Childrens Illustrated Encyclopedia

413

PVC

Electrical

wires have a

coating of flexible

PVC (polyvinyl

chloride), which is

also used to make

inflatable toys.

PolyEthylEnE

Plastic bags are often made of

polyethylene, a plastic that can

be made into a tough, flexible

film. When produced in thicker

layers, polyethylene is also used to

make bottles, bowls, and other

household containers.

Many MatErials that we use are

natural, such as cotton, wool, leather,

wood, and metal. they come from

plants or animals, or they are

dug from the ground. Plastics

can be used in place of natural

materials, and they are used to

make clothes, parts for cars, and

many other products. Plastics are

synthetic materials, which means

that they are made from chemicals

in factories. the chemicals come

mainly from oil, but also from natural gas and coal. an

important quality of plastics is that they are easy to shape.

they can be used to make objects of all kinds, as well as fibers

for textiles. Extra-strong glues, long-lasting paints, and lightweight

materials that are stronger than metal—all of these products are made

of plastics with special qualities. none can be made with natural materials.

Kinds of PlastiCs

there are thousands of

different plastics. some of

the most common types are

shown here.

Polymers

Plastics are polymers, which

are substances with molecules

composed of long chains of atoms.

this is why the names of plastics

often begin with poly, which

means “many.” long molecules

give plastics their special qualities,

such as flexibility

and strength.

PolystyrEnE

Packaging made from

polystyrene is light

and rigid. tough

plastics often contain

polystyrene.

nylon

fibers of nylon, a strong but

flexible plastic, are used to

make ropes and hard-

wearing fabrics.

solid nylon is

used to make

gearwheels and

other hardware.

PolyCarbonatE

Goggles need to be clear

and strong, two qualities

of polycarbonate plastic.

other uses include

car lights and

crash helmets.

Beech StarShip 1

in aircraft, composites can be used to

replace many metal parts. this aircraft

is made almost entirely of composites

that are highly resistant to corrosion and

cracking.

CoMPositEs

strong fibers are put into tough plastics

to create materials called composites

(right), which are very strong yet light

and easily shaped. thin fibers of glass,

carbon, or Kevlar (a strong plastic)

are used.

Molecule of

polyethylene

Carbon-fiber

sheet

Carbon-fiber

sheet

Epoxy layer

Honeycomb

of tough

plastic

Layer of

epoxy (plastic

adhesive) Find out more

atoms and molecules

Chemistry

Coal

Machines

oil

technology

baKElitE

bakelite was invented in 1909 by the

american chemist leo baekeland. it

was the first plastic to be made from

synthetic chemicals.

Plastics

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