Grade 9 Technology Summaries Term 4 (Via Afrika): These summaries are compiled using the Via Afrika textbook's Term 3 content. The summaries are in English, with additional notes provided by the compiler.
Contents:
Topic 3: Electrical/electronic systems
Unit 1: Electrical systems and c...
, Reduce - reuse - recycle Types of plastic and their uses
• How to produce less waste:
- Reuse containers and products to Polystyrene foam
reduce toxicity.
• Can be shaped and glued easily.
- Recycle and buy products made from
• Used to make 3D objects.
recycled material.
- Create compost from organic waste. • Polystyrene = the basis for ‘foamed’ plastics.
Sample
•
•
Properties of thermoplastic
Thermoplastics are the most commonly
used plastics - range from rigid to flexible.
Thermoplastics can be bent and shaped
U3: Processing:
investigation
skills - plastics
•
•
•
Made by heating.
Thermoplastic
Can be squeezed out into long shapes - extrusion.
Melted thermoplastics can be blown into shaped
cavities to make bottles and cans - blow
Summaries after sample
when heated, making them strong and easy
to work with. moulding.
• Thermoplastics are used as heat and • The plastic is heated by a vacuum-former.
electrical insulators and as packaging • Press moulding/compression moulding – pressing
containers. materials into various shapes.
• Plastics degrade slowly, releasing toxic • Injection moulding = process where heated
fumes and polluting the air. plastic is forced into a mould.
• Manufacturing plastic produces a lot of
Thermosetting plastic • Thermoplastics can be recycled.
chemical waste.
• Hardened thermosetting plastic can’t be soften
by reheating.
• Solidifies due to a chemical reaction.
• Made by heating powder in a mould to form
object.
• Ideal for products the must resist heat, scratching
and tough handling.
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