| 1. |
- Adal, M, et al.
(författare)
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Determination of monomer reactivity ratios in the copolymerization of ethylene oxide and propylene oxide
- 1994
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Ingår i: Tenside Surfactants Detergents. - 0932-3414 .- 2195-8564. ; 31, s. 9-11
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Tidskriftsartikel (refereegranskat)abstract
- The reactivity ratios r1 (EO) and r2 (PO) for the copolymerization of ethylene oxide (EO) and propylene oxide (PO) have been determined. The reactions were carried out in dry dimethyl formamide at 90°C using the potassium salt of ethylene glycol as initiator. The polymer composition at different EO/PO ratios in the feed was determined by 1H-NMR. Using the Fineman-Ross method to calculate reactivity ratios from the values of polymer composition, rl- and r2-values of 1.8 and 0.3, respectively, were obtained.
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| 2. |
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| 3. |
- Andersson, M., et al.
(författare)
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A New Class of Labile Surfactants that Break Down to Non-surface Active Products upon Heating or after a Pre-set Time, without the Need for a pH Change
- 2007
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Ingår i: Tenside Surfactants Detergents. - : Walter de Gruyter GmbH. - 0932-3414 .- 2195-8564. ; 44:6, s. 366-372
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Tidskriftsartikel (refereegranskat)abstract
- A new class of labile surfactants that break down at a controllable rate without the need for a change in pH will be presented. The invention has been patented by YKI Institute for Surface Chemistry, and is based on use of β-keto acids or their salts as surface-active compounds. These surfactants spontaneously break down through decarboxylation, to form an oil-like ketone and CO 2/HCO 3 -/CO 32 - depending on pH. The rate of breakdown can be controlled within a wide range by temperature or by certain additives, but, unlike most cleavable surfactants, a change in pH is not needed. Furthermore the surfactants can be conveniently activated from a stabile precursor just before use, and one (of many possible) precursors of this kind is already available on the industrial scale in the form of a wellknown chemical that is FDA-approved in other, non-surfactant, applications. The compound in question, alkyl ketene dimer (AKD), is produced in large scale by a number of large chemical producers today, and used for hydrophobization of paper. The present article gives an overview of the surfactant chemistry, with focus on recent studies of the kinetics of activation of the surfactant precursor and breakdown kinetics of the labile surfactant at different conditions. Furthermore, possible industrial applications of the surfactant will be discussed, with one example taken from a recent feasibility study performed within the car washing area. © Carl Hanser Publisher.
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| 4. |
- Blute, I, et al.
(författare)
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Phase behaviour of alkyl glycerol ether surfactants
- 1998
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Ingår i: Tenside Surfactants Detergents. - 0932-3414 .- 2195-8564. ; 35, s. 207-212
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Tidskriftsartikel (refereegranskat)abstract
- In this paper the phase behaviour and physical properties of a series of alkyl (C6, C8, C12 and iso-C8) monoglycerol ethers and 2-hydroxyalkyl (C6, C8, C12) monoglycerol ethers are presented. The binary phase diagram for the surfactants shows very little dependence on temperature. It is shown that as the alkyl chain length increases the tendency to form lamellar liquid crystalline phases increases. The branched alkyl chain shows no formation of lamellar phase even at high concentrations of surfactant. The differences in phase behaviour between the surfactants is attributed to the variation in the critical packing parameter (CPP) of the surfactants. The presence of an additional hydroxyl group in the alkyl chain causes a temperature independent solubility behaviour. Ternary phase diagrams were prepared using dodecane as the oil phase. Hexyl glycerol ether was the only of the alkyl glycerol ethers which was sufficiently water soluble to determine the surface tension and CMC. The CMC was determined to 15 mM (and surface tension to 26 mN m-1).
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| 5. |
- Han, Xu, et al.
(författare)
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Recent Developments on Surfactants for Enhanced Oil Recovery Neueste Entwicklungen bei Tensiden für die Enhanced Oil Recovery
- 2021
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Ingår i: Tenside, Surfactants, Detergents. - : Walter de Gruyter GmbH. - 0932-3414 .- 2195-8564. ; 58:3, s. 164-176
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Tidskriftsartikel (refereegranskat)abstract
- This review discusses surfactants used for chemical flooding, including surfactant-polymer flooding and alkali-surfactant-polymer flooding. The review, unlike most previous reviews in the field, has a surfactant focus, not a focus on the flooding process. It deals with recent results, mainly from 2010 and onward. Older literature is referred to when needed in order to put more recent findings into a perspective.
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| 6. |
- Karlkvist, Tommy, et al.
(författare)
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Flotation selectivity of novel alkyl dicarboxylate reagents for calcite-fluorite separation
- 2016
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Ingår i: Tenside, Surfactants, Detergents. - : Walter de Gruyter GmbH. - 0932-3414 .- 2195-8564. ; 53:6, s. 516-523
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Tidskriftsartikel (refereegranskat)abstract
- A series of amino acid-based surfactants with a fixed alkyl chain length and with two carboxyl groups separated by a spacer of one, two or three carbon atoms have been synthesized and evaluated as potential collectors for flotation of calcite and fluorite. A monocarboxylate amino acid-based surfactant having the same length of the hydrocarbon tail was also included for comparison in the study. Experiments using a Hallimond flotation tube showed that although the flotation reagents solely differ in terms of spacer, their efficacy in terms of flotation recovery varied very much. Whereas on calcite at pH 10.5 only the monocarboxylate collector gave a high yield, on fluorite at the same pH both the monocarboxylate and the dicarboxylate collectors with one carbon between the carboxyl groups gave good results. On calcite at the natural pH the monocarboxylate collector was most efficient but the dicarboxylate collectors with a two and a three-carbon spacer also gave a reasonable recovery. On fluorite at the natural pH the dicarboxylate collectors with a two- and a three-carbon spacer were most efficient. The zeta-potential and the flotation recovery of the mineral particles as a function of added collector were assessed and the adsorption was also monitored by diffuse reflectance infra-red spectroscopy. Taken together, the results showed that small changes in the head group region of the collector can radically affect flotation recovery. This type of knowledge is important to understand flotation selectivity in a mixture of similar minerals.
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| 7. |
- Kjellin, Mikael
(författare)
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Scientific results and economic effects from the centre for surfactants based on natural products (SNAP)
- 2012
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Ingår i: Tenside Surfactants Detergents. - 0932-3414 .- 2195-8564. ; 49:3, s. 199-210
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Tidskriftsartikel (refereegranskat)abstract
- This review article will give a broad overview of the synthesized and characterised surfactants within the competence centre SNAP (Centre for Surfactants Based on Natural Products). The surfactants differ within their hydrophilic groups, hydrophobic groups as well as the linkage between these groups. The main focus was put on sugar-based surfactants and surfactants containing polyhydroxyl groups so this part will be the most extensive in the review. Interactions between surfactants and polymers have also been investigated and will be described in the final part of the review. SNAP resulted in the publication of 239 scientific articles and 22 PhD degrees.
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| 8. |
- Laupheimer, Michaela, et al.
(författare)
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Transmission Measurements as Tool to Study Phase Transitions of Liquid Mixtures
- 2014
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Ingår i: Tenside Surfactants Detergents. - : Walter de Gruyter GmbH. - 0932-3414 .- 2195-8564. ; 51:1, s. 17-25
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Tidskriftsartikel (refereegranskat)abstract
- We present a quantitative method to determine the phase transition temperatures between one-phase and two-phase regions of multi-component liquid mixtures via temperature-dependent transmission measurements with an UV/Vis spectrometer. The method is based on the fact that multi-phase samples are turbid, while one-phase samples are transparent. We describe the method in detail and discuss the choice of the experimental parameters (wavelength, sample layer thickness), a suitable temperature program as well as the data analysis. We prove the validity of our method by measuring the phase diagrams of two model systems, namely a liquid and a gelled nnicroemulsion. The results are in good agreement with those obtained with the conventional visual method used for phase studies.
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| 9. |
- Macakova, Lubica, et al.
(författare)
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Rapid assessment of glass etching/corrosion using the quartz crystal microbalance with dissipation monitoring, QCM-D
- 2014
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Ingår i: Tenside Surfactants Detergents. - : Walter de Gruyter GmbH. - 0932-3414 .- 2195-8564. ; 51:6, s. 484-490
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Tidskriftsartikel (refereegranskat)abstract
- A new method to determine glass corrosion/etching is presented. The method enables a rapid screening of formulations in terms of their glass etching tendency as well as identification of the main components responsible for giving rise to the etching. Up to four formulations can be evaluated during one day. The high sensitivity of the QCM-D instrument enables measuring the etching of thicknesses less than one nm. Therefore, the technique can be used efficiently to screen components in the formulations and aid in the development phase of new tformatoptimised dishwash detergent formulations. In a planned work we will investigate the correlation between the etching rate of thin sputtered glass films at the surface of QCM-D crystals and good performance in a standardized dishwasher test using meltquenched glasses.
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| 10. |
- Pugh, RJ, et al.
(författare)
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Non-ionic surfactant monolayers
- 1995
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Ingår i: Tenside Surfactants Detergents. - 0932-3414 .- 2195-8564. ; 32, s. 278-284
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Tidskriftsartikel (refereegranskat)abstract
- The foam stability of aqueous solutions of pentaethylene glycol n-decyl ether and pentaethylene glycol n-dodecyl ether surfactants was related to experimental studies carried out on thin horizontal microscopic single films of the surfactant solutions using the microinterferometric film apparatus developed by Scheludko [1]. It was observed that an initial decrease in film thickness and reduction in potential at the air/solution interface of the film, occurred at a critical surfactant concentration where "black spots" appeared in the film when it was observed in reflected light. The black spots appeared to expand and coalesce, until the entire sheet was thinned down to a metastable common black film. In addition, a sharp increase in foam stability occured above this surfactant concentration, which was about 0.1 c. m. c, and corresponded to a high surface adsorption density of surfactant. We believe that the cause of the phenomenon was a change in state of the surfactant monolayer as originally proposed by Scheludko and Exerowa [2, 3]. Such a change (condensation) from gaseous to liquid expanded monolayers, has already been established for ionic surfactants and may change the rheological properties of the adsorbed film, enhancing the foam stability. Finally, the foam stability was determined at a range of electrolyte (KCI) concentrations from which it could be suggested that two types offoam stabilization methods were operating In the low electrolyte concentration, the stability appeared to be controlled by the metastable common first black film, but at high electrolyte concentrations the stability seemed to be dependent on secondary "Newton black" films
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| 11. |
- Ranieri, Davide, et al.
(författare)
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On the Influence of Intersurfactant H-Bonds on Foam Stability : A Study with Technical Grade Surfactants
- 2018
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Ingår i: Tenside Surfactants Detergents. - : CARL HANSER VERLAG. - 0932-3414 .- 2195-8564. ; 55:1, s. 6-16
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Tidskriftsartikel (refereegranskat)abstract
- From the literature on the foam stability of various surfactants with C-12 alkyl chains but different head groups a clear picture emerges: Foams are more stable when hydrogen bonds can form between the head groups, i.e. when the polar head group has a hydrogen bond donor and a proton acceptor. These observations suggest that hydrogen bonds between neighbouring molecules at the surface enhance foam stability. To support this hypothesis, we carried out a systematic foaming study of two types of technical grade surfactants, one of them being capable of forming H-bonds and the other one not. As was the case for the pure surfactants we found again that more stable foams are formed when the head group is capable of forming intersurfactant H-bonds: These results will certainly affect the future design of surfactants.
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| 12. |
- Raykundaliya, Nirav, et al.
(författare)
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The effect on Solution Properties of Replacing a Hydrogen Atom with a Methyl Group in a Surfactant
- 2015
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Ingår i: Tenside, Surfactants, Detergents. - : Walter de Gruyter GmbH. - 0932-3414 .- 2195-8564. ; 52:5, s. 369-374
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Tidskriftsartikel (refereegranskat)abstract
- Two surfactants, namely, dodecanoylglycinate and dodecanoylsarcosinate, differing only in a methyl group vs. a hydrogen atom on the amide nitrogen, have been studied with respect to solution behavior and adsorption at the air-water, oil-water and calcium carbonate-water interfaces. It was found that the ability of the glycinate surfactant of forming intermolecular hydrogen bonds via the amide group leads to tighter molecular packing, which greatly influenced the behavior at interfaces. Based on this molecular observation, potential applications were considered and emulsification, foaming and wetting tests were carried out. It could be concluded from this work that a minor change in the structure of a surfactant molecule can be very significant for technological systems and processes.
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| 13. |
- Stubenrauch, C., et al.
(författare)
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Comparison between interaction forces at air/liquid interfaces in the presence of non-ionic surfactants
- 2004
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Ingår i: Tenside Surfactants Detergents. - : Walter de Gruyter GmbH. - 0932-3414 .- 2195-8564. ; 41:4, s. 174-179
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Tidskriftsartikel (refereegranskat)abstract
- Interactions in thin liquid foam films and between solid/liquid surfaces coated with the non-ionic surfactant hexaoxyethylene dodecylether (C12E6) were investigated with TFPB (thin film pressure balance) and the MASIF (Measurement and Analysis of Surface Interaction Forces) technique, respectively. For foam films the formation of common black films (CBF) and Newton black films (NBF) was observed depending on the surfactant concentration and the applied pressure. With increasing surfactant concentration and increasing pressure the CBF is destablized, whereas a stabilization of the NBF is observed. In addition, MASIF measurements with two different hydrophobic surfaces were made. In one case silanated glass surfaces and in the other case thiolated gold surfaces were used. Differences and similarities of the interactions between these two surfaces are shown and discussed. Furthermore, the results of the MASIF measurements are compared with the ones of the thin films pressure balance measurements and the influence of the surfactant concentration on the interactions is discussed.
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