Polymers and Plastics - SWPS
Transcript of Polymers and Plastics - SWPS
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From Prentice Hall Science Explorer Chemical Interactions and Chemical Building Blocks©2006
Polymers and Plastics Table of Contents
Section 1 Chemical Bonding, Carbon Style Page 1. The Carbon Atom and Its Bonds Page 1
Forms of Pure Carbon Page 2
Section 2 Carbon Compounds Page 5 Oganic Compounds Page 5
Hydrocarbons Page 6
Straight Chains and Branches Page 7
Double and Triple Bonds Page 8
Saturated amd Imsaturated Hydrocarbons Page 9
Substitute Hydrocarbons Page 9
Polymers (Introduction) Page 11
Section 3 Polymers and Composites Page 13 Carbon’s Strings. Rings, and Other Things Page 13
Carbon Compounds Form Polymers Page 13
Natural Polymers Page 14
Synthetic Polymers Page 15
Composites Page 16
Too Many Polymers? Page 19
Appendix 1: Plastics Timeline Page 21
Appendix 2: Plastic Recyling Codes Page 22
Appendix 3: Some Common Synthetic Polymers Page 23
Appendix 4: 2000 U.S. Plastics Production
Appendix 5: Glossary
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Section 1 Chemical Bonding, Carbon Style
GUIDE FOR READING
Why can carbon form a huge variety of different compounds?
What are the different forms of pure carbon?
Open your mouth and say "ash." Uh-oh, you have a small cavity. Do you know
what happens next? Your tooth needs a filling. But first the dentist's drill clears away the
decayed part of your tooth.
Why is a dentist's drill hard enough and sharp enough to cut through teeth? The
answer has to do with the element carbon. The tip of the drill is made of diamond - a
form of carbon and the hardest substance on Earth. Because it has a diamond tip, a
dentist's drill stays sharp and useful. To understand why diamond is such a hard
substance, you need to take a close look at the carbon atom and the bonds it forms.
Figure 1 The tip of a dentist's drill is
made of diamond, a form of carbon.
The Carbon Atom and Its Bonds Recall that the atomic number of carbon is 6. This means that the nucleus of a
carbon atom contains 6 protons. Surrounding the nucleus are 6 electrons. Of these
electrons, four are valence electrons - the electrons available for bonding.
Figure 2 A. Only four of the six
electrons in a carbon atom are valence
electrons. B. Electron dot structures
show just the valence electrons.
Highlighted is a shared pair of
electrons between two carbon atoms.
C. Spherical models represent two
carbon atoms bonded together.
Interpreting Diagrams How many
valence electrons are involved in one
bond?
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As you have learned, a chemical bond is the force that holds two atoms together.
You can think of the two atoms as hooked together. A chemical bond between two atoms
is made up of the atoms' valence electrons. Two atoms gain, lose, or share valence
electrons in the way that makes the atoms most stable. The transfer or sharing of valence
electrons creates chemical bonds.
Atoms of all elements (except the noble gases) form chemical bonds. But few
elements have the ability of carbon to bond with both itself and other elements in so
many different ways.
Carbon atoms form more bonds than most other atoms. With four valence
electrons, each carbon atom is able to form four bonds. In comparison, hydrogen, oxygen,
and nitrogen can form only one, two, or three bonds. With four bonds to each carbon
atom, it is possible to form substances with many carbon atoms, even thousands of them.
As you can see in Figure 3, it is possible to arrange the same number of carbon
atoms in different ways. Carbon atoms can form straight chains, branched chains, and
rings. Sometimes even networks of two or more rings of carbon atoms are joined
together.
Figure 3 These carbon chains and
rings form the backbones for
molecules. In these molecules,
atoms of other elements are bonded
to the carbons.
Checkpoint How many bonds can a carbon atom form?
Forms of Pure Carbon Because of the ways that carbon forms bonds, the pure element can exist in
different forms. Diamond, graphite, and fullerene are three forms of the element carbon.
Diamond The hardest mineral-diamond-forms deep within Earth. At very high
temperatures and pressures, carbon atoms form diamond crystals. Each carbon atom is
bonded strongly to four other carbon atoms. The result is a solid that is extremely hard
and unreactive. The melting point of diamond is over 3,500°C. That's as hot as the
surface temperatures of some stars.
Diamonds are prized for their brilliance and clarity when cut as gems. They can
have color if there are traces of other elements in the crystals. Industrial chemists are able
to make diamonds artificially, but these diamonds are not beautiful enough to use as
gems. Like many natural diamonds, artificial ones are used in industry. Diamonds work
well in cutting tools, such as drills.
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Figure 4 The carbon atoms in a diamond are arranged in a crystal structure. Each atom
is bonded to 4 other atoms. The diamonds in this photo have not yet been cut and
polished by a jeweler.
Graphite Every time you write with a pencil, you leave a layer of carbon on the
paper. The "lead" in a lead pencil is actually graphite, another form of the element
carbon. In graphite, each carbon atom is bonded tightly to three other carbon atoms in flat
layers. However, the bonds between atoms in different layers are very weak, so the layers
slide past one another easily.
Run your fingers over pencil marks, and you can feel how slippery graphite is. If
you did the Discover activity, you have observed this property. Because it is so slippery,
graphite makes an excellent lubricant in machines. Graphite reduces friction between the
moving parts. In your home, you might use a graphite spray to help a key work better in a
sticky lock.
Figure 5 The carbon atoms in graphite are arranged in layers. The weak bonds between
the layers are not shown.
Applying Concepts How can you explain the slipperiness of graphite?
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Figure 6 The arrangement of
the carbon atoms in fullerenes
resembles the structure of a
geodesic dome or the pattern
on a soccer ball.
Fullerenes In 1985, scientists at Rice University in Texas made a third form of the
element carbon, a form that no one had identified before. The new form of carbon
consists of carbon atoms arranged in repeating patterns like the one shown in Figure 6.
This unique form of carbon is called a fullerene (FUL ur een) in honor of the architect
Buckminster Fuller. Fuller designed dome-shaped buildings, called geodesic domes,
which some fullerenes resemble. Because of its shape, one of these fullerenes, called
buckminsterfullerene, has been given the nickname "buckyballs."
Chemists are looking for ways to use fullerenes. Because fullerenes enclose a
ball-shaped open area, they may be able to carry other substances inside them. For
example, fullerenes may be used someday to carry medicines through the body.
Section 1 Review
1. What bonding properties of carbon allow it to form so many different compounds?
2. List three different forms of pure carbon.
3. What happens to valence electrons when a chemical bond forms between atoms?
4. Thinking Critically Comparing and Contrasting How do the differences in carbon
bonds explain why graphite and diamonds have different properties?
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Section 2 Carbon Compounds
GUIDE FOR READING
*What properties do many organic compounds have in common?
*What kinds of carbon chains are found in hydrocarbons?
*What are some examples of substituted hydrocarbons?
Imagine that you are heading out for a day of shopping. Your first purchase is a
red cotton shirt. Then you go to the drugstore, where you buy a bottle of shampoo and a
pad of writing paper. Your next stop is a hardware store to buy propane, a fuel used in
camping stoves and lanterns. Your final stop is the grocery store, where you buy cereal,
meat, and vegetables.
What do all of these purchases have in common? They all are made of carbon
compounds. Carbon atoms act as the backbone or skeleton for the molecules of these
compounds. Carbon compounds include gases (such as propane), liquids (such as olive
oil), and solids (such as wax and cotton). Mixtures of carbon compounds are found in
foods, paper, and shampoo. In fact, more than 90 percent of all known compounds
contain carbon.
Organic Compounds Carbon compounds are so numerous that they are given a specific name. With
some exceptions, a compound that contains carbon is called an organic compound. The
word organic means "of living things". Scientists once thought that organic compounds
could be produced only by living organisms. Organic compounds are indeed part of the
solid matter of every living thing on Earth. Products made from living things, such as
paper made from the wood of trees, are also organic com-pounds. However, organic
compounds can be produced artificially. For example, plastics, fuels, cleaning solutions,
and many other such products are organic compounds. The raw materials for most
synthetic organic compounds come from petroleum, or crude oil.
Figure 7 Did you know that
when you buy a shirt you are
buying carbon compounds?
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Figure 8 All living things contain organic compounds. Organic compounds include the
oils used to fry foods, the plastic wrap and foam tray in which these apples are packaged,
and even the apples themselves.
Inferring What does the dog have in common with the cooking oil, apples, plastic
wrap, and tray?
Many organic compounds have similar properties - for example, low melting
points and low boiling points. As a result, many organic compounds are liquids or gases
at room temperature. Organic liquids generally have strong odors. They also do not
conduct electricity. Many organic compounds do not dissolve well in water. You may
have seen vegetable oil, which is a mixture of organic compounds, form a separate layer
in a bottle of salad dressing.
Hydrocarbons Scientists classify organic compounds into different categories. The simplest
organic compounds are the hydrocarbons. A hydrocarbon (hy droh KAHR bun) is a
compound that contains only the elements carbon and hydrogen. The carbon chains in a
hydrocarbon may be straight, branched, or ring-shaped.
You might already recognize several common hydrocarbons. Methane, the main
gas in natural gas, is used to heat homes. Propane is used in portable stoves and gas grills
and to provide heat for hot-air balloons. Butane is the fuel in most lighters. Gasoline is a
mixture of several different hydrocarbons. And paraffin wax is a hydrocarbon that is used
to make candles.
Properties of Hydrocarbons All hydrocarbons are flammable, which means that
they burn easily. When hydrocarbons burn, they release a great deal of energy. This is
why they are used as fuels to power stoves and heaters, as well as cars, buses, and
airplanes.
Like most other organic compounds, hydrocarbons mix poorly with water. Have
you ever been at a gas station during a rainstorm? If so, you may have noticed a thin
rainbow-colored film of gasoline or oil floating on a puddle.
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Formulas of Hydrocarbons Hydrocarbon compounds differ in the number of
carbon and hydrogen atoms in each molecule. You can show how many atoms there are
of the elements that make up each molecule of a compound by writing a formula. A
molecular formula includes the chemical symbols of the elements in each molecule of a
compound, as well as the number of atoms of each element.
The simplest hydrocarbon is methane. Its molecular formula is CH4. The number
4 indicates the number of hydrogen atoms (H). Notice that the 4 is a subscript. Subscripts
are written lower and smaller than the letter symbols of the elements. Notice that the
symbol for carbon (C) in the formula is written without a subscript. This means that there
is one carbon atom in the molecule.
A hydrocarbon with two carbon atoms is ethane. The formula for ethane is C2H6.
The subscripts in this formula show that an ethane molecule is made of two carbon atoms
and six hydrogen atoms. A hydrocarbon with three carbon atoms is propane (C3H8). How
many hydrogen atoms does the subscript indicate? If you answered eight, you are right.
Checkpoint: What is a hydrocarbon?
Figure 9 The natural gas burning at
the top of this oil well is composed of
hydrocarbons.
Straight Chains and Branches If a hydrocarbon has two or more carbon atoms, the atoms can form a single line,
or a straight chain. In hydrocarbons with four or more carbon atoms, it is possible to have
branched arrangements of the carbon atoms as well as the straight chain.
Structural Formula To show how atoms are arranged in the molecules of a compound,
chemists use a structural formula. A structural formula shows the kind, number, and
arrangement of atoms in a molecule. Figure 10 shows the structural formulas for
molecules of methane, ethane, and propane. Each dash (-) represents a bond (two shared
electrons). In methane, each carbon atom is bonded to four hydrogen atoms. In ethane
and propane, each carbon atom is bonded to at least one carbon atom as well as to
hydrogen atoms. As you look at structural formulas, notice that every carbon atom forms
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four bonds. Every hydrogen atom forms one bond. There are never any dangling bonds -
no dangling dashes.
Figure 10 Each carbon atom in these
structural formulas is surrounded by
four dashes corresponding to four
bonds.
Each molecule of the propane
used as the fuel in this camping lantern
(right) has 3 carbon atoms.
Isomers Consider the molecular formula of butane - C4H10. This formula does not
indicate how the atoms are arranged in the molecule. In fact, there are two different ways
to arrange the carbon atoms in C4H10. These two arrangements are shown in Figure 11.
Compounds that have the same molecular formula but different structures are called
isomers (EYE soh murk). Each isomer is a different substance with its own characteristic
properties.
Notice in Figure 11 that a molecule of one isomer, butane, is a straight chain. A
molecule of the other isomer, isobutane, is a branched chain. Both molecules have four
carbon atoms and 10 hydrogen atoms, but the atoms are arranged
differently in the two molecules. And these two compounds have
different properties. For example, butane and isobutane have very
different melting points and boiling points.
Checkpoint: How do structural and molecular formulas differ?
Figure 11 C4H10 has two isomers, butane and isobutane.
Interpreting Diagrams Which isomer is a branched chain?
Double Bonds and Triple Bonds So far in this section, structural formulas have shown only single bonds between
any two carbon atoms. One bond; one dash. However, two carbon atoms can form a
single bond, a double bond, or a triple bond. A carbon atom can also form a single or
double bond with an oxygen atom. Structural formulas represent a double bond with a
double dash (C=C). You might think of the two atoms as doubly hooked together. A
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triple bond is indicated by a triple dash (C C). Bonds beyond triple bonds are not found
in nature.
Saturated and Unsaturated Hydrocarbons
Hydrocarbons can be classified according to the types of bonds between the
carbon atoms. If a hydrocarbon has only single bonds, it has the maximum number of
hydrogen atoms possible on its carbon chain. These hydrocarbons are called saturated
hydrocarbons. You can think of each carbon as being "saturated," or filled up, with
hydrogens. Hydrocarbons with double or triple bonds have fewer hydrogen atoms for
each carbon atom than a saturated hydrocarbon does. They are called unsaturated
hydrocarbons.
Notice that the names of methane, ethane, propane, and butane end with the suffix
-ane. Any hydrocarbon with a name that ends in -ane is a saturated hydrocarbon. If the
name of a hydrocarbon ends in -ene or -yne, it is unsaturated.
The simplest unsaturated hydrocarbon with one double bond is ethene (C2H4).
Many fruits, such as bananas, produce ethene gas. Ethene gas helps the fruit to ripen.
The simplest hydrocarbon with one triple bond is ethyne (C2H2), which is commonly
known as acetylene. Acetylene torches are used in welding.
ACTIVITY
Which of the following hydrocarbons contain single, double, or triple
bonds? (Hint: Remember that carbon forms four bonds and hydrogen forms
one bond.) C2H6 C2H4
C2H2 C3H8
C3H6 C3H4
C4H10
Figure 12 Unsaturated hydrocarbons have double and triple bonds. Ethene gas causes
fruits such as bananas to ripen.
Substituted Hydrocarbons
Hydrocarbons contain only carbon and hydrogen. But carbon can form stable
bonds with several other elements, including oxygen, nitrogen, sulfur, and members of
the halogen family. If just one atom of another element is substituted for a hydrogen atom
in a hydrocarbon, a different compound is created. Such compounds are called substituted
hydrocarbons. In a substituted hydrocarbon, atoms of other elements replace one or more
hydrogen atoms in a hydrocarbon. Substituted hydrocarbons include halogen-containing
compounds, alcohols, and organic acids.
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Compounds Containing Halogens In some substituted hydrocarbons, one or more
halogen atoms replace hydrogen atoms. Recall that the halogen family includes fluorine,
chlorine, bromine, and iodine.
One compound, Freon (CCl2F2), was widely used as a cooling liquid in
refrigerators and air conditioners. When Freon was found to damage the environment, its
use was banned. Safer compounds have taken Freon's place. Two compounds containing
halogens are still used in dry - cleaning solutions - trichloro-ethane (C2H3Cl3) and
perchloroethylene (C2H2Cl2).
Alcohols The group -OH can also substitute for hydrogen atoms in a hydrocarbon.
Each -OH, made of an oxygen atom and a hydrogen atom, is called a hydroxyl group
(hy DRAHKS il). An alcohol is a substituted hydrocarbon that contains one or more
hydroxyl groups.
Most alcohols dissolve well in water. They also have higher boiling points than
hydrocarbons of similar size. This is why the hydrocarbon methane (CH4) is a gas at
room temperature, while the alcohol methanol (CH3OH) is a liquid. Methanol is used to
make plastics and synthetic fibers. It is also used in solutions that remove ice from
airplanes. Methanol is very
poisonous.
Figure 13 Methanol is used for de-
icing an airplane in a snowstorm.
Classifying What makes methanol
a substituted hydrocarbon?
When a hydroxyl group is substituted for one hydrogen atom in ethane, the resulting
alcohol is ethanol (C2H50H). Ethanol is produced naturally by the action of yeast or
bacteria on the sugar stored in corn, wheat, and barley. Ethanol is a good solvent for
many organic compounds that do not dissolve in water. It is also added to gasoline to
make a fuel for car engines called "gasohol." Ethanol is used in medicines and found in
alcoholic beverages.
The ethanol used for industrial purposes is unsafe to drink. Poisonous compounds
such as methanol have been added. The resulting poisonous mixture is called denatured
alcohol.
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Figure 14 Formic acid is the simplest organic
acid. It is the acid produced by ands and is
responsible for the pain caused by an ant bite.
Organic Acids Bite into a lemon, orange, or grapefruit. These fruits taste a little
tart or sour, don't they? The sour taste of many fruits comes from citric acid, an organic
acid. An organic acid is a substituted hydrocarbon that contains one or more carboxyl
groups. A carboxyl group (kahr BAHKS il) is written as -COOH.
You can find organic acids in many foods. Acetic acid (CH3COOH) is the main
ingredient of vinegar. Malic acid is found in apples. Butyric acid makes butter smell
rancid when it goes bad. Stinging nettle plants make formic acid (HCOOH), a compound
that causes the stinging feeling. The pain from ant bites also comes from formic acid.
Esters If an alcohol and an organic acid are chemically
combined, the resulting compound is called an ester. Many
esters have pleasant, fruity smells. If you have eaten
wintergreen candy, then you are familiar with the smell of
an ester. Esters are also responsible for the smells of
pineapples, bananas, strawberries, and apples. Other esters
are ingredients in medications, including aspirin and the
local anesthetic used by dentists.
Checkpoint: What atoms are in a carboxyl group?
Figure 15 Esters are responsible for the pleasant
aroma and flavor of this strawberry shake.
Polymers Organic compounds, such as alcohols, esters, and others, can be linked together to
build huge molecules with thousands or even millions of atoms. A very large molecule
made of a chain of many smaller molecules bonded together is called a polymer (PAHL
ih mur). The smaller molecules-the links that make up the chain-are called monomers
(MAHN hi mur) The prefix poly- means "many," and the prefix mono- means "one."
Some polymers are made naturally by living things. For example, sheep make wool,
cotton plants make cotton, and silk-worms make silk. Other polymers, called synthetic
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polymers, are manufactured, or synthesized, in factories. If you are wearing clothing
made from polyester or nylon, you are wearing a synthetic polymer right now! And any
plastic item you use is most certainly made of synthetic polymers.
Figure 16 Chains of monomers that make up polymer
molecules are somewhat like these chains of plastic beads.
Natural polymers include the wool being sheared from
this sheep.
Comparing and Contrasting How do polymer molecules
differ from monomer molecules?
Section 2 Review 1. List properties common to many organic compounds.
2. Describe the different kinds of carbon chains that are found in hydrocarbons.
3. What is a substituted hydrocarbon? List four examples of substituted hydrocarbons.
4. Thinking Critically Problem Solving You are given two solid materials, one that is
organic and one that is not organic. Describe three tests you could perform to help you
decide which is which.
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Section 3 Polymers and Composites
GUIDE FOR READING
How does a polymer form?
Why are composite materials often more useful than single polymers?
D id you ever step into tar on a hot summer
day? Tar is a thick, smelly, black goo that sticks to
your shoes. Tar, from crude oil or coal, can be made
into rope, insulating fabric for clothes, and safety gear.
Manufacturers use tar to make countless products
ranging from sports equipment and automobile parts to
plastic house wares and toys.
Look around the room. How many things can
you see that are made of plastic? What materials do
you think people used to make these items before
plastic was invented? Many things that were once
made of metal, glass, paper, or wood have been
replaced by plastic materials.
Figure 1 The clothing, boots, goggles, and helmet
worn by this climber are all made of polymers. So is
the rope that protects her from falling off this frozen
waterfall in Colorado.
Carbon's Strings, Rings, and Other Things Plastics and the cells in your body have something in common. They are made of
carbon compounds. Carbon compounds contain atoms of carbon bonded to each other
and to other kinds of atoms. Carbon is present in more than two million known
compounds, and more are being discovered or invented every day.
Carbon's unique ability to form so many compounds comes from two properties.
Carbon atoms can form four covalent bonds. They can also bond to each other in chains
and ring-shaped groups. These structures form the "backbones" to which other atoms
attach.
Hydrogen is the most common element found with carbon in its compounds.
Other elements include oxygen, nitrogen, phosphorus, sulfur, and the halogens, especially
chlorine.
Carbon Compounds Form Polymers Molecules of some carbon compounds can hook together, forming larger
molecules. A polymer (PAHL uh mur) is a large, complex molecule built from smaller
molecules joined together. The smaller molecules from which polymers are built are
called monomers (MAHN uh murz). Polymers form when chemical bonds link large
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numbers of monomers in a repeating pattern. A polymer may consist of hundreds or even
thousands of monomers.
Many polymers consist of a single kind of monomer that repeats over and over
again. You could think of these monomers as linked like the identical cars of a long
passenger train. In other cases, two or three monomers may join
in an alternating pattern. Sometimes links between monomer
chains occur, forming large webs or netlike molecules. The
chemical properties of a polymer depend on the monomers from
which it is made.
Checkpoint: What are the patterns in which monomers come
together to form polymers?
Figure 2 Carbon atoms can form straight chains, branched
chains, and rings. In these drawings, lines represent covalent
bonds that can form between atoms.
Interpreting Diagrams How many covalent bonds does each
carbon atom form?
Figure 3 Like chains of paper clips
made of the same or different pieces,
polymers can be built from one kind or
several kinds of monomers.
Natural Polymers Polymers have been around as long as life on Earth. Plants, animals, and other
living things produce many natural materials made of large polymer molecules.
Plant Polymers Look closely at a piece of coarse paper, such as a paper towel. You
can see that it is made of long strings, or fibers. These fibers are bundles of cellulose.
Cellulose (SEL yoo lohs) is a flexible but strong natural polymer that gives shape to plant
cells. Cellulose is made in plants when sugar molecules (made earlier from carbon
dioxide and water) are joined into long strands. The cellulose then forms cell structures.
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Figure 4 Both animals and plants make polymers. A. The leaves and stems of these
desert plants are made of cellulose and other polymers. B. A cotton plant is a source of
polymers that people make into thread and cloth. C. These silk fabrics were made from
the threads of silkworm cocoons.
Comparing and Contrasting What do the polymers shown in these photos have in
common?
Animal Polymers Gently touch a spider web and feel how it stretches without
breaking. It is made from chemicals in the spider's body. These chemicals mix and react
to form a silken polymer that is one of the strongest materials known. Spiders spin webs,
egg cases, and traps for prey from these fibers. You can wear polymers made by animals.
Silk is made from the fibers of silkworm cocoons. Wool is made from sheep's fur. These
polymers can be woven into thread and cloth.
Your own body makes polymers. Tap your fingernail on a tabletop. Your
fingernails and the muscles that just moved your finger are made of proteins. Proteins are
polymers. Within your body, proteins are assembled from combinations of smaller
molecules (monomers), called amino acids. The properties of a protein depend on which
amino acids are used and in what order. One combination builds the protein that forms
your fingernails. Another combination forms the protein that carries oxygen in your
blood. Yet another forms the hair that grows on your head.
Checkpoint What are two examples of natural polymers from plants and animals?
Synthetic Polymers Many polymers you use every day are synthesized from simpler materials. Recall
that a synthesis reaction occurs when elements or simple compounds combine to form
complex compounds. The starting materials for polymers come from coal or oil. Plastics,
which are synthetic polymers that can be molded or shaped, are the most common
products. But there are many others. Carpets, clothing, glue, and even chewing gum can
be made of synthetic polymers.
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Figure 5 lists just a few of the hundreds of polymers people use. Although the
names seem like tongue-twisters, see how many you recognize. You may be able to
identify some polymers by their initials printed on the bottoms of plastic bottles.
Compare the uses of polymers listed in Figure 5 with their characteristics. Notice
that many products require materials that are flexible, yet strong. Others must be hard or
lightweight. When chemical engineers design a new product, they have to think about
how it will be used. Then they synthesize a polymer with properties to match.
Synthetic polymers are often used in place of natural materials that are too
expensive or wear out too quickly. Polyester and nylon fabrics, for example, are used
instead of wool, silk, and cotton to make clothes. Laminated countertops and vinyl floors
replace wood in many kitchens. Other synthetic polymers have uses for which there is no
suitable natural material. Compact discs, computer parts, artificial heart valves, and even
your bicycle tires couldn't exist without synthetic polymers.
Figure 5 You can find many applications of synthetic polymers in your own home (see
Appendixes 2 and 3.
Composites Every substance has its advantages and disadvantages. What would happen if you
could take the best properties of two substances and put them together? Composites
combine two or more substances as a new material with different properties. By
combining the useful properties of two or more substances in a composite, chemists can
make a new material that works better than either one alone. Many composite materials
include one or more polymers.
A Natural Composite The idea of putting two different materials together to get
the advantages of both comes from the natural world. Many synthetic composites are
designed to imitate a common natural composite-wood. Wood is made of long fibers of
cellulose, held together by another plant polymer called lignin. Cellulose fibers are
flexible and can't support much weight. At the same time, lignin is brittle and would
crack under the weight of the tree branches. But the combination of the two polymers
makes a strong tree trunk
POLYMERS AND PLASTICS
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The Development of Polymers The first synthetic polymers were made by changing natural
polymers in some way. Later, crude oil and coal became the
starting materials. Now new polymers are designed in
laboratories every year. See Appendix 1 for a more complete
timeline.
1839 Synthetic Rubber
Charles Goodyear invented a process that turned natural rubber
into a hard, stretchable polymer It did not get sticky and soft
when heated or become brittle when cold, a natural rubber does
Bicycle tires were an early use.
1869 Celluloid
Made using cellulose, celluloid became a substitute
for ivory in billiard balls and combs and brushes. It
was later used to make movie film. Because
celluloid is very flammable, other materials have
replaced it for almost all purposes, except table-
tennis balls.
1909 Bakelite
Bakelite was the first commercial polymer made from
compounds in coal tar. Bakelite doesn't get soft when heated,
and it doesn't conduct electricity. These properties made it
useful for handles for pots and pans, telephones, and for
parts in electrical outlets.
1934 Nylon
A giant breakthrough came with a synthetic fiber
that imitates silk. Nylon replaced expensive silk in
women's stockings and fabric for parachutes and
clothing. It can also be molded to make objects like
buttons, gears, and zippers.
1952 Fiberglass Composite
POLYMERS AND PLASTICS
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Fiberglass is mixed with polymers to form a material with the strength of glass fibers and
the moldability of plastic. Fiberglass composite is useful for
boat and airplane parts because it is much lighter than metal,
and it doesn't rust.
1971 Kevlar
Kevlar is five times as strong as the same weight of steel.
This polymer is tough enough to substitute for steel ropes
and cables in offshore oil-drilling rigs, but light enough to
use as parts for spacecraft. Kevlar is also used in protective
clothing for firefighters and police officers.
1989 LEP
Light-emitting polymers (LEP) are plastics that give off light
when exposed to low voltage electricity. Research on LEPs
points toward their use as flexible and more easy to- read
viewing screens in computers, digital camera monitors,
watch-size phones, and televisions.
Figure 6 Fiberglass makes a snowboard (left) both
lightweight and strong. The composites in a fishing rod
(right) make it so flexible that it will not break when
pulling in a large fish.
Synthetic Composites The idea of combining the properties of two substances to
make a more useful one has led to many new products. Fiberglass composites are one
example. Strands of glass fiber are woven together and strengthened with a liquid plastic
that sets like glue. The combination makes a strong, hard solid that may be molded
around a form to give it shape. These composites are lightweight, but strong enough to be
POLYMERS AND PLASTICS
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used as a boat hull or car body. Fiberglass also resists corrosion. It will not rust as metal
does.
Other composites made from strong polymers combined with lightweight ones
have many uses. Bicycles, automobiles, and airplanes built from such composites are
much lighter than the same vehicles built from steel or aluminum. Some composites are
used to make fishing rods, tennis racquets, and other sports equipment that need to be
flexible but strong.
Too Many Polymers? It is difficult to look around without seeing something made of synthetic
polymers. They have replaced many natural materials for several reasons. First, polymers
are inexpensive to make. Second, they are strong. Finally, they last a long time.
But synthetic polymers have caused some problems, too. Many of the disadvantages of
using plastics come from the same properties that make them so useful. It is often cheaper
to throw away plastic materials and make new ones than it is to reuse them. As a result,
they increase the volume of trash. Most plastics don't react very easily with other
chemical compounds. This means they don't break down into simpler materials in the
environment. In contrast, natural polymers do. Some plastics are expected to last
thousands of years. How do you get rid of something that lasts that long?
Is there a way to solve these problems? One solution is to use waste plastics as
raw material for making new plastic products. You know this idea as recycling.
Recycling has led to industries that create new products from discarded plastics. Bottles,
fabrics for clothing, and parts for new cars are just some of the many items that can come
from waste plastics. A pile of empty soda bottles can even be turned into synthetic wood.
Look around your neighborhood, and you may see park benches or "wooden" fences
made from recycled plastics. Through recycling, the disposal problem is solved and new,
useful items are created.
Figure 7 These rulers are just one product made from recycled plastic bottles.
Drawing Conclusions What would have happened to these bottles if they weren't
recycled?
POLYMERS AND PLASTICS
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Section 3 Review
1. How are monomers related to polymers?
2. What advantage does a composite have over the individual materials from which it is
made?
3. Why is it possible for carbon to form so many different kinds of compounds?
4. Make a list of polymers you can find in your home. Classify them as natural or
synthetic.
5. Thinking Critically Making Judgments Think of something plastic that you have
used today. Is there some other material that would be better than plastic for this use?
POLYMERS AND PLASTICS
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Appendix 1: Plastics Timeline
1862 Alexander Parker uses cellulose to make Parkesine but it is very expensive to
produce.
1865 End of the Civil War in the United States.
1866 Cellulose is used to make celluloid, which becomes a huge commercial success.
1891 Rayon is made from cellulose and used in clothing.
1907 Leo Baekeland creates Bakelite, a plastic that does not melt, burn, or dissolve in
acid.
1908 Cellophane, made from cellulose, becomes the first flexible, waterproof wrap.
1918 End of World War I.
1926 Polyvinyl chloride is developed from hydrocarbons.
1933 Polyethylene and Saran Wrap are produced in the same year.
1938 Teflon is discovered and is later developed for use as a non-stick coating in
cookware.
1939 Nylon is invented, and it replaces animal hair in toothbrushes.
1941 The creation of polyester eventually results in the manufacture of easy-care fabrics.
1943 Silly Putty is invented during the war and later sold as a toy.
1945 End of World War II.
1957 Both polypropylene and Velcro (made from nylon) are developed.
1965 The production of a polyamide known as Kevlar results in plastics with incredible
strength.
1971 The creation of hydrogels and hydroxyacrylates result in new products, such as
contact lenses.
1977 The first plastic that conducts electricity is developed.
1981 An increase in recycled plastic results in new applications. Recycled polyester
becomes Polar Fleece, a material used in outdoor gear.
1989 Technology to make extremely thin strands of different plastics results in
microfibers.
1990s Researchers create completely biodegradable plastics made from plants.
2001 Plastic superconductors are invented.
POLYMERS AND PLASTICS
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Appendix 2: Plastic Recycling Codes
POLYMERS AND PLASTICS
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Appendix 3: Some Common Synthetic Polymers
Type of Plastic Commercial
Names
Some Uses
Acrylic Acrylic, Orion sweaters, carpets
Cellulose acetate Tenite,
Chromspun,
Celera
toys, plastic forks, curtains double
knit fabrics
Nylon Cantrece, Antron clothing, carpet
Polyacrylic acid acrylic paint cars, homes, art
Polyacrylonitrile Orlon, Acrilan clothing, fabrics
Polybutadiene rubber, Buna S automobile tires
Polycarbonate Lexan, Merlon football helmets
Polyethylene Alathon shopping bags, electrical insulation
Polyethylene terephthalate
(polyester)
Mylar, Dacron,
Avisco,Jetspun,
Zantrel
soft drink bottles, photo-graphic film,
audiotapes, clothing, fabrics
Polymethacrylate Lucite, Plexiglass aircraft windshields
Polypropylene Herculon,Vectra luggage, fabrics
Polystyrene Styrofoam foam cups, videocassettes
Polytetrafluoroethylene Teflon stain-proof coating on upholstery,
non-stick coating on cooking utensils
Polyurethane foam rubber sofa cushions
Polyvinyl acetate Vinylite chewing gum, adhesives
Polyvinyl chloride Naugahyde,
Koroseal
raincoats, drain pipes, phonograph
records
Polyvinylidene chloride Saran Wrap food wrapping
Silicone RTV 615, Silastic water-repellant coatings, lubricants
Spandex Lycra, Spandelle elastic waistbands, tights, ski pants
Viscose rayon cellophane transparent tape
POLYMERS AND PLASTICS
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Appendix 4: 2000 U.S. Plastics Production
POLYMERS AND PLASTICS
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From Prentice Hall Science Explorer Chemical Interactions and Chemical Building Blocks©2006 - 25 -
Appendix 5: Glossary
acid A substance that tastes sour, reacts with metals and carbonates, and turns blue litmus
red. Releases an H+ ion when in solution.
alcohol A substituted hydrocarbon that contains one or more hydroxyl groups.
amino acid One of 20 kinds of organic compounds that are the monomers of proteins
base A substance that tastes bitter, feels slippery, and turns red litmus blue. Releases on
OH- ion in solution.
boiling point The temperature at which a substance changes from a liquid to a gas.
boiling The process that occurs when vaporization takes place inside a liquid as well as
on the surface.
bonding. The electrostatic attraction between atoms to form a stable unit, such as a
molecule.
BTU. Abbreviation for British Thermal Unit; unit of heat in the English system. Defined
as the amount of heat required to raise the temperature of one pound of water one degree
Fahrenheit. It is equivalent to 252 calories, 1055 joules, or 0.293 watt-hours.
buoyancy. Ability of an object to float in water. The less the density is compared to
water the more buoyant it will be.
calorie. The amount of heat required to raise the temperature of one gram of water one
degree Celsius. Food Calories (spelled with a capital C) are equal to 1000 calories, or one
kilocalorie.
carbohydrate An energy-rich organic compound made of the elements carbon,
hydrogen, and oxygen.
carboxyl group A -COOH group, found in organic acids. .
cellulose A flexible but strong natural polymer that gives shape to plant cells.
chemical bond The force that holds atoms together.
chemical change A change in which one or more substances combine or break apart to
form new substances.
chemical energy A form of energy that comes from chemical bonds.
chemical equation A short, easy way to show chemical reactions, using symbols instead
of words.
chemical formula A combination of symbols that represent the elements in a compound.
chemical reaction A process in which substances undergo chemical changes, forming
new substances with different properties.
chemical symbol A one- or two-letter representation of an element.
coefficient A number in front of a chemical formula in an equation that indicates how
many molecules or atoms of each reactant and product are involved in a reaction. In
3H2O the 3 is the coefficient, meaning there are 3 molecules of water.
combustion A rapid reaction between oxygen and fuel that results in fire.
complex carbohydrate A long chain, or polymer, of simple carbohydrates.
composite A combination of two or more substances that creates a new material.
compound A substance made of two or more elements chemically combined.
concentration The amount of one material in a certain volume of another material.
POLYMERS AND PLASTICS
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condensation The change of state from a gas to a liquid.
covalent bond A chemical bond formed when two atoms share electrons.
cross-linking. A process in which chemical links are set up between polymer chains.
crude oil. A fossil fuel; also known as petroleum; typically refers to oil taken directly out
of the ground (prior to processing).
density. The measurement of how much mass of a substance is contained in a given
volume; the mass per unit volume, specifically grams per milliliter. Density equals mass
divided by volume (d=m/v).
diamond A form of the element carbon; it is the hardest mineral crystal on Earth.
DNA DeoxyriboNucleic Acid.
double bond A chemical bond formed when atoms share two pairs of electrons.
elasticity. Ability of a material to stretch and then return to its original shape.
electron A tiny, negatively charged particle that move around the nucleus of an atom.
electron dot diagram A representation of the number of valence electrons in an atom,
using dots placed around the symbol of an element.
element A substance that cannot be broken down into any other substances by chemical
or physical means.
energy. A quantity possessed by an object or a system, which gives it the capability to do
work, or change the condition of matter. Energy can be measured in many units,
including kilocalories, joules or BTUs.
ester An organic compound made by chemically combining an alcohol and an organic
acid.
evaporation The process that occurs when vaporization takes place only on the surface
of a liquid.
feedstock. The raw or starting materials for industrial processes.
fiber. A slender and greatly elongated natural or synthetic filament capable of being spun
into yarn. Examples include wool, cotton, asbestos, and rayon.
flammable. Easily ignited. Syn: inflammable.
fluid Any substance that can flow.
fuel A material that releases energy when it burns.
fullerene A form of the element carbon that consists of carbon atoms arranged in a
repeating pattern.
gas A state of matter with no definite shape or volume.
glucose A sugar found in the body; the monomer of many complex carbohydrates.
graphite A form of the element carbon in which carbon atoms form flat layers.
halogen family The elements in Group 17 (7A) of the periodic table.
hydrocarbons. Molecules composed mostly of hydrogen and carbon atoms.
hydrogen ion A positively charged ion (H+) formed of a hydrogen atom that has lost its
electron.
POLYMERS AND PLASTICS
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hydroxide ion A negatively charged ion made of oxygen and hydrogen, OH-. found in
alcohols.
indicator A compound that changes color in the presence of an acid or a base.
International System of Units (SI) The system of units used by scientists to measure the
properties of matter.
ion An atom or group of atoms that has become electrically charged.
ionic compound A compound made of ironically bonded atoms or molecules.
ionic bond The attraction between oppositely charged ions.
isomer One of a number of compounds that have the same molecular formula but
different structures.
isotope An atom with the same number of protons and different number of neutrons from
other atoms of the same element.
Joule. International System of Units (SI) unit of energy; defined as the amount of energy
exerted by a force of one Newton over one meter. One joule (J) equals 0.239 calories.
Kilocalorie. International System of Units (SI) unit of heat; defined as the amount of heat
needed to raise the temperature of one kilogram of water by one degree Celsius. One
kilocalorie (kcal) equals 4,184 joules.
kilogram. International System of Units (SI) unit of mass. One kg (1000 grams) is
equivalent to 2.2 pounds.
liquid A state of matter that has no definite shape but has a definite volume.
mass A measure of how much matter is in an object.
mass number The sum of the protons and neutrons in the nucleus of an atom.
matter Anything that has mass and occupies space.
melting point The temperature at which a substance changes from a solid to a liquid.
melting The change in state from a solid to a liquid.
mixture Two or more substances that are mixed together but not chemically combined.
model. Any representation of a system, or its compo-nents, to help one study and
understand how it works.
molecular compound A compound consisting of molecules of covalently bonded atoms.
molecular formula A combination of chemical symbols that represent the elements in
each molecule of a compound.
molecule. A combination of two or more atoms.Smallest unit of matter that retains its
physical and chemical properties. A molecule may be a single atom or a group of atoms
bonded together. Examples include Ne, H2, H2O.
monomer One molecule that makes up the links in a polymer chain. Small, carbon-based
molecules from which polymers are built. Literally means "one part."
natural polymer. Polymers found in the environment. Examples include cellulose, DNA,
and starch.
neutralization A reaction of an acid with a base, yielding a solution that is not as acidic
or basic as the starting solutions were.
POLYMERS AND PLASTICS
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neutron A small particle in the nucleus of the atom, with no electrical charge.
noble gas An element in Group 18 of the periodic table.
nonpolar The description of a covalent bond in which electrons are shared equally, or of
a molecule containing nonpolar bonds, or polar bonds that cancel out.
nucleic acid A very large organic compound made up of carbon, oxygen, hydrogen,
nitrogen, and phosphorus; examples are DNA and RNA.
nucleotide An organic compound that is one of the monomers of nucleic acids.
nucleus The central core of an atom containing protons and usually neutrons.
organic acid A substituted hydrocarbon with one or more of the -COOH group of atoms.
organic compounds Most compounds that contain carbon.
period A horizontal row of elements in the periodic table.
periodic table A chart of the elements showing the repeating pattern of their properties.
petroleum. A fossil fuel; also known as crude oil; typically refers to oil during and after
industrial processing.
pH scale A measure of the concentration of hydrogen ions in a solution.
physical change A change in a substance that does not change its identity; for example, a
change of state.
physical property. An intrinsic property of a material, such as density, melting point, or
hardness.
plasma A state of matter in which atoms are stripped of their electrons and the nuclei
packed closely together.
plastic A synthetic polymer that can be molded or shaped. (adjective) Capable of being
molded. (noun) Any of numerous processed polymers of high molecular weight.
plasticizer. A material added to a plastic to increase its flexibility and workability.
polar The description of a covalent bond in which electrons are shared unequally, or of a
molecule containing polar bonds that do not cancel out.
polyatomic ion An ion that is made of more than one atom.
polymer. A very large molecule made of many repeating small molecular units bonded
together; lit-erally means "many parts."
polymerization. The act of chemically bonding many identical or related basic units
(monomers) together to form a polymer.
precipitate A solid that forms from a solution during a chemical reaction.
product A substance formed as a result of a chemical reaction.
protein An organic compound that is a polymer of amino acids.
pure substance A substance made of only one kind of matter and having definite
properties.
PVA. Abbreviation for polyvinyl alcohol, a liquid polymer.
PVC. Abbreviation for polyvinyl chloride, a solid plastic polymer used to make objects
such as pipes.
reactant A substance that enters into a chemical reaction.
reactivity The ease and speed with which an element or compound combines with other
elements and compounds.
POLYMERS AND PLASTICS
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replacement reaction A reaction in which one element replaces another in a compound;
or when two elements in different compounds trade places.
RNA RiboNucleic Acid.
salt An ionic compound that can form from the neutralization of an acid with a base.
saturated hydrocarbons A hydrocarbon in which all the bonds between carbon atoms
are single bonds.
saturated solution A mixture that has so much solute in it that no more will dissolve.
semiconductor An element that can conduct electricity under some conditions.
solid A state of matter that has a definite volume and a definite shape.
solubility A measure of how well a solute can dissolve in a solvent at a given
temperature.
solute The part of a solution present in a lesser amount and that is dissolved by the
solvent.
solution A very well-mixed mixture.
solvent The part of a solution present in the largest amount and that dissolves other
substances.
structural formula A description of a molecule that shows the kind, number, and
arrangement of atoms. Method of expressing chemical bonds among atoms in a molecule
using lines to represent bonds between shared pairs of electrons.
subscript A number in a formula written lower and smaller than the symbol to indicate
the number of atoms of an element in a molecule. In 3H2O the 2 is the subscript, meaning
there are 2 atoms of hydrogen in a molecule of water.
substituted hydrocarbon A hydrocarbon in which one or more hydrogen atoms have
been replaced by atoms of other elements.
suspension A mixture in which particles can be seen and easily separated by settling or
filtration.
symbol A one- or two-letter set of characters that is used to identify elements.
synthesis A chemical reaction in which two or more simple substances combine to form
a new, more complex substance.
synthetic. Produced by chemical reactions in a laboratory rather than through natural
processes, manufactured.
temperature A measure of the average energy of motion of the particles of a substance.
thermal energy The total energy of a substance's particles due to their movement or
vibration.
thermoplastic. Any of the plastics that can be continually and repeatedly formed and
reshaped with the application of heat and pressure.
thermosetting. Applied to plastics that cannot be reshaped once formed. Thermosetting
polymers are often a result of cross-linked bonds.
trade-off. A balancing of factors, all of which are not attainable at the same time; getting
one thing at the cost of another. The trade-off is the aspect that is given up and can only
be evaluated in the context of what it was exchanged for.
unsaturated hydrocarbon A hydrocarbon in which one or more of the bonds between
carbon atoms is double or triple.
POLYMERS AND PLASTICS
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unsaturated solution A mixture in which more solute can be dissolved.
valence electrons The electrons that are farthest away from the nucleus of an atom and
are involved in chemical reactions.
vaporization The change of state from a liquid to a gas.
viscosity The resistance of a liquid to flowing.
volume The amount of space that matter occupies.
waste stream. General term used to denote the discarded material output of an area,
location, or facility.
weight A measure of the force of gravity on an object.