WATER REDUCIBLE POLYMERS

True water soluble polymers as previously discussed, are usually those having repeating polar groups in the polymer chain, and are water soluble in their own right, typical groups being hydroxyl, ether, carbonyl, amide, etc. 

Water reducible, or water thinnable, synthetic polymers are usually acidic, typically containing carboxyl groups built into the polymer chain. These require neutralisation with a base, with ammonia, triethylamine, dimethyl aminoethanol being typical, and often the use of cosolvents, such as glycol ethers, to produce complete compatibility with water. 

Many types of synthetic polymers can be rendered water reducible utilising this principle, and these will be dealt with in the individual volumes of this series of eight books. 

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Water-Reducible Polymers. Water-reducible polymers have been developed in recent years in an effort to overcome the deficiencies of aqueous emulsions and to make the handling properties of water-based systems more like those of traditional solvent systems. In principle, any solution acrylic polymer can be rendered water reducible by polymerizing the monomers in a water-miscible organic solvent and by Increasing the acrylic or methacrylic acid content so that the addition of water and some solubilizing amine will maintain the polymer in solution. 

The major limitation of this approach to a low-emission coating is the fact that in order to meet Rule 66 requirements the polymer solids must be high and, as a consequence, the molecular weight must be kept low. As a result, water-reducible polymers are restricted to thermosetting vehicles if adequate performance properties are to be maintained. In applications where thermosetting vehicles are required, this is no particular disadvantage since carboxyl and hydroxyl functionality is already present in the backbone to render the polymer water soluble. 

Reqrdrol. [Hoechst Cebmese] Water-reducible polymers fix coatings and inks. 

Resydrol. [Hoechst Celanese] Water-reducible polymers for coatings and inks. 

Water reducible polymers are often described as waterborne, water based or water soluble materials although only a few polymers may be regarded as truly water soluble. For coatings, the term waterborne can be regarded as generically correct for coatings containing water in their volatile components, which includes emulsion resins. 

Since the overwhelming majority of commercially available water reducible polymers are carboxyl functional, the discussion in this chapter will consider the use of arrtines. However, the calcirlations used to determine the quantities of neutralising agent reqitired by a given polymer can be used with modification for acid neutraUsed systems. 

Suspension polymerization of VDE in water are batch processes in autoclaves designed to limit scale formation (91). Most systems operate from 30 to 100°C and are initiated with monomer-soluble organic free-radical initiators such as diisopropyl peroxydicarbonate (92—96), tert-huty peroxypivalate (97), or / fZ-amyl peroxypivalate (98). Usually water-soluble polymers, eg, cellulose derivatives or poly(vinyl alcohol), are used as suspending agents to reduce coalescence of polymer particles. Organic solvents that may act as a reaction accelerator or chain-transfer agent are often employed. The reactor product is a slurry of suspended polymer particles, usually spheres of 30—100 pm in diameter they are separated from the water phase thoroughly washed and dried. Size and internal stmcture of beads, ie, porosity, and dispersant residues affect how the resin performs in appHcations. 

In addition to the normal problems of completely dissolving particles of water-thickening polymers, xanthan gum contains insoluble residues which decrease polymer injectivity. Various methods of reducing insolubles content and improving xanthan solution injectivity are available (80—87). None appears economically viable. Oxygen scavengers (88) and bactericides (77,89) are commonly used to stabili2e injected polyacrylamide and xanthan gum solutions (90—102). 

Water-soluble polymers (qv) can increase the viscosity of the foam external phase. This improves foam stabihty and reduces mobihty. Gelation of... 

Surfactants evaluated in surfactant-enhanced alkaline flooding include internal olefin sulfonates (259,261), linear alkyl xylene sulfonates (262), petroleum sulfonates (262), alcohol ethoxysulfates (258,261,263), and alcohol ethoxylates/anionic surfactants (257). Water-thickening polymers, either xanthan or polyacrylamide, can reduce injected fluid mobiHty in alkaline flooding (264) and surfactant-enhanced alkaline flooding (259,263). The combined use of alkah, surfactant, and water-thickening polymer has been termed the alkaH—surfactant—polymer (ASP) process. Cross-linked polymers have been used to increase volumetric sweep efficiency of surfactant—polymer—alkaline agent formulations (265). 

HPC is compatible with many natural and synthetic water-soluble polymers and gums (50). Generally, blends of HPC with another nonionic polymer such as HEC yield water solutions having viscosities in agreement with the calculated value. Blends of HPC and anionic CMC, however, produce solution viscosities greater than calculated. This synergistic effect may be reduced in the presence of dissolved salts or if the pH is below 3 or above 10. 

The original Polacolot negative had water-coated intedayers of gelatin (60). The SX-70 and Polacolot 2 negatives use as intedayers a combination of a polymeric latex with a water-soluble polymer. A key development was the constmction of lattices that function as temporary batnets, reducing interimage problems. The water-soluble polymer functions as a permeator, so that the harder properties ate tunable (61). 

Under certain conditions hydrogen cyanide can polymerize to black soHd compounds, eg, hydrogen cyanide homopolymer [26746-21-4] (1) and hydrogen cyanide tetramer [27027-02-2], C H N (2). There is usually an incubation period before rapid onset of polymer formation. Temperature has an inverse logarithmic effect on the incubation time. Acid stabilizers such as sulfuric and phosphoric acids prevent polymerization. The presence of water reduces the incubation period. 

Weathering. This generally occurs as a result of the combined effect of water absorption and exposure to ultra-violet radiation (u-v). Absorption of water can have a plasticizing action on plastics which increases flexibility but ultimately (on elimination of the water) results in embrittlement, while u-v causes breakdown of the bonds in the polymer chain. The result is general deterioration of physical properties. A loss of colour or clarity (or both) may also occur. Absorption of water reduces dimensional stability of moulded articles. Most thermoplastics, in particular cellulose derivatives, are affected, and also polyethylene, PVC, and nylons. 

The hydrophobic interaction results in the existence of a lower critical solution temperature and in the striking result that raising the temperature reduces the solubility, as can be seen in liquid-liquid phase diagrams (see Figure 5.2a). In general, the solution behaviour of water-soluble polymers... 

Water-based polymers Thickener, to transport proppant reduces leak-off in formation... 

Fluid loss additives such as solid particles and water-thickening polymers may be added to the drilling mud to reduce fluid loss from the well bore to the formation. Insoluble and partially soluble fluid loss additives include bentonite and other clays, starch from various sources, crushed walnut hulls, lignite treated with caustic or amines, resins of various types, gilsonite, benzoic acid flakes, and carefully sized particles of calcium borate, sodium borate, and mica. Soluble fluid loss additives include carboxymethyl cellulose (CMC), low molecular weight hydroxyethyl cellulose (HEC), carboxy-methYlhydroxyethyl cellulose (CMHEC), and sodium acrylate. A large number of water-soluble vinyl copolymers and terpolymers have been described as fluid loss additives for drilling and completion fluids in the patent literature. However, relatively few appear to be used in field operations. 

Both nonionic and anionic surfactants have been evaluated in this application (488,489) including internal olefin sulfonates (487, 490), linear alkylxylene sulfonates (490), petroleum sulfonates (491), alcohol ethoxysulfates (487,489,492). Ethoxylated alcohols have been added to some anionic surfactant formulations to improve interfacial properties (486). The use of water thickening polymers, either xanthan or polyacrylamide to reduce injected fluid mobility mobility has been proposed for both alkaline flooding (493) and surfactant enhanced alkaline flooding (492). Crosslinked polymers have been used to increase volumetric sweep efficiency of surfactant - polymer - alkaline agent formulations (493). 

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