What makes a diaper absorbent?

Answer 1

Most diapers make use of a property called 'adhesion'. Water molecules like to be in contact with a variety of substances. If you fill a glass half-full of water, you can see this by looking closely where the water meets the glass... it doesn't lie flat, but sort of crawls up the side a little bit.

This is also how towels work. Towels are fuzzy. This gives them a huge surface area - every side of every little fiber is a place for a water molecule to stick. So if you rub a towel against your wet skin, your skin will lose a lot of water to the towel. A cloth diaper might be thought of as just a kind of small towel... though usually they rely on just the natural weave of the threads in the fabric instead of creating a huge surface area (there's no need for a diaper to hold THAT much!).

Modern diapers tend to rely on chemicals that water sticks to much better than fabrics and glass. A common one is 'hydrogel', which can absorb something like a hundred times its weight in water. This requires a more sophisticated design, to keep the hyrdrogel contained and wick fluids to it, but not let it come directly into contact with skin. But it's still the same general thing happening.

Hope that helps!

Answer 2

chemcial absorbancy stuff