PROPERTIES OF MATERIALS: CERAMICS, PLASTICS, AND RUBBER
IDENTIFICATION OF CERAMICS:
Ceramics are solid articles that are produced from clay, mud, cement, or glass. Clay is the most common of
all the ceramic minerals. Thus, the term ceramics is simply means making articles with clay. Ceramic
materials are easily identified by the fact that they are brittle; that is, they can break or crack easily.
Ceramic Materials: In technology, ceramic products are grouped into three (3), which are:
1. Clay Ceramic Products- These include clay pots, tea cups, bricks, blocks, floor and wall tiles, ovens,
art pottery and kitchen and sanitary wares etc.
2. Glass Ceramic Products- These include bottles, lenses, mirrors, window panes, bulbs, flasks, and glass
tubes loaves etc
3. Cement Ceramic Products- some example are cement blocks, concrete, plaster and mortal etc.
Refractories: Refractories are clay ceramic products used for oven and furnace linings. Refractory ceramics
can withstand very high temperatures without breaking or melting.
Properties of Ceramics:
1. Ceramics can withstand very high temperatures.
2. They have high insulating property.
3. They can withstand chemical effect, that is they are corrosion resistant.
4. They have shiny surface.
5. They can withstand heavy compressive load.
6. They are very brittle in nature. That is, they can crack or break easily when dropped. This particular
property of ceramic is undesirable.
IDENTIFICATION OF PLASTICS:
Plastics are synthetic materials obtained from petroleum products. The word plastics originated from the
Latin word “plasticus” which means, “that which can be shaped or moulded”.
Types of Plastics: Plastics are classified into two main types:
A. Thermoplastics: Thermoplastics are plastics which can melt whenever they are subjected to heat. When
heated, they became soft and flow like liquid and they can be remoulded.
Examples of thermoplastic products are:
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Plastic cups,
Plastic plates,
Plastic buckets,
Plastic bowls, basins,
Plastic jerry cans use for domestic purposes
Crates for use in breweries.
B. Thermosetting Plastics / Thermosets: These are plastics which do not melt when subjected to heat.
They cannot be re-melted or remolded, instead they can burn when heated. The main advantage they
have over thermoplastics is that they cannot be readily dissolved in solvents and they are harder.
Examples of thermosets are:
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TV, telephone, and radio parts.
Plastic handles of cooking utensils e.g. pots and knives.
Plastic part of automobiles.
Plastic buttons of dresses.
Electrical fitting e.g. switches, plugs, sockets.
Plastic handles of screwdrivers.
Properties of Plastics:
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Plastics are light in weight.
Plastics do not rust.
They are good electrical insulators. That is they are very poor conductors of heat and electricity.
They are generally unstable at high temperatures.
They can change colour if exposed to sunlight for a long time.
Plastic do not decay even when they are buried in the soil.
IDENTIFICATION OF RUBBERS:
Rubber can be defined as a material which can be stretched or compressed, but can return to their original
length and shape when the applied force is removed. Rubber differs from plastics because rubber is more
elastic.
Types of Rubber: There are two types of rubbers:
i.
Natural rubber: This type of rubber is made from a milky liquid called rubber latex. This liquid is
obtained from rubber trees. Natural rubber is flexible, but has a poor resistance to abrasion.
ii.
Synthetic rubber: Synthetic rubber is manufactured from organic compounds, which are petroleum
bye products. It has a poor flexibility, but a very high resistance to abrasive.
Properties of Rubber:
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Rubbers are good electrical insulators.
They are lighter than water and hence can float when immersed in water.
They do not rust or corrode.
They are good shock-absorbers.
They are generally flexible.
Rubbers are highly elastic.
Elasticity is the property of a material which enables it to return to its original shape or length after being
stretched or compressed.
Evaluation Questions: Answer the following questions.
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Name the raw material for making each of the following: ceramics, plastics, and rubber.
State at least three properties of ceramics, plastics, and rubber respectively.
Name the two types of plastics.
What are the two types of rubber?
Give one major difference between plastics and rubber.