Why is it that a wet tissue or piece of cardboard or paper tear more easily? How does water affect the structural integrity of paper products?
In: Chemistry
The fibers that make up those materials are held together by hydrogen bonds. Now don’t let the name mislead you – hydrogen bonds are not actually chemical bonds. Rather, they are intermolecular forces that rely on molecular polarity. Polarity can basically be described by the distribution of electrons that can make a part of a molecule partially positive or partially negative. So the partially positive part of one fiber is attracted to the partially negative part of another, and thus we get a sheet of fibers held together by hydrogen bonds.
Now introduce water. One of the most important properties of water is its polarity, so when you put these often hydrophilic (or water-loving) fibers in the presence of water, the partially charged parts of these fibers will form hydrogen bonds with the water instead. Thus, it takes much less force to actually pull these fibers apart after it has been exposed to water as there are fewer attractions holding the fibers together!
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