Amy Weiskittel Amy'WeiskittelEquistar'com

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BOUNCY BALLS THE SCIENCE OF POLYMERS

• Amy Weiskittel Amy.Weiskittel_at_Equistar.com

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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.

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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.

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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?

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EXPLAIN

• You compared the solubility of polyvinyl alcohol
  (PVA) and polyethylene (PE) in water. Why dont
  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. Waters 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.

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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 dont 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.

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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

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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.

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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?

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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)

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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.

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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/8thGra
  deSOL/EffectofTem perature.htm

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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_20
  03/handouts/degroot- Happy_Sad_Balls.pdf

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QUESTIONS ???
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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
• Polymeans 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

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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

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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, 80A,
  20B) but totally different structure because the
  comonomer is distributed differently

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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