Amy Weiskittel Amy.Weiskittel@Equistar.com

1. BOUNCY BALLS THE SCIENCEOFPOLYMERS Amy Weiskittel Amy.Weiskittel@Equistar.com

2. ENGAGE • Why are baseball bats made of aluminum or wood instead of iron? • When a patient receives an X-ray at the dentist, the dental assistant or hygienist places a lead vest on the patient. Why? • Could one use a nice bath towel instead of the lead vest? Explain. • Before the 1970s, the automobile industry used a lot of steel to produce a car. Today, plastic replaces much of the steel. Develop a list of reasons why this occurred.

3. ENGAGE • Plastics are very important to us because we make numerous products from plastic. However, there are different types of plastic as there are different types of oak trees. Since each type of plastic is different, we use them differently. Investigate to notice similarities and differences between the two different bags. • All of these questions were about “properties.” Discuss to develop a definition of what you think is the meaning (definition) of “properties.” Write the definition below.

4. EXPLORE • Place one piece of each type of plastic on a paper towel. Add 10 drops of water in different places on each plastic. • While keeping the plastic on the paper towel, gently move the plastic around to see what the water does. What differences did you notice? • Slowly lift up the pieces of plastic. What did you observe?

5. EXPLAIN • You compared the solubility of polyvinyl alcohol (PVA) and polyethylene (PE) in water. Why don’t we make milk jugs with PVA? • Why would you want a water soluble bag? • Solubility is an example of a property. Many metals have properties, such as magnetism, a shiny luster, and the ability to conduct electricity. Water’s properties include a specific boiling and freezing point. Discuss and develop a definition for property. • Review the Engage questions. How are these questions about properties? • Why it is important to design a product around its properties.

6. ELABORATEPart I • Demo- Sodium polyacrylate in water and PE in water • Absorbency is an example of a property. This demo compared the relative absorbency of PE powder and sodium polyacrylate. Why don’t we make ketchup bottles with sodium polyacrylate? • Discuss and develop reasons why plant nurseries and gardeners use something similar to sodium polyacrylate. • Grocery, drug, and general merchandise stores (such as Wal-Mart) sell products containing sodium polyacrylate. Discuss to determine a list of possible products found/used in a home that contain this water-absorbing chemical.

7. ELABORATEPart I (Teacher notes) • Hydrophobic “water-hating”: plastic cups, bags, raincoats, etc. • Hydrophilic “water-loving”: cotton fibers, synthetic hydrophilic polymers • Sodium polyacrylate is the major ingredient inside diapers (outside is PE), also in some types of potting soil, water beds, and fuel filters for automobiles or jets

8. ELABORATEPart II • Obtain a vial with 20 mL of 4% PVA solution (this mixture also contains a phosphorescent zinc sulfide) • Add 5 mL of 4% sodium metaborate solution to the vial and shake. • Remove slime with your fingers. Try to form into a ball. • Place slime on a hard surface and observe. • Allow slime to sit for a minute. Observe. • Be sure to put the cap on to prevent it from drying out • Place vial under a flashlight • Turn off the lights and observe. • For long term storage, keep refrigerated to prevent mold growth.

9. ELABORATEPart II • Cross-linking is example of a polymer property.You cross-linked polyvinyl alcohol with borate ions from the sodium metaborate (Borax) solution to form a non-Newtonian fluid. What are some characteristics of non-Newtonian fluids? • What happened when the lights were turned off? • Why do you think that happened? • Many cross-linked polymers contain additives to give the polymers certain properties. Does the amount of additives added to the polymer change its properties?

10. ELABORATEPart II (Teacher Note) Glow Processes There are “Hot” and “Cold” light emission processes. The hot light, incandescence, emits light because of its high temperature. Cold light, or luminescence, emits light without a rise in temp. There are 5 types of luminescent processes: • Photoluminescence is when the light emitted after the energy being absorbed is from light. Glow in the dark pigments, such as phosphorescent zinc sulfide, are examples of photoluminescence • Chemiluminescence is when the light emitted after the energy being absorbed is from a chemical reaction not a living organism (e.g. glow sticks) • Bioluminescence is when the light is emitted after the energy being absorbed is from a chemical reaction in a living organism. (e.g. jellyfish, coral, fungi, insects-Fireflies) • Triboluminescence is when light emitted after the energy being absorbed is mechanical. (e.g. crushing a wintergreen Lifesaver) • Thermoluminescence is when the light emitted after the energy being absorbed is from heat. (e.g. minerals-Chlorophane when heated)

11. EVALUATE • Rubber is formed by cross-linking polybutadiene and sulfur vulcanizing agent. Obtain two black rubber balls. • Discuss to develop a procedure for Do all rubber balls bounce? Why? Questions to think about: • Are all rubbers the same or do differences exist? If differences exist, what are the differences? • Do the differences affect the rubbers performance? Are there any similarities? • What are some applications of the different rubbers? • Have your teacher approve your procedure.

12. EVALUATE(Teacher Note) Bouncing Ball Activities (Happy/Sad Balls) • Drop each ball separately • Drop all balls from a measured height. Measure how high they bounce • Obtain several super balls and have a bouncing contest The Effect of Temperature • Put the balls in the freezer or ice water for a set time, then drop balls • Boil balls in a beaker of water for a set time, then drop balls http://galileo.phys.virginia.edu/outreach/8thGradeSOL/EffectofTem perature.htm

13. EVALUATE(Teacher Note) cont. Comparing Densities • Place balls in a beaker half full of water. Do they float or sink? • Place the balls in a beaker half full of glycerin (glycerol). Observe. Glycerin has a specific gravity of approximately 1.3 g/mL. The Happy Ball has a specific gravity of ~1.03 g/mL. The Sad Ball has a specific gravity of ~1.17 g/mL. • Mix the glycerin and the water and observe. Disposal: The glycerin and water solution may be rinsed down the drain with excess water. Safety Precautions: Always wear safety glasses or goggles; watch for rebounding balls and materials that may be damaged; wear proper PPE when handling hot or cold balls http://www.eas.caltech.edu/openhouse/joint_cc_2003/handouts/degroot- Happy_Sad_Balls.pdf

14. QUESTIONS ???

15. What Is a Polymer? • A polymer is a large molecule built up by repetition of small, simple, chemical units • Some terminology • “Mer” is “unit” • Monomer = one unit (A) • Dimer = two units (AA) • Trimer = three units (AAA) • and so forth • “Poly”means “many,” so polymer means many units - In this case … -A - A - A - A - A - A - A - A - A - A - A - • A polymer is formed from many monomers

16. More Terminology • A polymer made entirely one one monomer is called a Homopolymer (“homo” meaning “same”) A - A - A - A -A -A -A -A -A -A- A - A - ... • A polymer composed of two different monomers is called a copolymer … A - A - A - A - B - A - A - A - B - A- A - A - … Monomer Comonomer • The additional, different monomer is called the comonomer, especially when it is present in smaller amounts

17. Types of Polymer Structure - Linear • Linear molecules - homopolymers … A - A - A - A - A - A - A - A - A - A A- A - A- A - A - ... • Linear molecules - copolymers ... A - A - A - B - A - A - A - A - A - B - A- B - A- A - A - A … Random ... A - B - A - B - A - B - A - B - A - B - A- B - A- B - A - B … Alternating ... A - A - A - A - A - A - A - A - A - B - B- B - B- B - B - B … Block • Can have same composition (for example, 80%A, 20%B) but totally different structure because the comonomer is distributed differently

18. A- A- A- A- A A - A- A- A- A- A- A- A- A- A- A- A -... Types of Polymer Structure - Branched • Long branched molecules - homopolymers A - A - A -... - A - A - A - A - A - A • … - A - A - A - A • Short branched - homopolymers …- A - A - A - B - A - A- A - A- A - A- A - A- A - A- A - A - ... • Combined branching, comonomers, and different distribution of comonomer wide variety of possible structures A- A- A- A - A- A- A- A A A A