materials and their properties

• ceramics are non-metal solids with high melting points that aren't made from carbon-based compounds
• some ceramics can be made from clay
• clay is a soft material when it's dug up from the ground, so can be moulded into different shapes
• most glass made is soda-lime glass, which is made by heating a mixture of limestone, sand and sodium carbonate until it melts. when the mixture cools it becomes glass
• when fired at high temperatures, clay hardens to form a clay ceramic
• borosilicate glass has a higher melting point than soda-lime glass. it's made in the same way as soda-lime glass, using a mixture of sand and boron trioxide
• composites are made of one material embedded in another
• fibres or fragments of a material are surrounded by a matrix acting as a binder
• fibreglass consists of fibres of glass embedded in a matrix made of polymer. it has a low density, but is very strong
• carbon fibre composites also have a polymer matrix. the reinforcement is either made from long chains of carbon atoms bonded together or from carbon nanotubes. they are strong and light so are used in aerospace and sports car manufacturing
• concrete is made from aggregate embedded in cement. it's very strong.
• aggregate is any material made from fragments
• wood is a natural composite of cellulose fibres held together by an organic polymer matrix
• the properties of poly(ethene) depend on the catalyst that was used and the reaction conditions that it was made under
• low density poly(ethene) is made from ethene at a moderate temperature under a high pressure. it is flexible and used for bags and bottles
• high density poly(ethene) is also made from ethene but at a lower temperature and pressure with a catalyst. it's more rigid and is used for water tanks and drainpipes
• the monomers that a polymer is made from determine the type of bonds that form between the polymer chains. these weak bonds between the different molecule chains determine the properties of the polymer
• thermosetting polymers contain monomers that can form cross-links between the polymer chains, holding the chains together in a solid structure. these polymers do not soften when heated. they are strong, hard and rigid
• thermosoftening polymers contain individual polymer chains entwined together with weak forces between the chains. you can melt and remould them
• ceramics include glass and clay cermaic such as porcelain and bricks. they're insulators of heat and electricity, brittle and stiff
• polymers are insulators of heat and electricity, they can be flexible and easily moulded. they have applications in clothing and insulators in electrical items
• the properties of composites depend on the matrix/binder and the reinforcement used to make them
• in composites, a matrix is a material that holds the fibres together
• in composites, a reinforcement is a material that is used to increase the strength of a material
• metals are generally malleable, good conductors of heat and electricity, ductile, shiny and stiff. they have many uses, including in electrical wires, car bodywork and cutlery