resources - thermosoftening and thermosetting polymers

Question 1

what are the factors that determine the properties of polymers?

Answer 1

• properties depend on the monomer and conditions used to make the polymer

Question 2

how do we change the conditions of a polymer?

Answer 2

• change the reaction temperature, the reaction pressure or the catalyst

Question 3

what is LDPE? how is it formed?

Answer 3

low density polyethene
- under high pressures and a trace of oxygen
- branched polymer chains make it so it can’t be tightly packed

Question 4

what is HDPE? how is it formed?

Answer 4

high density poly ethene
- formed using a catalyst at 50 degrees and a slightly raised pressure
- straighter polymer chains that can be packed more tightly together (stronger than LDPE)

Question 5

what are thermosoftening polymers? what happens when we heat them?

Answer 5

• polymer that will melt when heated, then remoulded/reshaped while they are soft and then go back to solid when cooled back down
  (form plastics)
• joined by intermolecular forces which are weak which break when heated. now polymer strands can separate from each other + melt. when cooled, melted polymer reforms intermolecular forces. polymer goes back to solid.

Question 6

what are thermosetting polymers?

Answer 6

• don’t melt when heated
• they form extensive cross-linking covalent bonds between chains in rigid materials which are heat resistant so do not break