1. Activity 20 Analysis Questions
Analyze each of the models you built.
Models of Polymers
Type of polymer model
Strengths
Weaknesses
Paper clips linked together
Classmates holding hands
Class molecular model (Activity 19)
Fits on a desktop.
Can be used by one person.
Clearly shows the dif. between a monomer as one paper clip and a polymer as a chain of the same unit.
Does not show structure of the monomers.
Takes a lot of people to use.
Doesn’t show the structure of the monomers.
Shows how cross-linking makes it harder to move the polymer around.
It is difficult to build and work with a polymer with five or more subunits.
The bonds are very rigid.
You cannot use these models to test how easily a polymer can be poured or stirred.
Shows atomic level.
Shows the bonding within each monomer and between the monomer molecules (for example, shows the double bond in the monomer).

2. Compare the models you built in this activity.
Which was most helpful when you analyzed the physical properties of a polymer?
Paper clips handled easily
Both reflected change in physical properties of the material as the polymers were cross-linked
Which gave you a better image of the process?
Most helpful when analyzing chemical reactions?
Different colored paper-clips made it easy to see polymerization and cross-linking
Student model showed the double bond in the vinyl alcohol and the need to break it to form a polymer.

3. many monomers linked together with chemical bonds = polymer
Using examples from this and Activity 19, explain the relationships between a monomer, a polymer, and a cross-linked polymer. Include a sketch.
a monomer is a molecule.
many monomers linked together with chemical bonds = polymer
chemically link polymers together = cross-linked polymer
Cross-linked polymer
Monomer
Polymer

4. How does cross-linking affect the properties of a polymer?
becomes harder, thicker, more difficult to pour
Based on observations, what advantages do you think polymers have on monomers?
monomers are individual units
means they move around easily
aren’t held together in any way
polymers are connected units
means they are flexible and bend
also have strength of molecules joined together
being polymers, may give plastics their strength and flexibility.

5. Activity 21
Title: Polymer Parts

6. What are the properties of polyvinyl alcohol and sodium borate, as well as the physical properties of the product that resulted when you combined them (Activity 19)?
Viscosities are very different
Viscosities of the models were different
(viscosity: resistance of a liquid to sheer forces (and therefore to flow)

7. What does the prefix “poly-” in polyvinyl alcohol indicate?
It is a polymer
It is made up of many repeating monomers of molecules
What was the purpose of the sodium borate?
The sodium borate provided the links to form a cross-linked polymer.

8. Was this a physical or a chemical change?
The thickness of the substance changed
The color of the final product is cloudy
These are two physical changes that indicate a chemical reaction occurred.
Both physical and chemical change took place.

9. Key Terms Monomer Polymer Cross-Link Reactants Products
Chemical Reaction: B-49

10. Look at Activity 12
Transparency 12.1, “Graphing Data About Aluminum, Plastic, and Glass.”
Aluminum: easy and inexpensive to recycle
Glass: more difficult and more expensive
Chemical properties made the process for breaking down each container type different.
Cross-Linked polymers are very difficult if not impossible to break down, making recycling difficult.

11. Doing Activity 21 Read as a group pages B-47 to B-49
Each person take turns reading a paragraph out loud
Technical reading can be difficult, help each other with the pronunciation of chemical names
Fill in “Three-Level Reading Guide: Polymer Parts” together
Make sure to discuss your choices

12. Three-Level Read Guide: Polymer Parts
Check the statements below that you agree with and be ready to support your choices with ideas from the reading and from your own knowledge.
cross out the words “be ready to”
For parts a and b, explain whether you agree or disagree and support your choices as mentioned above.