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Details van artikel 77 van 189 gevonden artikelen
| Titel: |
Interactions between Hydrophobically Modified Associating Polyacrylamide and Cationic Surfactant at the Water-Octane Interface: Interfacial Dilational Viscoelasticity and Relaxation Processes |
| Auteur: |
Luo, Lan Wang, Dong-Xian Zhang, Lu Zhao, Sui Yu, Jia-Yong |
| Verschenen in: |
Journal of dispersion science and technology |
| Paginering: | Jaargang 28 (2007) nr. 2 pagina's 263-269 |
| Jaar: |
2007-02-01 |
| Inhoud: |
The interfacial dilational viscoelastic properties of hydrophobically associating block copolymer composed of acrylamide (AM) and a low amount of 2-ethylhexyl acrylate (EHA) (<1.0 mol%) with a hydrolyzed degree of about 1.5-2.0% at the octane-water interfaces were investigated by means of two methods: the interfacial tension response to sinusoidal area variations (oscillating barriers method) and the relaxation of an applied stress (interfacial tension relaxation method) respectively. The influence of cationic surfactant cetyl trimethylammonium bromide (CTAB) on the dilational viscoelastic properties was studied. The results obtained by oscillating barriers method showed that dilational modulus decreased moderately with the increase of CTAB concentration. The results obtained by interfacial tension relaxation measurements showed that two main relaxation processes exist in the interface at 7,000 ppm polymer concentration: one is the fast process involving the exchange of hydrophobic blocks between the proximal region and distal region in the interface; the other is the slow relaxation process involving conformational changes of polymer chain in the interface. By adding CTAB, the slow process changed obviously due to the strong electrostatic interaction between oppositely charged surfactant and hydrolyzed part of polymer chain. Only when the CTAB concentration was close to the “equal charge point,” the associations formed mainly by the hydrophobic interaction like that in SDS/polymer system appeared and the characteristic time of fast process decreased obviously. The information of relaxation processes obtained from interfacial tension relaxation measurements can explain the results from dilational viscoelasticity measurements very well. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 77 van 189 gevonden artikelen
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