polymers Flashcards
where are polymers from
most plastics are made from crude oil
what are thermoforming polymers?
these plastics can be reheated and therefore shaped in various ways.
what can thermoforming polymers do when they are reheated?
they become mouldable after reheating as they do not undergo significant chemical change.
what happens to the molecules of thermoforning polymers whe reheated?
the molecules bonds aere weak and they become weaker when they are reheated.
what are some pros for thermoforming polymers?
highly recycable, astethically superior finishes, high impact resistance, can be remoulded/reshaped, chemical resistant
what are some cons for thermoforming polymers?
generally more expensive than thermoseeting polymers, can melt if heated.
what are thermosetting polymers?
once ‘set’ these plastics can not be reheated to soften shape and moulds.
what is the molecule structure for thermosetting polymers?
the molecules are cross linked in three dimensions and thid is why thry cannot be reshaped or recycled. the bond between the molecules are very strong.
what are some pros for thermosetting polymers?
more resistant to high temperatures, highly flexible, cost effective, thick to thin wall capabilities, astethic appearance, dimensional stability
what are some cons for thermosetting polymers?
cannot be recycled, cannot be reshspaed or moulded>
what are the properties of High impact polystyrene
clear, rigid, brittle and moderatly strong
what are common uses for High impact polystyrene
yougert containers, plastic cutlery,salad bowls
what are the properties of High density polythene?
flexible, translucent/waxy, waterproof, low cost, good chemical resistance
what are common uses of High density polythene?
food and drink containers, cleaning products, shoe parts
what are the properties of polythene teraphthate?
high strength, high rigity, low moisture absorbtion, good chemical resistance
