AC14: Polymers

Question 1

What is addition polymerisation

Answer 1

addition of large numbers of alkene molecules to each other to form a long chain polymer

Question 2

what conditions are required for addition polymerisation

Answer 2

higher temperature and high atm

Question 3

State 5 benefits of addition polymers

Answer 3

1- these polymers are inexpensive as they’re made from alkenes which are easily and cheaply produced from petroleum
2- have several applications
3- recyclable
4- can be burned and heat released used for energy
5- chemical feedstock - can be converted chemically into other useful products

Question 4

State 2 disadvantages of addition polymers

Answer 4

1- non-biodegradable
2- when burnt, need to deal with possibly toxic combustion products e.g. HCl - removed by neutralisation with an alkali

Question 5

What is condensation polymerisation

Answer 5

polymerisation involving the elimination of water

Question 6

What are polyesters made from

Answer 6

monomers reacted together by esterification reactions

Question 7

Give two ways polyesters can be formed, and give an example and a use of polyesters

Answer 7

1- monomer containing both an alcohol and a carboxylic acid group
2- two monomers: a diol and a dicarboxylic acid
an example is PGA polyglycolic acid - used for medical sutures

Question 8

Explain how a monomer containing both an alcohol and a carboxylic acid group can form a polyester

Answer 8

a H2O molecule is removed from the monomer (a H atom from the -OH, and the OH from the COOH for example) - condensation polymerisation

Question 9

Explain how two monomers, a diol and a dicarboxylic acid can form a polyester

Answer 9

condensation polymerisation - 2 H2O molecules are removed (OH and H from diol, OH and H from dicarboxylic acid, forms an ester link)

Question 10

what is a more efficient method to make polyesters rather than using alcohol/carboxylic acid condensation, why is this and what is the byproduct

Answer 10

alcohol/acyl chloride condensation:
higher yield and no concentrated acid catalyst is required
2 HCl molecules are formed as a byproduct instead of H2O

Question 11

What are polyamides made from

Answer 11

monomers linked by secondary amide groups

Question 12

Give two ways polyamides can be formed, and give two examples example and their uses

Answer 12

1- monomer containing both an amine (-NH2) and a carboxylic acid group
2- two monomers: a diamine and a dicarboxylic acid
an example is nylon - for fabrics, guitar strings
nomex - oven gloves, fire protective suits

Question 13

Explain how a monomer containing both an amine (-NH2) and a carboxylic acid group can form a polyamide

Answer 13

condensation polymerisation - H2O molecule is removed (H from NH2 and OH from COOH)

Question 14

Explain how two monomers: a diamine and a dicarboxylic acid can form a polyamide

Answer 14

condensation polymerisation - 2 H2O molecules are removed (OH from both COOH and H from both NH2 to form an amide linkage)

Question 15

what is a more efficient method to make polyamides rather than using amine/carboxylic acid condensation, why is this and what is the byproduct

Answer 15

acyl chloride/amine condensation:
higher yield and no concentrated acid catalyst needed
two molecules of HCl are formed as a byproduct

Question 16

are polyesters/polyamides chemically degradable? explain why and how

Answer 16

yes - ester and amide bonds undergo hydrolysis when heated under reflux with aqueous acid or alkali

Question 17

What are the products of acid catalysed hydrolysis of polyesters and what is the reactant

Answer 17

alcohol and carboxylic acid are the products
2 molecules of H2O is the reactant

Question 18

What are the products of alkali/base catalysed hydrolysis of polyesters and what is the reactant

Answer 18

alcohol and carboxylate ion are the products
2 molecules of OH- ion is the reactant

Question 19

What are the products of acid catalysed hydrolysis of polyamides and what is the reactant

Answer 19

carboxylic acid and hydrocarbon with NH3+ on both ends are the products
2 molecules of H2O and H+ are the reactants

Question 20

What are the products of alkali/base catalysed hydrolysis of polyamides and what is the reactant

Answer 20

carboxylate ion and amide are the products
2 molecules of OH- is the reactant

Question 21

What is a disadvantage of fibres being made from polyamides/polyesters

Answer 21

because of hydrolysis reactions by acids/alkalis, fibres made by these polymers are easily damaged by spills of acid or alkali

Question 22

What is the difference between biodegradable and photodegradable polymers

Answer 22

biodegradable - broken down by microorganisms
photodegradable - broken down by UV light

Question 23

Why are degradable polymers beneficial

Answer 23

they will be more sustainable as they should degrade rather than accumulate as waste polymers

Question 24

State 6 ways waste polymers can be sustainably rid of

Answer 24

1- recycling
2- PVC recycling
3- Using waste polymers as fuel
4- Feedstock recycling
5- Biodegradable
6- Photodegradable polymers

Question 25

How are polymers recycled and how do their promote sustainability

Answer 25

Discarded polymers are sorted by type, once sorted - they are chopped into flakes, washed, dried & melted. Recycled polymer is cut into pellets & used to make new products reduces polymers' environmental impact by conserving finite fossil fuels & decreasing waste going to landfill

Question 26

Describe and explain the process of PVC recycling

Answer 26

Recycling PVC is hazardous - when burnt, releases hydrogen chloride which is a corrosive gas & other pollutants like toxic dioxins PVC is dissolved in solvents, high-grade PVC is recovered by precipitation from the solvent, solvent is used again

Question 27

How can waste polymers be used as fuel

Answer 27

Can be incinerated to produce heat, generating steam to drive a turbine producing electricity

Question 28

Describe the process of feedstock recycling

Answer 28

chemical and thermal processes that can reclaim monomers, gases, or oil from waste polymers. The products resemble those produced from crude oil in refineries -> can be used as raw materials for production of new polymers. This process is able to handle unsorted and unwashed polymers

Question 29

Describe the process of biodegradable recycling

Answer 29

polymers broken down by microorganisms into water, carbon dioxide & biological compounds. These polymers usually are made from starch/cellulose, or have additives that altar their structure so microorganisms can break them down.

Question 30

Describe the process of photodegradable recycling

Answer 30

oil based polymers, contain bonds that are weakened by absorbing light to start the degradation, alternatively, light-absorbing additives are used