Using resources 3 Flashcards
Ceramics/composites/polymers, The Haber process, NPK fertilisers
What are ceramics?
Non- metal solids with high melting points but that are NOT made from carbon-based compounds.
How are clay ceramics made?
Shaping wet clay and then heating in a furnace.
What is clay’s ability to be moulded when wet and hardened when fired at high temps useful for?
Making pottery and bricks.
Name ceramics.
-Clay
-Glass
Properties of glass
Glass is generally transparent, can be brittle when thin, and can be moulded when hot.
What is most of the glass we use?
Soda-lime glass.
How is soda-lime glass made?
By heating a mixture of sand, sodium carbonate and limestone until it melts.
When the mixture cools, it comes out as glass.
Which type of glass has a higher melting point than soda-lime glass?
Borosilicate glass.
How is borosilicate glass made?
By heating a mixture of sand and boron trioxide until it melts.
When the mixture cools, it comes out as glass.
What do the properties of polymers depend on?
-What monomers they are made from
-The conditions under which they are made
Which 2 polymers are produced from ethene?
Low density (LD) and high density (HD) poly(ethene).
Low density poly(ethene).
-Made from ethene at a moderate temperature under a high pressure
-It’s flexible, so used in bags and bottles
High density (HD) poly(ethene).
-Made from ethene at a lower temperature and pressure
-With a catalyst
-It’s more rigid so used for water tanks and drainpipes
Which type of polymers melt when heated?
Thermosoftening polymers.
Which type of polymers do not melt when heated?
Thermosetting polymers.
Explain what thermosoftening polymers are in terms of their structures.
Thermosoftening polymers contain individual polymer chains joined by weak intermolecular forces, allowing the plastic to be melted and remoulded.
Explain what thermosetting polymers are in terms of their structures.
(On the other hand)
Thermosetting polymers contain monomers which form cross-links between the polymer chains and hold the chains together in a solid structure.
Unlike thermosoftening polymers, they don’t soften when heated.
Instead, they are strong, hard and rigid.
What are cross-links?
Covalent bonds found between the polymer chains in thermosetting polymers.
What are composite materials?
Materials consisting of two or more materials with DIFFERENT properties, that have been combined to produce a material with more DESIRABLE properties.
What two materials are most composites made of?
-Reinforcement
-Matrix
What is the reinforcement? (composites)
Fibres or fragments of a material.
What is the matrix? (composites)
Usually something that starts soft and then hardens.
It binds the reinforcement together.
Describe the structure of a composite material.
Most composites are made of two materials:
A matrix which surrounds and binds together fibres/ fragments of the other material (which is called the reinforcement).
Name some composite materials.
Fibreglass
Carbon fire
Concrete
Wood