- Students can add materials to be tested.
- Students can put materials in baggies and place in
freezer to see what effect cold has on the adhesive.
- Students can use lamps or hair dryer to heat the
adhesive and then retest.
- Students can use water to wet adhesives and then
retest(chemical vs.physical change).
- Students can make their own adhesives using skimmed
milk and vinegar.
Testing Procedures For Adhesives
Tack
There are four tests scientists use to see how sticky an
adhesive is. Choose only one for your experimentation.
1. Polyken Probe Tack Test - This test is
done on equipment sometimes re- ferred to as the "mechanical
finger." We can come to the same conclusions by using
everyday materials.
|
Steps
a) Place two chairs of the same height back to
back, 6" apart.
b) Place the ruler in the center across the
backs of both chairs.
c) Cut a 6" piece of tape.
d) Tape 2" of the tape to a plastic bag so that
the bag hangs open when you hold the top of the
tape.
e) Tape 1" of the other end of the tape to the
center of the ruler so the bag hangs down.
f) Drop in pennies one at a time until the bag
falls.
g) Write number of pennies on data sheet and
repeat experiment for each tape.
|
|
2. Loop
Steps
a) Cut 10" piece of each tape.
b) Attach the tape to the tabletop from left to right
with the adhesive side down.
c) Lift the tape from the right side to form a 2" loop.
d) Attach a spring scale to the loop and with one hand,
pull it back towards your left 2".
|
e) Take a reading on the scale, and write it on
your data sheet. Repeat experiment for each tape.
|
|
3. Qualitative
Steps
a) Cut 6" piece of each tape, and place each one on the
table side by side with
adhesive side up.
b) Have each member of the group feel each adhesive.
c) Put the tapes in order from most sticky to least
sticky.
d) Put results on your data sheet.
4. Rolling Ball
Steps
a) Cut 10" piece of each tape.
b) Place each tape on the table from left to right with
the adhesive side up.
c) Place the ramp on the right of the tape so the incline
faces the tape.
d) Roll the marble down the ramp by releasing and not
pushing.
e) Measure the distance from the end of the ramp to the
marble.
f) Repeat this step three times on each tape and use an
average to get your result. Clean the marble between tests
with rubbing alcohol.
a+b+c
3 = results
g) Put your results on your data sheet.
Shear
Use this test to determine how strong the adhesive is.
Use cardboard 1" squares with a hole punched in the center
and a staple above and below the hole to prevent tearing of
the cardboard.
|
Steps
a) Cut a 5" piece of tape.
b) Attach the 1" cardboard square to one end of
the tape by putting 1" of the tape across the
square over the staples and the hole. Repunch the
hole.
c) Tape the other end (1/2") to the side of a
tabletop. Place foam rubber or polyurethane (or a
pillow) under the tape to prevent damage to the
floor by the weight.
|
|
d) Place a 1 kg weight through the hole in the
cardboard, and let it hang.
e) Time how long it takes the weight to fall
when the tape releases.
f) Enter the time on your data sheet. Repeat
experiment for each tape.
|
|
Peel
Use this test to determine how strong the adhesive is
when it is peeled away by force. Various materials may be
used such as plastic, cardboard, glass, and wood.
Steps
a) Place 10" strip of tape adhesive side down on the
material which is lying on the tabletop.
b) Roll a rolling pin one time over the tape.
c) Repeat this for each tape.
d) Lift each tape off of the tabletop to determine which
is stronger.
e) Put the tapes in order from strongest to least strong.
f) Put your results on your data sheet.
Making Your Own Adhesive
Slowly heat 1 cup of skim milk with 2 tablespoons of
white vinegar. Keep stirring until the mixture thickens and
lumps form. Take it off the stove. Keep stirring as long as
lumps are forming. The lumps called curds are casein. Strain
them out and throw away the liquid. Now you can use the
curds to make a plastic. The plastic you make from casein is
liquid. It's so sticky you can make glue from it. Put the
curds in a jar. Add 2 tablespoons of water and 1/2 teaspoon
of baking soda. The mixture bubbles and changes into a gooey
white liquid (glue). Paste two sheets of paper together to
test the glue. Let it dry. The glue is strong.
Adapted from: Science Fun with a Homemade Chemistry
Set
Author: Rose Wyler
Publisher: Simon & Schuster Inc., New York, 1987
| 
