The Experts below are selected from a list of 2046 Experts worldwide ranked by ideXlab platform
Jacob N. Israelachvili - One of the best experts on this subject based on the ideXlab platform.
-
Contact Angle and Adhesion Dynamics and Hysteresis on Molecularly Smooth Chemically Homogeneous Surfaces
2017Co-Authors: Szu-ying Chen, Yair Kaufman, Alex M. Schrader, Dongjin Seo, Dong Woog Lee, Steven H. Page, Peter H. Koenig, Sandra Isaacs, Yonas Gizaw, Jacob N. IsraelachviliAbstract:Measuring truly equilibrium Adhesion energies or contact angles to obtain the thermodynamic values is experimentally difficult because it requires loading/unloading or advancing/receding boundaries to be measured at rates that can be slower than 1 nm/s. We have measured advancing–receding contact angles and loading–unloading Adhesion energies for various systems and geometries involving molecularly smooth and chemically homogeneous surfaces moving at different but steady velocities in both directions, ±V, focusing on the thermodynamic limit of ±V → 0. We have used the Bell Theory (1978) to derive expressions for the dynamic (velocity-dependent) Adhesion energies and contact angles suitable for both (i) dynamic Adhesion measurements using the classic Johnson–Kendall–Roberts (JKR, 1971) theory of “contact mechanics” and (ii) dynamic contact angle hysteresis measurements of both rolling droplets and syringe-controlled (sessile) droplets on various surfaces. We present our results for systems that exhibited both steady and varying velocities from V ≈ 10 mm/s to 1 nm/s, where in all cases but one, the advancing (V > 0) and receding (V < 0) Adhesion energies and/or contact angles converged toward the same theoretical (thermodynamic) values as V → 0. Our equations for the dynamic contact angles are similar to the classic equations of Blake & Haynes (1969) and fitted the experimental Adhesion data equally well over the range of velocities studied, although with somewhat different fitting parameters for the characteristic molecular length/dimension or area and characteristic bond formation/rupture lifetime or velocity. Our theoretical and experimental methods and results unify previous kinetic Theories of Adhesion and contact angle hysteresis and offer new experimental methods for testing kinetic models in the thermodynamic, quasi-static, limit. Our analyses are limited to kinetic effects only, and we conclude that hydrodynamic, i.e., viscous, and inertial effects do not play a role at the interfacial velocities of our experiments, i.e., V < (1–10) mm/s (for water and hexadecane, but for viscous polymers it may be different), consistent with previously reported studies
Israelachvili, Jacob N. - One of the best experts on this subject based on the ideXlab platform.
-
Contact Angle and Adhesion Dynamics and Hysteresis on Molecularly Smooth Chemically Homogeneous Surfaces
'American Chemical Society (ACS)', 2017Co-Authors: Chen Szu-ying, Kaufman Yair, Schrader, Alex M., Seo Dongjin, Lee, Dong Woog, Page, Steven H., Koenig, Peter H., Isaacs Sandra, Gizaw Yonas, Israelachvili, Jacob N.Abstract:Measuring truly equilibrium Adhesion energies or contact angles to obtain the thermodynamic values is experimentally difficult because it requires loading/unloading or advancing/receding boundaries to be measured at rates that can be slower than 1 run/s. We have measured advancing receding contact angles and loading unloading Adhesion energies for various systems and geometries involving molecularly smooth and chemically homogeneous surfaces moving at different but steady velocities in both directions, +/- V, focusing on the thermodynamic limit of +/- V -> 0. We have used the Bell Theory (1978) to derive expressions for the dynamic (velocity-dependent) Adhesion energies and contact angles suitable for both (i) dynamic Adhesion measurements using the classic Johnson Kendall Roberts (JKR, 1971) theory of "contact mechanics" and (ii) dynamic contact angle hysteresis measurements of both rolling droplets and syringe-controlled (sessile) droplets on various surfaces. We present our results for systems that exhibited both steady and varying velocities from V approximate to 10 mm/s to 1 nm/s, where in all cases but one, the advancing (V > 0) and receding (V < 0) Adhesion energies and/or contact angles converged toward the same theoretical (thermodynamic) values as V -> 0. Our equations for the dynamic contact angles are similar to the classic equations of Blake & Haynes (1969) and fitted the experimental Adhesion data equally well over the range of velocities studied, although with somewhat different fitting parameters for the characteristic molecular length/dimension or area and characteristic bond formation/rupture lifetime or velocity. Our theoretical and experimental methods and results unify previous kinetic Theories of Adhesion and contact angle hysteresis and offer new experimental methods for testing kinetic models in the thermodynamic, quasi-static, limit. Our analyses are limited to kinetic effects only, and we conclude that hydrodynamic, i.e., -viscous, and inertial effects do not play a role at the interfacial velocities of our experiments, i.e., V< (1-10) mm/s (for water and hexadecane, but for viscous polymers it may be different), consistent with previously reported studies
Szu-ying Chen - One of the best experts on this subject based on the ideXlab platform.
-
Contact Angle and Adhesion Dynamics and Hysteresis on Molecularly Smooth Chemically Homogeneous Surfaces
2017Co-Authors: Szu-ying Chen, Yair Kaufman, Alex M. Schrader, Dongjin Seo, Dong Woog Lee, Steven H. Page, Peter H. Koenig, Sandra Isaacs, Yonas Gizaw, Jacob N. IsraelachviliAbstract:Measuring truly equilibrium Adhesion energies or contact angles to obtain the thermodynamic values is experimentally difficult because it requires loading/unloading or advancing/receding boundaries to be measured at rates that can be slower than 1 nm/s. We have measured advancing–receding contact angles and loading–unloading Adhesion energies for various systems and geometries involving molecularly smooth and chemically homogeneous surfaces moving at different but steady velocities in both directions, ±V, focusing on the thermodynamic limit of ±V → 0. We have used the Bell Theory (1978) to derive expressions for the dynamic (velocity-dependent) Adhesion energies and contact angles suitable for both (i) dynamic Adhesion measurements using the classic Johnson–Kendall–Roberts (JKR, 1971) theory of “contact mechanics” and (ii) dynamic contact angle hysteresis measurements of both rolling droplets and syringe-controlled (sessile) droplets on various surfaces. We present our results for systems that exhibited both steady and varying velocities from V ≈ 10 mm/s to 1 nm/s, where in all cases but one, the advancing (V > 0) and receding (V < 0) Adhesion energies and/or contact angles converged toward the same theoretical (thermodynamic) values as V → 0. Our equations for the dynamic contact angles are similar to the classic equations of Blake & Haynes (1969) and fitted the experimental Adhesion data equally well over the range of velocities studied, although with somewhat different fitting parameters for the characteristic molecular length/dimension or area and characteristic bond formation/rupture lifetime or velocity. Our theoretical and experimental methods and results unify previous kinetic Theories of Adhesion and contact angle hysteresis and offer new experimental methods for testing kinetic models in the thermodynamic, quasi-static, limit. Our analyses are limited to kinetic effects only, and we conclude that hydrodynamic, i.e., viscous, and inertial effects do not play a role at the interfacial velocities of our experiments, i.e., V < (1–10) mm/s (for water and hexadecane, but for viscous polymers it may be different), consistent with previously reported studies
Chen Szu-ying - One of the best experts on this subject based on the ideXlab platform.
-
Contact Angle and Adhesion Dynamics and Hysteresis on Molecularly Smooth Chemically Homogeneous Surfaces
'American Chemical Society (ACS)', 2017Co-Authors: Chen Szu-ying, Kaufman Yair, Schrader, Alex M., Seo Dongjin, Lee, Dong Woog, Page, Steven H., Koenig, Peter H., Isaacs Sandra, Gizaw Yonas, Israelachvili, Jacob N.Abstract:Measuring truly equilibrium Adhesion energies or contact angles to obtain the thermodynamic values is experimentally difficult because it requires loading/unloading or advancing/receding boundaries to be measured at rates that can be slower than 1 run/s. We have measured advancing receding contact angles and loading unloading Adhesion energies for various systems and geometries involving molecularly smooth and chemically homogeneous surfaces moving at different but steady velocities in both directions, +/- V, focusing on the thermodynamic limit of +/- V -> 0. We have used the Bell Theory (1978) to derive expressions for the dynamic (velocity-dependent) Adhesion energies and contact angles suitable for both (i) dynamic Adhesion measurements using the classic Johnson Kendall Roberts (JKR, 1971) theory of "contact mechanics" and (ii) dynamic contact angle hysteresis measurements of both rolling droplets and syringe-controlled (sessile) droplets on various surfaces. We present our results for systems that exhibited both steady and varying velocities from V approximate to 10 mm/s to 1 nm/s, where in all cases but one, the advancing (V > 0) and receding (V < 0) Adhesion energies and/or contact angles converged toward the same theoretical (thermodynamic) values as V -> 0. Our equations for the dynamic contact angles are similar to the classic equations of Blake & Haynes (1969) and fitted the experimental Adhesion data equally well over the range of velocities studied, although with somewhat different fitting parameters for the characteristic molecular length/dimension or area and characteristic bond formation/rupture lifetime or velocity. Our theoretical and experimental methods and results unify previous kinetic Theories of Adhesion and contact angle hysteresis and offer new experimental methods for testing kinetic models in the thermodynamic, quasi-static, limit. Our analyses are limited to kinetic effects only, and we conclude that hydrodynamic, i.e., -viscous, and inertial effects do not play a role at the interfacial velocities of our experiments, i.e., V< (1-10) mm/s (for water and hexadecane, but for viscous polymers it may be different), consistent with previously reported studies
John L Parker - One of the best experts on this subject based on the ideXlab platform.
-
deformation and Adhesion of elastic bodies in contact
Physical Review A, 1992Co-Authors: Phil Attard, John L ParkerAbstract:The elastic deformation and Adhesion of two convex bodies that interact via surface forces of finite range are calculated self-consistently. Hertz theory is compared to the result of an exponential repulsion, and it is found to be valid in the limit of short-ranged forces and high loads. A Lennard-Jones law is used to examine the classical Theories of Adhesion, which relate the surface energy to the pull-off force, and their regime of validity is explored. Explicit expressions are given for the displacement prior to contact, and for the jump instabilities due to elastic deformation, which occur for compliant bodies with rapidly changing surface forces. The loading-unloading cycle is shown to be hysteretic for large Adhesions, and this is correlated with the onset of jumps. In these cases the pull-off force is demonstrated to depend upon the history of the sample, and it increases with increasing maximum applied loads.