Speaker 1: Welcome to Brainstuff from house stuff works dot com, where
Speaker 1: smart happens him marshial brain with today's question, why is
Speaker 1: cotton more absorbent than nylon? The answer lies in the
Speaker 1: basic but remarkable molecular structure of cotton, nylon, and water.
Speaker 1: The simple water molecule, with its one oxygen atom attached
Speaker 1: to two hydrogen atoms, causes a different action when it
Speaker 1: comes in contact with the complex molecules that make up
Speaker 1: cotton and nylon. Water has a sticky quality that comes
Speaker 1: from its molecular structure. The oxygen atom attracts electrons, giving
Speaker 1: it a slightly negative charge. The two hydrogen atoms have
Speaker 1: a slightly positive charge. The positive and negative ends make
Speaker 1: the water molecule a little like a magnet or dipole,
Speaker 1: which keeps water molecules together and makes the surface of
Speaker 1: a drop of water slightly a last stick It also
Speaker 1: means that water molecules will bond easily with molecules with
Speaker 1: an opposite charge that come nearby. Cotton and nylon are
Speaker 1: both made up of giant polymer molecules. Polymer molecules are
Speaker 1: often long chains of atoms linked in repeating patterns. There
Speaker 1: are a lot of atoms bonded to one another in
Speaker 1: these molecules, giving a lot of places where sticky water
Speaker 1: molecules can find a place to bond. Cotton is pure cellulose,
Speaker 1: so naturally occurring polymer. Cellulose is a carbohydrate, and the
Speaker 1: molecule is a long chain of glucose or sugar molecules.
Speaker 1: If you look at the structure of a cellulose molecule,
Speaker 1: you can see the oh groups that are on the
Speaker 1: outer edge. These negatively charged groups attract water molecules and
Speaker 1: make cellulose and cotton absorb water well. Cotton can absorb
Speaker 1: about twenty five times its weight and water. Chemists refer
Speaker 1: to substances like cotton as hydrophilic, which means that they
Speaker 1: attract water molecules. Nylon is a synthetic material, meaning that
Speaker 1: chemists create the polymer molecules that make up nylon. More
Speaker 1: than one hundred repeating units of carbon, oxygen, hydrogen, and
Speaker 1: nitrogen atoms make up the long chain nylon molecule. The
Speaker 1: strength of the long nylon molecule made it a great
Speaker 1: replacement for silk, which had a similar fuel and texture.
Speaker 1: The nylon molecule two has a great number of places
Speaker 1: where it can form bonds with water molecules, but not
Speaker 1: nearly as many places as the cotton molecule. Nylon absorbs water,
Speaker 1: but not nearly as much as cotton. It only absorbs
Speaker 1: about ten percent of its weight and water. There are
Speaker 1: a couple of other things about cotton towels and nylon
Speaker 1: jackets that help them to do what they are supposed
Speaker 1: to do. Terry cloth, the Fabrican towels has lots of
Speaker 1: loops on its surface that gives more places for the
Speaker 1: cotton and water to come into contact. To extile, makers
Speaker 1: add resins and other water repellent chemicals to nylon so
Speaker 1: that the water drops will run off rather than being
Speaker 1: absorbed into the fabric. Be sure to check out our
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