ISSN:0193-2691    

DOI:10.1080/01932698108943905

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

ISSN:0193-2691    

DOI:10.1080/01932698108943906

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

ISSN:0193-2691    

DOI:10.1080/01932698108943907

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Although a large number of methods are available for the determination of critical micelle concentrations many of these cannot be applied to the highest members of homologous series which are insufficiently soluble in water. The number of latex particles formed and consequently the rate of emulsion polymerization of such monomers as styrene which have only a very low solubility In water increase rapidly at the c.m.c. of the surfactant. When the surfactant is a salt which can be formed at the interface by dissolving the long-chain acid in the monomer and a slight excess of alkali in the water, observation of surfactant concentration at which this increase in particle number and polymerization rate takes place provides an experimental method for the determination of the c.m.c. which gives results in good agreement with expectation based on an extrapolation of results obtained by other methods on lower members of the series in the case of potassium docosanoate.

ISSN:0193-2691    

DOI:10.1080/01932698108943908

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Monodisperse polystyrene latexes were prepared with and without emulsifier using persulfate initiator. The latexes were ion-exchanged with purified Dowex 50W(H+)-Dowex 1(0H−) mixed resin to remove solute electrolyte and adsorbed emulsifier and to convert acidic surface groups to the H+form. Conductometric titration showed that all latexes contained only strong-acid surface groups, presumably the sulfate endgroups of the polymer chains introduced by the persulfate initiator. The sulfate-stabilized latexes (H+form) were hydrolyzed to the hydroxyl form after 2–8 weeks at room temperature or 48–120 hours at 363°K. The rate of the acid-catalyzed hydrolysis is enhanced by increasing the glass contact surface area, by adding Pyrex glass beads. Conductometric titration of the hydrolyzed latexes after ion exchange showed no titratable groups, indicating that the latexes were stabilized by hydroxyl groups. The latexes were oxidized to the carboxyl form by heating the hydroxyl-stabilized latex with persulfate and traces of heavy metal ions or the sulfate-stabilized latex in contact with Pyrex glass beads. For example, latex 520′ prepared without emulsifier using persulfate initiator and bicarbonate buffer contained only strong-acid surface groups after cleaning, no titratable groups after hydrolysis, and only carboxyl groups in the same number as the original sulfate groups after oxidation. Thus the three forms of the latex provide ideal model colloids, rigid monodisperse spheres stabilized with the same number of chemically bound surface groups of three types —strong-acid sulfate, weak- acid carboxyl, and uncharged hydroxyl.

ISSN:0193-2691    

DOI:10.1080/01932698108943909

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Adsorption isotherms of ethoxylated nonylphenols on poly(styrene) and poly(vinyl chloride) latexes have been measured. The isotherms all reach a limiting adsorption at concentrations somewhat higher than the critical micellar concentrations of the surfactants. The relative affinity of the surfactants to the latex surfaces was found to decrease with increased ethylene oxide chain length. Analysis of the isotherms indicates some affinity of the ethylene oxide chain to the latex surface. This affinity may possibly be attributed to the presence of surface carboxylic groups

ISSN:0193-2691    

DOI:10.1080/01932698108943910

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Conductometric coap titration and Maron's3method of plotting polymer concentration vs. soap concentration is used to determine the molecular adsorption area (MAA) of potassium oleate in a number of polymer and copolymer latex systems. It is demonstrated that the MAA of potassium oleate increases in the series polystyrene→ polybutadiene→polystyrene-coacrylonitrile as well as in a series of polystyrene-coacrylonitrile systems with increasing acrylonitrile content in the polymer composition

ISSN:0193-2691    

DOI:10.1080/01932698108943911

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

ISSN:0193-2691    

DOI:10.1080/01932698108943912

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

ISSN:0193-2691    

DOI:10.1080/01932698108943913

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

ISSN:0193-2691    

DOI:10.1080/01932698108943914

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor