What is soda lime glass?
- A (ceramic) mixture of sand, limestone and sodium carbonate.
- When heated it can then be solidified into any desired shape.
- However, it has quite a low melting point, which limits its use.
What is borosilicate glass?
- It is a (ceramic) mixture of sand and boron trioxide.
- it has a high melting point, so is often used as kitchenware or in the lab.
What are clay ceramics?
- Clay is a ceramic material that can be found in the ground
- When wet, it can be moulded into a desired shape, and hardened by heating. This is because the water gets inbetween the layers of clay to make it slimy and malleable. When heated, the water evaporates away and strong bonds form between the layers as a result.
- It is an electrical insulator
What are composites?
A material that is made from two different materials with distinct properties.
One of these materials is the REINFORCEMENT. It is made of fibres or fragments of that material.
The other material is the MATRIX. It surrounds the reinforcment material and acts as a binder.
e.g, in concrete, sand and gravel are the reinforcement, wheras cement is the matrix/binder.
Why are most polymers solids at room temperature?
They have very strong intermolecular forces that take more energy (therefore higher temperatures) to be overcome.
[THIS HAS NOTHING TO DO WITH THE COVALENT BONDS!!]
W
Why are clay ceramics brittle?
When hit with a sharp blow, ions with the same charge become adjacent, and therefore repel one another and crack.
What are the two factors that affects a monomer’s properties?
- the conditions it was made in
- the monomer it was made from
What is the difference between LDPE and HDPE and why are these differences there?
LDPE (low density polyethene)
- is flexible
- because it is produced at room temperature under high pressures
HDPE (high density polyethene)
- is rigid/inflexible
- because it is produced at a low pressure and low temperature
(they both use different catalysts)
What are the two types of polymers and what are their properties?
Thermosetting:
- rigid/inflexible
- has links between chains
- does not melt when heated
Thermosoftening:
- flexible
- has weak intermolecular forces between chains
- does melt when heated
