Plastics

1
Plastics
2
History of Polymers

• Plastic is a polymer.
• A polymer is a substance made up of many
  repeating units called monomers.

What is a polymer?
3
History of Polymers

• Natural polymers such as tar, horns, and tree
  saps that produce amber and latex, have always
  been with us.

Natural polymers were chemically modified during
the 1800's to produce rubber.
Extracting latex from the rubber tree.
4
History of Polymers

• Synthetic polymers were produced in the early
  1900's and developed during
• World War II.
• Nylon, polyethylene and many more polymers
  took the place of natural materials that were
  scarce.

5
Structure of Polymers

• Many common polymers are composed of
  hydrocarbons. In the simplest polymer structure,
  polyethylene, carbon makes up the backbone of the
  molecule.

Products made from polyethylene
6
Structure of Polymers

• There are some polymers that have silicon or
  phosphorous backbones. One of the most famous
  silicon-based polymers is
• Silly Putty?

7
Plastics

• Plastics are an industrially important type of
  polymer. Plastics can be divided into two
  classes depending on how they are structurally
  and chemically bonded.
• 1. thermoplastics - can be recycled
• 2. thermosetting plastics - once formed,
• they cannot be melted and reformed

8
Thermoplastics

• Thermoplastics can be heated and made soft and
  then become hard when cooled.
• hot glue

Thermoplastics are easily processed and recycled.
Polymers formed by addition polymerization are
often thermoplastic in nature.
9
Addition Polymerization

• Polymerization is initiated by breaking the
  double bond. Monomers are joined by adding on to
  the end of the last monomer.

10
Common Plastics
11
Polyethylene Terephthalate
12
High-Density Polyethylene
13
Polyvinyl Chloride
14
Low-Density Polyethylene
15
Polypropylene
16
Polystyrene
17
Plastics by the Numbers

• The Society of the Plastics Industry (SPI)
  introduced its resin identification coding system
  in 1988. Each container is stamped with a number
  which assists recyclers in sorting the plastics.