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  • 1.
    Agerkvist, I
    YKI – Ytkemiska institutet.
    Mechanisms of flocculation with chitosan in Escherichia coli distintegrates: effects of urea and chitosan characteristics1992In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 69, p. 173-187Article in journal (Refereed)
    Abstract [en]

    Four different chitosans with different charge densities and different molecular weights were used for investigation of the mechanisms involved in selective flocculation of cell debris particles in E.coli disintegrates. It was found that the main mechanism for flocculation is a "non-equilibrium" bridging process in which a very efficient removal of cell debris particles can be achieved with highly charged chitosans. The high molecular weight (6.5-6.6x105) chitosans produce very large and shear resistant flocs suitable for filtration as well as settling and centrifugation. The low molecular weight (1x105) product forms smaller and more shear sensitive flocs best suited for centrifugation. There are small differences in flocculation dosages depending on molecular weight, but large differences are found with significant changes in charge densities. A decrease in the deacetylation degree from 93 to 39% increased the flocculation dosages by 100 to 150%. A low molecular weight chitosan gave a much broader flocculation region than that of a high molecular weight. Flocculation by addition of urea revealed a hydrogen bonding capacity of chitosan toward cell debris particles which was not involved in chitosan´s interaction with proteins or nucleic acids. The purification of the enzyme -galactosidase could be increased by a factor of 3.7 when using a two step flocculation procedure. The enzyme yield was 82% and the enzyme solution was essentially free of both nucleic acids and cell debris particles.

  • 2. Ardebrant, H
    et al.
    Pugh, RJ
    YKI – Ytkemiska institutet.
    Surface acidity/basicity of road stone aggregates by adsorption from non-aqueous solutions1991In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 53, p. 101-116Article in journal (Refereed)
    Abstract [en]

    The surface of several road stone aggregates were characterized by the adsorption of organic probe molecules (with acidic and basic functional groups) from cyclohexane. The results show differences in the adsorption affinity and adsorption capacity of the molecules for the different mineral surfaces. In most cases it was found convenient to represent the data by a Langmuir-Freundlich type of isotherm, which defines a quasi-Gaussian energy distribution around a peak value. From the theory a range of adsorption free energies and surface coverages (site densities) were calculated, and the heterogenity of the surfaces evaluated. Generally the interaction strengths were rationalized in terms of Lewis acid-base theory.

  • 3. Ardebrant, H
    et al.
    Pugh, RJ
    YKI – Ytkemiska institutet.
    Wetting studies on silicate minerals and rocks used in bituminous highways1991In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 58, p. 111-130Article in journal (Refereed)
    Abstract [en]

    A study has been made on the wetting characteristics of quartz and several other silicate minerals and road stones used in bituminous roads. From contact angle measurements using the "two-liquid phase" method the nondispersive interaction energy between the mineral or road stone and water (I_S(p;sw)) with and without heat treatment was obtained. The results indicate a wide range of I_S(p;sw)-values, which appear to depend on the chemical composition of the aggregate. It was also suggested that the result may be related to the degree of contamination. From these studies it also appears that I_S(p;sw) is a useful parameter defining the vulnerability of stripping.

  • 4.
    Bergström, K
    et al.
    Berol Nobel, Sweden.
    Holmberg, K
    YKI – Ytkemiska institutet. Berol Nobel, Sweden.
    Microemulsions as reaction media for immobilization proteins to hydrophilized surfaces1992In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 63, p. 273-280Article in journal (Refereed)
    Abstract [en]

    The effect of microemulsion as reaction medium for immobilization of proteins to polystyrene hydrophilized with poly(ethylene glycol) or polysaccharide has been investigated. The amount of albumin, immunoglobulin G (IgG) and collagen immobilized from microemulsion was increased 10-100 times, compared with immobilization from an aqueous buffer system. The stability of anti-IgG and interleukin-2 was studied in different microemulsion systems. Anti-IgG was found to be stable in microemulsions based on sodium bis(2-ethylhexyl)sulphosuccinate (AOT) and C12EO5, whereas the non-ionic surfactant di-C9EO9 almost instantly destroyed the antigen-binding properties. Interleukin-2 completely lost its biological activity in an AOT-based microemulsion. We have also found that the choice of microemulsion influences coupling efficiency of the protein. An AOT-based system is preferred for immobilization of mycoplasma antibody, while a microemulsion based on C12EO5 is preferred for borrelia antigen.

  • 5.
    Bergström, L
    YKI – Ytkemiska institutet.
    Surface chemistry of silicon nitride powders: adsorption from non-aqueous solutions1992In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 69, p. 53-64Article in journal (Refereed)
    Abstract [en]

    The adsorption behaviour in cyclohexane of different silicon nitride powders have been studied. Adsorption isotherms of organic probe molecules covering a wide spectra of Lewis acidity/basicity showed large variation in adsorption behaviour between the different probes. Mathematical analysis showed that the adsorption data could be described by a Langmuir-Freundlich type of isotherm. Using a previously presented model of the silicon nitride surface, it was possible to relate the variation of isoelectric point in water between the three powders to a difference in the relative site density of silanol and amino groups on the surface. It was found that the maximum concentration (M) of benzoic acid increased linearly while M of pyridine decreased with an increase in the relative amount of amino groups on the surface.

  • 6.
    Bergström, L
    et al.
    YKI – Ytkemiska institutet.
    Bostedt, E
    Surface chemistry of silicon nitride powders: electrokinetic behaviour and ESCA studies1990In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 49, p. 183-197Article in journal (Refereed)
  • 7. Boutonnet, M
    et al.
    Kizling, J
    YKI – Ytkemiska institutet.
    Stenius, P
    YKI – Ytkemiska institutet.
    The preparation of monodisperse colloidal metal particles from microemulsions1982In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 5, p. 209-225Article in journal (Refereed)
  • 8.
    Brink, C
    et al.
    Berol Nobel, Sweden.
    Österberg, E
    Berol Nobel, Sweden.
    Holmberg, K
    YKI – Ytkemiska institutet. Berol Nobel, Sweden.
    Tiberg, F
    Lund University, Sweden.
    Using poly(ethylene imine) to graft poly(ethylene glycol) or polysaccharide to polystyrene1992In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 66, p. 149-156Article in journal (Refereed)
    Abstract [en]

    A novel method of grafting poly(ethylene glycol) (PEG) or polysaccharide to polystyrene has been developed. The non-charged hydrophilic polymer is firstly grafted to poly(ethylene imine). After prior oxidation of the solid surface, the graft copolymer is subsequently adsorbed. Analysis by electron spectroscopy for chemical analysis and ellipsometry indicates a trains-and-loops arrangement of the copolymer on the surface with densely packed PEG or polysaccharide chains oriented towards the bulk water phase. Ellipsometry also shows that whereas the PEG grafting is fast, the polysaccharide grafting is more sluggish. Attachment of both graft copolymers is completely irreversible, as seen also by ellipsometry. The surfaces obtained are highly protein repellent, as shown by enzyme-linked immunosorbent assay using fibrinogen and immunoglobulin G as model proteins.

  • 9. Eriksson, F
    et al.
    Eriksson, JC
    Stenius, P
    YKI – Ytkemiska institutet.
    Thermodynamics of micelle formation : model calculations for alkyl carboxylates1981In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 3, p. 339-356Article in journal (Refereed)
  • 10.
    Forsberg, S
    et al.
    YKI – Ytkemiska institutet.
    Aldén, L
    YKI – Ytkemiska institutet.
    Dewatering of Peat: Characterization of Colloidal and Subcolloidal Particles in Peat1988In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 34, no 4, p. 335-343Article in journal (Refereed)
  • 11. Fäldt, P
    et al.
    Bergenståhl, B
    YKI – Ytkemiska institutet.
    Claesson, PM
    YKI – Ytkemiska institutet.
    Stabilization by chitosan of soybean oil emulsions coated with phosphilipid and glycocholic acid1993In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 71, p. 187-195Article in journal (Refereed)
    Abstract [en]

    The interaction between chitosan, a cationic polyelectrolyte having a pKa of about 6.2, and emulsified lipids been measured as a function of pH by electrophoretic mobility. The strongest adsorption of chitosan has been observed on emulsion droplet surfaces stabilized with sodium glycocholic acid (bile salt) mixed with phosphatidyl choline pH of about 5. The forces acting between layers Or chitosan adsorbed on negatively charged solid surfaces (mica) measured as a function Or pH. From these measurements it is clear that, al low pH, the adsorption of cationic chitosan on to the negatively charged mineral surface results in a charge reversal. When the pH is increased (without changing the adsorbed amount), the charge passes through zero, and, at higher pH values, a negative charge develops. The range of the steric force was used to describe the structure of the adsorbed chitosan layer at different pH values. The flocculation behaviour of an emulsion stabilized by phospholipid and bile salt emulsifiers and adsorbed chitosan been rationalized by considering the forces acting between negatively charged solid surfaces coated with a chitosan layer.

  • 12.
    Gölander, CG
    et al.
    YKI – Ytkemiska institutet.
    Caldwell, K
    Lin, Y-S
    A new technique to prepare gradient surfaces using density gradient solutions1989In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 42, p. 165-172Article in journal (Refereed)
    Abstract [en]

    We present a new method to prepare quartz slides with a wettability gradient by confining a concentration gradient of dichlorodimethyl silane, the hydrophobation agent, in a density gradient formed by mixing diiodomethane and trichloroethylane. The gradients were characterized by means of contact angle measurements using the Wilhelmy plate technique and by the adsorption of human lysozyme, IgG or fibrinogen as measured by total internal reflectans fluorescence (TIRF) spectroscopy.

  • 13.
    Gölander, C-G
    et al.
    YKI – Ytkemiska institutet.
    Hlady, V
    Caldwell, K
    Andrade, JD
    Absorption of human lysozyme and adsorbate enzyme activity as quantified by means of total internal reflection fluorescence, 125I labelling and ESCA1990In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 50, p. 113-130Article in journal (Refereed)
    Abstract [en]

    The adsorption of human lyozyme to bare mica and mica hydrophobised with a C20NH2/C20OH Langmuir-Blodgett film was quantified by means of ESCA, radiotracer technique and total internal retlection fluorescence (TIRF). The ESCA isotherm on bare mica showed a sigmoidal shape with a transition region in the concentration range 0.02-0.04 mg ml -1 and a semiplateau region above 0.05-0.2 mg ml -1. The adsorption values here rougly corresponded to a side-up monolayer, 2.2-2.5 mg m-2. In contrast, on hydrophobised mica, a gradual increase in adsorption was obseved over the whole concentration range studied, 10-3-10 mg ml-1. The adsorbed amount in equilibrium with a 1 mg ml -1 slution was 1.4 mg m -2. At concentrations above phobised mica surface. These results are consistent with a strong electrostatic force dominationg the adsorption on bare mica and a weak hydrophobic driving force for adsorption on hydrophoised mica. Although the isotherm shapes were similar, the absolute adsorption values obtained from TIRF and radioactive measurements were considerably different from those obtained from ESCA. The lower apparent adsorption values, can be rationalized by a change in fluorescein-labelled lysozyme, e.g., roughly half of the ESCA values, can be rationalized by a change in fluorescence quantum yield of the fluors on adsorption or possibly by preferential adsorption of unlabelled lysozyme. The apparent two to three times higher adsorption values obtained from 125 I labelling measurements can be explained by an apparent sample area which is lager than the geometric area due to adsorption of labelled lysozyme in the interstices between mica layers. The normalized adsorption of fluorescein labelled polyclonal anti-lysozyme antibodies was similar on bare and hydrophilised mica. around 0.9 mole/mole for a surface equilibrated in a lysozyme solution at 0.02 mg ml -1. and 0.3 mole/mole at 2.0 mg ml -1(size exclusion). The steady state binding and steady state enzymatic cleavage of a fluorogenic lysozyme substrate, 4-methylumbelliferyl N,N,N-triacetyl-B-chitotrioside, on the lysozyme adsorbate layers.

  • 14.
    Gölander, C-G
    et al.
    YKI – Ytkemiska institutet.
    Lin, Y-S
    Hlady, V
    Andrade, JD
    Wetting and plasma-protein adsorption studies using surfaces with a hydrophobicity gradient1990In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 49, p. 289-302Article in journal (Refereed)
  • 15. Herder, P
    et al.
    Vågberg, L
    Stenius, P
    YKI – Ytkemiska institutet.
    ESCA and contact angle studies of the adsorption of aminosilanes on MICA1988In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 34, no 2, p. 117-132Article in journal (Refereed)
  • 16. Hlady, V
    et al.
    Gölander, C
    YKI – Ytkemiska institutet.
    Andrade, JD
    Hydrophobicity gradient on silica surfaces: A study using total internal reflection fluorescene spectroscopy1988In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 33, p. 185-190Article in journal (Refereed)
  • 17. Jansson, M
    et al.
    Eriksson, L
    YKI – Ytkemiska institutet.
    Skagerlind, P
    The effect of tetraalkylammonium ions on the stability of dilute o/w emulsions1991In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 53, p. 157-167Article in journal (Refereed)
    Abstract [en]

    The effects of tetraalkylammonium ions on the stability of dilute o/w emulsions were investigated with turbidimetric measurements. Large tetraalkylammonium ions were found to induce flocculation of emulsions stabilized by ionic emulsifiers at ten times lower concentrations compared to divalent cations. Emulsions stabilized by nonionic surfactants were also destabilized by low concentrations of organic ions. Increasing the effective size of sodium ions by inclusion complex formation with a crown ether, was also found to destabilize the emulsion. All these observations demonstrate the importance of the ion size/hydrophobicity on the stability of emulsions in the presence of electrolyte.

  • 18.
    Jansson, M
    et al.
    YKI – Ytkemiska institutet.
    Jönsson, A
    YKI – Ytkemiska institutet.
    Li, P
    Stilbs, P
    Aggregation in tetraalkylammonium dodecanoate systems1991In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 59, p. 387-397Article in journal (Refereed)
    Abstract [en]

    Aggregation in some different tetraalkylammonium dodecanoate systems has been studied. The influence of counterions on the phase behaviour of both binary surfactant/water systems and more complicated, multi-component systems were investigated, by applying NMR self-diffusion and Langmuir Blodgett techniques. Increasing the size of the tetra_x001F__x001F_alkylammonium counterions was found to lead to a substantial reduction of the critical micelle concentration. This is due to increased ion-micelle interactions associated with the enhanced hydrophobicity of the larger counterions. Furthermore, the increase in the ion size was found to be correlated with a depression of the tendency of the surfactant to form aggregates with low surface curvature, such as liquid-crystalline phases and rod-like micelles. The importance of the counterion size with regard to the formation of microemulsions in surfactant/water/oil systems was also demonstrated.

  • 19. Johansen, EJ
    et al.
    Skjärvö, IM
    Lund, T
    Sjöblom, J
    YKI – Ytkemiska institutet.
    Söderlund, H
    YKI – Ytkemiska institutet.
    Boström, G
    Water-in-crude oil emulsions from the Norwegian continental shelf. Part I. Formation, characterization and stability correlations1988In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 34, no 4, p. 353-370Article in journal (Refereed)
  • 20.
    Johansson, K
    et al.
    YKI – Ytkemiska institutet.
    Larsson, A
    YKI – Ytkemiska institutet.
    Ström, G
    YKI – Ytkemiska institutet.
    Stenius, P
    YKI – Ytkemiska institutet.
    Adsorption of phenol-formaldehyde resin onto cellulose1987In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 25, p. 341-356Article in journal (Refereed)
  • 21.
    Johansson, K
    et al.
    YKI – Ytkemiska institutet.
    Ström, G
    Stenius, P
    YKI – Ytkemiska institutet.
    The interactions between alkyd resin binders and kaolinite1991In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 56, p. 313-338Article in journal (Refereed)
    Abstract [en]

    The interaction between alkyd resins and kaolinte has been studied by means of adsorption measurements and spectroscopic methods such as electron spectroscopy for chemical analysis (ESCA) and diffuse reflectance infrared Fourier transform spectroscopy. The interaction is mainly governed by Lewis acid-base interactions but the molecular weight distribution and the oil length of the alkyds are of great importance. The kaolinite surface appears to be amphoteric since both acidic and basic species are adsorbed. The alkyd resins are very polydisperse. The experimental results are in agreement with the prediction of the theory of Cohen Stuart et al. (M.A Cohen Stuart, J.M.H.M. Scheutjens and G.J. Fleer, J. Polym. Sci., Polym. Phys. Ed., 18(1980) 559) for adsorption of polydisperse polymers. The alkyds are strongly adsorbed on the kaolinite, but not aluminium or hydroxxyl groups next to the aluminium. Double bonds, orginationg from the fatty acid part of the alkyd, play an active role in the adsorption process. The adsorption is only slightly affected by the temperature.

  • 22. Järnström, L
    et al.
    Stenius, P
    YKI – Ytkemiska institutet.
    Adsorption of polyacrylate and carboxy methyl cellulose on kaolinite: Salt effects and competitive adsorption1990In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 50, p. 47-73Article in journal (Refereed)
    Abstract [en]

    The adsorption of sodium polyacrylate (NaPAA) and sodium carboxy methyl cellulose (NaCMC) on homoionic sodium and calcium kaolinite has been investigated. Adsorption is strongly dependent on Ca2+/polyelectrolyte interactions in solution , while the nature of the kaolinite is of less importance. Adsorption takes place on two types of sites where the energetically more favorable sites appear to be the edges and the other sites are the basal planes. On addition of Ca2+ to a PAA solution, a maximum binding (saturation) corresdponding to 0.306 Ca2+ /PAA segement is reached. An adsorption model has been developed in which it is assumed that while any PAA may be adsorbed on the more favoable sites, only PAA molecules that are saturated with Ca2+ adsorb on the other sites. Equilibrium calculations using apparent binding constants of Ca2+ to the PAA determined from potentiometric titration show that this model is able to predict the experimentally determined isotherms with good accuracy. Although detailed calculations have not been perfomed, the model appears to be applicable also to the adsorption of NaCMC.

  • 23. Kiss, E
    et al.
    Gölander, C-G
    YKI – Ytkemiska institutet.
    Chemical derivatization of muscovite mica surfaces1990In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 49, p. 335-342Article in journal (Refereed)
    Abstract [en]

    A method to modify mica chemically by means of a plasma discharge in water vapour, to form reactive silanol groups, followed by silyation with isocyanatopropyldimethylchlorosilane has been developed. The introduction of isocyanatopropyl moieties on the surface enables the performance of a wide range of organic derivatization reactions. As examples, amino- and ethylene oxide-functional surfaces have been prepared. The surface film compositions have been quantitatively studied by ESCA. The interaction force in water between poly (ethylene oxide) layers covalently attached to mica, as measured in a surface force apparatus, was repulsive at separations less than 20-30 nm.

  • 24. Kiss, E
    et al.
    Gölander, C-G
    YKI – Ytkemiska institutet.
    Static and dynamic wetting behaviour of poly(ethylene oxide) layer formed on mica substrate1991In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 58, p. 263-270Article in journal (Refereed)
    Abstract [en]

    Dynamic wetting of poly(ethylene oxide)-, PEO; grafted mica surface has been investigated by a tensiometric method based on the Wilhelmy balance. Advancing and receding contact angles were determined under static conditions as well as at different contact line velocities in the range 0.1-5.0 mm s-1. The wetting medium and conditions were chosen according to the phase behaviour of PEO determined in solution. Wetting parameters characterizing the surface/liquid interaction measured on a system below and above the theta conditions differ considerably. Contact angles of water or aqueous electrolyte solution were found to be increased while heterogeneity of the surface was reduced with increasing temperature and salt concentration stressing the role of chain mobility in the special properties of PEO surface. Dynamic wetting of poly(ethylene oxide)-, PEO; grafted mica surface has been investigated by a tensiometric method based on the Wilhelmy balance. Advancing and receding contact angles were determined under static conditions as well as at different contact line velocities in the range 0.1-5.0 mm s-1. The wetting medium and conditions were chosen according to the phase behaviour of PEO determined in solution. Wetting parameters characterizing the surface/liquid interaction measured on a system below and above the theta conditions differ considerably. Contact angles of water or aqueous electrolyte solution were found to be increased while heterogeneity of the surface was reduced with increasing temperature and salt concentration stressing the role of chain mobility in the special properties of PEO surface.

  • 25.
    Kizling, J
    et al.
    YKI – Ytkemiska institutet.
    Kronberg, B
    YKI – Ytkemiska institutet.
    On the formation and stability of concentrated water-in-oil emulsions, aphrons1990In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 50, p. 131-140Article in journal (Refereed)
    Abstract [en]

    The stability of concentrated w/o emulsions is discussed on the basis of stability measurements of systems containinmg water, dodecane ( or hexadecane) and a nonionic surfactant, viz., polyoxyethylene dodecyl ether. In these emulsions the ratio of the dispersed aqueous phase to the organic phase is so high that the aqueous domains are polyhedral, so-called aphrons, so that the maximum available space is filled. The stability is dependent on: (i) the structure of the surfactant, which determines the preferencial solvency of the surfactant in the organic or the aqueous phase; and (ii) the presence of salts in the aqueous phase, which influences the stability by stopping the Ostwald ripening and/or decreasing the attractive force across the oil lamellae between the aqueous droplets.

  • 26.
    Kronberg, B
    et al.
    YKI – Ytkemiska institutet.
    Kuortti, J
    Stenius, P
    YKI – Ytkemiska institutet.
    Competitive and cooperative adsorption of polymers and surfactants on kaolinite surfaces1986In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 18, p. 411-425Article in journal (Refereed)
  • 27.
    Kronberg, B
    et al.
    YKI – Ytkemiska institutet.
    Stenius, P
    YKI – Ytkemiska institutet.
    Thorsell, Y
    Adsorption of nonylphenol-poly(propylene oxide)-poly(ethylene oxide) nonionic surfactants on polystyrene latex1984In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 12, p. 113-123Article in journal (Refereed)
  • 28.
    LeBell, J
    YKI – Ytkemiska institutet.
    Determination of floc sizes in kaolin suspensions dispersed by sodiumlignosulphonate1982In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 5, p. 285-299Article in journal (Refereed)
  • 29.
    LeBell, JC
    YKI – Ytkemiska institutet.
    The relation between the structure of lignosulphonates and their effect as stabilizers for latex particulate dispersions1984In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 9, p. 237-251Article in journal (Refereed)
  • 30. Nordli Börve, KG
    et al.
    Sjöblom, J
    Stenius, P
    YKI – Ytkemiska institutet.
    Water-in-crude oil emulsions from the Norwegian continental shelf Part V. A comparative monolayer study of model polymers1992In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 63, p. 241-251Article in journal (Refereed)
    Abstract [en]

    Monomolecular films based on poly(styrene-allylalcohol), PSAA, (mean molecular weight = 1500 g/mol) have been studied by means of the Langmuir technique. PSAA forms a highly compressible film which is not affected by changes in subphase pH. Addition of hexadecylaniline (HDA) and eicosylamine modifies the PSAA film. PSAA/HDA films obey additivity at low surface pressures, but not at pressures exceeding 12 mN/m and at low subphase pH. The mixed monolayers of PSAA and HDA have larger collapse pressures than the single component films. All the unionized films show a relaxation behaviour characteristic for polymer reorganizations in monomolecular films. Addition of 1-butanol and benzylalcohol to the subphase reveals substitution effects with regard to spreading as well as specific incorporation into the films. Model films of PSAA containing additives reproduce to essential parts the film behaviour of the previously investigated, interfacially active fraction of authentic crude oils. There seems to be small deviations with regard to maximal compression and surface activity between authentic crude oils and PSAA-based model systems.

  • 31. Nordli, KG
    et al.
    Sjöblom, J
    Kizling, J
    YKI – Ytkemiska institutet.
    Stenius, P
    YKI – Ytkemiska institutet.
    Water-in-crude oil emulsions from the Norwegian continental shelf. 4. Monolayer properties of the interfacially active crude oil fraction1991In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 57, p. 83-98Article in journal (Refereed)
    Abstract [en]

    Monolayer properties of interfacially active fractions in six different North Sea crude oils have been studied. The fractions were separated by a consecutive adsorption procedure utilizing functionalized silica as adsorbent. The molecular weight of the fractions are between 950 and 1450 g mol - 1. They are built up of carbon and hydrogen to 99 mol% and of nitrogen, oxygen and sulfur to 1 mol%. The fractions form monomolecular films in the air/water interface. The films enter the highly compressible liquid expanded state at specific areas in the rage of 0.20-0.28m2mg-1 lytes, pH, temerature and chemical additives is reported. It is shown that aromatic solvents strongly interact with the film hence modifying its monolayer properties. Relaxation studies of strongly interact with partly water-soluble groups. Correlation between the monolayer properties of these fractions and their ability to stabilize water-in crude oil emulsions is undertaken.

  • 32.
    Pugh, R
    YKI – Ytkemiska institutet.
    The role of the solution chemistry of dodecylamine and oleic acid collectors in the flotation of fluorite1986In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 18, p. 19-41Article in journal (Refereed)
  • 33.
    Pugh, RJ
    et al.
    YKI – Ytkemiska institutet.
    Bergström, L
    YKI – Ytkemiska institutet.
    Surface and solution chemistry studies on galena suspensions1986In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 19, p. 1-20Article in journal (Refereed)
  • 34.
    Pugh, RJ
    et al.
    YKI – Ytkemiska institutet.
    Tjus, K
    Flotation depressant action of poly(oxyethylene)alkyl ethers on talc1990In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 47, p. 179-194Article in journal (Refereed)
    Abstract [en]

    The adsorption and depressant action of short chain poly (oxyethylene) alkyl ethers on fine grain hydrophobic talc particles was studied. It was shown that the increase in the number of ethoxy units from (EO)3 to (EO)8 at a constant alkyl group (C12) increased the adsorption density on the talc and the depressant action. Also, maximum depressant action and plateau adsorption were shown to occur at concentrations just above the critical micelle concentration. Although non-ionic depressant also adsorbed on galena in xanthale solution, it was found possible to selectively float galena from a galena/talc mixture by careful control of the depressant concentration. From these studies it is suggested that both hydrophobic association and hydrogen bonding are important in the adsorption of the non-ionic on the talc. In the addition, it appears that the main contribution to the depressant action is the repulsive hydration forces from the multitude of ethoxy hydropholic head groups of the adsorbed micellar species.

  • 35.
    Stenius, P
    et al.
    YKI – Ytkemiska institutet.
    Eriksson, JC
    Preparation and protein adsorption properties of photopolymerized hydrophilic films containing N-vinylpyrrolidone (NVP), acrylic acid (AA) or ethyleneoxide (EO) units as studied by ESCA1986In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 21, p. 149-165Article in journal (Refereed)
  • 36.
    Stenius, P
    et al.
    YKI – Ytkemiska institutet.
    Järnström, L
    Rigdahl, M
    Aggregation in concentrated kaolin suspensions stabilized by polyacrylate1990In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 51, p. 219-238Article in journal (Refereed)
    Abstract [en]

    Aggregation in coating coluors is, in many cases, considered as a drawback since it may have negative consequences with regard to the runnability of the coluor. On the other hand, with a controlled aggregation, the structure of the colour may, in principle, be tailored in order to improve the properties of the coated paper. In both cases a better understanding of the aggregation mechanism is desired. Here the calcium ion induced aggregation of kaolin suspensions, dispersed with sodium polyacrylate (NaPAA), is characterized with rheological measurements and scanning electron microscopy. The aggregation behaviour of these systems is compared with that of kaolin suspensions (without dispersant) aggregated using pH changes. The results obtainded indicate the structure of the aggregates differ in these two systems. The calcium ion induced aggregation of the kaolin particles is extensively controlled by the interaction between the dispersant NaPAA and the cations. The aggregation is initiated at a critical ratio between the total concentration of calcium ions and the total concentration of polyacrylate monomers. It is suggested that the aggregation induced by the calcium ions can be understand in terms of Manning's counterion condensation theory as a result of delocalized binding of the calcium ions the PAA molecules reducing the charge of the PAA. It is, however, also possible that partly localized binding may influence the aggregation.

  • 37. Ström, G
    et al.
    Barla, P
    Stenius, P
    YKI – Ytkemiska institutet.
    The formation of polyelectrolyte complexes between pine xylan and cationic polymers1985In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 13, p. 193-207Article in journal (Refereed)
  • 38. Ström, G
    et al.
    Stenius, P
    YKI – Ytkemiska institutet.
    Formation of complexes, colloids and precipitates in aqueous mixtures of lignin sulphonate and some cationic polymers1981In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 2, p. 357-371Article in journal (Refereed)
  • 39.
    Tjus, K
    et al.
    YKI – Ytkemiska institutet.
    Pugh, Robert J
    YKI – Ytkemiska institutet.
    Herder, P
    YKI – Ytkemiska institutet.
    Eriksson, JC
    Stenius, P
    YKI – Ytkemiska institutet.
    The stability of thin aqueous films between an air bubble and hydrophobic substrate immersed in dilute solutions of flotation depressants1988In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 34, no 1, p. 95-99Article in journal (Refereed)
  • 40. Touroude, R
    et al.
    Girard, P
    Maire, G
    Kizling, J
    YKI – Ytkemiska institutet.
    Boutonnet Kizling, M
    Stenius, P
    YKI – Ytkemiska institutet.
    Preparation of colloidal platinum/palladium alloy particles from nonionic microemulsions: Characterization and catalytic behaviour1992In: Colloids and Surfaces, ISSN 0166-6622, E-ISSN 1873-4340, Vol. 67, p. 9-19Article in journal (Refereed)
    Abstract [en]

    Bimetallic particles of platinum and palladium have been prepared by reduction with hydrazine at ambient temperature of H2PtCl6 and PdCl2 dissolved in microemulsions consisting of water, hexadecane and pentaetyleneglycol dodecyl ether. The particles were deposited onto Al2O3.. Examination by STEM and EXAFS of particles with atomic ratio Pt:Pd = 35:65 showed that the particles are true Pt/Pd alloys. Indirect evidence was also obtained that particles containing only 4% Pd are alloys. The diameter of the particles ranges from 10-100 nm; there is evidence that they are formed by aggregation of particles in the diameter range 2-5 nm. The catalytic properties of the Pt/Pd/Al2O3 catalysts prepared from microemulsions were similar to those of catalysts prepared by conventional impregnation. Catalysts with low Pd content had the same selectivity in the isomerization of 2-methylpentane and hydrogenolysis of methylcyclopentane as a highly dispersed Pt catalyst (or a pure Pd catalyst). The catalytic cracking of 2-methylpentane indicates that the particle surfaces behave as Pt surfaces up to a Pd concentration of 60% in the particles. Isomerization of hexanes is dominated by the cyclic mechanism already at Pd concentrations as low as 4%; for these very low Pd concentrations hydrogenolysis of methylcyclopentane is the same as observed for very small Pt particles. It is concluded that Pd is enriched in the particle surfaces in such way that they consist of Pd and some highly dispersed Pt, even at bulk Pd concentrations as low as 4%.

1 - 40 of 40
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