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Contact Angle Hysteresis Formula:
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Contact Angle Hysteresis is a reflection of the activation energy required for the movement of a droplet from one metastable state to another on a surface. It represents the difference between advancing and receding contact angles.
The calculator uses the Contact Angle Hysteresis formula:
Where:
Explanation: The formula calculates the difference between the advancing contact angle (formed during wetting) and the receding contact angle (formed during de-wetting), which quantifies the surface heterogeneity and roughness.
Details: Contact Angle Hysteresis is crucial for understanding surface wettability, droplet mobility, and surface characterization. It provides insights into surface energy heterogeneity, chemical heterogeneity, and surface roughness.
Tips: Enter both advancing and receding contact angles in radians. The advancing contact angle should be greater than or equal to the receding contact angle. All values must be positive.
Q1: What causes contact angle hysteresis?
A: Contact angle hysteresis is primarily caused by surface roughness, chemical heterogeneity, surface deformation, and adsorption/desorption processes.
Q2: What are typical values for contact angle hysteresis?
A: Hysteresis values can range from less than 5° on smooth homogeneous surfaces to over 50° on rough or heterogeneous surfaces.
Q3: How is contact angle hysteresis measured experimentally?
A: It is typically measured using tilt plate method, needle method, or by measuring advancing and receding angles separately using syringe methods.
Q4: What does high contact angle hysteresis indicate?
A: High hysteresis indicates strong droplet pinning, meaning the droplet resists movement on the surface, which is characteristic of rough or chemically heterogeneous surfaces.
Q5: Can contact angle hysteresis be negative?
A: No, contact angle hysteresis cannot be negative as the advancing contact angle is always greater than or equal to the receding contact angle.