Latex polymer, stability

In choosing an epoxy and polymeric latex, it is important that they have compatibility. Incompatibility usually occurs when the pH of the epoxy resin dispersion alters the pH of the latex into a range where the ionically stabilized latex is broken, causing agglomeration of the latex polymer. The pH of the epoxy resin s emulsion may need to be adjusted before blending with the polymeric latex. 

Figure 5. Mechanical stability of PVC latices. Effect of age of latex. Polymer 45% by weight. Na 0.01 mol/t.

Compared to conventional anion exchangers such as the AS4A column, the acrylate-based latex polymer of a Fast-Sep column exhibits a lower pH stability. However, longterm experiments with the Fast-Sep column showed no deterioration as long as the pH value of the mobile phase was kept between 2 and 11. The pH value of the sample to be analyzed should not exceed 13. 

Also, the solid particles may contain water-soluble substances, which undergo leaching and specific adsorption. Reference [1865] reports the IEP of phosphate-containing goethite. One sample studied in [32] contained sulfate and phosphate, and its IEP and PZC differed significantly. The silica studied in [2929] was prepared in the presence of a nonionic surfactant. No attempt was made to remove that surfactant from the final product. Phosphate-doped titania was studied in [2930] and polymer-stabilized latex was studied in [2931], A few results presented above have been cited by others as pristine PZCs/IEPs. 

Agerlte . [R.T. Vand ilt] Antioxidants, polymer stabilizers to rubbers, latex, automodve, appliance pods. 

Polymers with pendant cyclic carbonate functionality were synthesized via the free radical copolymerization of vinyl ethylene carbonate (4-ethenyl-l,3-dioxolane-2-one, VEC) with other imsaturated monomers. Both solution and emulsion free radical processes were used. In solution copolymerizations, it was found that VEC copolymerizes completely with vinyl ester monomers over a wide compositional range. Conversions of monomer to polymer are quantitative with complete incorporation of VEC into the copolymers. Cyclic carbonate functional latex polymers were prepared by the emulsion copolymerization of VEC with vinyl acetate and butyl acrylate. VEC incorporation was quantitative and did not affect the stability of the latex. When copolymerized with acrylic monomers, however, VEC is not completely incorporated into the copolymer. Sufficient levels can be incorporated to provide adequate cyclic carbonate functionality for subsequent reaction and crosslinking. The unincorporated VEC can be removed using a thin film evaporator. The Tg of VEC copolymers can be modeled over the compositional range studied using either linear or Fox models with extrapolated values of the Tg of VEC homopolymer. 

BASF, Performance Chemicals Brochure — Products for the Manirfacture, Stabilization. and Formulation of Latex Polymers 1989... 

Uses Antioxidant for PE, PR ABS, NR, synthetics, latexes, adhesives, oils for fiber finishes, food-grade polymers stabilizer for syn. polymers, resins, inks stabilizer, antigellant for drying oils antioxidant, stabilizer for paper coatings, photographic coatings, thermal fax paper food pkg. adhesives, coatings, mbber articles... 

Uses Antioxidant for rubber and latexes. NR. synthetics, cellulosics. EVA, polyamide, polyesters, polyolefins, PVC, PU, PS polymer stabilizer in food-pkg. adhesives can end cement for food contact finish component for poly (phenyleneterephthalamide) food-pkg. resins antioxidant in food-contact rubber articles for repeated use antioxidant/sta-bilizer for food-grade polymers... 

Uses Primary antioxidant for syn. rug-backing, latex paints, rosin, ester gums, in gasoline and aviation fuels, insulating oiis, paraffin wax, polymer stabilization Manuf/Dlstrib. Rhodia Trade Names Uvi-Nox 1494... 

Toxicology LD50 (mammal) 10 g/mg TSCA listed Uses Antioxidant for cellulosics, polyamides, polyesters, polyolefins, POM, PU, PS, rubbers, adhesives, lubricants, oils, latex, varnishes in food-pkg. adhesives in side seam cements for food-contact containers antioxidant/stabilizer for food-grade polymers stabilizer in food-con-tact PU resins antioxidant in lubricants for incidental food-contact use in surf, lubricants for mfg. of food-contact metallic articles Regulatory FDA 21CFR 175.105, 175.300, 177.1680, 178.2010, 178.3570,178,3910... 

Polychloroprene latex. Anionic or non-ionic latices can be used. The polymer determines the initial tack and open time, the bond-strength development and hot bond strength, the application properties and the adhesive viscosity. Anionic latices are stabilized with rosin soaps. Carboxylated polychloroprene latex is stabilized with polyvinyl alcohol and provides better freeze-thaw stability than the anionic types [78]. 

Einarson and Berg (1993) have attempted to explain the data on flocculation kinetics of latex particles with a block copolymer adsorbed on them. The polymer was polyethylene oxide (PEO)/polypropylene oxide (PPO). PPO is water insoluble and forms the part that adsorbs on the latex PEO forms streaming tails into water. Some charge effects remain after the polymer adsorption. The total potential is DLVO plus elastic plus osmotic effects. After fitting the model to the experimental data, they were able to calculate the value of 6, which they called the adlayer thickness. Their data on the stability ratio of latex with and without the polymer and as a fimction of NaCl concentration are shown in Figure 3.23. Note that the polymer stabilizes the colloid by almost one order of magnimde in NaQ concentration. That is, polymers may be necessary to maintain stability in aqueous media containing substantial electrolyte. 

Rubber, natural (India rubber, Caoutchouc) n. An amorphous polymer consisting essentially of ds-1,4-polyisoprene, obtained from the sap (latex) of certain trees and plants, mainly the Hevea brasiliensis tree. The material is shipped from tropical plantations in one of two primary forms latex, usually stabilized and preserved with ammonia and centrifuged to remove part of the water or sheets made by milling the coagulum from the latex. Natural rubber has very high molecular weight and is usually masticated to reduce the molecular weight and improve processability. A major use is sidewalls of automotive tires. 

The ever-increasing raw material choice available to the adhesive formulator is demonstrated with particular reference to Hercules resin dispersions for the modification of acrylic latex polymer systems used in pressure sensitive adhesive formulations. The requirements of a tackil g resin are examined and the advantages afforded by such products from Hercules as Tacolyn 1070, Tacolyn 3179 and Res A-2603 are discussed, in terms of their ability to offer balances of peel, tack and shear and consistently high levels of stability, it is claimed. 5 refs. 

Some peculiarities of the thermal and thermooxidative decomposition of polyvinyl chloride depend on the conditions of its production. Thus, it is known that samples of the polymer produced by initiating the polymerization of vinyl chloride with ultraviolet irradiation possess higher stability in comparison with samples produced in polymerization under the action of chemical agents [26, 27]. Reversibility of the process of dehydrochlorination in the decomposition of samples of polyvinyl chloride produced by the latex method is noted, while in the process of decomposition of suspension polymer, the phenomenon of reversibilily is not observed [21]. It has been shown that the rate of dehydrochlorination of the latex polymer is significantly higher than that of the suspension polymer under the same conditions [21]. It has been established that the polymerization of vinyl chloride in the presence of oxygen leads to the formation of unstable peroxide groups, which can initiate decomposition of the polymer [28, 29]. It is noted that an extremely substantial influence on the stability of polyvinyl chloride is exerted by the purity of the monomer, as well as the presence of impurities of metals of variable valence [28]. 

Of the heterocyclic nitrogen-containing compounds, a-phenylindole is used to stabilize latex polymers and copolymers of vinyl chloride [99]. Melamine has foimd use for the stabilizing of suspension polymers, where a-phenylindole proves inactive [63]. Derivatives of morpholine [274], symmetrical triazine [275], pyrazole [276], as well as derivatives of imidazole, imidazoline, oxazole, oxazoline, thiazole, and thiazoline [277] are recommended in the patent literature for stabilization. 

Coatings. Acrylic ester latex polymers are used widely as high quality paint binders because of their excellent durability, toughness, optical clarity, uv stability, and color retention. These properties allow acrylics to And use as binder vehicles in all types of paints (76) interior and exterior flats, semigloss, and gloss as well as primers to topcoats. Although all-acrylic compositions are most... 

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