24 - Polymers Flashcards
What is a polymer?
A substance of high average relative molecular mass made up of small repeating units
What is polymerisation?
The process in which monomers join together
Why don’t Polymers have a specific relative molecular mass?
The polymer molecules can be different lengths
What is Addition Polymerisation?
Many small molecules (monomers) join together to create very large molecules (polymers)
What is poly(ethene)?
A polymer formed when a large number of ethene monomers join together
Describe how ethene molecules form poly(ethene)
Ethene molecules have a double covalent bond between carbon atoms
One of the bonds in the double bond breaks open & another ethene molecule adds on
Process repeats, forming a long chain
Addition polymer is poly(ethene)
What process is used to combine ethene molecules to make poly(ethene)?
Addition polymerisation
What type of bond does Ethene molecules have between the carbon atoms?
Double covalent bond
What is the repeating unit?
Shows how the monomer has changed & how it repeats throughout the polymer chain
What is a synthetic polymer?
A polymer that is manufactured in a laboratory or factory
What type of polymer is poly(ethene)?
A synthetic polymer
Give some examples of naturally occurring polymers
And give the monomers of each polymer named
- DNA - nucleotides
- Starch - glucose
- Protein - amino acids
What is the general equation for ANY addition polymerisation?
What are the properties of Poly(ethene)?
- Flexible
- Cheap
- Electrical insulator
What are the uses of Poly(ethene)?
- Plastic bags
- Coating on electrical wires
What are the properties of Poly(propene)?
- Flexible
- Strong
What are the uses of Poly(propene)?
- Buckets
- Crates
What are the properties of Poly(chloroethene)?
- Tough
- Cheap
- Long lasting
What are the uses of Poly(chloroethene)?
Window frames
What is Poly(chloroethene) also known as?
PVC
What are the characteristics of PFTE?
- Tough
- Non-stick
What are the uses of PFTE?
Non stick coating on pans
What is condensation polymerisation?
When monomers join together & eliminate a small molecule (e.g. water)
What is the functional group of Esters?
-COO-
How are Esters formed?
Carboxylic acid reacts with an alcohol in the presence of a catalyst
What are the requirements to form a long chain of monomers?
Each monomer must have 2 functional groups, one at each end of the molecule
What is an Ester link?
Link is present in all polyester molecules
—> Consists of -COO-
What are some problems associated with polymers?
- Crude oil is finite & non-renewable
- Polymers are non-biodegradable - they cannot rot in landfill sites
- Greenhouse gases are produced during disposal by combustion
- Polymers need to be sorted correctly so that they can be melted and reformed into a new product
Why is it a problem that ** crude oil is finite & non-renewable for polymers?
Most of the monomers needed to make synthetic polymers are obtained from crude oil
—> Chemists will need to find new sources of monomers in the future
What does biodegradable mean?
A substance that can be broken down by microorganisms
How can we reduce the amount of waste that goes into incinerators or landfill sites?
- By reducing amounts of materials we use & reusing materials
- By recycling
What are the benefits to reducing the amount of waste that goes into incinerators or landfill sites?
- Helps conserve supplies of crude oil
- Less greenhouse gases are released into the atmosphere
How can we make the sorting of polymers easier?
Codes & symbols are used on plastic items to show what they are made of
Why is it difficult to recycle polymers?
Many steps are needed to obtain a new item
