These are plastics which can be repeatedly reheated and remoulded.
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What are Thermosetting plastics?
These undergo a chemical change resulting in them becoming permanently rigid. ie they cannot be reheated or reshaped.
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What are Elastomers?
These polymers have good elasticity i.e they can be distorted under pressure but will return to their original shape when the pressure is removed.
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What are the general properties of plastics?
They are good electrical and thermal insulators. They have good strength to weight ration, They have good atmospheric and chemical corrosion.
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What are the electrostatic forces which hold the molecule together known as?
Van der Waals bonds.
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Why do van der Waals allow the shape to be remoulded/reshaped?
These bonds can be easily broken with heat, breaking all bonds causes the material to return to its original shape.
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Where are rigid cross-links found?
Rigid cross-links are found within thermosetting platics and elastomers. They are a more rigid bond than van der Waals and do not react with the application of heat.
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What do Elastomers consist of?
Long chain molecules that can be considered to be coils, when the material is compressed the molecules distort, when released they return to their original shape. These coiled molecules give the Elastomers their elastic properties.
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Give an example of a thermoplastic material and why it's a thermoplastic material.
Clay. It is a thermoplastic because before it's been fired by the kiln it can be softened and reshaped with water. However when it has been fired, it becomes a much more rigid material that behaves as a thermosetting material.
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Give examples of non polymer thermosetting materials.
Ceramic materials is the most common, examples are: Cements, concretes, refractory materials (e.g firebricks used in kilns) House and engineering blocks, plant pots, paving slabs and wall tiles.
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Examples of thermoplastic materials
Clay in the wet state, used for model making and sculptures. Paper, can be reformed once mixing with water to make recycled paper. Metals - steel can be heated and reshaped. Glass.
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Examples of thermosetting materials.
Clay - once fired in the kiln, used for plant pots, domestic crockery, wall and floor tiles. Concrete - once the chemical reaction has occured it cannot be reshaped/remixed.
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Other cards in this set
Card 2
Front
What are Thermosetting plastics?
Back
These undergo a chemical change resulting in them becoming permanently rigid. ie they cannot be reheated or reshaped.
Card 3
Front
What are Elastomers?
Back
Card 4
Front
What are the general properties of plastics?
Back
Card 5
Front
What are the electrostatic forces which hold the molecule together known as?
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