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8/8/2019 Plastics Presentation Teacher Notes
http://slidepdf.com/reader/full/plastics-presentation-teacher-notes 1/4
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