Measuring advancing contact angle

[Experience111]

Hi everyone !

I'm currently working on a project for which I need to measure the advancing contact angle of a liquid on a solid, specifically the advancing contact angle of a molten thermoplastic on carbon fibers.

My understanding is that there is a difference between dynamic contact angles and contact angles at rest. I know of two methods to measure the dynamic contact angles : the dynamic sessile drop method and the modified dynamic Wilhelmy method.

However, these two methods look like they measure something different to me : in the sessile drop method the liquid is advancing (or receding) on the solid, and in the Wilhelmy method, the solid (fiber in my case) is advancing or receding into the liquid.

So my question to you is : is what we call the advancing contact angle measured using these two methods the same ? Or is the advancing contact angle different depending on if the solid is moving into the liquid or the liquid on the solid ?

Thanks for your answers !

NB : Not sure if I should have posted this in Classical Physics instead of General Physics, let me know if I did something wrong !

 

[Andy Resnick]

However, these two methods look like they measure something different to me : in the sessile drop method the liquid is advancing (or receding) on the solid, and in the Wilhelmy method, the solid (fiber in my case) is advancing or receding into the liquid.

Given that the capillary number for these measurements is very low, why do you think it matters?