Lesson Notes By Weeks and Term - Junior Secondary School 1

FIRST TERM

SUBJECT:� BASIC TECHNOLOGY

CLASS:� JSS1

REFERENCE MATERIALS

• NERDC, Basic Technology for JSS, Book 1
• EVANS, Basic Technology for JSS, Book 1

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WEEK NINE AND TEN

TOPIC:� IDENTIFICATION OF PLASTIC AND RUBBER

CONTENT

• Plastic Material and Properties
• Rubber Material and Uses
• Methods in Processing Plastics and Rubber

PLASTIC MATERIALS AND PROPERTIES

Plastic is a light material that� is� produced by chemical processes and can be formed into� shapes when heated.� Plastic materials are produced by melting some chemicals together and allowing them to solidify.

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CLASSES OF PLASTIC

1. Thermoplastics are plastic materials that become soft and pliable when heated, without a change in its intrinsic properties. Polystyrene and polyethylene are thermoplastics. They are not affected by the application of heat and can be remolded . Examples are plastic plates, buckets, cups.�
2. Thermosets are polymers. Thermosets are plastic materials which cannot be affected by the application of heat. It sets permanently when heated and cannot be remolded. Examples are plastic handles of cooking utensils and knives, telephone parts etc

PROPERTIES OF PLASTIC

1. They are very light.
2. They are very cheap in price.
3. They are insulators.
4. They are corrosion resistant.

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ADVANTAGES OF PLASTICS

1. They� are lightweight.
2. They can be moulded into different shapes and sizes.
3. They are relatively inexpensive� to produce.

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DISADVANTAGES OF PLASTICS

1. Some plastic produce poisonous flames when burnt.
2. They litter the surroundings.

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EVALUATION

1. State three (3) properties of ceramic.
2. State three (3) properties of plastic.

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RUBBER MATERIAL AND USES��

Rubber is a non-metal product. It looks like plastics but is more elastic than plastic. It can be stretched easily .It returns to its original length� when it is� released after� being� stretched. Rubber does not allow water to pass through it. Rubber floats on water.

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The two types of rubber are natural or synthetic rubber.

Natural rubber comes from a milky liquid called LATEX which is extracted from the rubber tree. Synthetic rubber is produced from organic material derived from petroleum.

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USES OF RUBBER

1. It is used to make tyres for vehicles, hand gloves, electrical insulation.
2. It can be used to make buckets, rain coats, rain boots, catapults,�
3. It can be used as an elastic, water proof, shock absorber.

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METHODS OF PROCESSING PLASTICS AND RUBBER

Plastic can be processed by

1. Vacuum forming�
2. Extrusion
3. Calendaring�
4. Compression moulding
5. Injection moulding

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Rubber can be processed by

1. � Vacuum forming�
2. � Extrusion
3. � Calendaring�
4. � Compression moulding

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EVALUATION

1. Define rubber materials and state 3 uses of it.
2. State the common methods of processing plastics and rubber.

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READING ASSIGNMENT

Read Processing of materials from Introductory Technology (JSS1) by Evans.� Pages 36-38

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WEEKEND ASSIGNMENT

1. _____ is a hard brittle heat-resistant material made by firing a mixture of clay and chemicals at high temperature (a) Plastic� (b) Rubber (c) Ceramic (d) Wood
2. The following are properties of ceramics except (a) Ceramics are resistant to corrosion (b)They can withstand very high temperature� (c)They are electrical resistant .(d)ceramics are not brittle
3. ______ is a� light material that� is� produced by chemical processes and can be formed into� shapes when heated � (a) Rubber (b) Plastic (c) Metal (d) Wood
4. _______ are plastic materials that become soft and pliable when heated, without a change in their intrinsic properties (a) Thermometers (b) Thermo engine ( c) Thermosets (d) Thermoplastics
5. Rubber can be processed by the following methods except (a) Vacuum forming (b) Extrusion (c)� Calendaring� and Compression moulding� (d) Injection moulding

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THEORY

1. Differentiate between thermosets and thermoplastic materials.
2. Define rubber materials and uses.