[article]
| Titre : |
Determination of CMCs – Results from CESIO/TEGEWA Working Groups |
| Type de document : |
texte imprimé |
| Auteurs : |
Joachim Venzmer, Auteur |
| Année de publication : |
2020 |
| Article en page(s) : |
p. 60-65 |
| Note générale : |
Bibliogr. |
| Langues : |
Anglais (eng) |
| Catégories : |
Concentration micellaire critique
Surfactants
Tension superficielle
|
| Index. décimale : |
668.1 Agents tensioactifs : savons, détergents |
| Résumé : |
Because of the trend towards “micellar” formulations, surfactant manufacturers often get requests to prove the existence of micelles and/or provide values for Critical Micelle Concentrations (CMC). Therefore, the CESIO Working Group “Test Methods of Surfactants” and the TEGEWA Working Group "Surface Active Substances" have conducted round robin tests using “technical” surfactants, i.e. surfactants having alkyl chain length distributions : A) fatty alcohol ethoxylates with 9EO and different alkyl chain lengths (C12-C18) and B) two alkylamidopropyl betaines (coco vs. C12). The methods employed were the standard procedures established in industry, e.g. Wilhelmy Plate, du Noüy Ring or Pendant Drop. Two aspects have been the focus of this work : A) the effect of alkyl chain length variations on the CMC values, and B) the influence of the experimental procedures on the results of the surface tension measurements. There is indeed a significant influence of the experimental procedure on the surface tension values – especially for surfactants with broad alkyl chain distribution. Since these differences are mostly below CMC, the values of the CMCs itself are somewhat consistent. However, giving more “precise” values than one significant digit does not make much sense. But this should be sufficient, since in practical applications one is always well above CMC. |
| Note de contenu : |
- Fig. 1 : Surface tension of C12/14E9 as a function of concentra-tion; filled symbols in blue: Automated CMC by stepwise addition of surfactant stock solution to water; filled symbols in brown: Pendant Drop method of individually prepared surfactant solutions; open symbols: Automated „reverse“ CMC. (Different shapes are a code for the different participants, e.g. data D, E and L have been determinded in the same laboratory)
- Fig. 2 : Surface tension of C12-18E9 as a function of concentra-tion; filled symbols in blue: Automated CMC by stepwise addition of surfactant stock solution to water; filled symbols in brown: Pendant Drop method of individually prepared surfactant solutions; open symbols: Automated „reverse“ CMC. (Different shapes are a code for the different participants, e.g. data D, E and L have been determinded in the same laboratory)
- Fig. 3 : Surface tension of C10E9 as a function of concentration; filled symbols in blue: Automated CMC by stepwise addition of surfactant stock solution to water; filled symbols in brown: Pendant Drop method of individually prepared surfactant solutions; open symbols: Automated „re-verse“ CMC. (Different shapes are a code for the different participants, e.g. data D, E and L have been determinded in the same laboratory)
- Fig. 4 : Surface tension of C18E9 as a function of concentration; filled symbols in blue: Automated CMC by stepwise addition of surfactant stock solution to water; filled symbols in brown: Pendant Drop method of individually prepared surfactant solutions; open symbols: Automated „re-verse“ CMC. (Different shapes are a code for the different participants, e.g. data D, E and L have been determinded in the same laboratory)
- Fig. 5 : Surface tension of LAPB (brown) and CAPB (blue) as a func-tion of concentration using the Pendant Drop Method; (Different shapes are a code for the different participating laboratories)
- Fig. 6 : Surface tension of LAPB as a function of concentration; filled symbols in blue: Automated CMC by stepwise addition of surfactant stock solution to water; filled symbols in brown: Pendant Drop method of individually prepared surfactant solutions; open symbols: Automated „reverse“ CMC. (Different shapes are a code for the different participants, e.g. data E, L and N have been determinded in the same laboratory)
- Fig. 7 : Surface tension of CAPB as a function of concentration; filled symbols in blue: Automated CMC by stepwise addition of surfactant stock solution to water; filled symbols in brown: Pendant Drop method of individually prepared surfactant solutions; open symbols: Automated „reverse“ CMC. (Different shapes are a code for the different participants, e.g. data E, L and N have been determinded in the same laboratory) |
| En ligne : |
https://drive.google.com/file/d/1VV58Fyw_nkcAQQ29o1Z4x2ObA6dNwzTv/view?usp=drive [...] |
| Format de la ressource électronique : |
Pdf |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33829 |
in SOFW JOURNAL > Vol. 146, N° 3 (03/2020) . - p. 60-65
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