Page 49 - Carrahers_Polymer_Chemistry,_Eighth_Edition

12 Carraher’s Polymer Chemistry

Poly(ethylene terephthalate) — PET or PETE
PET is the plastic used to package the majority of soft drinks. It is also used for
PETE some liquor bottles, peanut butter jars, and edible-oil bottles. About one-quarter
of plastic bottles are PET. PET bottles can be clear; they are tough and hold
carbon dioxide well.
High-density polyethylene — HDPE
HDPE is a largely linear form of PE. It accounts for more than 50% of the
plastic bottle market and is used to contain milk, juices, margarine, and some
grocery snacks. It is easily formed through application of heat and pressure and is
relatively rigid and low cost.
HDPE
Poly(vinyl chloride)—PVC or V
PVC is used “pure” or as a blend to make a wide variety of products, including
PVC pipes, food packaging film, and containers for window cleaners, edible oils,
V and solid detergents. It accounts for only 5% of the container market.
Low-density polyethylene—LDPE
LDPE has branching and is less crystalline, more flexible, and not as strong as
HDPE. The greater amount of amorphous character makes it more porous than
LDPE
HDPE, but it offers a good inert barrier to moisture. It is a major material for
films from which trash bags and bread bags are made.
Polypropylene—PP
PP has good chemical and fatigue resistance. Films and fibers are made from it.
Few containers are made of PP. It is used to make some screw-on caps, lids,
PP yogurt tubs, margarine cups, straws, and syrup bottles.
Polystyrene—PS
PS is used to make a wide variety of containers, including those known as
Styrofoam plates, dishes, cups, etc. Cups, yogurt containers, egg cartons, meat
PS trays, and plates are made from PS.

Other Plastics
A wide variety of other plastics are coming to the marketplace including
OTHER copolymers, blends, and multilayered combinations.

FIGURE 1.1 The Society of Plastics Industry recycling codes utilizing the numbers 1–7 and bold, capital
letters to designate the material utilized to construct the container.

crystalline and weaker but more flexible because of the presence of more branching in comparison
to HDPE. The thicker glossy shopping bags from malls are LLDPE, which, like HDPE, is largely
linear. This increased thickness results in the bags being less flexible. These bags can be used many

times.
Thus, most of the common items about us are polymeric. Table 1.4 gives a brief listing of some
of these materials along with the locations where they will be dealt within the book.
With the electronic age we can access the web to gather lots of general information about almost
any topic, including polymers. This book allows you to have a greater appreciation and understand-
ing of such information and the products about us, including our own bodies.

1.3 TODAY’S MARKETPLACE
As noted above, polymers are all around us. More than 100 billion pounds (50 million tons) of synthetic
polymers is produced annually in the United States (Tables 1.5 through 1.8), and the growth of the indus-
try is continuing at a fast rate. There is every reason to believe that this polymer age will continue as long
as petroleum and other feedstocks are available and as long as consumers continue to enjoy the comfort,

protection, and health benefits provided by elastomers, fibers, plastics, adhesives, and coatings. The 100

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