Glurch II

Developers:

Carolyn L. Minor
Steel School
Philadelphia

Dr. Trish Maxson
Applications Development Lab
Rohm and Haas Company, Bristol

Dr. Cheryl Martin
Modifiers Research
Rohm and Haas Company, Bristol

Topic Area:

Plastics

Grade Level:

Grade 3-5

Specific
Objectives:

Students will make Glurch II and conduct tests to compare its properties to those of the commercial materials.

Materials:

For each student
20 ml liquid starch	5 grams salt
10 ml white glue	5 grams cornstarch
spoon or stirrer	paper towels
centimeter ruler	small, plastic bag
record sheet	1 small cup

For each team
4 paper cups	ice
tape	scissors

Teacher demonstration
aluminum foil	hair dryer

Background:

The properties of an object are important to scientists. It helps them to predict how an object will behave. Changes in temperature and force can change a material's properties. Chemists are often involved with creating new materials that can be used for specific purposes. They may, for example, need to create material for an object that must keep its shape under high temperatures or withstand a drop of several meters without breaking or changing its shape.

Management Suggestions:

1. Each student should have the opportunity to make Glurch II. If this is not possible, have students work in teams of two or four. The sag towers may be constructed in teams of four students.
   When exposed to air, this material will dry out.
2. Small plastic bags can be used to take Glurch II home.
3. Glurch II will be "tacky". It will become less tacky when handled. More cornstarch may be added to change this property.
4. Duplicate student record sheets.
5. Make certain that the students record their observations while they are doing the experiment.

Procedures:

Have students:

1. Measure out the laundry starch, cornstarch and salt and mix them together.
2. Add glue and stir.
3. Once a lump of material forms, squeeze the liquid from the lump.

This material is Glurch II. Use it to conduct the following experiments: Experiment One Have students: Roll it. Twist it. Listen to it as it moves. Squeeze it. Press it on a piece of paper. Press their fingers into it. Experiment Two Drop it from a height of 10 centimeters. Drop it from a height of 100 centimeters. Experiment Three Put the Glurch II into a small plastic bag and seal it. Place the bag into a cup of ice for 5 minutes. Remove the Glurch II and stretch it. Teacher demonstration Place a piece of Glurch II on a piece of aluminum foil. Turn hair dryer on low and direct hot air toward the Glurch II. Stretch it. Experiment Four Construct two paper cup towers. Diagram Form Glurch II into a roll 10 centimeters long. Anchor ends of Glurch II to notches in towers. Measure sag distance (vertical distance from the bottom of the notch to the lowest point of the object) after 5 minutes.

Discussion:

1. Can you describe some of the properties of Glurch II?
2. What are some of the similarities and differences between Glurch II, Color Dough, Silly Putty and the Super Ball? [This information might be entered on a large, class or individual chart.]
3. Would Glurch II be a good material for a car bumper? A helmet? Why or why not.
4. Can you think of another use for Glurch II? Why do you think it would work? (Remember Glurch II's properties).

Extended
Activity:

Have students conduct an interview with a senior citizen, (this might be done with a tape or video recorder) in which they ask questions about the materials used to make objects - 30 to 50 years ago. Examples could be car bumpers, refrigerators, clothing, radio cabinets. Ask the children to note how these have changed.

References:

Materials Science - A Continuing Frontier. National Science and Technology Week '91. National Science Foundation, Washington D.C. 20550.