addition polymerisation Flashcards
define addition polymerisation
reacting lots of monomers to form a polymer
what does the compound have to have for an addition reaction to take place
a double bond
C = C
what is the tip for drawing addition polymerisation reactions
do C = C and then build of it
how do you modify plastics
by using plasticisers as they get between the polymer chains forcing them apart so they can slide across each other
why can’t polyalkene be biodegraded
polyalkenes have a backbone of saturated alkene molecule
these have strong non polar covalent bonds causing them to be unreactive
so they can’t be biodegraded by enzymes
how do you make low density polyethene
polymerising ethene at a high pressure and temperature through the free radical mechanism
name the properties of low density polyethene
a branched polymer so strands don’t pack together well
so is flexible, stretches, low density
makes it suitable for:
- plastic bags
- sheeting
- insulation for electric cables
how do you make high density polyethene
made at temperatures and pressures little greater than room conditions
uses a Ziegler- Natta catalyst
name the properties of high density polyethene
polymer with less branching so chain can pack together well
so more dense, higher boiling point due to more surface contact
makes it suitable for:
- milk crates
- buckets
- bottles
name 2 solutions to pollution by plastics
- mechanical recycling
- feedstock recycling
explain the process of mechanical recycling
- separate different types of plastics
- plastics are washed
- sort
- ground them up into small pellets
- these are melted and remoulded
explain the process of feedstock recylcing
- plastics are heated to temperatures that break polymers bonds
- this produces monomers
- which are then used to make more plastics
what is the issue with thermoplastic polymers
thermoplastic polymers will soften when heated so can be reused
but heating causes some of chains to break and become shorter which degrades the plastics properties
