cermaics, composites and polymers

• • ceramics are non metal solids with high melting points that aren't made from carbon-based compounds
• • some ceramics are made from clay
  • clay is a soft material when dug up, so can be moulded into different shapes, so can be used for pottery or bricks
  • clay is heated in a furnace to form a clay ceramic
• • some ceramics are made from glass
  • glass can be molded when hot and brittle when thin
  • most glass made is soda-lime glass, which is made from heating a mixture of limestone, sand and sodium carbonate
  • borosicilate glass has a higher melting point, and is made from heating a mixture of sand and boron trioxide
• • polymers are influenced from how it is made and what it is made from
  • for example, the properties of polyethene are depended on the catalyst used and the reaction conditions
  • low density polyethene is made from ethene at a moderate temperature under a high pressure - it is flexible and used for bags and bottles
  • high density polyethene are made from ethene at a lower temperature and pressure with a catalyst - it is rigid and used for water tanks and drainpipes
• • the monomers that a polymer is made from determine the bonds formed between the polymer chains
  • thermosoftening polymers contain individual polymer chains etwined with weak forces between the chains - they are melted when heated and can be remoulded
  • thermosetting polymers contain monomers that can form cross links between the polymer chains, holding the chains in a solid structure - they do not melt when heated and are strong and rigid