1. D.16_17: Polymer Technology
Mr. Fleming

2. Content Standard
D16. Explain how simple chemical monomers can be combined to create linear, branched and/or cross-linked polymers.
D.17 Explain how the chemical structure of polymers affects their physical properties.

3. Thermoplastics vs Thermosets
Sets or hardens when heat is applied.
Curing is another way. This creates permanent links between polymers called cross-links.
Permanent connections made
Plastic Spatula
Softens when heat is applied.
Does not form cross-links between polymers and chemical bonds are not permanent.
Can be remolded
Disposable water bottle

4. Thermoplastics vs Thermosets

5. Thermoplastic vs Thermoset Recall
What would be easier to recycle? Thermoset or Thermoplastics

6. How important is oil to our economy?
Top 10 Companies worldwide:
Microsoft BP Bank of China Agricultural Bank of China Limited Samsung Exxon Mobil China Construction Bank Corporation Gazprom OAO Apple Industrial and Commercial Bank of China Limited
How many are oil companies? What do the others sell?

7. What’s in our gas prices?

8. Extracting Monomers
Crude oil extracted from the ground is complex and full of a variety of hydrocarbon structure.
Crude oil refineries sort the different hydrocarbons by size, structure, and weight.
Large hydrocarbons can be broken down into more useful “pieces” or synthetic polymers like plastics

9. Where does the material to make polymers come from?
Materials produced from the “cracking” of petroleum are the starting points for the production of many synthetic compounds like polymers.
Cracking is the process
whereby complex organic
molecules such as heavy
hydrocarbons are broken
down into simpler
molecules.

10. Where does the material to make polymers come from?
Distillation is a form of thermal cracking or the use of heat to break apart large molecules.
Distillation separates hydrocarbons within crude oil by their boiling points.

14. Examples of HCs in Crude Oil
All of these are hydrocarbons, bonded together in various structures.
Which of these can you name?

15. Extracting Monomer Recall
What is the process by which long chains of hydrocarbons are broken down into smaller hydrocarbon monomers?
Cracking
What type of cracking does crude oil undergo at an oil refinery?
Distillation

16. What are “polymers”?
A polymer is a large molecule that is created when monomers are joined together. A monomer is a single unit that is used to build a polymer. Polymers may be naturally occurring or man-made (synthetic).

17. Polymerization

18. Properties of Polymers
Properties are determined by the structure of the molecules and depend on:
-type of monomers used
-chain length
-branching
-degree of cross-linking

19. Straight Chained Polymer (made up of one type of monomer)
Spaghetti-like structure of straight chain polymers. Coils lead to entanglement (stiffness).

20. Branched Chain Polymer
Branching reduces the density and increases the flexibility of a polymer.

21. Branching creates more flexibility; less rigid plastic
Low density polyethylene has more branches, so it cannot be packed as closely as in linear, high density polyethylene.

22. Cross Linked Polymers
Cross-linking increases stiffness and strength of a polymer.

23. Vulcanizing Rubber to make it more flexible, tougher and temperature resistant and involves adding Sulfur atoms to create cross-links.

24. Branching and Cross-links affect strength
DIRECTION OF INCREASING STRENGTH

25. Polymer Structure
Branched, Cross-linked or Linear?

26. Type of Polymer Recall
If you were designing a strong piece of plastic, then what polymer shape would you use?
Cross-Linked

27. CAPT LAB: Synthetic Polymers
Polymers are large molecules consisting of
chains of small molecules called monomers
joined together in a repeating pattern. In the
early 1900s, scientists began to understand
the makeup of natural polymers and how to make synthetic polymers with properties that complement, or improve on, those of natural materials. One simple synthetic polymer chemists developed is polyethylene. They developed it by repeating units of the monomer ethylene (H2C=CH2). Polyethylene is a very large, zigzag-shaped molecule. One small part of a polyethylene chain is shown below.

28. CAPT LAB: Synthetic Polymers
Chemists and engineers have learned to
process and modify molecules of polyethylene
in different ways to manufacture common
household products with a variety of
characteristics. Polyethylene is used to make plastic trash bags, dry cleaning bags, milk jugs and soda bottles. In industry, materials made from polyethylene are tested for what are called “stress-strain behaviors.” stress-strain behaviors include:
Tensile strength - the amount of pulling force placed on a material
before it breaks
Abrasion resistance - toughness of a material against scraping,
scuffing or scarring
Puncture resistance –ability of a material to keep moving objects from
perforating the surface.

29. CAPT LAB: Synthetic Polymers
Your task
You and your lab partners will design an experiment that investigates one stress-strain behaviors of various plastic products made of the synthetic polymer polyethylene.
You have been provided with an assortment of plastic products to test. The stress-strain behaviors you will investigate are tensile strength or puncture resistance. Remember the importance of only testing ONE variable at a time, keeping all others constant as much as possible.

30. CAPT LAB: Synthetic Polymers
Tensile strength
The tensile strength of a material measures how much pulling stress the material will endure
before failing. This is very important in applications that depend on a polymer's physical strength or durability. For example, a rubber band with a higher tensile strength will hold a greater weight before snapping. In general, tensile strength increases with polymer chain length.
Puncture resistance
The puncture resistance of a material measures how much force is required for a moving object to break through a material. This is also very important for certain applications such as trash bags –a greater puncture resistance will result in less trash poking through and spilling out on the ground! Puncture resistance also generally increases with greater chain length.

31. CAPT LAB: Synthetic Polymers
Designing Your Experiment
In your own words, state the problem you are going to investigate. Write a hypothesis using an “If… then… because..” statement that describes what you expect to find and why. Include a clear identification of the independent and dependent variables that will be studied.
Your experimental design should match the statement of the problem and should be clearly described so someone else could replicate the experiment. Use a diagram if necessary to help explain your design.

32. CAPT LAB: Synthetic Polymers
Things to consider in your design:
1. How will you measure the amount of stretching the plastic can endure? What will you consider the starting point? What will be the ending point?
2. How can you keep the force of a moving object constant? Is there a natural force you can use that is ALWAYS the same?
Remember the importance of only testing ONE variable at a time, keeping all others constant as much as possible. Also remember the importance of making valid conclusions from your data… how many trials will you do?