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Plastics that are Recycled |
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Recycle Code |
Abbreviation and Chemical Name of Plastic |
Types of Uses and Examples |
|
1 |
PET - polyethylene terephthalate |
Clear, 2 liter beverage
bottles |
|
2 |
HDPE - High density polyethylene |
Milk jugs, detergent bottles,
some water bottles |
|
3 |
PVC - Polyvinyl chloride |
Saran wrap, plastic drain pipe,
shower curtains, some water bottles |
|
4 |
LDPE - Low density polyethylene |
Plastic bags, garment bags,
coffee can lids |
|
5 |
PP - Polypropylene |
Aerosol can tops, rigid bottle
caps, candy wrappers,
bottoms of bottles |
|
6 |
PS - Polystyrene |
Hard clear plastic cups, foam
cups, eating utensils,
deli food containers, some packing popcorn |
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7 |
Other |
Biodegradable, Some packing
popcorn |
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Polymers
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Introduction:
Polymers are long chain giant organic molecules are
assembled from many smaller molecules called monomers.
Polymers consist of many repeating monomer units in long
chains. A polymer is analogous to a necklace made from many small
beads (monomers).
Another common name for many synthetic polymers is plastic
which comes from the Greek word "plastikos", suitable
for molding or shaping. Many objects in daily use from packing,
wrapping, and building materials include half of all polymers
synthesized. Other uses include textiles, TV's, CD's, automobiles,
and many other all are made from polymers.
A quarter of the solid waste from homes is plastic materials
- some of which may be recycled as shown in the table on the
left.
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Types of Polymers:
There are many types of polymers including synthetic and natural
polymers.
Natural polymers are discussed in other web pages and
include:
Proteins - silk, collagen, keratin.
Carbohydrates - cellulose, starch,
glycogen
DNA - RNA
Other Natural polymers: Rubber (hydrocarbon base) and
silicones (alternating silicon and oxygen).
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Classification of Polymers: |
Homopolymers - consist of chains with
identical bonding linkages to each monomer unit. This usually
implies that the polymer is made from all identical monomer molecules.
These may be represented as : -[A-A-A-A-A-A]- |
Copolymers - consist of chains with two
or more linkages usually implying two or more different types
of monomer units.
These may be represented as : -[A-B-A-B-A-B]- |
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Polymers are further classified by the reaction mode of polymerization,
these include:
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Addition Polymers - the monomer molecules bond to each
other without the loss of any other atoms. Alkene monomers are
the biggest groups of polymers in this class.
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Condensation Polymers - usually two different monomer
combine with the loss of a small molecule, usually water. Polyesters
and polyamides (nylon) are in this class of polymers. Polyurethane
Foam in graphic.
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Classification based upon the physical property related to
heating:
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Thermoplastics - plastics that soften when heated and
become firm again when cooled. This is the more popular type
of plastic because the heating and cooling may be repeated.
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Thermosets - plastics that soften when heated and can
be molded, but harden permanently. They will decompose when reheated.
An example is Bakelite, which is used in toasters, handles for
pots and pans, dishes, electrical outlets and billiard balls.
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