Materials and their Properties Flashcards
What is a ceramic?
Ceramics are non-metal solids with high melting points that aren’t made from carbon-based compounds.
- What is clay used to make?
- What properties of clay make it useful for this?
- Pottery and bricks
- When wet, clay can be moulded into different shapes. When it is fired at high temperatures, it hardens to form a clay ceramic.
Give some properties of glass.
- usually transparent
- can be moulded when hot
- can be brittle when thin
How is soda-lime glass made?
By heating a mixture of limestone, sand and sodium carbonate (soda) until it melts. When the mixture cools, it comes out as glass.
Is the melting point of soda-lime glass higher or lower than that of borosilicate glass?
Lower
How is borosilicate glass made?
A mixture of sand and boron trioxide is heated until it melts. When the mixture cools, it comes out as glass.
What is a composite?
A composite is made of one material embedded into another. Fibres or fragments of material (REINFORCEMENT) are surrounded by a MATRIX acting as a binder.
FIBREGLASS
1. Name the reinforcement and matrix that make up fibreglass.
2. Name two properties of fibreglass that come from its components.
3. Name some uses of fibreglass.
- Reinforcement = glass fibres
Matrix = polymer (plastic) - Low density (like plastic), very strong (like glass)
- Used in surfboards, skis and boats.
CARBON FIBRE
1. What matrix is used in carbon fibre composites?
2. What reinforcement is used in carbon fibre composites? [two options]
3. Name two properties of carbon fibre composites.
4. Name some uses of carbon fibre composites.
- Polymer
- Long chains of carbon atoms bonded together (carbon fibres) OR carbon nanotubes
- Very strong, light
- Used in aerospace and sports car manufacturing.
CONCRETE
1. Name the reinforcement and matrix.
2. Name a property of concrete.
3. Name a use of concrete.
- Reinforcement = aggregate (any material made from fragments - usually sand/gravel are used in concrete)
Matrix = cement - Strong
- Used as a building material (e.g in skate parks, pavements)
WOOD
Name the reinforcement and matrix in wood.
Reinforcement = cellulose fibres
Matrix = organic polymer
What two factors influence a polymer’s properties?
HOW it’s made and WHAT it’s made from.
What two factors influence a polymer’s properties?
HOW it’s made and WHAT it’s made from.
What reaction conditions are used to make low density poly(ethene)?
Moderate temperature, high pressure
Is low density poly(ethene) flexible or rigid?
Flexible
Name some uses of low density poly(ethene)
Plastic bags, water bottles
Name some uses of low density poly(ethene)
Plastic bags, water bottles
What reaction conditions are used to make high density poly(ethene)?
Lower temperature than that used to make low density poly(ethene).
Lower pressure
Catalyst
Give two uses of high density poly(ethene)
Water tanks, drainpipes
What is a monomer?
The repeating unit of a polymer.
THERMOSETTING vs THERMOSOFTENING POLYMERS
1. Describe the differences between the structure of a thermosetting and a thermosoftening polymer.
2. Can thermosoftening polymers be melted and remoulded when heated?
3. Can thermosetting polymers be melted and remoulded when heated?
- The monomers in a thermosetting polymer can form cross-links between the polymer chains, holding them together in a rigid structure. Thermosoftening polymers contain individual polymer chains entwined together with weak forces between chains.
- Yes
- No - they are strong, hard and rigid.
Name some properties of a ceramic.
- insulators of heat and electricity
- brittle
- stiff
Name some properties of polymers.
- flexible (can be bent without breaking)
- insulators of heat and electricity
- easily moulded
Name some properties of metals.
- malleable
- good conductors of heat and electricity
- ductile (can be drawn into wires)
- shiny
- stiff
