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Titolo:
PREPARATION AND CHARACTERIZATION OF MONOP ARTICULATE LAYERS COMPOSED OF PARTIALLY HYDROPHOBIC GLASS AND SILICA PARTICLES - A LANGMUIR FILM BALANCE STUDY .1.
Autore:
HORVOLGYI Z; NEMETH S; FENDLER JP;
Indirizzi:
BUDAPEST MUSZAKI EGYET,FIZ KEM TANSZEK,EGRY J U 20-22 H-1518 BUDAPESTHUNGARY SYRACUSE UNIV,DEPT CHEM SYRACUSE NY 13244
Titolo Testata:
Magyar kemiai folyoirat
fascicolo: 11, volume: 101, anno: 1995,
pagine: 488 - 497
SICI:
0025-0155(1995)101:11<488:PACOMA>2.0.ZU;2-W
Fonte:
ISI
Lingua:
HUN
Soggetto:
CAPILLARY INTERACTION; COLLOIDAL PARTICLES; OIL; SURFACE; INTERFACES; FOAM; AGGREGATION; MECHANISM; STABILITY; FORCES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
46
Recensione:
Indirizzi per estratti:
Citazione:
Z. Horvolgyi et al., "PREPARATION AND CHARACTERIZATION OF MONOP ARTICULATE LAYERS COMPOSED OF PARTIALLY HYDROPHOBIC GLASS AND SILICA PARTICLES - A LANGMUIR FILM BALANCE STUDY .1.", Magyar kemiai folyoirat, 101(11), 1995, pp. 488-497

Abstract

Monoparticulate layers of partially hydrophobic (silanized) glass andsilica beads (2R = 75 +/- 5 and 3 +/- 1 mu m, respectively) were studied in Langmuir film balance. Surface pressure vs. surface area isotherms were determined which permitted some conclusions concerning particle-particle (p-p) and particle-subphase (p-s) interactions. 1, Methodswere suggested a, for the determination of the p-p distance in the secondary potential energy minimum as well as the p-p repulsive interaction energy as a function of interparticle distance for weakly cohesivemonoparticulate layers and b, for the approximation of p-p adhesion energy for (strongly) cohesive monoparticulate layers. Interparticle distances between particles of weakly cohesive monoparticulate layers intheir secondary interaction energy minimum have been assessed to be 490 nm by method a,. This distance is in fair agreement with that calculated by the DLVO theory, augmented by capillary interaction. However,the calculated total (repulsive) interaction energies (E(rep) = (0,5 - 1,3)10(-13) J) between these particles are some two orders of magnitude greater than expected (10(-16) - 10(-15) J). This discrepancy is not completely understood at present. The particle-particle adhesion energies for the strongly cohesive layers of the most hydrophobic particles (Theta = 90 degrees, 2R = 75 mu m and 3 mu m) were approximated bymethod b,. They were in good agreement with each other (85 - 100 mJm(-2) for the larger and 111-133 mJm(-2) for the smaller particles, respectively) and with the ''pull-off'' energy obtained earlier for silanized glass surfaces (41). 2, The p-s interaction was examined by comparing the energy which is necessary for particle removal from the monoparticulate layer, E(r), determined via II vs. A isotherms, with the adhesion work, W-r, determined by in situ contact angle measurements. Satisfactory agreement between E(r) and W-r was obtained for the monoparticulate layers which were prepared from the more hydrophobic particles(Theta = 90 degrees, 2R = 75 mu m and 2R = 3 mu m). Significant discrepancies between E(r) and W-r for the monoparticulate layers which were prepared from the less hydrophobic (Theta = 72 degrees and Theta = 55 degrees) particles were interpreted in terms of contact angle hysteresis, dynamic wetting, and distortion of the electric double layer around the interfacial particles.

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Documento generato il 29/11/20 alle ore 05:00:07