Experimental Investigation of the Link between Static and Dynamic Wetting by Forced Wetting of Nylon Filament

Abstract

Forced wetting experiments with various liquids were conducted to study the dynamic wetting properties of nylon filament. The molecular-kinetic theory of wetting (MKT) was used to interpret the dynamic contact angle data and evaluate the contact-line friction zeta0 at the microscopic scale. By taking account of the viscosity of the liquid, zeta0 could be related exponentially to the reversible work of adhesion. This clearly establishes an experimental link between the static and dynamic wetting properties of the material. Moreover, statistical analysis of the equilibrium molecular displacement frequency K0 and the length of the displacements lambda reveals that these two fundamental parameters of the MKT are strongly correlated, not only in the linearized form of the theory (valid close to equilibrium) but also when the nonlinear form of the equations has to be considered at higher wetting speeds.

Dissipation mechanisms in ionic liquids

“…(5)- (7). We find that, for both ionic liquids, k $ 0.9 nm and K 0 $ 0.1-0.7 MHz (Table 1), in reasonable agreement with other work [42,43].…”

“…A number of experiments have tested the validity of Eq. (6) [42,43] where various authors have found realistic molecular scale values for K 0 and k [42,43], while others, have observed systems where the model fails or returns unrealistic values for K 0 and k [37,44,45]. Recently, Rolley and Guthmann [46] have suggested that contact line motion in the molecular kinetic model is more related to pinning/depinning of the contact line on mesoscopic defects, rather than thermally activated adsorption/desorption events as in the original molecular kinetic theory.…”

Contact line stick-slip motion and meniscus evolution on micrometer-size wavy fibres

“…A more accurate approach is to use a mathematical model with a sound physical description of the shape of the meniscus [2,18,19]. In static and quasi-static conditions, the liquid/vapour interface is well described by the Young-Laplace equation [20][21][22].…”

On the microscopic parameters at a moving contact line during wetting process

“…Finally, a curve-fitting by equation 7for V CL versus θ d gives measured values for the microscopic displacement frequency and length. The details of the experimental setup and procedure have been described in literature (De Ruijter and De Coninck, 1997;Phan et al, 2006;Bayer and Megaridis, 2006;Vega et al, 2007;Ray et al, 2008). Blake and De Coninck (2002) approximated the microscopic displacement frequency in a wetting process as:…”

“…The advancing angle is the largest contact angle observed before the wetting line begins to move in the direction of the vapour phase (also known as the wetting process) and the receding angle is the smallest contact angle achievable (also known as the dewetting process) before the wetting line begins to move in the direction of the liquid phase (Šikalo et al, 2005b). Extensive experimental studies on the wetting phenomenon are available in the literature (Foister, 1990;De Ruijter et al, 2000;Petrov et al, 2003aPetrov et al, , 2003bRoux and Cooper-White, 2004;Šikalo et al, 2005a;Bayer and Megaridis, 2006;Xiaodong et al, 2007;Petrov and Petrov, 1992a;Hayes and Ralston, 1993;Schneemilch et al,1998;Drelich et al, 2002;Phan et al, 2003Phan et al, , 2006Ranabothu et al, 2005;Vega et al, 2007). One of the main objectives intended in these experiments has been to understand the phenomena occurring in the vicinity of the moving three-phase contact line (Foister, 1990;Petrov et al, 2003a;Bayer and Megaridis, 2006;Vega et al, 2007).…”