Gluep Solid or Liquid?
Plastics are all around us. 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.
For this experiment you will need:
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
Here's what to do:
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 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.
Experiment from:
http://scifun.chem.wisc.edu/HomeExpts/HOMEEXPTS.HTML
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.
For this experiment you will need:
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
Here's what to do:
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 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.
Experiment from:
http://scifun.chem.wisc.edu/HomeExpts/HOMEEXPTS.HTML
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