C15//2 Flashcards
what does the property of a polymer depend on
the monomers used to make it
what is high density poly(ethene) made from
ethene using a catalyst at 50 degrees and a slightly raised pressure
how is low density poly(ethene) formed
when using very high pressures and a trace of oxygen
what is different about the two types of poly(ethene)
High density has a higher softening temperature and is stronger
what is a thermosoftening polymer
a polymer made of individual polymer chains that are tangled together
what are the properties of a thermosoftening polymer
forces between the polymer chains are weak
what happpens when you heat a thermosftening polymer
the weak intermolecular forces are broken and the polymer softens
when the polymer cools down the intermolecular forces bring the polymer molecules back together so it hardens
what can you do with a thermosoftening polymer
moulded into shape and remoulded
what is a thermosetting polymer
do not melt or soften when heated
why do thermosetting polymers not melt or soften when heated
they have strong covalent bonds which forms cross links between their polymer chains
what is the most common form of glass
soda - lime
what is soda lime glass made from
sand
limestone
sodium carbonate
what is borosilicate made from
sand and boron trioxide
what is borosilliate used for
ovenware as it has a high melting point
what are some examples of ceramics
bricks, sinks, pottery
what are clay ceramics
hard, but brittle materials
they are electrical insulators and resistant to chemicals
how are ceramics made
by moulding wet clay into shape and then heating them in a furnace
what is reinforcement
a matrix (binder) of one material surrounding and binding together fibres or fragments of the other material
give an example of one composite and how it is made more useful
glass and ceramics are both brittle and when they are combined and heated together they are hard and very tough
