Dispersing agents anhydride

EMA resins [Solutia], TM for ethylene-maleic anhydride copolymers. Water-soluble resins that serve as dispersing agents in cold-water detergents, thickeners, binders, stabilizers, and emulsifiers. 

Typical suspending agents for the vinyl acetate polymerization are poly(vinyl alcohol) [particularly a grade represented as approximately 88% hydrolyzed poly(vinyl acetate)], gum arabic, hydroxyethyl cellulose, methyl cellulose, starches, sodium polyacrylate or sodium polymethacrylate, gelatin, and an equimolar copolymer of styrene and maleic anhydride neutralized with either sodium hydroxide or aqueous ammonia. Water-insoluble dispersing agents or... 

Extending ideas of other applications involves the technique known as an association of ideas. For example, in U.S. Patent 4,637,867 [48], colloidal silica is used as a dispersing agent (and probably a crystal modifier) for preparing fine crystal particles of maleic anhydride. This same idea can be used for making crumb rubbers in elastomer systems [49] into fine-grain emulsions in photographic systems [50]. 

The polymerization is a precipitation polymerization from gaseous formaldehyde in an inert solvent such as cyclohexane at fairly low temperatures to prevent depolymerization reactions. Amines such as tri-n-butyl amine are used as initiators. The polymer precipitates in the dispersing agent as powder. After completion of the polymerization, it is necessary to stabilize the hydroxyl end groups, for example by esterification with acetic anhydride to prevent the unzipping reaction of Eq. (49). 

To increase the percentage of natural polymer incorporated, compatibilizing agents such as silanes, EVA, maleic anhydride copolymers, dispersing agents as petroleum resins or partial crosslinking were tested with good results. 

Styrene—maleic anhydride copolymer [9011-13-6] engineering thermoplastics, paper treatment chemicals, floor poHshes, emulsifiers, protective coUoids, antisoil agents, dispersants... 

The dimensional stability of low density, water blown rigid PU foams for pour-in-place thermal insulation applications was improved by the use of a phthalic anhydride based polyester polyol containing a dispersed cell opening agent. The foam systems obtained allowed some of the carbon dioxide to be released through the cell windows immediately after filling of the cavity, and to be rapidly replaced by air. Studies were made of the flowability, density, open cell content, dimensional stability, mechanical properties, thermal conductivity and adhesion (particularly to flame treated PE) of these foams. These properties were examined in comparison with those of HCFC-141b blown foams. 21 refs. 

Through copolymerization there can be made materials with different properties than those of either homopolymer, and thus another dimension is added to the technology. Consider, for example, styrene. Polymerized alone, it gives a good electric insulator that is molded into parts for radios, television sets, and automobiles. Copolymerization with butadiene (30%) adds toughness with acrylonitrile (20-30%) increases resistance to impact and to hydrocarbons with maleic anhydride yields a material that, on hydrolysis, is water-soluble, and is used as a dispersant and sizing agent. The copolymer in which butadiene predominates (75% butadiene, 25% styrene) is an elastomer, and since World War II has been the principal rubber substitute manufactured in the United States. 

Even though partially esterified copolymers of methyl vinyl ether-maleic anhydride copolymers were orignally designed to dissolve abruptly with an increase in external pH, in a constant pH environment they undergo a controlled dissolution process and are therefore useful materials for the controlled release of therapeutic agents dispersed within them (12),... 

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