The Application of Polymers: Plastics!
Students are introduced to different types of household plastics and the concept of polymers and then complete two related experiments.
This workshop is designed to introduce Grade 7-12 students to a specific type of materials: polymers. The activity is divided into two parts. In the first part, the students are introduced to different types of household plastic, the concept of polymers and their different applications. The experiment section contains two separate experiments: making a balloon skewer and making "plastic" from milk.
What You Need
Activity 1: Balloon Skewer
- 2 balloons
- 2 bamboo skewers
- Permanent marker
- Dish soap
- Vegetable oil
Activity 2: Making Plastic from Milk
- Steel casserole dish
- 4 tsp. of vinegar
- 1 cup of fat free skim milk
- Silicone cake mold
Safety Notes
Be cautious when using bamboo skewers in Activity 1 and when using the stove in Activity 2. Students can become injured if they are not cautious.
Be sure to check for any allergies with the educator before using food products with students.
What To Do
Activity 1: Balloon Skewer
- Separate students into two groups. One group would perform this activity with vegetable oil and the other with dish soap.
- Apply vegetable oil all over the skewer, or apply dish soap on two points on the balloon. Puncture slowly through the balloon anywhere or through the points coated with dish soap.
- Use a permanent marker to draw 7-10 dots on the second balloon roughly the size of a dime. Inflate the balloon, and ask the students to take observations of the size of the dots. What does this mean?
- Ask the students to decide on the best spot to puncture the balloon with the skewer without popping the balloon.
Activity 2: Making your own Plastic
- Pour a cup of milk into the pot, add vinegar and stir with a spoon. Turn on high heat (CAUTION), wait for two minutes and then stir.
- Take it out of the pot, put into the silicone mold when it is still warm. Flip the mold upside down to prevent bending and allow plastics to cool down.
Discovery
The surface tension is reduced at the points coated with dish soap, the polymer chains close around the skewer, preventing the balloon from popping. After removing the skewer, the balloon will not pop, instead the air will gradually leak out. The polymers are stretched out the least at the end of the balloon, which is the best place to puncture the balloon.
Milk contains monomeric casein. A chemical reaction, namely polymerization, occurs with the help the acid under heating condition. The casein chains formed will then harden into plastics.
What's Happening?
The surface tension is reduced at the points coated with dish soap, the polymer chains close around the skewer, preventing the balloon from popping. After removing the skewer, the balloon will not pop, instead the air will gradually leak out. The polymers are stretched out the least at the end of the balloon, which is the best place to puncture the balloon.
Milk contains monomeric casein. A chemical reaction, namely polymerization, occurs with the help the acid under heating condition. The casein chains formed will then harden into plastics.