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Glue Ball Chemistry
Making Rubber from Glue
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What is a Polymer?
Polymers are very large molecules made of a
chain of many smaller molecules bonded together.
The prefix “poly” means many.
The small molecules that are used to create
polymers are called monomers. The prefix
“mono” means one.
Most polymers are made of organic compounds
that contain the elements carbon and hydrogen,
but may also include other elements like oxygen
and nitrogen.
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How are Polymers made?
Polymers form when chemical bonds link large numbers
of monomers together in a repeating pattern.
Think of polymers like chains of many paper clips connected
together. This is why chemists often call them “polymer
chains.” Each paper clip would represent a monomer molecule.
When two different monomers combine, they form a copolymer
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What is Elmer’s Glue?
Elmer’s glue is a mixture of a polymer called
polyvinyl acetate and water.
The long “chains” of the polymer can slide past
each resulting in a viscous liquid.
Below is a picture of the chemical structure of a small
section of the polyvinyl acetate chain:
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How does the glue become rubber?

Step 1
When Borax, also known as Sodium Perborate
(Na2B4O7), dissolves in water, borate ions are
formed in 2 successive reactions:
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How does the glue become rubber?

Step 2
The borate ions react with the polyvinyl acetate to
form polyvinyl alcohol.
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How does the glue become rubber?

Step 3
The borate ions combine with the polyvinyl
alcohol chains to link them together in cross-links.
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Why does the glue become rubber?
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The Experiment
1. Make a saturated solution of Borax in water.
2. Measure 5 ml of water in a cup, place a mark
on
the cup at the 5 ml level, and discard the water.
3. Pour Elmer’s white glue into the cup until it
reaches the 5 ml mark you made in step 1.
4. Pour 20 ml of the Borax solution into the cup
containing the glue-water mixture and stir.
5. After the material becomes like rubber, scrape it out
and form it into a ball, squeezing out the excess
liquid into a wastebasket.
The liquid glue has been transformed into
a rubber ball by polymer cross-linking.
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