Tensiometric studies on wetting. I. Some effects of surface roughness (theoretical)

1981 ◽  
Vol 59 (13) ◽  
pp. 1954-1961 ◽  
Author(s):  
Erdal Bayramli ◽  
Theodore G. M. van de Ven ◽  
Stanley G. Mason
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
Solid Surfaces ◽  
Surface Slopes ◽  
Receding Contact ◽  
Receding Contact Angle ◽  
Wetting Hysteresis ◽  
Non Equilibrium ◽  
Roughness Size

The effect of roughness on the wettability of an axisymmetric cylinder is investigated theoretically by making use of equilibrium meniscus shapes on solid surfaces analogously to previous studies for drops on horizontal surfaces. Employing circumferential sinusoidal and saw-toothed grooved structure, and using mechanistic arguments, one can explain wetting hysteresis, the formation of composite surfaces, and the presence of non-equilibrium jumps during contact line motion.On unidirectionally random surfaces the maximum surface slopes mainly determine the value of the advancing, and the minimum slopes of the receding contact angle. These effects of surface slopes diminish with decreasing roughness size. Diminishing roughness size also gives rise to numerous small non-equilibrium jumps imposed upon larger jumps during wetting. The contact angle hysteresis is found to show a nearly linear relationship with the spread in the distribution of solid surface slopes.

The Surface Modification with Fluorocarbon Thin Films for the Prevention of Stiction in Mems

1998 ◽  
Vol 518 ◽  
Author(s):  
Sang-Ho Lee ◽  
Myong-Jong Kwon ◽  
Jin-Goo Park ◽  
Yong-Kweon Kim ◽  
Hyung-Jae Shin
Keyword(s):  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
Contact Angles ◽  
Fluorocarbon Films ◽  
Perfluorodecanoic Acid ◽  
Large Hysteresis ◽  
Static Contact ◽  
Receding Contact ◽  
Highly Hydrophobic ◽  
Receding Contact Angle

AbstractHighly hydrophobic fluorocarbon films were prepared by the vapor phase (VP) deposition method in a vacuum chamber using both liquid (3M's FC40, FC722) and solid sources (perfluorodecanoic acid (CF3(CF2)8COOH), perfluorododecane (C12F26)) on Al, Si and oxide coated wafers. The highest static contact angles of water were measured on films deposited on aluminum substrate. But relatively lower contact angles were obtained on the films on Si and oxide wafers. The advancing and receding contact angle analysis using a captive drop method showed a large contact angle hysteresis (ΔH) on the VP deposited fluorocarbon films. AFM study showed poor film coverage on the surface with large hysteresis. FTIR-ATR analysis positively revealed the stretching band of CF2 groups on the VP deposited substrates. The thermal stability of films was measured at 150°C in air and nitrogen atmospheres as a function of time. The rapid decrease of contact angles was observed on VP deposited FC and PFDA films in air. However, no decrease of contact angle on them was observed in N2.

Measurement Studies on Superhydrophobic Materials

2014 ◽  
Vol 988 ◽  
pp. 134-142
Author(s):  
Sheila Devasahayam ◽  
Prasad Yarlagadda
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Reynolds Number ◽  
Drag Reduction ◽  
Contact Line ◽  
Contact Time ◽  
Contact Angle Hysteresis ◽  
Surface Friction ◽  
Solid Surfaces ◽  
Geometrical Configuration

Superhydrophobicity is directly related to the wettability of the surfaces. Cassie-Baxter state relating to geometrical configuration of solid surfaces is vital to achieving the Superhydrophobicity and to achieve Cassie-Baxter state the following two criteria need to be met: 1) Contact line forces overcome body forces of unsupported droplet weight and 2) The microstructures are tall enough to prevent the liquid that bridges microstructures from touching the base of the microstructures [1]. In this paper we discuss different measurements used to characterise/determine the superhydrophobic surfaces.Keywords: Wettability, contact angle, contact angle hysteresis, contact time, surface roughness, drag reduction measurements, morphology, surface friction, Reynolds number

Contact angle hysteresis on plasma treated polyethylene terephthalate

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Marcela Bachurová ◽  
Jakub Wiener
Keyword(s):  
Contact Angle ◽  
Polyethylene Terephthalate ◽  
Photoelectron Spectroscopy ◽  
Contact Angle Hysteresis ◽  
Surface Wetting ◽  
Time Intervals ◽  
Receding Contact ◽  
Surface Dielectric Barrier Discharge ◽  
Receding Contact Angle ◽  
Modification Of The Surface

AbstractKnowledge of contact angle hysteresis is important to the understanding of surface wettability and to controlling further surface wetting behaviour. The wettability can be affected by surface modification. This study is a look on surfaces modified by the usage of plasma. We describe the effect of plasma treatments on contact angle hysteresis by the use of Diffuse Coplanar Surface Dielectric Barrier Discharge (DCSBD). Modification of the surface was achieved using textile made from polyethylene terephthalate (PET). Results have shown that both advancing and receding contact angle were significantly reduced by the process. The contact angle hysteresis was decreased after the plasma treatment as was observed by measurement taken at various time intervals and this fact correspond with introduction of functional groups detected by X - ray photoelectron spectroscopy (XPS).

Contact Angle Hysteresis – Advantages and Disadvantages: A Critical Review

2020 ◽  
Vol 8 (1) ◽  
pp. 47-67
Author(s):  
Andrew Terhemen Tyowua ◽  
Stephen Gbaoron Yiase
Keyword(s):  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
Theoretical Models ◽  
Contact Angles ◽  
Solid Surfaces ◽  
Advantages And Disadvantages ◽  
Volatile Liquid ◽  
Receding Contact ◽  
Rain Drops ◽  
The Difference

The existence of contact angle hysteresis – the difference between the values of the advancing and receding contact angles – is evident in nature (e.g. sticking of rain drops to car windscreens and window panes) and many industrial processes (e.g. surface coating, spraying, and dyeing of fabrics). This phenomenon is often viewed as a nuisance, but it is advantageous in many processes including dip and spin coating, spraying, and painting. With the early theoretical framework of Thomas Young, Robert Wenzel, and A. B. D. Cassie and S. Baxter, describing the wettability of solid surfaces and by extension contact angle, contact angle hysteresis has been deeply investigated. We review here the various ways of measuring contact angle and, consequently, contact angle hysteresis as well as related theoretical models. The successes and limitations of these models are highlighted. We conclude with the advantages and disadvantages of contact angle hysteresis whose presence in many processes is often considered as a nuisance, especially when "coffee stain" forms from the evaporation of a volatile liquid drop containing nonvolatile components.

The effect of contact line dynamics and drop formation on measured values of receding contact angle at very low capillary numbers

2012 ◽  
Vol 404 ◽  
pp. 63-69 ◽  
Author(s):  
Carmen L. Moraila-Martínez ◽  
Francisco J. Montes Ruiz-Cabello ◽  
Miguel A. Cabrerizo-Vílchez ◽  
Miguel A. Rodríguez-Valverde
Keyword(s):  
Contact Angle ◽  
Contact Line ◽  
Drop Formation ◽  
Receding Contact ◽  
Receding Contact Angle ◽  
Contact Line Dynamics

scholarly journals Effect of Surface Roughness on Contact Angle Hysteresis.

1991 ◽  
Vol 57 (544) ◽  
pp. 4124-4129 ◽  
Author(s):  
Kenji KATOH ◽  
Hideomi FUJITA ◽  
Masayoshi YAMAMOTO
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
Effect Of Surface

Measurement of dynamic/advancing/receding contact angle by video‐enhanced sessile drop tensiometry

1996 ◽  
Vol 67 (8) ◽  
pp. 2852-2858 ◽  
Author(s):  
Shi‐Yow Lin ◽  
Hong‐Chi Chang ◽  
Lung‐Wei Lin ◽  
Pao‐Yao Huang
Keyword(s):  
Contact Angle ◽  
Sessile Drop ◽  
Receding Contact ◽  
Receding Contact Angle
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