Condensation part 2

Question 1

How is nylon made indsutrially?

Answer 1

nylon-6,6 is made from 1, 6-diaminohexane and hexane-1, 6-dicarboxylic acid

Question 2

What is kevlar?

Answer 2

• made from benzene–1, 4-diamine and benzene-1, 4-dicarboxylic acid

Question 3

How is Kevlar strong?

Answer 3

• due to the rigid chains and the ability of the flat aromatic rings to pack together held by strong intermolecular forces
• the polymer, developed in the 1960s by Stephanie Kwolek of the DuPont company, is credited with saving some 3000 lives because of its use in bullet proof vest and anti-stab clothing as warn by the police

Question 4

What are polypeptides

Answer 4

also are polyamides

they may be made from a single amino acid monmer or different ones

Question 5

What is different about polypeptides?

Answer 5

• each amino acid has both an amine group and a carboxylic group
• so the amine group of one amino acid can react with the carboxylic acid group of another
• a molecule of water is eliminated and a condesnation polymer can begin to form

Question 6

What is the problem with poly(ethene) and poly(propene) ?

Answer 6

• they are not biodegradeable
• nothing in the natural environment that will easily break then down and they persist for years
• usually disposed in landill or incineration
• some are melted and remoulded

Question 7

Why are these polymers not biodegradeable?

Answer 7

• they are basically long-chain alkane molecules
• alkanes are unreactive because have only strong, non polar C-H and C-C bonds

Question 8

What are the potential uses of these polymers? What is the downside?

Answer 8

• they can be burnt to CO2 and water to produce energy
• although posonous Co may be released into the atmospher if the combustion is incomplete
• add to the increasing level of CO2 in the atmosphere

Question 9

What is the problem with burning polystyrene?

Answer 9

• may release toxic produicts on burnig
• complete combustion of polysytrene (a hydrocarbon) would produce CO2 and H2O only
• however under cetrain condition the polymer may depolymerise and produce toxic styrene vapour
• incomplete combustion produced CO and unburnt carbon particles

Question 10

What can be done with condesnation polymers like polyester and polyamides?

Answer 10

can be broken down by hydrolysis and are potentially biodgradeable by the reveerse of polymerisation reaction by which they were formed

Question 11

What are the advantages and disadvantages of recycling?

Answer 11

advantages:

• almost all plastics are derived from crude oil
• recycling saves this expensive and ever diminishing resource
• as well as the enrgy used in refining it
• if plastics are not recycles they will end up in landfill

disadvantages:

• plastics need to be collected, transported and sorted
• this uses energy and mapower and is therefore expensive

Question 12

How is Kevlar biodegradeable?

Answer 12

• polar bonds / has petide link
• hydrolysed by nucleophiles