Using Resources Flashcards
What is meant by a material’s strength?
The resistance of a material to an applied force
How are ceramics made?
Shaping and then firing a non-metallic material, such as clay, at a high temperature.
Types of clay ceramics are?
Brick, china and porcelain.
What does it mean for a material to be brittle?
It will snap easily
What are ceramics?
A group of hard, brittle, heat-resistant and corrosion-resistant materials
What are the two main types of ceramics?
Clay ceramics and glass
What is the type of glass we mostly use?
Soda-lime glass
How is soda-lime glass made?
by melting a mixture of sand (silicon oxide), sodium carbonate, and limestone, then allowing the molten liquid to cool and solidify.
Why can clay ceramics be used for building?
They have a high compressive strength
How is borosilicate glass made and how is it different from soda-lime?
Borosilicate glass is made by heating sand with boron trioxide. Borosilicate glass has a much higher melting point than soda-lime glass.
What is a composite material?
A composite material consists of two or more materials with different properties, that have been combined to produce a material with more desirable properties.
What are the two components making up most composites.
The reinforcement and the matrix
What is the reinforcement of a composite?
It is often long solid fibres or fragments.
What is the matrix of a composite?
Usually something that is soft, then hardens - it binds the reinforcement together.
What are polymers?
Polymers re large molecules of high relative molecular mass, made by linking together lots of smaller molecules called monomers
What to the properties of a polymer depend on?
the monomers from which it was made and the conditions of the chemical reaction.
Generally, polymers have properties such as?
flexible, easily shaped, and good insulators of heat and electricity.
What are the two main types of poly(ethene)?
Low-density (LDPE) and high-density (HDPE)
Structure of LDPE
Low density branched chains which prevent tight packing
Structure of HDPE
High density straight chains which allow for tight packing.
Bonding and forces of LDPE
Weak intermolecular forces
Bonding and forces of HDPE
Strong intermolecular forces
Formation of LDPE
Moderate temperatures, high pressure and trace of oxygen (catalyst)
Formation of HDPE
Lower temperatures/pressure, and a catalyst at 50 degrees c
Properties of LDPE
Weaker structure, flexible with low melting points
Properties of HDPE
Stronger structure, rigid with high melting points
Thermosoftening polymers are?
- Made from lots of polymer chains held together by weak intermolecular forces
- The weak intermolecular forces break easily when heated, melting the polymer
- They can be remoulded into a different shape and will harden when cooled
Thermosetting polymers are?
-Made from lots of polymer chains, held together by strong covalent bonds
- These covalent bonds require a lot of energy to break, so don’t soften when heated
- These polymers are hard, strong, and rigid.
Structure of thermosoftening polymers
Long straight chains that are tangled up
Structure of thermosetting polymers
Rigid structure with fixed chains
What is the key difference between metals and alloys
Alloys are malleable
