摘要:

The surface tension components and parameters for nine naturally occurring colloidal-sized volcanic ash samples were determined by thin-layer wicking. These materials include rhyolites, trachytes, phonolites, and an andesite, and were collected from deposits in California, Arizona, Italy and Martinique. The samples are principally volcanic glass (with minor amounts of mixed materials of various compositions) with silica contents ranging (average values)from 74%(rhyolite) to 57% (andesite). The surface tension components were determined by means of thin-layer wicking to provide contact angles which were used to solve the Young-Dupré equation. The Lifshitz-van der Waals component of the surface tension, γLWLWLWfor these ash samples varies between 26.6 mj/2and 38.7 mj/m2The Lewis acid parameter γ⌖ values are small with values ranging from 0 mJ/m2to 1.8 mJ/m2, while the Lewis base parameter, values varied between 15.6 mJ/m2and 45.6 mJ/m2Of the nine samples, five were hydrophobic and the other four were hy-drophilic. The hydrophobic ashes were produced by eruptions with a dominantly

ISSN:0193-2691    

DOI:10.1080/01932699708943732

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Dispersion characteristics of the monomolecular films of hematoporphyrin mixed with stearic acid has been studied. The average molecular areas of mixed monolayers coincided approximately with the ideal additivity rule when the“solid” films were extrapolated to zero surface pressure. The orientation of the macrocycles was given by infrared dichroism with the tilting angle of 10. 1° to the plane of the film. The SERS of LB films deposited on silver island films was observed- The results showed that there are two possible contribution, i. e., electromagnetic and chemical interaction between the hematoporphyrin molecules and Ag island films.

ISSN:0193-2691    

DOI:10.1080/01932699708943733

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Adsorption of sodium polystyrene sulphonate (PSSNa)and cetyltrimethylammonium bromide (CTAB) on TiO2in aqueous dispersion has been investigated. Correlation between adsorption isotherms, zeta potential and stability measurements has shown that interactions between PSSNa and CTAB influence strongly the stability of the dispersions.

ISSN:0193-2691    

DOI:10.1080/01932699708943734

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Since geometry has been shown to play a significant part in the behavior of emulsions, a series of calculations have been made to determine the increase in area of a spherical drop when it is deformed into an oblate or prolate spheroid. The results may be of use in designing dispersion machinery

ISSN:0193-2691    

DOI:10.1080/01932699708943735

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The effect of dispersant concentration on the rheological behavior of suspensions of Sub-micron aluminum oxide particles in either water or dodecane was studied using a double concentric cylinder rheometer. In the electrosterically stabilized aqueous system, the suspensions underwent a sharp transition from coagulated to dispersed as the concentration of the dispersant, ammonium poly(methacrylate)l, was increased. In the sterically stabilized dodecane system, as the concentration of the dispersant, 12-hydroxy stearic acid ester, was increased, the initially coagulated suspensions became highly thtxotropic at concentrations less than that needed for stability. The difference in behavior between these two systems is caused by the way that the interparticle forces are affected by the concentration of dispersant for the two types of stabilization mechanisms. The technique of inducing thixotropy by control of the dispersant concentration has certain advantages including wide applicability and not requiring special additives.

ISSN:0193-2691    

DOI:10.1080/01932699708943736

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A comparative study of the chemically induced dynamic electron polarization (CIDEP)spectra has been made experimentally with the time resolved ESR spectrometer for the photolyzed p-benzosemiquinone radicals (PBQH)in ethylene glycol and Triton X-100 (TX-100)micelle solutions.The polarization of PBQH'is mainly the triplet mechanism (TM) of origin and at times also is involves some radical pair mechanism (RPM)in TX-100 micelle solution, the effect of RPM increases, but there is not the same effect in homogeneous ethylene glycol (EG) solution; thus the influence of micelle microenviroment on transient behavior of radicals is shown. The polarization transference mechanism is discussed to explain these experimental results.

ISSN:0193-2691    

DOI:10.1080/01932699708943737

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:0193-2691    

DOI:10.1080/01932699708943739

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor