Our entry for the Google Science Fair 2012. Does heating affect the strength of glue?

1. Google Science Fair
Project
How does heat affect the strength of glue?
By Bruno Brazda, Sarai Hatayama, Kristof Pákozdi

2. Question and Hypothesis
• The question that was being answered was “How does
heating affect the strength of glue?” The hypothesis was
that the higher the temperature glue was made to work at,
the weaker it became. To prove this, an experiment was
conducted on the glue. Glues chemistry was taken into
account, with its rather high viscosity. When heated, the
glue becomes less viscous. This is because when heated,
the particles move faster which results in more gaps
between them giving the liquid better flow. When heated
the hardened glue becomes a low viscosity liquid, which
held less weight than the adhesive at a room temperature.
This process carried itself out faster at higher
temperatures.

3. Apparatus
• The following apparatus was set up and used in the
experiment:
• Bunsen burner
• Tripod and Gauze mat
• Beaker
• String
• Weights – 10g, 20g, 30g
• Thermometer ( degrees Celsius)
• Adhesive
• Stopwatch
• Cello tape

4. Set-Up Diagram
Thermometer 30g weight
10ml water
Bunsen Burner

5. Method
• Firstly, the apparatus was set up as seen in the diagram, with the
Bunsen burner lit and the air hole open.
• ̊
Secondly, 10ml of water was heated to 90C and 10g weight was
glued to the 30g weight which was cello taped onto the string. After
waiting 10 seconds, the weight was placed 1cm from the water, being
held by the string, and the stopwatch began timing.
• ̊
Next, assuring that the water remained at 90C, we waited until the
weight separated from the glue and fell into the beaker. The
stopwatch was then stopped and the time taken for that specific
weight at that specific temperature was written down.
• Then, the Bunsen burner was removed from underneath the tripod
and turned to the safety flame (closed air hole) and the beaker was
let to cool down before being emptied and filled up with 10ml of water
and returned to the starting position.
• Finally, these steps were repeated 9 times altogether: with 10g, 20g,
̊ ̊ ̊
30g weights on temperatures of 90C, 100C and 110C, writing down
how long each weight took to fall at each temperature.

6. Results

7. Results

8. Results
• After the data was analyzed, the conclusion could be drawn that the higher
the temperature the glue was heated to, the less time it could hold weight for,
thus the weaker it became. In total, our data consisted of 9 measurements,
which had an uncertainty for temperature and time of half a Celsius and 1
second respectively. This was due to the fact that the temperature altered
during the experiment, as well as the fact that there was a delay before and
after we started and stopped the stopwatch because our reaction times are
flawed. Altogether, the results correspond to our hypothesis. In addition, there
was one measurement that stood out of the 8 other consistent ones, the 10
gram weight at 90 degrees Celsius. This measurement stands out from the
rest and we think that this is because perhaps the glue had a longer amount
of time to dry (over 10 seconds) which would have resulted in a longer time
taken for it to give away. Therefore, if this experiment is ever repeated, extra
care must be taken to assure that the glue gets attached to the weights for
exactly the same time span each time.

9. Conclusion
• In Conclusion, using the data that had been collected, the
conclusion can be drawn that the higher the temperature
glue is made to work at, the weaker it becomes. We have
proved our hypothesis because we have a sufficient
amount of data and even though one measurement is not
consistent, we can still presume that it took the longest
therefore agreeing with our predictions. Furthermore, the
experiment was a fair test, keeping the glue we used
throughout the experiment the same, always waiting 10
seconds before exposing the glued weights to heat and
always keeping 100ml of water in the beaker. These
factors were vital for the data to be as reliable it is.

10. Bibliography
• Family Members – ( Dr. Edgar Brazda, )
• Educator – Ms. Holmes, Technician Szilard
• Idea - http
://www.scienceproject.com/projects/intro/intermediate/IP112.
asp
• Viscosity - http://www.spacegrant.hawaii.edu/class_acts/
ViscosityTe.html