8/8/2019 Plastics Presentation Teacher Notes

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Plastics Presentation Teacher’s Guide 

The class should have started the unit with an

activity exploring natural polymers like corn starch.The classic OBLECK activities such as found here:

http://www.raft.net/ideas/Ooh%20Ooh%20Oobleck.pdf  

will suffice. Provide students with the structure of 

corn starch and ask them to connect the structure

to the behavior of the Oobleck.

This Bell Ringer activity asks them to construct what

think a polymer is (based on the corn starch

example) using a sample of K’NEX blocks and record

their thoughts in their science journal. An

assortment of K’NEX pieces and connectors in a bag

for each student will suffice.

Share the responses and discuss leading the class to

the idea that polymers are made up of smaller

repeating units. This will set the stage for deeper

discussion later in the lesson.

Explain that monomers are like the small repeating

units of the K’NEX while the entire connected

structure represents a polymer. For a mini-lecture

of the relationship between monomers and

polymers click here: 

http://www.uwsp.edu/chemistry/polyed/audio_polymer.htm 

Here would be the most appropriate place to use

the nylon synthesis demonstration to show the

polymerization reaction between two monomers.

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Details are on the demonstration page of this site.

The first polymers discovered were natural polymers.

For a brief lecture about natural polymers click here: 

http://www.uwsp.edu/chemistry/polyed/audio_natural_poly

mers.htm 

Polymer chemistry is a relatively new science. For a

brief introduction to polymer chemistry click here: 

http://www.uwsp.edu/chemistry/polyed/audio_polymer_che

mistry.htm 

For more information about Ziegler and Natta look read

their entry on the noble prize website:

http://nobelprize.org/nobel_prizes/chemistry/laureates/1963

/index.html# 

This slide and the next present an overview of how

plastics are produced from petroleum.

This would be a good opportunity to discuss the types of 

products that are made with plastics, the types of 

plastics, and the positive and negative effects of plastics

on society and the environment.

Discussion of bioplastics would also be relevant but be

careful of overselling the environmental benefits of these new plastics as told in the journal of the NSTA:

The Science Teacher, December 2010, Vol. 77 No. 9

which discusses that the environmental issues of plastics

still persist with bioplastics offering little or no

improvement over petroleum based plastics.

If you have a petro-chemical facility (think large oil

companies) near you they may offers tours to schools

showing the process of making plastic resins.

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Thermo plastics analogy: ICE

When ice is heated, it melts. When a thermoplastic object

is heated, it melts as well.

The melted ice can be formed into a new shape, and it

will keep that shape when it's refrozen. Similarly, a

melted thermoplastic object can be formed into a

different shape, and it will keep that new shape when it's

cooled.

Thermoset analogy: EGGS

Just as a raw egg has the potential to become a boiled

egg, a fried egg, and so on, thermosetting polymers have

the potential to become all sorts of different objects.

Once an egg has been boiled, however, you can't make it

into a fried egg. In the same way, once a thermosetting

plastic object has been formed, it can't be remade into a

different object.

Forming thermoset and thermoplastics use different

techniques based on their properties:

The most common method for making plastics is molding.

To make a thermoplastic object, plastic granules known as

resin are forced into a mold under high heat and pressure.

When the material has cooled down, the mold is opened

and the plastic object is complete. When making plastic

fibers, the molten resin is sprayed through a strainer with

tiny holes.

Thermosets are produced in two steps:

First, linear polymers are formed then the linear polymers

are forced into a mold where "curing" takes place. This

may involve heating, pressure, and the addition of 

catalysts. During this process, a cross-linked or networked

structure forms, creating a permanently hard object that

is no longer meltable or moldable.

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This slide presents the main learning objectives of the

lesson. Asking students to pick one of the take-home

points and expand on it in class can be a great way tostart discussion, identify misconceptions, and confirm

understanding.

Reinforcement activity:

The “Heating Plastics” game is a great and fun resource

to have students learn and assess their understanding of 

plastics production and the difference in thermosets and

thermoplastics. Click Here for a direct link.

http://nobelprize.org/educational/chemistry/plastics/game/in

dex.html 

The major source of information for this presentation is

the NobelPrize.org website called Plastics and Polymersfound here: 

http://nobelprize.org/educational/chemistry/plastics/readmo

re.html