulose acetate butyrate and poly (vinyl chloride), is very sensitive to adhesive changes because only 1-2% of a carboxylated...

During the semi-continuous polymerization, 4-5 small samples were withdrawn from the polymerization for the determination of the comonomer and copolymer composition. A few drops of the sample latex were mixed with hydroquinone, cooled in ice, and subjected to GC analysis to determine the amounts of unreacted monomer. The rest of the sample (5-8 ml) was poured into mixed solvent of ispropanol/hexane (45/55) containing hydroquinone, and the precipitated polymer, after it was washed with hexane, was dried in a vacuum oven at 45°C for more than 5 hours. A certain amount of the dried polymer was dissolved in dimethyl formamide (DMF), and titrated for the carboxyl content with NaOH solution using phenolphthalein as the indicator. 

The initiation was assumed to occur by formation of the disodium adduct followed by fraws-metallation with toluene because no octane was found in the polymeric oils, a product which must arise by addition of a butadiene molecule to the disodium adduct. The transfer step is necessary to explain the very low carboxyl content of the polymer. 

Characterization. Polymer composition was determined by a variety of classical analytical techniques that included elemental analysis and NMR. The carboxyl content of the polymers was determined by potentiometric titration following conversion to the acid form with an ion-exchange column. Analysis of the sodium content in the polymers gave carboxyl values within a few percent of those found by the titration technique. The number of hydrophobic groups in the polymers in this study was too low to allow quantification by conventional analytical techniques. The levels cited in this chapter refer to amounts added to the reactor and complete incorporation into the polymer was assumed. A recent study (8) using a UV spectroscopic technique on model hydrophobic monomers indicated that this was a fairly good assumption. 

Associative ASTs. Nonionic and anionic associative thickeners are presently considered state of the art in many important industrial applications. The anionic associative thickeners are a subclass of hydrophobically modified, water-soluble polymers (HWSPs), and are predominantly represented by hydrophobically modified ASTs (HASEs and HASNEs), the chemical architectures of which were previously described. Because these polymers are very similar to conventional ASTs in molecular weight and carboxyl content, thickening is by a dual mechanism hydrodynamically (a function of molecular weight, anionic content, cross-link density, and other... 

Determination of carboxyl capacity For the determination of carboxyl content 100 mg of the resin was equilibrated with HCl (0.2 mol L, 10 mL) for 24 h with magnetic stirring. The resin samples were filtered, washed with distilled water to remove unreacted HCl and the filtrate was titrated with NaOH (0.2 mol L ) to a phenolphthalein end point. The polymer contains -3.3 mmol g carboxylic acid groups. 

The acrylamide-based polymers used in the study were obtained commercially in powder form. The homopolymers designated as PS-2806, SPP-34 and ALD-18127-7 were supplied by Polysciences, Scientific Polymer Products and Aldrich respectively. Supplied also by Polysciences were our two poly(acrylamide-co-acrylic acid) samples of high and low carboxyl content, PS-2220 and PS-4652. Table I illustrates the molecular weight distribution of these samples as determined by aqueous GPC/Laser light scattering. The acrylic acid contents of PS-2220 and PS-4652 copolymers measured by 90 MHz C NMR were approximately 63% and 15% respectively. Both the GPC and the NMR analyses indicated PS-2220 contained appreciable amounts of impurities. 

Fig. 6. Microgel analysis chromatograms of medium carboxyl content polyacrylamides. SI, a commercial polymer (Mw appx. 6x10 ) free of microgels S2 and S3, laboratory samples (Mw appx. 9x10 ) showing significant microgel content S3a, sample S3 after treatment with NaOH. The numbers refer to filtration test flow rates (through a 25-mm diameter 5/xm pore size Millipore filter).

The carboxyl content of the polymer was determined by potentiometric titration with KOH in methyl ethyl ketone solution. The epoxy content of the polymer was determined by potentiometric titration with KOH in methyl ethyl ketone solution, using an excess of hydrogen chloride-acetone solution prior to the titration. 

We gratefully acknowledge financial support by the National Bureau of Standards (U.S.A.) in the form of a research grant, PL480. Thanks are also due to the Dow Chemical Company for a generous gift of the polymer samples with known carboxyl content. 

The ambient temperature stability (shelf life) of poly(caprolactone) is strongly affected by its carboxyl content (16). Upon storage at ambient temperature the polymers display a gradual decrease in molecular weight with time which seems to proceed autocatalytically and is related to a random hydrolytic reaction. The average decrease in intrinsic viscosity observed for several samples after 12 and 24 months of storage was 10 and 25%, respectively. 

The adhesive characteristics of an elastomer are recognizably altered by the inclusion of as little as 0.01 equivalent of carboxyl per hundred grams of rubber (ephr) although larger amounts, even in excess of 0.1 ephr, are often preferable. The optimum carboxyl content, molecular weight, and the particular elastomeric polymer selected for use as an adhesive depend on the nature of the surfaces to be adhered and the requirements of the adhesive bond. 

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