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The effect of pre‐wetting on dynamic contact angles
Author(s) -
Ghannam M. T.,
Esmail M. N.
Publication year - 1992
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450700231
Subject(s) - wetting , contact angle , materials science , dimensionless quantity , coating , entrainment (biomusicology) , composite material , displacement (psychology) , mechanics , physics , acoustics , rhythm , psychotherapist , psychology
A roll‐coating experimental system is used to study the effect of pre‐wetting on dynamic contact angles, the interfacial displacement depth, and the associated phenomenon of air entrainment. The system consists of a roll, which is horizontally rotating in a liquid pool. The dynamic contact angle is recorded by a macrophotography system. The test liquids are glycerol solutions with viscosities in the range 104 < μ < 748 mPa · s. The value of (μV/ρg) 0.5 is taken as the characteristic length to be used in the dimensionless relationships which correlate experimental measurements. The effect of base layer entry angle into the liquid pool on the dynamic contact angles and other flow parameters is studied. Comparison is made with measurements in dry tape‐coating and other pre‐wet roll–coating systems.