foam and foam Films

STUDIES IN I N T E R F A C E SCIENCE F o a m and F o a m Films Theory, Experiment, Application STUDIES IN I N T E R F A C E SCIENCE SERIES E D I T O R S D M ~ b i u s and R M i l l e r Vol I Dynamics of Adsorption at Liquid Interfaces Theory, Experiment, Application by S.S Dukhin, G Kretzschmar and R Miller Vol z An Introduction to Dynamics of Colloids by J.K.G Dhont Vol Interfacial Tensiometry by A.I Rusanov and V.A Prokhorov Vol New Developments in Construction and Functions of Organic Thin Films edited by T Kajiyama and M Aizawa Vol Foam and Foam Films Theory, Experiment, Application by D Exerowa and P.M Kruglyakov Vol Drops and Bubbles in Interfacial Research edited by D M6bius and R Miller Foam and Foam Films Theory, Experiment, Application DOTCHI EXEROWA Institute of Physical Chemistry Bulgarian Academy of Sciences Sofia Bulgaria PYOTR M KRUGLYAKOV State Academy of Architecture and Building Penza Russia I998 ELSEVIER Amsterdam - Lausanne - New York- Oxford - Shannon - Singapore - Tokyo ELSEVIER SCIENCE B.V Sara Burgerhartstraat 25 P.O Box 211, iooo AE Amsterdam, The Netherlands ISBN: o 444 81922 © 1998 Elsevier Science B.V All rights reserved No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publisher, Elsevier Science B.V., Copyright & Permissions Department, P.O Box 521, IOOO AM Amsterdam, The Netherlands Special regulations for readers in the U.S.A - This publication has been registered with the Copyright Clearance Center Inc (CCC), 222 Rosewood Drive, Danvers, MA o1923 Information can be obtained from the CCC about conditions under which photocopies of parts of this publication may be made in the U.S.A All other copyright questions, including photocopying outside of the U.S.A., should be referred to the publisher No responsibility is assumed by the publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein This book is printed on acid-flee paper This book was translated into English from a manuscript in Bulgarian and Russian by Mrs Roumyana Stoyanova and Dr Khristo Khristov, and was edited by Dr Emil Manev The authors appreciate highly their dedicated work and express their deep gratitude D Exerowa P.M Kruglyakov Sofia, September 1997 vi It is sure4 e t t e r t o strive f o r a complete understandiy of the phenomena than t o despair of the human mind After Stephen Hawking (Hack Holes and Baby Universes and Other Essays Bantam Books, New York, 1993) Contents vii Preface Ackmwledgemenls Ipltroduct ion Chapter 1.1 1.2 1.4 Chapter 2.1 2.2 2.3 Formation and Structure of Foams Pressure in the Liquid and Gas Phases of Foams Methods for Foam Generation Shape of Films and Bubbles in Foam Foam Dispersi ty Pressure in Liquid Phase of Foam and Bubbles References 14 25 31 37 Expermineta1 Methods Involved in the Study of Foam Films Microscopic Thin Liquid Films 2.1.1 Thin Liquid Films: Microinterferometric Technique 2.1.2.Measuring cells for formation and study of microscopic foam films 2.1.3 Determination of foam film thickness 2.1.4 Determination of the capillary pressure 2.1.5 Determination of the contact angle between the foam film and the bulk phase 2.1.6, Foam film study with a-particle irradiation 2.1.7 Fluorescence recovery after photobleaching (FRAP) of foam films 2.1.8 Thin Liquid Films - Pressure Balance Technique Macroscopic Foam Films 2.2.1 Large flat foam films on a frame 2.2.2 Methods for measurement of foam film elasticity 2.2.3 Techniques for measurement of the lateral electrical conductivity of foam films 2.2.4 Ellipsometry of black foam films 2.2.5 FT-IR Spectroscopy studies of foam films 2.2.6 X-ray reflectivity of foam films Spherical Foam Films 2.3.1, Measurement of the coefficient of gas permeability trough foam films 2.3.2 Method for formation of foam films from insoluble surfactants References 42 42 43 Physical Chemistry of Foams Films Elements of the Thermodynamics of Foam Films 3.1.1 Curved liquid films 3.1.2 Ftane-parallel thin liquid fiIms 88 43 47 50 52 55 56 58 60 61 64 67 70 71 73 74 78 80 89 89 91 viii Contents 3.2 3.3 3.4 3.1.3 Thermodynamics of foam films 3.1.4 Mechanical model of the foam film and its adjacent meniscus 3.1.5 Contact angles 3.1.6 Line tension at a circular liquid film Non-Equilibrium Properties of Foam Films 3.2.1 Kinetics of thinning of foam films 3.2.1.1 Asymmetric drainage of foam films 3.2.1.2 Kinetics of formation of foam films 3.2.2 Kinetics of rupture of foam films 3.2.2.1 Critical thickness of film rupture 3.2.2.2 Critical thickness of rupture and black spot formation in microscopic foam films Surface Forces in Foam Films 3.3.1 Disjoining pressure isotherm and experimental verification of the DLVO-theory 3.3.2 Potential of the diffuse electric layer at solution/air interface 3.3.3 Surface forces in foam films from amphiphilic block copolymers 3.3.3.1 Transition from electrostatic to steric stabilisation in foam films from ABA triblock copolymers 3.3.3.2 Dynamic method for surface force measurment in foam films from ABA triblock copolymers 3.3.3.3 Disjoining pressure in foam films from ABA triblock copolymers Black Foam Films (Nano Black Films) 3.4.1 Surface forces in black foam film 3.4.1.1 Isotherms of disjoining pressure of black films from non-ionic surfactant solutions 3.4.1.2 Isotherms of disjoining pressure of black films from phospholipids 3.4.1.3 Isotherms of disjoining pressure of black films from ionic surfactant solutions 3.4.2 Transition from common black to Newton black films 3.4.2.1 Two equilibrium states of black foam films 3.4.2.2 Experimental investigations of CBF/NBF transition 3.4.2.3 Metastable black foam films 3.4.2.4 Elestrostatic origin of the transition to NBF 3.4.2.5 Main differences between CBF and NBF 3.4.2.6 Thickness transition in foam films 3.4.3 Relationship between black foam film formation and the properties of the surfactant adsorption layers 3.4.3.1 Properties of the adsorption layers 93 96 98 O0 102 102 llO ll3 ll5 115 118 122 124 134 150 150 157 162 167 168 171 179 191 199 200 201 209 212 216 218 226 226 Contents 3.4.3.2 Probability for observation of black foam films depending on the adsorption layer state 3.4.3.3 Formation of black foam films from an insoluble surfactant monolayer 3.4.4 Bilayer Black Foam Films (NBF) 3.4.4.1 Comparison of the lifetime/surfactant concentration dependence of CBF and NBF 3.4.4.2 Theory of rupture of amphiphile bilayers 3.4.4.3 Experimental results on stability of amphiphile bilayers 3.4.4.4 Phase transitions in phospholipid foam bilayers 3.4.4.5 Linear energy of holes in amphiphile bilayers 3.4.4.6 Linear energy of the contact line black foam film/ bulk liquid 3.5 Diffusion Processes in Foam Films 3.5.1 Gas permeability of foam films 3.5.2 Gas permeability of NBF 3.5.3 Lateral diffusion in phospholipid black foam films 3.5.4 Lateral diffusion of vacancies in NBF 3.6 Similarity of Foam Films with Emulsion and Asymmetric Thin Liquid Films 3.6.1 Emulsion films 3.6.2 Asymmetric films of the liquid/liquid/gas type References ix 230 234 236 237 238 249 263 273 276 282 282 290 295 300 303 303 309 322 Chapter Foam Structural Parameters and Related Properties: Techniques for Determination 4.1 Relation between the geometrical (structural) parameters of a foam and its physicochemical characteristics 4.2 Determination of foam expansion ratio (foam density) 4.3 Determination of pressure in foam Plateau borders 4.4 Determination of foam dispersity 4.5 Study of foam liquid distribution and Plateau border profiles References 345 Chapter 5.1 5.2 5.3 381 381 383 385 385 392 Foam Drainage A brief characterisation of foam drainage Techniques for the study of foam drainage Foam drainage at high pressure drop 5.3.1 Hydrodynamic model of a foam 5.3.2 Liquid flow through polyhedral foams with different types of foam films 5.3.2.1 Liquid flow in gravitational field 5.3.2.2 Liquid flow under pressure drop 345 357 359 362 375 377 392 397 760 Chapter 11 52 V.V Erokhin and L.N Filippenko, Priroda, 10 (1981) 32 53 B Hills, Thorax, 37 (1982) 713 54 A Bangham, N Miller and R Davies, Colloids & Surface, 10 (1984) 337 55 E.R Weibel, Morphometry of the Human Lung, Springer-Verlag, Heidelberg, 1963 56 V.V Erokhin, Funktsionalnaya morfologiya legkikh, Meditsina, Moscow, 1987 (in Russian) 57 E.M Scarpelli and A.J Mautone, Biophys J., 67 (1994) 1080 58 A Nikolova and D Exerowa, Langmuir, 12 (1996) 1846 59 E.M Scarpelli, Proc Intern Symp Perinatal Medicine and Human Reproduction, Monduzzi Editore, Bologna, 1995, Chapter 60 E.M Scarpelli, B.C Clutario, A.J Mautone and J.Baum, Pflugers Arch Eur J Physiol., 401 (1984) 287 61 E.M Scarpelli, B.C Clutario and D Traver, Pediatr Res., 13 (1979) 1285 62 M.J Blank, J Coll Interface Sci., 75 (1980) 435 63 E.M Scarpelli, A.J Mautone and M.R Chinoy, Anat Res., 244 (1996) 344 64 E.M Scarpelli, A.J Mautone, M.R Chinoy, D.O DeFouw and B.C Clutario, Anat Res., (1997) submitted 65 E.M Scarpelli, A.J Mautone, Z Lalchev and D Exerowa, Colloids & Surfaces B, (1997) 133 66 W Tooley, J.A Clements, K Muramatsu, C Brown and M Schleuter, AM Rev Resp Dis., 136 (1987) 651 67 E.A Egan, R.H Notter, M.S Kwong and D.L Shapiro, J Appl Physiol., 55 (1983) 875 761 Symbols* A area (film; border cross-sectional; etc.) A Hamaker' s constant Ao area of a molecule B structural coefficient C,c concentration C~t concentration of black spot formation Cc critical concentration of NBF formation Ce equilibrium concentration of NBF stability Cel electrolyte concentration Gel, cr critical electrolyte concentration Cs surfactant concentration D coefficient of molecular diffusion; D lateral diffusion coefficient in foam films D optical density Dv coefficient of vacancy diffusion in an amphiphile bilayer E elasticity modulus F Faradays' s number g acceleration due to gravity h film thickness hw equivalent film thickness her critical thickness of film rupture hcr, bl critical thickness of film rupture via black spot formation ho initial film thickness I light intensity k Boltzman' s constant K gas permeability * This is a list of the more often used symbols of the physical quantities; all symbols employed in the book are explained at the place of their first appearance in the particular chapter; since the authors have preserved the symbols employed in the original publications cited, including the figures, in some cases the same quantity is denoted with different symbols 762 gvw van der Waals-Hamaker's constant NA Avogadro' s number refractive index foam expansion ratio pressure Pry capillary pressure O binding energy of an amphiphile molecule in the foam bilayer R bubble radius gas law constant RF radius of gyration radius of film curvature accumulation ratio film radius S area T absolute temperature, K temperature, ~ time V,v volume AV surface potential difference W probability for observation of a black film Wi work for fluctuation formation of an/-sized hole in an amphiphile bilayer water flooding coefficient surface concentration; surface excess F~o maximum surface concentration film tension hole specific edge energy in an amphiphile bilayer e specific surface area 763 dielectric permeability energy of lateral bonds between the nearest neighbour molecules in an amphiphile bilayer e0 energy of normal bonds between the nearest neighbour molecules in an amphiphile bilayer wetting angle volume fraction of dispersed phase ~0 potential of the diffuse electric layer specific electrical conductivity line tension of the film/meniscus contact 1/to Debye screening length electrokinetic potential dynamic viscosity ~s surface viscosity contact angle at film/bulk phase wavelength chemical potential ~b chemical potential of the amphiphile molecules in a bilayer chemical potential of the amphiphile molecules in a solution kinematic viscosity 1-I disjoining pressure liel electrostatic disjoining pressure list steric disjoining pressure l'-I v W van der Waals disjoining pressure surface tension ty0 charge density of the diffuse electric layer time 764 lifetime of a foam film or foam foam lifetime at constant pressure in Plateau borders lifetime of a film or foam at m-particle irradiation Zbt lifetime of a black film Indices f film F foam G,g gas phase L liquid phase v volume" bulk Acronyms AF amniotic fluid AS alveolar surfactant BF black film BLM bilayer lipid membrane BSA bovine serum albumine CBF common black film CMC critical micelle concentration CPC ceryl pyridine chloride CTAB cetyltrimethylammonium bromide DLPE dilaurylphosphatidylethanolamine DMPC dimiristoylphosphatidylcholine DMPE dimiristoylphosphatidyletahnolamine DMPE L-t~-phosphatidylethanolamine dimyristoyl DMPG dimiristoylphosphatidylglycerol DMS decylmethylsulfoxide DOPE L-ct-phosphatidylethanolamine dioleoyl 765 DPPA dipalmitoylphosphatidylamine DPPC dipalmitoylphosphatidylcholine DPPE L-cz-phosphatidylethanolamine dipalmitoyl DSPC disaturated phosphatidylcholine Egg PC egg phosphatidylcholine EL egg lecithin EOR enhenced oil recovery EX Exosurf HLB hydrophile-lipophile balance HLPS hydrophobic fraction of lung surfactant HLR hydrophile-lipophile ratio HSA human serum albumine IN Infasurf LS lung surfactant LSAM lung surface active material Lyso PC lysophosphatidylcholine Lyso PE lysophospatidylethanolamine NaDoBS sodium dodecylbenzenesulphate NaDoS sodium dodecylsulphate NaDS sodium decylsulphate NaOL sodium oleate NaOS sodium octylsulphate NaTDS sodium tetradecylsulphate NBF Newton black film NP20 20-oxyethyl nonylphenol PC phosphatidylcholine PEO polyoxyethyleneoxide PG phosphatidylglycerol PI phosphatidylinosytol 766 PL phospholipids PPO polyoxypropilene oxide RDS respiratory distress syndrom SAD surfactant affinity difference SFA surface forces apparatus SP-A specific protein of LS SU Survanta TBF tributhyl phtalate TBP tributhyl phosphate 2D two dimensional 3D three dimensional Commercial surfactants Aerosol OT sodium bis(2-ethylhexyl)sulfosuccinate Alfapol-12 12-oxyethylated nonylphenol DC-10 10-oxyethylene decanol Emulfor FM thriethanolamine monooleate Emulgator 30 sodium alkansulphonate Enorfet AOS 1618 C16 - Cl8 olefin sulphonate Feepol mixture of the reaction products of C8 to C~8 olefins with sulphuric acid GKZh-94 polyethylhydrosilicon KAV-1 polyorganosilicon KIL hydrophobised clay KOZh-2 antifoaming organosilicon liquid KS-1, EEP-2, BS-3 organosilicon surfactants Nekal sodium alkyl naphtalene sulphonate Nrkal BX di-isobutylnaphthalene sulphonate OP-(n=4, 7,10, 20) oxyethyl phenols 767 PKZh-891 polyorganosilicon PMS-200 polyorganosilicon PO- 1, PO- 1D, PO-6 alkylaryl sulphonates PO-3A sec-alkylsulphonate Siponate DS- 10 commercial NaDoBS Span 80 sorbitan monooleate Sulfonole alkylaryl sulphonate Synperonic PE F108 A-B-A block copolymer, M = 14 000 Synperonic PE P85 A-B-A block copolymer, M = 600 Triton-X- 100 9,6-oxyethyl nonylphenol Tween 80 oxyethylated sorbitan monooleate Volgonate alkylsulphonate 768 SUBJECT INDEX ABA triblock copolymers foam films from disjoining pressure in, 162-6 dynamic method for surface force measurement in, 157-162 transition from electrostatic to steric stabilisation in, 150-7 Accumulation in a foam effectiveness of, 666-681 of individual surfactants and mixtures, 682-697 Accumulation ratio definition of, 667-672 Adsorption layers properties of, 226-230 black foam films formation and, 226 state of, 230-4 Alveolar surface a new hypothesis of the structure and stability of, 751-4 Alveolar surfactant, 738 Amniotic fluid phase state of foam bilayers from, 744-751 Amphiphile bilayers linear energy of holes in, 273-6 theory of rupture of, 238-249 Antifoam efficiency estimation of, 614; 617-8 Antifoams, 611-2 role of spreading of, 628-631 Aqueous core (see Foam films, thickness of) Asymmetric thin liquid films liquid/liquid/gas type, 309-322 similarity of foam films with emulsion and, 303-9 Biconcave drop, 44 Bilayer black foam films, 236 phase transitions in phospholipid, 263-273 linear energy of the contact line black foam film/bulk liquid, 276-282 Binding energy of an amphiphile molecule, 243; 746-9 Black foam films, 167 application in medicine, 738 ellipsometry of, 70 formation of, from insoluble surfactant monolayers, 234-6 and maximum adsorption, 229 isotherms of disjoining pressure of from non-ionic surfactants, 171-9 from phospholipids, 179-191 from ionic surfactants, 191-9 lateral diffusion in phospholipid, 295-300 metastable, 209-212 probability for observation of, 239-4 surface forces in (see Surface forces) transeference number of ions in, 69 two equilibrium states of, 200 Black Film Method, 738-743 for assessment of therapeutical surfactants, 754-8 Black spot formation concentration of, 119-122 Border radius of curvature profile of, 397-403 Bubbles shape of, 14 size distribution of, 25 Capillary pressure critical, 479-486; 525-7; 725-9 of the meniscus, determination of, 50 limiting, 725-9 of bubbles, 31 Capillary micromanometer, 359-362 CBF (common black film) definition of, 167; 200 CB F and NBF main differences between, 216-8 Circular liquid film line tension of, 100 Collective effect definition of, 529 Contact angles, 52; 98-100 769 measurement of, film expansion technique for, 54 topographic technique for, 53 Critical electrolyte concentration, 201-9 Critical thickness of film rupture, 115-8 and black spot formation, 118-122 Coalescence and structural rearrangement of foams, 464-7 Curved liquid films, 89-91 Defoaming ability and entry coefficient, 624-5 and spreading coefficient, 624-5 definition of, 613-8 coefficient of, 613-7 inversion of, of alcohols, 647-652 of oils, 644-6 of solid hydrophobic particles, 638-646 Defoaming in heterogeneous systems, 623-6 heterogenous mechanism of, 631-8 techniques for determination of, 611-9 Diffuse electric layer potential of, at the solution/air interface, 134-150 Diffusion coefficient lateral, 57; 295-300 Diffusion gas transfer and internal foam collapse, 455-464 Dimple formation diffusion, 307 due to hydrodynamic resistance, 307 Disjoining pressure definition of, 89; 125 electrostatic, 125-7 isotherms of, 124-133 oscillaroty, 221-2 van der Waals, 125-7 Dry foams, 34-6 DVLO-theory experimental verification of, 124-133 Dynamic foams stability of, 556-561 AV-potential at the solution/air interface, 141-2 Elasticity modulus definition of, 64-6 Electrical conductivity of foams, 586-590 Electrokinetic potential of a foam, 590-3 Electroosmosis, 590-2 Electroosmotic pressure, 591 Emulsion bilayers rupture of, 259-260 Emulsion films, 303-9 Emulsion metal working fluids, 716-8 Enhenced oil recovery (EOR), 719-720 Entry coefficient, 624-5 Equation of foam state, 447-9 Equivalent film thickness definition of, 48 Exerowa Black Film Method, 739 Expansion ratio definition of, 2-3 Extraction, 716 Extraction effectiveness coefficient of, 673 Foetal lung maturity, 738-743 Films asymmetric, 309-322 on a substrate, 309-322 plane-parallel, 91 pseudoemulsion, 309-322 shape of, 14 Film thickness definition of, 91-3 determination of, 47-9 equilibrium effect of surfactant concentration on, 135-8 effect of temperature on, 129 equivalent, 48 Film surface tension definition of, 93 Film tension definition of, 91 Film thinning driving forces of, 93 stepwise, 218-226 Foam hydrodynamic model, 385-392 Foam breakdown adsorption mechanim of, 619-623 770 in centrifugal field, 480-493 Foam bilayers adsorption isotherm of surfactant vacancies in, 257-9 lifetime of, 250 probability for observation of, 253-4 rupture of by m-particles, 254-5 stability of effect of temperature, 255-7 experimental results, 249-263 theory of rupture of amphiphile, 238-249 Foam cells shape of, 18 models of compact dodecahedron, 19; 20 mininal tetrakaidecahedron, 17; 20 pentagonal dodecahedron, 18; 20 Foam chromatography, 666 Foam collapse due to evaporation, 466-7 internal, at diffusion gas transfer, 455-464 rate of internal, 494-8 kinetics of internal, 468-473 technqiues for study of internal, 449-455 Foam column decay of, 473 in gravitational field, 474-6 characteristics of stability related to, 505-510 distruction of influence of Plateau border pressure on, 476-486 Foam density, 357-9 Foam dispersity definition of, 3; 25-30 determination of; 362-375 Foam destruction avalanche-like, 476-486 critical pressure for, 479-486 Foam drainage and equilibrium pressure in the foam liquid phase, 409 at high pressure drop, 385 characterisation of, 381-3 equations for, under pressure drop, 403-9 gravitational, 420 equations of,420-6 influence of the types of foam films on, 418-420 influence of internal foam collapse on, 442 initial stage of, 426-431 rate of, 431-9 techniques for the study of, 383-5 Foam expansion ratio determination of, 357-9 Foam films asymmetric drainage of, 110-3 diffusion process in, 282-303 disjoining pressure isotherms, 124-133 elasticity of, 64-6 from insoluble surfactants, methods for formation of, 80 FT-IR spectroscopy of, 71 gas permeability of, 282-290 inhibition of black spot formation in, 626-8 kinetics of formation of, 113-4 kinetics of rupture of, 115 kinetics of thinning, 102-110 lateral electrical conductivity of, 67-9 mechanical model of, 96-8 microscopic measuring cells for, 43-7 multilayers, 218-226; 751-3 non-equilibrium properties of, 102 similarity of, with emulsion and asymmetric thin liquid films, 303-322 spherical, 74-8 stratified, 218-226 study of, by m-particles irradiation, 55 study of, by FRAP, 56 surface forces in (see Surface forces) thickness of, 47-9 thickness transition in, 218-226 thermodynamics of, 89 X-ray reflectivity of,73 Foam formation dynamic regime of, mechanism of lamella division, 725 771 leave behind, 725 snap-off, 725 static regime of, Foam generation methods for barbotage, condensation, dispersion, Foam inhibition definition of, 616-8 examples of, 716-8 Foam in porous media, 720-9 Foam mobility, 723 Foam model boder, 348-9; 670 film, 669 Foam numbers, 383-5 Foam power (F.P.), 384 Foam Pressure Drop Technique, 10-1; 534-9 Foam properties electrical, 586-590 electrokinetic, 590-3 mechanical, 571-4 optical, 593-601 physicochemical general principles of regulation, 658-662 rheological, 574-586 thermophysical, 601-6 Foam quality, 721 Foam separation of surfactant components, 697-703 Foam stability characteristics of, related to foam column decay, 505-510 definition of, 3; 502-5 effect of the isoelectric state on, 539-543 kinetic factors of, 510-9 model approach to study of, 520 role of foam films in, 520-7 thermodynamic factors of, 519-20 Foam structure honeycomb, 14 polyhedral, 14 Foam structural coefficient, 586-9 Foam structural parameters and foam physicochemical characteristics, 345-356 Foam syneresis, 381-2 Foam viscosity, 584-6 Foamed emulsions, 561-4 Foaming ability and foam stability, 545-9 definition of, 3; 502-5 dependence of, on foam formation, 543-5 Foaming agents natural products as, 718-9 FRAP, 56 Frozen foams thermal insulators from, 704-712 FT-IR Spectroscopy, 71 Gas emulsions, Gas industry use of foams in, 719-729 Gas permeability coefficient of, definition of, 283-295 measurement of, 78 diminishing bubble method, 79 stationary bubble method, 79 of NBF, 290-5 Gas volume fraction, Gibbs elasticity, 64-6; 512-5 Hamaker' s constant, 161-2 Heat capacity of a foam, 601-4 Hole-nucleation theory of rupture of bilayers, (see Theory of rupture of amphiphile bilayers) Hydrophile-lipophile balance (HLB), 549-556 Hydrophile-lipophile ratio (HLR), 550-6 Interactions long-range, 122-4 short-range, 122-4 Isoelectric point, 134; 143 Isoelectric state at the solution/air interface, 143-150 effect on foam stability, 539-543 Kelvin's minimal tetrakaidecahedron, 17 772 Kinetics of establishing pressure in the foam liquid phase, 410-8 Lateral diffusion coefficient, 56-7; 295-300 in phospholipid black foam films, 295-300 in lung surfactant foam films, 749-751 of vacancies in NBF, 300-3 Limiting capillary pressure, 725-9 Line tension at a circular liquid films, 100 Linear energy of holes in amphiphile bilayers, 273-6 of the contact line black foam film/bulk liquid, 276-282 Liquid flow in gravitational field, 392-7 through polyhedral foams, 392 under pressure drop, 397-403 Liquid phase pressure in, 32-7 Liquid volume fraction, 345 Macroscopic foam films, 60 on a frame, 61-4 Marangoni effect, 103 Marangoni elasticity, 64-6; 512-5 Marangoni number, 104 Maxium adsorption and black foam film formation, 229 Measuring cells, 43-7 Method for assesment of foetal lung maturity (see Black Film Method) Method of equilibrium foam film, 134-5 Methods for foam generation, 4-13 for foam film elasticity measurements, 64 for surface separation, 663-6 Microinterferometric technique, 43; 47-9 Modulus of elasticity of a foam, 512-5 Multilayer foam film, 218-226; 751-3 Nano foam films, 167 Natural products as foaming agents, 718-9 NBF (Newton black film) definition of, 167; 200 Oil flotation, 720 Oil recovery, 721 Omega potential, 93-5 Optical density of a foam, 593; 507-600 Osmotic pressure in a foam, definition of, 34 Petroleum industry use of foams in, 719-729 Phospholipids isotherms of disjoining pressure, 179-191 Plateau borders cross-section, 14; 21 determination of pressure in, 359-362 pressure in, 32 profiles of foam liquid distribution and, 375-7 Plateau triangle, 14 Polyhedral foam, aggregative stability of, 504 hydrodynamic stability of, 502-3 Polymer foams, 712-6 Pore volume (p.v.), 721; 724 Pour test, 12; (see Ross-Miles test) Pressure difference definition of, 34 Pressure Balance Technique, 58-9 Pressure drop, 31-7; 385 Pseudoemulsion films definition of, 309 Purification coefficient of, 680 of surfactant solutions, 666-681 Radius of gyration, 151 Real foam stability of, 527-530 Respiratory distress syndrom (RDS), 738 Retention time definition of, 557 Reynolds' relation, 102 Reynolds' number, Ross-Miles test, 534-9 773 Selectivity coefficient definition of, 672 Separation in a foam effectiveness of, 666-681 Shear modulus of a foam, 577-580 Shear stress of a foam, 576-7 Solid foams, Solidifying foams optimisation of the properties, 703 Spherical foam, Spreading coefficient, 624-5 Steady-state foams, (see Dynamic foams) Stokes' law, Streaming potential of a foam, 590-2 Structural coefficient of a foam, 586-9 Structural rearrangement, 464-7 Surface charge density at solution/air interface, 134-150 Surface forces DLVO, 122-4 in black foam films, 168-171 in foam films, 122-4 from amphiphilic block copolymers, 150 dynamic method of measurement of, 157-162 hydration, 122-4 hydrophobic, 122-4 non-DLVO, 122-4 solvatation, 122-4 steric, 122-4; 165 Surface separation methods of, 663-6 Surfactant affinity difference (SAD), 551-3 Surfactants accumulation of, in a foam, 663; 666-673; 682-697 foam stabilising properties of, 534-9 hydrophile-lipophile balance of, 549-554 ionic, isotherms of disjoining pressure of, 191-9 physicochemical properties of, 530-4 non-ionic, isotherms of disjoining pressure of, 171-9 therapeutic, 754-8 separation of, in a foam, 663-6; 697-703 Surfactant adsorotion layers (see Adsorption layers) Syneresis, definition of, 381-2 Techniques for lateral electrical conductivity measurements, 67-9 for foam drainage study, 383-5 microinterferometric, 43; 47-9 Technological application classification of foams by their, 656-8 classification of films by their, 656-8 Thermal conductivity of a foam, 601-6 Theory of rupture of amphiphile bilayers, 238-249 Therapeutic surfactants, 754-8 Thin liquid filmsPressure Balance Technique, 58-9 Three-dimensional foam, Three-layer film model, 49 Three-phase foams drainage of, 439-441 Threshold concentration, 741 Threshold dilution, 742-3 Transition CBF to NBF, 199 experimental investigation of, 201-9 critical electrolyte concentration of, 201-9 electrostatic to steric stabilization, in foam films, 150-7 electrostatic origin of, to NBF, 212-5 thickness, in foam films, 218-226 Van der Waals-Hamaker's constant, 127 Velosity of bubble rise definition of, 5-6 Veritical film marginal regeneration in, 113 profile of, 62 Water flooding coefficient; 673-9 X-ray reflectivity of foam films, 73 Yield stress of a foam, 576-580 Youn~ modulus, 579 This Page Intentionally Left Blank [...]... method of Foam Pressure Drop Technique, developed by P.M Kruglyakov, Khr Khristov and D Exerowa On the other hand, the book treats fairly thoroughly the whole array of physicochemical properties of foam and foam films by pulling on both outstanding older works and the latest achievements in the research of foams and other disperse systems (especially emulsions) and surface phenomena Understandably enough,... stability related to foam column decay Kinetic factors of foam stability Thermodynamic factors of foam stability Model approach to the study of foam stability and analysis of the stabilising factors 7.5.1 Role of foam films in the stability of foams 7.5.2 Stability of a real foam 7.6 Physicochemical properties of surfactants and the stabilising ability of their solutions 7.6.1 Foam stabilising properties... column 6.5.1 Foam column decay in gravitational field 6.5.2 Influence of Plateau border pressure on foam column destruction 6.5.3 Foam breakdown in centrifugal field 6.6 Comparison between the rate of internal foam collapse and the decrease in foam volume References Chapter 7 Foam Stability and the Stabilising Ability of Surfactants 7.1 7.2 7.3 7.4 7.5 Definition of the term foam stability and foaming ability... processing properties of solidifying foams 10.4.1 Thermal insulators from frozen aqueous foams 10.4.2 Oligomer polymer foams 10.5 Examples of foam inhibition in the process of extraction and in emulsion metalworking fluids 10.6 Examples of the use of natural products as foaming agents 10.7 Use of foams in petroleum and gas industries References Chapter 11 Black Foam Films: Application in Medicine 11.1... 5.3.4 Foam drainage and the kinetics of establishing equilibrium pressure in the foam liquid phase: experimental studies 5.3.4.1 Kinetics of establishing pressure in the foam liquid phase 5.3.4.2 Influence of the type of foam films on foam drainage 5.4 Gravitational drainage of a foam 5.4.1 Equations of gravitational drainage 5.4.2 Initial stage of drainage 5.4.3 Influence of the foam structure and the... the foam itself and a comparison of the foam and foam film properties from different perspectives Another original trait of the book is the formulation of the general scientific principles, underlying the regulation of the physicochemical parameters of foam and foam films and the technological application of foams based on them Of course, the applications of foam are XV so numerous that they could... to a great extent foam stability With the Plateau borders and the vertexes, the films form a unified capillary system All the most essential foam processes, including those determining gas bubble expansion and their lifetime, bear on the thickness, structure and physicochemical properties of foam films The study of the physicochemical properties of the thin liquid films inside the foam itself, is a... of soap foams were carried out in the seventeen century Some foam forming recipes must have been known even earlier The foundations of the research on foam films and foams have been laid by such prominent scientists as Hook, Newton, Kelvin and Gibbs Hook's and Newton's works contain original observations on black spots in soap films The first systematic study of the various properties of soap films has... the foam column occurs when the foam is open to the atmosphere The most important parameters characterising a polyhedral foam are expansion ratio, dispersity and foam stability The expansion ratio n is the ratio between the foam volume VF and the volume of the liquid content VL in it Formation and Structure of Foams 3 n - v~ _ ~v~ + v~~ = l + V ~ v,~ v~ v,~ where Vc (1.1) is the gas volume in the foam. .. scientific results and methods, published in Bulgarian and Russian, therefore, inaccessible to the majority of readers and not having exerted an overwhelming influence on future works but, which may, hopefully, be elaborated further One of the outstanding features of the monograph is the circumstantial elucidation of the role of foam films in the various processes and phenomena in the foam itself and a comparison