The Properties of Gluep
by Sarah Powers
The purpose of this research project was to try to make the best kind of Gluep possible
for bounciness, and stretchiness. Gluep is a mixture of white glue, sodium borate (Na4B2O7),
and water. We also tried to see if temperature had an impact on the stretchiness of Gluep. Gluep
is held bonded together by cross-linking. This study will help to explore the different properties
of cross-linking.
Polymers are materials that have high molecular weights that are made up of repeating
subunits called monomers (1). The polymer in Gluep is polyvinyl acetate (see Figure 1), which
comes from the white glue used.
(Figure 1: Polyvinyl Acetate Polymer) (3)
The polyvinyl acetate monomer is seen Figure 2:
(Figure 2: Polyvinyl Acetate Monomer)
The polymerization reaction is seen in Figure 3:
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H H
I
I
C==C
I
I
O H
I
C=O
I
CH3 n
H
I
C
I
H
I
C=O
I
CH3
H
I
C
I
O
H
I
C
I
H
I
C=O
I
CH3
H
I
C
I
O
H
I
C
I
H
I
C=O
I
CH3
H
I
C
I
O
n
(Figure 3: Polymerization reaction of polyvinyl acetate)
Vinyls, such as polyvinyl acetate, where the monomers are connected to each other by their
carbons, are formed when initiation, by the addition of a catalyst, starts a reaction in a mixture of
mostly monomers and polymers (4). In this case, we added sodium borate which acts as a crosslinker Although glue is mostly water, the polyvinyl acetate in glue is coated with polyvinyl
alcohol (see Figure 4).
---CH2-CH-------CH2-CH-----CH2-CH--I
I
I
OH
OH
n
OH
(Figure 4: Polyvinyl Alcohol) (1)
The polyvinyl alcohol keeps the polyvinyl acetate polymers from sticking together. The
polymers are present, but they have not all stuck to one another. Water is also in glue. When,
for example, two pieces of paper are glued together, the water in the glue evaporates, leaving all
the polyvinyl acetate molecules. They stick together and bond to the two pieces of paper. When
sodium borate is added to glue, it reacts with the polyvinyl alcohol, cross-linking it (see Figure
6). Although the polymer, polyvinyl acetate, is in glue, it is the polyvinyl alcohol that reacts
with the sodium borate.
We dissolved sodium borate, also called sodium tetraborate, (Na2B4O7) in water, which
produces borate ions (B(OH)4- ) (see Figure 5) (3,5).
Na2B4O7 + 9(H2O)  2(Na+) + 2(H+) + 4(B(OH)4-)
(Figure 5: Sodium borate dissolving in water)
The sodium borate reacts with the polyvinyl alcohol, which helps make the polyvinyl acetate (5).
It cross-links the strands of the polyvinyl alcohol together. It forms hydrogen bonds and crosslinks the polyvinyl acetate together, making it a gel. See Figure 6 for what the cross-linking
looks like.
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(Figure 6: Cross-linking of polyvinyl acetate) (1)
The open spaces between the hydrogen bonds are filled by the water (5). The bounciness and
stretch of Gluep is caused by the hydrogen bonds in the cross-linking. Hydrogen bonds are very
weak, therefore they are able to bend and stretch (2). Polymers that can be distorted by using
force and then will restore to their original state are elastomers. In a natural state, elastomers
lean towards entropy. Entropy is the loss of order. They are chaotic. When the elastomer is
stretched the polymer chains become more organized, they line up, but once that stretch is
released, they release into their entropic state. Also, the more cross-links there are, the more
force that is needed to stretch that polymer because there are more bonds to deal with (4).
This polymer is viscoelastic, meaning it can act as a liquid or a solid (4). Gluep can flow
like a liquid, but when it is stretched and a lot of force is acted on it, the Gluep will snap and
break (5). When it acts as a liquid it follows Newton’s Law, but when it acts as a solid it follows
Hooke’s Law (4). Newton’s Law is that viscosity (the ability to flow; honey is more viscous
than water) is proportional to the rate at which the different parts of the fluid are being separated
from each other because of the flow (6). Hooke’s Law says that load and deflection are linearly
proportional to each other, like how a spring behaves (7).
Organic, inorganic, synthetic, or natural polymers are in innumerable amounts of things:
adhesives, paper, cloths, fibers, concretes, coatings, glass, and are important to biology, nutrition,
anything that involves plastics, and the environment. Using something plastic, getting dressed in
the morning, or driving a car: all of these have one thing in common. They all require the use of
polymers (4).
In order to make the basic control Gluep recipe we dissolved 10 g of white glue in 10 g of
water in one beaker, then 10 g of sodium borate and 10 g of water in another. Then we added the
glue mixture to the sodium borate mixture, which made the Gluep. We stored all of the different
types of Gluep in plastic re-sealable bags. Next we varied the standard control Gluep recipe by
first making it with 11 g of glue up to 14 g of glue, increasing by 1 g increments. Then we did
the same by increasing the amount of sodium borate by 1 g increments, while keeping the water
and the glue constant. Once all the different types of Gluep had been made, we tested the
different stretch of each one by slowly stretching each one horizontally over a meter stick until it
broke. We did three trials for each variation of the Gluep. Next we took the Gluep with 11 g of
sodium borate and tested its stretch at different temperatures. We cooled it down by surrounding
its plastic bag in ice, and heated it by putting it in its plastic bag in a hot water bath. We
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stretched it the same way as we did at room temperature, again with three trials each time. Next
we tested the bounciness of each of the different Glueps. After making it into a ball as best as
possible, we dropped it from a height of 50 cm, then recorded the bounce. We repeated the
process three times. Then we tried making a Gluep ball using 12g of glue with 4 g of body
butter (a very rich lotion, that happened to contain sodium borate) dissolved in 10 g of water, and
then adding 10 g of sodium borate dissolved in 10 g of water. We next put the standard Gluep
balls (ones without body butter) on weighing trays into the sun for about 45 minutes. After
leaving them out in the lab overnight, we tested the stretch and bounce of each of the different
Gluep balls by using the same methods as before.
We found that as the amount of glue in Gluep increases, the length of the stretch decreases,
and after the Glueps with more glue were exposed to the sunlight the length of the stretch fell.
With 10.303 g of glue the average stretch before exposure to sunlight was 48.56 cm and after
exposure was 7.21. When there was 14.122 g of glue its average stretch was 17.15 cm before
exposure, and 8.51 cm after exposure (see Figure 7).
Figure 7: Amount of glue in Gluep and its effects
on average stretch before and after exposure to
sunlight
50
Length of stretch (cm)
45
40
35
stretch before
exposure to sunlight
stretch after exposure
to sunlight
30
25
20
15
10
5
10
11
12
13
14
Amount of glue (g)
As the amount of glue in Gluep increased, the bounce gradually increased before it was exposed
to sunlight. Its average bounce was 0.37 cm with 10.303 g of glue, and then it bounced 1.19 cm
with 14.122 g of glue. After the exposure to sunlight, the height of the bounce decreased as the
amount of glue increased, but the bounce heights were higher than the bounce heights before
being exposed to sunlight. When there was 10.303 g of glue it bounced 4.24 cm, and with
14.122 g of glue it bounced 1.62 cm (see Figure 8).
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Figure 8: Amount of glue in Gluep and its effect on
average bounce before and after exposure to
sunlight
4.5
Height of bounce (cm)
4
3.5
3
2.5
bounce before
exposure to sunlight
bounce after exposure
to sunlight
2
1.5
1
0.5
0
10
11
12
13
14
Amount of glue (g)
We found that as the amount of sodium borate in Gluep increased, so did its stretch, generally.
Its average stretch with 10.676 g of sodium borate was 48.65, but with 13.011 g of sodium borate
it stretched 119.10 cm. But, after being exposed to sunlight the length of the stretch plummeted
and barely increased as the amount of glue increased With 11.184 g of sodium borate it had an
average stretch of 8.51 cm, and 13.80 cm with 14.281 g of sodium borate (see Figure 9).
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Length of stretch (cm)
Figure 9: Amount of sodium borate in Gluep at its
effects on the average stretch before and after
exposure to sunlight
120
100
80
stretch before
exposure to sunlight
stretch after exposure
to sunlight
60
40
20
0
10
11
12
13
14
Amount of sodium borate (g)
Before exposure to sunlight, the height of the bounce for Gluep increased as the amount of
sodium borate increased, starting with an average bounce of 0.37 cm with 10.676 g of sodium
borate, and ending with 6.09 cm with 14.281 g of sodium borate. After being exposed to
sunlight however, the bounce was higher than it was before exposure, but it gradually decreased.
It had an average bounce of 4.24 cm with 10.676 g of sodium borate, then 2.08 cm with 13.011 g
of sodium borate (see Figure 10).
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Figure 10: Amount of sodium borate in Gluep and
its effects of the average bounce before and after
exposure to sunlight
Height of bounce (cm)
6
5
4
bounce before
exposure to sunlight
bounce after exposure
to sunlight
3
2
1
0
10
11
12
13
14
Amount of sodium borate (g)
When testing the Gluep with 11 g of sodium borate and the amounts in the control formula for
everything else, we found that as temperature increases, so does the length of the average stretch.
At 16.5C it had an average stretch of 22.75 cm, and at 29.8C an average stretch of 102.01 cm
(see Figure 11).
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Figure 11: Temperature of Gluep and its effect on
average stretch
105
Length of stretch (cm)
95
85
75
65
55
45
35
25
15
10
15
20
25
30
Temperature (°C)
When more glue is present in Gluep there is more polyvinyl alcohol for the sodium
borate to react with, which means that more cross-links are formed. That is why the average
length of stretch decreases as the amount of glue increases; they are inversely related (see Figure
7). Since there are more cross-links, there is more resistance to stretch. The presence of more
cross-links is also why the average height of bounce increases as the amount of glue increases, a
direct relationship (see Figure 8). If the Gluep has more cross-linked bonds when there is more
glue, then the Gluep is more likely to go back to its original shape once bounced against a
surface. The bonds contract then return to their starting shape, making the Gluep bounce.
As more sodium borate is added to Gluep, there is proportionately less glue, therefore,
less cross-linking occurs. Because there is less cross-linking, there is less resistance to stretch,
which means the average stretch increases as the amount of sodium borate increases. They are
approximately directly related (see Figure 9). The cross-linking argument doesn’t really hold
true for the increase in average bounce as the amount of sodium borate increases (see Figure 10).
In my opinion, there should be more research done on sodium borate and its effect on bounce.
As Gluep was being exposed to sunlight, I think that water evaporated from the Gluep,
leaving this gel much more of a solid than a liquid. Maybe more bonds were formed due to the
lack of water, and perhaps these bonds were stronger then the fairly weak hydrogen bonds in
cross-linking. The Gluep after exposure to sunlight had a much lower average stretch (see
Figures 7 and 9) because it was more solid and had a lot less give to it. Overall, Gluep bounced
much higher after being exposed to sunlight (see Figures 8 and 10). I think that is because it held
a ball form better than before exposure.
As Gluep was heated, its stretch increased (see Figure 11). In Gluep, temperature and
average stretch are directly related. The cross-linking hydrogen bonds were broken by the
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addition of heat; therefore the resistance to stretch decreased. The Gluep was able to stretch
farther before breaking, because there were very few bonds to break.
In our research project, our definition of stretch was how far the Gluep could be pulled
until breaking. Another definition of stretch would be the ability for the Gluep to return to its
original shape. I think that further research should be done on Gluep using the latter definition,
of the ability for the cross-linked bonds to return to their original shape.
Sources Cited
1. L. Fruen, The Real World of Chemistry (Kendall/Hunt, Dubuque, IA, ed 6, 2003), pp.
177, 201.
2. L. Fruen, personal communication, (2004 April 15).
3. “Gluep Production Lab: Student Laboratory Kit,” Flinn Scientific Inc. 1 (1999).
4. C. E. Carraher, “Polymer” (2004) <http://www.accessscience,com/serverjava/Arknoid/science/AS/Encyclopedia/5/53/Est_535100_Frameset.html> Accessed 2004
April 15.
5. “The Goofy Glowing Gel Experiment Kit,” Educational Innovations 32 (1999).
6. Lewis E. Wedgewood, “Viscosity” (2002) <http://accessscience,com/serverjava/Arknoid/science/AS/Encyclopedia/5/53/Est_535100_Frameset.html> Accessed 2004
April 22.
7. “Biorheology” (2004) <http://accessscience,com/serverjava/Arknoid/science/AS/Encyclopedia/5/53/Est_535100_Frameset.html> Accessed 2004
April 22.