Gluep
In this science experiment we will make Gluep.  Plastics are all around us. Plastics are made of
polymers or tiny chains of molecules. There are many different kinds, with a wide range of properties.
Some are hard, others are soft. Some are transparent, others are opaque. Most plastics are made in
factories, but here’s one you can make at home. We will try to answer the question as to whether
Gluep is a solid or liquid.

Materials

1 teaspoon (5 cm3) laundry borax
1 tablespoon (15 mL) white glue (e.g., Elmer's Glue-All)
food coloring (optional)
two cups
spoon
water


Process to Make Gluep! Solid or Liquid
In one of the cups, dissolve 1 teaspoon of laundry borax in 5 tablespoons (75 mL) of water. You will
need to stir this for a while to get it to dissolve. (If a tiny bit does not dissolve, that is OK.)

In the other cup, combine 1 tablespoon of water and 1 tablespoon of white glue. If you wish, you may
color the mixture with a couple drops of food coloring. With a clean spoon, stir the mixture thoroughly
until it is uniform.

Put 2 teaspoons of the borax solution from the first cup into the glue mixture in the second cup. Stir
the mixture.

As you stir the mixture, it will stiffen into a soft lump. After the lump has formed, take it from the cup
and knead it in your hand for a couple minutes.

The material you have made is called Gluep, and it is ready for you to examine.

Roll the Gluep into a ball and then let it rest. Does the ball maintain its shape?

Drop a Gluep ball onto a table top. What does the ball do?

Flatten the Gluep into a thin strip. Hold up the strip by one end. What happens to the strip?

Roll the Gluep into a cylinder and pull the ends slowly. What happens to the cylinder?

Roll the Gluep into a cylinder and pull the ends quickly. What happens to the cylinder?

The Science Behind Make Gluep! Solid or Liquid

The materials we call plastics are all composed of large molecules whose structure is like a chain.
These molecules are composed of many small repeating units, like the links in a chain. Like a chain,
the molecules of a polymer are long and narrow. The name plastic is applied to a wide variety of
substances, some of them soft and others very hard. Originally, plastic referred to something
shapeable or bendable. However, as new polymer materials were made that were hard and stiff, the
name plastic was applied to them, too.

White glue is a mixture of water with a polymer. The polymer molecules are shaped like very tiny
pieces of spaghetti. The tangled molecules make glue thick and viscous rather than thin and runny.
When glue is exposed to air, the water evaporates, leaving the tangled polymer molecules. The
tangled molecules stick to the surfaces on which they dried, and hold the surfaces together.

Borax solution contains borate ions. These ions can form links between the long, thin polymer
molecules in the glue, turning it into a 3-dimensional network. This network makes Gluep more like a
solid than the plain liquid glue. The network holds its shape for a short time, and as long as it is not
strained. When Gluep rests, the flexible network gradually relaxes, and the Gluep flattens. When
Gluep is stretched quickly, the links between molecules break, and the Gluep snaps apart into pieces.

The polymer molecules in white glue are called polyvinyl acetate. These molecules are composed of
long chains of carbon atoms, with an acetate group attached to every other one. Acetate comes from
acetic acid, the compound that gives vinegar its odor and flavor. This is why white glue smells a bit
like vinegar. When borax is mixed with white glue, each borax ion replaces two acetate groups,
forming a borate link between two polymer molecules.

Gluep contains a lot of water trapped in the network of linked polymer molecules. This water
contributes to the liquid-like properties to Gluep. If the Gluep is left exposed to open air, the water will
evaporate, and the Gluep will gradually stiffen. To preserve the Gluep, store it in an air-tight plastic
bag.

A material similar to Gluep can be made using a gel glue in place of white glue. Fluid gel glue
contains polyvinyl alcohol in place of polyvinyl acetate. Borate ions form links between these
molecules, too. In this case, the alcohol groups are displaced, forming water.

Now go and make a batch of solid or liquid gluep!

Experiment from:
http://scifun.chem.wisc.edu/HomeExpts/HOMEEXPTS.HTML
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