Polymers

Question 1

What are addition polymers?

Answer 1

nade from a monomer or monomors with a carbon-carbon double bond

made from monmers based on ethene

Question 2

How can plastics be modified?

Answer 2

small molecules added between the chains, forcing them apart and allowing them to slide across eachother

Question 3

How is low density poly ethene formed?

Answer 3

polymerising ethene at high pressure and temperature via a free radical mechanism

this produces a molecule with a certian amount of chain branching

the branched chains don’t pack together which make them flexible and low dense.

useful for packing

Question 4

How are high density polyethen produced?

Answer 4

made a temperatures and pressures little greater than room

uses a Ziegler-Natta catalyst - named after its developers

much less branching

melting point and density is higher

Question 5

What is mechanical recycling?

Answer 5

seperate types of plastics

washed and may be ground into small pellets

can be melted and remoulded

Question 6

What is feedstock recyling?

Answer 6

plastics are heated to a temperature that will break the polymer bonds and produce monomers, can be used to make new plastics

for polypropene, it is a thermoplastic, it can only be reheated a limited number of time as the chains break and become shorter thus degrading the plastics properties