Page 349 - Carrahers_Polymer_Chemistry,_Eighth_Edition

312 Carraher’s Polymer Chemistry

burns rapidly forming water and energy, generally producing a flame. As early as 1914, firemen tried to

curtail the use of hydrogen-filled balloons. In 1922, New York City banded the use of hydrogen-fi lled

balloons because a city official was badly burned because of a fire caused by hydrogen-fi lled balloons.
There is an experiment that is often used in polymer demonstrations. Pointed objects such as long
pins and sticks are gently pushed into a blow-up balloon without exploding the balloon. This results
because the rubber polymer chains form about the impacting object to seal up the “hole” created
by the object. Thus, even in its seemingly solid state, the rubber balloon’s polymer chains are suffi -
ciently mobile to allow it to “heal” itself.
Balloons today are still made from the rubber latex from the rubber tree using molds. Color is
added as desired.
Foil balloons are derived from the effort of NASA Space Command with the concept and tech-
nology to metalizate plastic sheeting. While the balloons are often referred to as Mylar or silver

Mylars, they are not made from Mylar, a trade name for certain polyester film. They should be
referred to as simply foil balloons. They are made from nylon film coated on one side with polyeth-

ylene and metallized on the other. The nylon film gives the balloon some strength and the polyeth-

ylene gives it some flexibility and helps retard the release of the held gas.
9.13 LIGNIN
Lignin is the second most widely produced organic material after the saccharides. It is found in
essentially all living plants and is the major noncellulosic constituent of wood. It is produced at
11
10
an annual rate of about 2 × 10 tons with the biosphere containing a total of about 3 × 10 tons. It
contains a variety of structural units, including those pictured in Figure 9.7.
O
CH 3
O CH 3
O
O
O
O
O
O O
O
CH 3
O
HO
O
O HO H 3 C O H O
CH 3 O O

O
OH
O
H C O CH 3
3
O
H C OH
O 3 O
O OH
O
O

HO
FIGURE 9.7 Representative structure of lignin.

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