Unit 3: Section 7 - Polymers MDY * Flashcards

condensation polymers disposing of polymers

1
Q

what does condensation polymerisation involve?

A

2 different types of monomer, each with at least 2 functional groups
the functional groups react together
a molecule of water is lost for each link form

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2
Q

how are polyamides formed?

A

the carboxyl groups of dicarboxylic acids react with the amino groups of diamines
to form amide links

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3
Q

how are polyesters formed?

A

the carboxyl groups of dicarboxylic acids react with the hydroxyl groups of diols to form ester links

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4
Q

what is hydrolysis?

A

the reverse of condensation polymerisation

water molecules are added back in to break the links

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5
Q

are condensation or addition polymers stronger?

A

condensation are generally stronger and more rigid

because they are made up of chains containing polar bonds

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6
Q

what bonds are there between condensation polymers?

A

van der waals
permanent dipole-dipole
hydrogen bonds

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7
Q

what are polyalkenes?

A

addition polymers
they are made up of non-polar carbon chains
so they are unreactive and chemically inert

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8
Q

what are the effects of polyalkenes being unreactive?

A

useful - they can be used without reacting, durable

bad - they are non-biodegradable

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9
Q

why are condensation polymers biodegradeable?

A

they have polar bonds in their chains, making them open to attack by nucleophiles
so can be broken down by hydrolysis
so biodegrade slowly

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10
Q

how can plastics be disposed of?

A

burying
burning
sorting for reusing or recycling

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11
Q

how can plastics be disposed of by burying?

A

landfill

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12
Q

when is landfill used?

A

when plastic is:
difficult to separate from other waste
not in sufficient quantities to make separation financially worthwhile
too difficult to recycle

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13
Q

advantages of landfill?

A

cheap

easy

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14
Q

disadvantages of landfill?

A

requires areas of land
waste releases methane (greenhouse gas) as it decomposes
leaks can contaminate water supplies

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15
Q

what happens when waste is burned?

A

heat used to generate electricity

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16
Q

why does burning waste plastic have to be carefully controlled?

A

to reduce the release of toxic gases

e.g. polymers containing chlorine produce HCl

17
Q

how is burning waste plastic controlled?

A

waste gases from combustion are passed through scrubbers which can neutralise by allowing them to react with a base
but gases still contribute to greenhouse effect

18
Q

why are waste plastics recycled?

A

because many plastics are made from non-renewable oil-fractions

19
Q

how can plastics be recycled after being sorted?

A

some plastics can be melted and remoulded

some plastics can be cracked into monomers, and these can be used to make plastics or other chemicals

20
Q

what are the advantages of recycling waste plastics?

A

reduces amount of waste going into landfill
saves raw materials
cost of recycling is lower than making from scratch
produces less CO2 emissions than burning

21
Q

what are the disadvantages of recycling waste plastics?

A

technically difficult
collecting,sorting and processing more expensive than burning/landfill
often can’t remake plastic you started with
plastic can become contaminated

22
Q

what are polymers?

A

long chain molecules made from lots of small molecules joined together

23
Q

what are monomers?

A

small molecules that join together to make polymers

24
Q

what is addition polymerisation?

A

the formation of long chain molecules from lots of small molecules joining together with no other products
formed by double bond of alkenes opening up to form bonds

25
why are addition polymers unreactive?
all the molecules are saturated