Velocity influences contact angle

For high surfactant concentrations ( 5%) the yield is almost stable and remains well above 95% for velocities ranging from 0 to 80 pm.s . Same observations can be done down to 5% of surfactant concentration. When reaching this limit, the yield is not stable anymore in the 0-80 pm.s velocity range. At low speed (t3 ically below 30 pm.s ), no deposition is observed, meaning that the assembly mechanism is ineffective, when increasing the value above 30 pm.s , the yield jumps suddenly above 95% and remains 

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Wetting (velocity at impact can influence the advancing contact angle formed between the tablet surface and the droplet and the degree to which the droplet spreads immediately after contact) and, ultimately, film adhesion... 

The work of Elliott and Riddiford has been frequently cited as evidence that the dynamic contact angle is influenced by the molecular state of the liquid at the three-phase boundary. They report, for example, that at very low velocities the dynamic contact angle is equal to the equilibrium contact angle (0 = 0 ) but that at some critical rate the dynamic angle begins to increase with velocity. They suggest that when 0d = 0,. the rate of advance is slow compared to the relaxation time of the molecules to assume the equilibrium configuration. At a certain critical velocity the rate at which the liquid molecules advance exceeds this relaxation time. 

In these experiments, contact angles were measured at a constant substrate velodly of 1 om.s . No significant influence of the velocity on the contact angle could be range. 

Abstract We study the dynamics of two phospholipid monolayers brought into contact by oblique drop impact on a liquid surface and bilayer/multilayer formation. Drop impact without monolayers shows that for low impact angles (a < 23°) and low drop velocities the drop spreads as a thin sheet on the target liquid without immersion and mixing of the two liquids. When drop and target liquid surface are covered with monolayers, bilayer/multilayer formation is expected. The composition and mechanical properties of the monolayers can strongly influence the pattern of drop impact and bilayer/multilayer formation. Monolayers with either pure satu-... 

Due to the facts, that the parameter y is constant and is independent of the normal stress o during every point of shearing, the vibrations reduce the shear stress t for each applied normal stress a by the same amount. Therefore, the yield loci are parallel lines shifted towards smaller shear stresses, see Fig, 7. Thus, the angle of internal friction cpi is not influenced by the vibration velocity. It amounts to (pi = 34° 1° unvibrated and cpi 34° 2° vibrated for the limestone powder. That means a more or less constant Coulomb friction at particle contacts. But the unconfined yield strength ac is strongly reduced due to the vibrations, see Fig. 8. The unconfined yield strength can be approached as a function of the angle of internal friction cp, and the cohesion Xc by Eq. (6) [6] ... 

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