The effect of drop size on contact angle over a wide range of drop volumes

Journal Article · Mon Feb 01 04:00:00 EST 1993 · Journal of Colloid and Interface Science; (United States)

DOI:https://doi.org/10.1006/jcis.1993.1050· OSTI ID:6131780

Drelich, J; Miller, J; Hupka, J ^[1]

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1. Univ. of Utah, Salt Lake City (United States)

Contact angle measurements for the air/water/polyethylene and for the oil/water/quartz systems have been carried out over a wide range of drop (bubble) sizes, from 60[mu]m to 2 mm. Two distinctly different experimental techniques were used: placement of the drop (bubble) with a microsyringe, the static technique, and collision of the drop (bubble) with the surface due to the buoyant force, the dynamic technique. A nonlinear relationship between the cosine of the contact angle measured through the aqueous phase (cos [theta]) and the reciprocal radius of the drop base (1/r) was obtained. The lack of linearity for this range of drop sizes cannot be attributed to a variation in line tension which should be constant. Nevertheless, a pseudo line tension can be calculated and it was found that negative pseudo line tensions on the order of [minus] 1 x 10 [sup [minus]8] N ([minus] 1 .2 x 10 [sup [minus]8] to [minus]6.6 x 10[sup [minus]6] N) were obtained for small drops or bubbles (drop volume less than 0.1 [mu]l, drop base diameter less than 0.3 to 0.4 mm). The pseudo line tensions increased when the drop (bubble) volume increased above 0.1[mu]l, reaching a maximum of about [minus]1 X 10 [sup [minus]6] N ([minus].6 x 10 [sup [minus]6] to [minus]10 [sup [minus]6] N). Thus, it was found that the contact angle for small drops (bubbles) changes significantly from that measured for large drops (bubbles) which may be an important fundamental aspect in certain phase separation phenomena.

• DOE Contract Number: FC21-89MC26268
• OSTI ID: 6131780
• Journal Information: Journal of Colloid and Interface Science; (United States), Journal Name: Journal of Colloid and Interface Science; (United States) Vol. 155:2; ISSN 0021-9797; ISSN JCISA5
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
AIR
BUBBLES
DROPLETS
FLUIDS
GASES
HYDROGEN COMPOUNDS
INCIDENCE ANGLE
MATHEMATICAL MODELS
MEASURING METHODS
MINERALS
OILS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
OTHER ORGANIC COMPOUNDS
OXIDE MINERALS
OXYGEN COMPOUNDS
PARTICLES
POLYETHYLENES
POLYMERS
POLYOLEFINS
QUARTZ
SEPARATION PROCESSES
SIZE
WATER
WETTABILITY