14.3- ADDITION POLYMERS

Question 1

What are polymers?

Answer 1

very large molecules built-up from small molecules called monomers

Question 2

Examples of naturally occurring polymers? (4)

Answer 2

starch
proteins
cellulose
DNA

Question 3

What was the first completely synthetic polymer?

Answer 3

Bakelite

Question 4

When was Bakelite patented?

Answer 4

1907

Question 5

What is one way of classifying polymers?

Answer 5

by the type of reaction by which they are made

Question 6

What are addition polymers made from?

Answer 6

monomer(s) with a carbon-carbon double bond (alkenes)

Question 7

The monomers that make up polymers are based on what?

Answer 7

ethene

Question 8

What happens to the double bond in the monomer when it polymerises?

Answer 8

double bond opens and monomers bond together to form backbone of carbon atoms

Question 9

What is phenylethane sometimes called?

Answer 9

styrene

Question 10

What is poly(phenylethane) sometimes called?

Answer 10

polystyrene

Question 11

What must addition polymers have?

Answer 11

backbone of carbon atoms

Question 12

What must the monomers of addition polymers must contain?

Answer 12

at least two carbon atoms

Question 13

Why must monomers of addition polymers must contain at least two carbon atoms?

Answer 13

so that there can be a carbon-carbon double bond

Question 14

How can the properties of polymers materials be modified?

Answer 14

use of additives i.e. plasticisers

Question 15

What are plasticisers?

Answer 15

small molecules than get between the polymer chains forcing them apart + allowing them to slide across each other

Question 16

e.g. of plasticiser being used (before + after)

Answer 16

PVC rigid enough for use as drainpipes, with addition of plasticiser become flexible enough for making aprons

Question 17

What is the backbone of a polyalkene?

Answer 17

long chain saturated alkane molecule

Question 18

How are the bonds in alkanes described to be?

Answer 18

strong, non-polar C-C and C-H bonds

Question 19

As the bond in alkenes are strong and non-polar, how reactive are they?

Answer 19

very unreactive molecules

Question 20

As alkanes are very unreactive molecules, what cannot be done to them?

Answer 20

not attacked by biological agents, like enzymes

Question 21

As alkanes cannot be attacked by biological agents, what are they described as?

Answer 21

not biodegradable

Question 22

How is low density poly(ethene) made?

Answer 22

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

Question 23

What does polymerising ethene at high pressure + high temperature via a free-radical mechanism produce?

Answer 23

polymer with a certain amount of chain branching

Question 24

What is the chain branching in LDPE due to?

Answer 24

consequence of rather random nature of free-radical reactions

Question 25

Are the branched chains in LDPE packed together?

Answer 25

not packed together particularly well

Question 26

How flexible is LDPE?

Answer 26

quite flexible

Question 27

How well does LDPE stretch?

Answer 27

stretches well

Question 28

What is the density of LDPE like?

Answer 28

fairly low density

Question 29

What does the properties of LDPE make it suitable for?

Answer 29

packaging (plastic bags), sheeting + insulation for electrical cables

Question 30

At what conditions is high density polythene made?

Answer 30

temperatures + pressures little greater than room conditions + uses Ziegler-Natta catalyst

Question 31

What does polymerising ethene at temperatures + pressures little greater than room conditions + use of Ziegler-Natta catalyst produce?

Answer 31

polymer with much less chain branching than LDPE

Question 32

Can the chain pack together well? (HDPE)

Answer 32

yes

Question 33

What is the density of HDPE like In comparison to LDPE?

Answer 33

greater

Question 34

What is the melting temperature of HDPE like in comparison to LDPE?

Answer 34

higher

Question 35

Typical uses of HDPE? (3)

Answer 35

milk crates buckets bottles

Question 36

How can the amount of plastic be reduced?

Answer 36

by reusing or recycling it

Question 37

What is the simplest form of recycling called?

Answer 37

mechanical recycling

Question 38

What is the first step of mechanical recycling?

Answer 38

separate the different types of plastics

Question 39

What is the second step of mechanical recycling?

Answer 39

plastics washed and once sorted they may be ground up into small pellets

Question 40

What can happen to the small pellets of plastics in mechanical recycling?

Answer 40

be melted or remoulded

Question 41

Example of mechanical recycling?

Answer 41

recycled soft drinks bottles made from PET used to make fleece clothes

Question 42

What happens in feedstock recycling?

Answer 42

plastics heated to temperature that will break the polymer bonds + produce monomers

Question 43

What can the monomers from feedstock recycling be used to do?

Answer 43

make new plastics

Question 44

What type of plastic is poly(propene)? (feedstock recycling)

Answer 44

thermoplastic polymer

Question 45

What happens to thermoplastic polymers when heated? (feedstock recycling)

Answer 45

soften so can be melted and re-used

Question 46

Why can thermoplastics only be heated and re-used only be done a limited number of times?

Answer 46

as at each heating some of the chains break and become shorter so degrading the plastic's properties