Download Properties of materials

Unit 2: The Lifecycle of Materials
Section 3: Properties of materials
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Would you use paper to make a car?
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The answer is probably not, because paper is
not resistant enough to support strong forces.
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Steel, on the other hand, is tough and it's very
useful in car making.
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Likewise, glass is very useful to make windows
because of its transparence
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Copper is useful to make electrical wires
because of its electrical conductivity
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Plastic is useful to make bottles because it is
cheap and easy to mould
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Toughness, transparence and electrical
conductivity are examples of properties, which
are the way materials react to external
interactions, like forces, light, electricity, heat,
magnetism, chemical substances, etc.
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The properties of materials can be classified into
three types:
1.Physical
2.Chemical
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3. Ecological
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1. Physical properties
Physical properties involve the following interactions:
Electricity
Heat
Light
Magnetism
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External forces
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1. Physical properties
Regarding electricity and heat, materials can be classified in two groups:
●
●
Conductors: Electric current
and heat can be transmitted.
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Metals are good conductors
of heat and electricity:
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Insulators: Neither electric
current nor heat can be
transmitted. Wood, plastic,
glass, etc. are good
insulators of electricity and
heat.
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1. Physical properties
Regarding light, materials can be classified in three groups:
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Transparent, like
glass:
●
Translucent, like
plastic:
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Opaque, like
wood:
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1. Physical properties
Regarding magnetism, materials can be classified in two groups:
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Magnetic, like steel:
●
Non-magnetic, like all the rest:
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1. Physical properties
Regarding external forces, materials respond in several ways:
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Tough-brittle:
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Hard-soft:
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Elastic-Plastic:
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1. Physical properties
Regarding external forces, materials respond in several ways:
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Tough-brittle:
●
Steel is tough,
which means that
is difficult to
break. Cars are
made out of steel
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Glass is brittle,
which means that
is easy to break.
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1. Physical properties
Regarding external forces, materials respond in several ways:
●
● Hard-soft:
Glass is hard,
which means that it
is difficult to
scratch.
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Steel is soft,
which means that
is easy to scratch.
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1. Physical properties
Regarding external forces, materials respond in several ways:
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Rubber is elastic
because it can be
deformed
temporarily.
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Plasticine is
plastic, because it
can be deformed
permanently.
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Elastic-Plastic:
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2. Chemical properties
There are lots of chemical properties, but oxidation is a very important one:
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Steel is oxidable: it
combines with
oxygen and gets
rusty.
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Gold is
inoxidable: it
never gets rusty.
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Steel and other
metals can be
protected against
oxidation by
painting them.
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3. Ecological properties
In order to be ecological, a material must have four properties:
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Renewable
●
Recyclable
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Biodegradable
●
Non toxic
●
Wood has these
properties:
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Plastic hasn't:
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Summary
●
Physical properties:
–
Conductor / Insulator
–
Transparent /translucent
/opaque
●
Chemical
properties:
●
Ecological
Properties:
–
Oxidable
–
Renewable
–
Inoxidable
–
Recyclable
–
Magnetic /non-magnetic
–
Biodegradable
–
Hard/soft
–
Non toxic
–
Tough/brittle
–
Elastic/plastic
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