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Interfacial activity of narrow‐range alcohol oxyethylates
Author(s) -
Blaszczak Jan,
Zimoch Jolanta,
Hreczuch Wieslaw,
Matuszewski Aleksander,
Szymanowski Jan
Publication year - 1999
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1007/s11743-999-0061-z
Subject(s) - surface tension , chemistry , adsorption , alcohol , hexadecane , saturation (graph theory) , degree (music) , range (aeronautics) , thermodynamics , gibbs isotherm , analytical chemistry (journal) , logarithm , chromatography , organic chemistry , materials science , composite material , physics , mathematics , combinatorics , acoustics , mathematical analysis
Surface and interfacial tension isotherms for narrow‐range distribution ALFOL 1214 alcohol oxyethylates were determined and compared with those obtained for broad‐range alcohol oxyethylates. Various adsorption parameters were estimated. The effectiveness of surface tension reduction decreases when the length of polyoxyethylene hydrophile increases. Micellization is observed at log cmc ranging from −4.7 to −3.3. Effects of the length and distribution of the polyoxyethylene chain on cmc are very small. A minimum of A min / N av 0.5 is obtained for N av =8, where A min and N av denote the minimum interfacial area occupied by a statistical molecule at the saturated interface and the average degree of oxyethylation, respectively. The interface becomes saturated at pC 20 =−5.61±0.35, where pC 20 denotes the logarithm of concentration required to obtain the surface pressure equal to 20 mNm −1 . The highest and lowest values of the surface excess at saturation and the free energy of adsorption, respectively, are obtained for an average degree of oxyethylation equal to 8. Parameters are correlated with the average degree of oxyethylation and the oxyethylene chain distribution parameter according to empirical second‐order polynomials. Small differences in adsorption abilities at the water/air interface are only observed for narrow‐ and broad‐range distributed oxyethylates. The differences become important for adsorption at the hexadecane/water interface. The lowest values of interfacial tension are obtained for narrow‐range oxyethylates with N av =7 and 8. The Krefeld fabric detergency tests indicated that the best detergency was observed for alcohol oxyethylates with N av =5–7. Narrow‐range oxyethylates exhibit somewhat better washing abilities than the broad‐range products. No relationship between detergency of alcohol oxyethylates and their abilities to adsorb at the water/air and water/hydrocarbon interfaces is observed.