There is no easy way to determine changes in surface energy on non-woven and woven substrates and we know of no official standards such as an ASTM method but there is a procedure.
There are several methods to characterize the surface energy of nonwovens fibers. Of these, contact angle is the most readily applied. One of the contact angle methodologies used in the industry is the following:
- Attach untreated and treated sections of your nonwoven material side-by-side to a surface, such as a clipboard, that can be inclined.
- Lay the surface on a horizontal/flat surface.
- Deposit a single drop of water to the top side of each material.
- Holding the base of the incline surface static, slowly raise the top side of the incline surface in 10 degree increments. Observe the water drop’s position on each surface.
In general, a water droplet which “runs” to the base of the incline surface at a low incline angle indicates that the material has a low surface tension. Water droplets which do not run at low angles indicate the material has a high surface energy.
We have also used a method where a drop of colored wetting tension solution is applied to an untreated non-woven. After waiting two seconds, measure the diameter of wet spot. Repeat the procedure with the treated sample and compare the two. The treated sample should have a larger diameter.
|