FIND OUT MORE. Alloys 174 • Chemistry 162 • Heat 168–169 • New Materials 175
170 Science and Technology
Any substance that is used to make something is a
material. Natural materials such as stone and wood
are used as they are found in nature.. SYNTHETIC
materials are made from natural materials with the
help of heat and chemical reactions.
HOW ARE MATERIALS USED?
The chosen materials for a product need to be shaped
and joined. Wood is shaped by sawing, planing, and
drilling. It is joined with nails, screws, or glue. Metal
is bent and hammered into shape — or heated until it
melts, and poured into moulds. Metal is joined with
nuts and bolts, rivets, or by welding.WHAT ARE MATERIALS’ PROPERTIES?
Materials are selected for use according to their
properties (characteristics). Mechanical properties, such
as strength, are important for materials used in
construction. Chemical properties show if a material
will react with other materials. Thermal properties
show how a material conducts heat.HOW STRONG IS A SPIDER’S WEB?
Millions of years of evolution have produced natural
materials ideally suited to the jobs they do. A spider's
web is, weight-for-weight, 10 times as strong as steel,
and far more elastic. Bones, teeth, and tusks are also
very strong natural materials. They can be used every
day for a hundred years without breaking.A substance made artificially, by heat and chemical
reactions, is a synthetic. It may be similar
to a natural material, or have
completely new properties.WHAT WERE THE FIRST SYNTHETICS?
Heat melts sand and other minerals to make glass.
The first glass bottles were made about 3,500 years
ago in Ancient Egypt. The first modern synthetic was
made in 1909, when Leo Baekeland, an American
chemist, created a plastic called Bakelite.WHAT IS A COMPOSITE MATERIAL?
Composite materials combine the useful properties of
two or more materials in one. Steel is strong and
concrete is strong, but steel-reinforced concrete is
even stronger. It is used for constructing tall buildings
and long bridges.1 HEAT-RESISTANT CLOTHING
Many natural and synthetic fibres burn easily, but the
fibres used to make a firefighter’s suit are heat and
flame resistant. The whole suit is coated with a thin
layer of aluminium to reflect heat away from the
surface, like a mirror.1 GLASS-REINFORCED PLASTIC
(GRP) CHAIR
A GRP chair is light and tough.
It is made from glass fibres in
plastic. The fibres stop cracks
from spreading through the
material, giving it great strength.1 SPIDER’S WEB
A spider weaves its web from
silk fibres made from proteins
called fibroin. The silk is not
easily broken because it is both
strong and elastic.SYNTHETICS
Materials
TENSILE TEST 3
This machine tests the strength of
the plastic toy by using a pulling
(tensile) force. If the head comes
off easily, the toy is a choking
hazard to small children.materials