Zusammen


M. K. Bemett, N. L. Jarvis, and W. A. Zisman, J. Phys. Chem., 66, 328 (1962).  [c.38]

The situation illustrated by the case of benzene appears to be quite common for water substrates. Low-surface-tension liquids will have a positive initial spreading coefficient but a near-zero or negative final one this comes about because the film pressure r of the Gibbs monolayer is large enough to reduce the surface tension of the water-air interface to a value below the sum of the other two. Thus the equilibrium situation in the case of organic liquids on water generally seems to be that of a monolayer with any excess liquid collected as a lens. The spreading coefficient 5b(A)/a can be determined directly, and Zisman and co-workers report a number of such values [12].  [c.107]

The topic of spreading rates is of importance in the technology of the use of mono-layers for evaporation control (see Section IV-6) it is also important, in the opposite sense, in the lubrication of fine bearings, as in watches, where it is necessary that the small drop of oil remain in place and not be dissipated by spreading. Zisman and coworkers have found that spreading rates can be enhanced or reduced by the presence of small amounts of impurities in particular, strongly adsorbed surfactants can form a film over which the oil will not spread [48].  [c.111]

The detailed mathematical developments are difficult to penetrate, and a simple but useful approach is that outlined by Garrett and Zisman [130]. If gravity is not important, Eq. 11-36 reduces to  [c.122]

W. D. Garrett and W. A. Zisman, J. Phys. Chem., 74, 1796 (1970).  [c.162]

The classic techniques for measuring contact angle have been reviewed in detail by Neumann and Good [95]. The most commonly used method involves directly measuring the contact angle for a drop of liquid resting on a horizontal solid surface (a sessile drop) as illustrated in Fig. X-8. Commercial contact angle goniometers employ a microscope objective to view the angle directly much as Zisman and co-workers did 50 years ago [96]. More sophisticated approaches involve a photograph or digital image of the droplet [46, 97-100]. An entirely analogous measurement can be made on a sessile bubble captured at a solid-liquid interface as illustrated in Fig. X-8 [101, 102]. The use of bub-  [c.362]

Fig. X-9. Zisman plots of the contact angles of various homologous series on Teflon O, RX , alkylbenzenes (f), n-alkanes , dialkyl ethers , siloxanes A, miscellaneous polar liquids. (Data from Ref. 78.) Fig. X-9. Zisman plots of the contact angles of various homologous series on Teflon O, RX , alkylbenzenes (f), n-alkanes , dialkyl ethers , siloxanes A, miscellaneous polar liquids. (Data from Ref. 78.)
A major contribution to the rational organization of contact angle data was made by Zisman and co-workers. They observed that cos 6 (advancing angle) is usually a monotonic function of 7l for a homologous series of liquids. The proposed function was  [c.367]

Figure X-9 shows plots of cos 6 versus 7l for various series of liquids on Teflon (polytetrafluoroethylene) [78]. Each line extrapolates to zero at a certain 7l value, which Zisman has called the critical surface tension 7 since various series extrapolated to about the same value, he proposed that 7 was a quantity characteristic of a given solid. For Teflon, the representative 7 was taken to be about 18 and was regarded as characteristic of a surface consisting of —CF2 — groups. Figure X-9 shows plots of cos 6 versus 7l for various series of liquids on Teflon (polytetrafluoroethylene) [78]. Each line extrapolates to zero at a certain 7l value, which Zisman has called the critical surface tension 7 since various series extrapolated to about the same value, he proposed that 7 was a quantity characteristic of a given solid. For Teflon, the representative 7 was taken to be about 18 and was regarded as characteristic of a surface consisting of —CF2 — groups.
An important and expensive problem in surface science occurs in the prevention of the attachment of marine animals such as barnacles to ship surfaces, a process known as biofouling. Baier and Meyer [159] have shown that the Zisman plot can be used to predict biofouling, thus avoiding costly field tests to find a successful coating to prevent biofouling.  [c.369]

What is the critical surface tension for human skin Look up any necessary data and make a Zisman plot of contact angle on skin versus surface tension of water-alcohol mixtures. (Note Ref. 136.)  [c.381]

Take the data from Fig. X-12 on the propyl monolayers and make a Zisman plot to determine the critical surface tension for the surface.  [c.382]

H. W. Fox, E. F. Hare, and W. A. Zisman, J. Phys. Chem., 59, 1097 (1955) O. Levine and W. A. Zisman, J. Phys. Chem., 61, 1068, 1188 (1957).  [c.385]

W. C. Bigelow, D. L. Pickett, and W. A. Zisman, J. Colloid Sci, 1, 513 (1946) see also R. E. Johnson and R. H. Dettre, J. Colloid Sci, 20, 173 (1965).  [c.385]

H. W. Fox and W. A. Zisman, J. Colloid Interface Sci., 5, 514 (1950).  [c.387]

E. G. Shafrin and W. A. Zisman, J. Phys. Chem., 64, 519 (1960).  [c.387]

Levine and Zisman [46] confirmed and extended Hardy s results, using films on glass and on metal surfaces that were deposited by adsorption either from  [c.444]

However, the actual strengths of good adhesive joints are only about a tenth of the ideal values [119], so that failure to wet completely does not seem to be an adequate explanation. Since adhesive joints are subject to shear as well as to normal force, there can be a peeling action in which the applied force concentrates at an edge to produce a crack that then propagates. Such stress concentrations can occur without deliberate intent simply because of imperfections and trapped bubbles in the interfacial region [120]. Zisman [69] remarks that adhesives may give stronger joints with rough surfaces simply because such imperfections, including trapped air bubbles, will not be coplanar, and the propagation of cracks will then be less easy. An adhesive joint may be weakened by penetration of water [72] the effect is of great importance in the stripping of blacktop road surfaces where water penetrates the interface between the rock aggregate and the asphalt.  [c.457]

R. C. Bowers and W. A. Zisman, Mod. Plast., 41, (December 1963).  [c.460]

O. Levine and W. A. Zisman, J. Phys. Chem., 61, 1068, 1188 (1957).  [c.461]

W. A. Zisman, Advances in Chemistry, No. 43, American Chemical Society, Washington, DC, 1964, p. 1.  [c.462]

Glycerol has been used as a polar substrate. Glycerol is a very poor electrical conductor, and this made it possible to measure the conductivity of spread monolayers films of some charge-transfer complexes were found to be highly conducting [100]. Ellison and Zisman [101] reported studies of monolayers of polymethylsiloxane polymer and of the protein zein on such substrates as white mineral oil, n-hexadecane, and tricresyl phosphate. Jarvis and Zisman [102] report qualitative spreading studies with a number of fluorinated organic compounds at a variety of organic liquid-air interfaces and ir-a data for some of the Gibbs monolayer systems.  [c.552]

A. H. Ellison and W. A. Zisman, J. Phys. Chem., 60, 416 (1956).  [c.567]

N. L. Jarvis and W. A. Zisman, J. Phys. Chem., 63, 727 (1959).  [c.567]

C. O. Timmons and W. A. Zisman, J. Phys. Chem., 69, 984 (1965).  [c.569]

Zaikin A N and Zhabotinsky A M 1970 Concentration wave propagation in two-dimensional liquid-phase self-oscillating system Nature 225 535-7  [c.1117]

For ketoximes, the group which is syn or anti to the hydroxyl group must be specified. Difficulty in assigning the terms cis and trans arises when there is no pair of identical, or similar, groups substituting an alkene. Then the terms (E) [German entgegen = slCTOSs] and (Z) [German zusammen = together] replace the terms iransjcis. In many cases, but not all, the term cis corresponds to (Z) and trans to (E). Under this new system the two ligands attached to each olefinic carbon atom are put in order of precedence by application of sequence rules and the symbols (E) and (Z) are then used to describe those isomers in which the ligands of higher precedence are on the opposite side (E), etc. Maleic acid is then referred to as the (Z)-isomer and fumaric acid  [c.225]

P. Pomerantz, W. C. Clinton, and W. A. Zisman, J. Colloid Interface Sci., 24, 16 (1967) C. O. Timons and W. A. Zisman, ibid., 28, 106 (1968).  [c.159]

When a surface-active agent is present in a liquid droplet, it can adsorb to the surface, lower the surface energy, and cause the liquid contact angle to increase. This phenomenon, known as autophobicity, was postulated by Zisman many years ago [78, 79]. Autophobicity is quite striking in wetting films on clean  [c.360]

The interesting implication of Eq. XII-24 is that for a given solid, the work of adhesion goes through a maximum as 7b(a) is varied [69]. For the low-energy surfaces Zisman and co-workers studied, )3 is about 0.04, and Wmax is approximately equal to the critical surface tension yc itself the liquid for this optimum adhesion has a fairly high contact angle.  [c.453]

Precision combustion measurements are primarily made to detennine enthalpies of fonnation. Since the combustion occurs at constant volume, the value detennined is the energy change AJJ. The enthalpy of combustion A //can be calculated from A U, provided that the change in the pressure within the calorimeter is known. This change can be calculated from the change in the number of moles in the gas phase and assuming ideal gas behaviour. Enthalpies of fonnation of compounds that do not readily bum hr oxygen can often be detennined by combusting in fluorine and the enthalpy of fonnation of volatile substances can be detennined using flame calorimetry. For compounds that only combust at an appreciable rate at high temperature, such as zhconium in chlorine, the teclmique of hot-zone calorimetry is used. In this method one heats the sample only very rapidly with a known amount of energy until it reaches a temperature where combustion will occur. Alternatively, a well characterized material such as benzoic acid can be used as an auxiliary material which, when it bums, raises the temperahire sufficiently for the material to combust. These methods have been discussed in detail [2, 3 and 4].  [c.1910]

Cakmak M, Teitge A, Zachman FI G and White J L 1993 On-line small-angle and wide-angle x-ray scattering studies on melt-spinning poly(vinylidene fluoride) tape using synchrotron radiation J. Polym. Sc/. 31 371- 81  [c.2539]

Bigelow WC, Piokett D L and Zisman W A 1946 Oleophobio monolayers. 1. Films adsorbed from solution in non-polar liquids J. Colloid Interface Scl. 1 513-38  [c.2635]


See pages that mention the term Zusammen : [c.412]    [c.124]    [c.160]    [c.161]    [c.376]    [c.382]    [c.385]    [c.386]    [c.445]    [c.453]    [c.461]    [c.464]    [c.596]    [c.746]    [c.1418]    [c.2995]   
Carey organic chemistry (0) -- [ c.193 , c.194 , c.220 ]

Organic chemistry (0) -- [ c.193 , c.194 , c.220 ]