1.11 The Development Of Plastics For The Future

Question 1

State the main non-renewable material used in the
production of plastic. {1}

Answer 1

Crude oil {1}

Question 2

State the trend in the global production of plastic
each year. {1}

Answer 2

Continues to increase. {1}

Question 3

State the name of the process required to convert crude oil
into the feedstocks required for plastic manufacture. {2}

Answer 3

Distillation. {1}
Fractional distillation. {2}

Question 4

Crude oil is the main source of feedstock for the plastics industry.
(i): Explain how the feedstock is obtained from crude oil. {2}
{ii}: Explain how and why the feedstock is prepared for storage before use.
{2}

Answer 4

(i): Crude oil undergoes fractional distillation to separate it into different
substances including gases that can be used to make plastics.
Award [2] for a full explanation and [1] for a limited explanation.
(ii): The gases obtained by fractional distillation are cooled and liquefied
because liquids are much easier than gases to store, transport and use.

Question 5

Identify two pollution problems associated with the use of plastics derived from fossil fuels.
{2}

Answer 5

Cannot be broken down by microorganisms. {1}
Incineration produces toxic materials. {1}

Question 6

Name two toxic gases that may be released during
the incineration of plastics {2}

Answer 6

Any two from;
Carbon monoxide / hydrogen cyanide/ hydrochloric acid.

Question 7

Traditional plastics are manufactured from crude oil.
One method used to dispose of these plastics is incineration which can release
toxic gases.
List two toxic gases that may be released during the incineration of plastics. {2}

Answer 7

Any two from the following;
Carbon monoxide {1}; hydrogen cyanide {1}; hydrogen chloride {1}.

Question 8

Plastics derived from crude oil are building up in the Earth’s oceans causing
significant pollution problems.
Explain why plastics cause pollution problems in the oceans. {2}

Answer 8

Plastics cannot be broken down by micro-organisms or easily recycled so they
build up in the environment creating pollution issues such as the great Pacific
garbage patch.

Question 9

If BPE is not recycled, it may be disposed of by incineration. Name two toxic
gases that may be released during the incineration of plastics such as BPE.
1: _____________ {1}
2: ______________ {1}

Answer 9

Any two from:
Hydrogen cyanide [1]
Hydrogen chloride/Hydrochloric acid [1]
Carbon monoxide [1]

Question 10

State 1 application for photodegradable plastic and
describe its impact on crops or the environment. {4}

Answer 10

Option 1;
Plastic Mulch {1}
Used as a growth promoter for saplings {1}
In forestry or poor land {1}
Allows soil to be stabilised whilst sapling takes root in otherwise unstable soil.
{1}
Option 2;
Coatings for slow release fertiliser / pesticide pellets Controlled release of active agent Particularly where risk of leaching Or where risk of run off is high {1}
{1}
{1}
{1}
Option 3;
Germination enhancing in maize {1}
Where the soil temperature is raised {1}
Above the ambient seasonal temperatures {1}
Thereby speeding up the germination rate {1}
Option 4;
Solarisation {1}
Where plastic over film {1}
Builds up heat {1}
To temperatures harmful to soil pathogens {1}

Question 11

Modern plastic manufacturing processes are moving
towards the production of biodegradable plastics.
Explain what is meant by the term ‘biodegradable plastic’.
{1}

Answer 11

Can be broken down by micro-organisms, bacteria or other biological means.

Question 12

Describe two applications of biodegradable plastics.
{4}

Answer 12

Any two from;
• Biodegradable plastics can be used as packaging for single use items such
as carrier bags, food packaging and drink and food cartons for the takeaway
food industry.
• Films. Biodegradable plastic agricultural films as mulch can be used to
supress weeds, increase soil temperature, prevent loss of water and
minerals from the soil. It can be ploughed into the soil after use.
• Improvement of soil structure when the decomposed plastic can make the
soil more fertile and improve plant growth.

Question 13

Identify a piece of laboratory apparatus that could be used
to measure the tensile strength of photodegradable plastics. {1}

Answer 13

A Newton meter. {1}

Question 14

Incorporating an additive into a polymer during the
manufacturing process can enhance the biodegradability of the plastic.
Complete the key in the figure below by identifying the additive which can cause
a plastic bag to be broken down at the end of its useful life. {1}

Answer 14

Oxygen {1}

Question 15

Explain how the additive in the key above can cause
a plastic bag to be broken down at the end of its useful life. {3}

Answer 15

Stage 1 – Additive is included in the basic polymer resin during the
manufacturing process. {1}
Stage 2 – Breaks the molecular chains so that at the end of its predetermined
service life the plastic starts degrading in the presence of oxygen by a process
of oxidation, which is accelerated by light, heat and stress {1}
Stage 3 – Bio-degradation is completed by microorganisms. {1}

Question 16

Explain one other option, apart from the use of an
additive, that can be used in modern plastic manufacturing processes to
improve biodegradability. {2}

Answer 16

Option 1;
Modification of the process to enhance thermal and photodegradation {1}
Addition of different chemical links into long chain molecules of plastic which
breaks up when hit by UV light {1}
Option 2;
Production of bioplastics {1}
Addition of starch which is digested by microorganisms – breaks up plastics into
smaller pieces {1}
Option 3;
Production of compostable plastics {1}
Made from e.g. corn starch fully biodegradable and compostable {1}

Question 17

Many plastics are photodegradable. Describe how a
plastic can be modified during the manufacturing process to make it
photodegradable. {2}

Answer 17

It is manufactured to contain a chemical additive {1} which absorbs light, attacks
the polymer and breaks it down. {1}.

Question 18

Plastics can be manufactured to be compostable.
Describe one agricultural use of compostable plastics. {2}

Answer 18

Any one from;
* Compostable plastics can be used to improve soil composition {1}. They
break down in the environment to provide useful soil nutrients {1}.
* They can be used as weed suppressant {1} as they can cover ground
around plants preventing weed growth {1}.
* They can be used as mulch {1} keeping soil temperatures raised in
winter / conserving moisture {1}.

Question 19

Describe a modern manufacturing process used to address the polluting effect
of plastics. {2}

Answer 19

Any one from:
Additives/metal salts (such as d2w) are mixed with the plastic during manufacture to
increase biodegradability. At the end of the useful life of the product these
additives/salts catalyse the breakdown of the plastic in the presence of oxygen. [2]
Plastics can be manufactured to include a bond in the structure that breaks down when
heated or when it absorbs uv light. This increases their thermal or photodegradability.
[2]

Question 20

Describe how bioderived polyethylene (BPE) is
produced. {2}

Answer 20

Ethanol from fermentation of crop biomass converted to ethylene {1}
Ethylene is then polymerised by addition polymerisation {1}

Question 21

The production of bioderived polyethylene (BPE), is
often described as not being ‘a sustainable manufacturing process’.
Why is this so? {2}

Answer 21

It is energy intensive process. {1}
And energy used in its production will almost certainly come from a non-
renewable source. {1}

Question 22

BPE is an example of a recyclable plastic. What does the
letters BPE stand for? {1}

Answer 22

Bioderived polyethylene. {1}

Question 23

Describe fully how BPE is manufactured, {3}

Answer 23

• A plant such as corn/sugar cane undergoes fermentation to produce ethanol.
{1}
• Ethanol is converted to ethylene (dehydration). • Ethylene then undergoes (addition) polymerisation to form BPE. {1}
{1}

Question 24

BPE is an example of a recyclable plastic.
(i): State what the letters BPE stand for. (ii): Describe how BPE is manufactured. {1}
{2}

Answer 24

Answer:
(i): Bioderived polyethylene
(ii): A starchy substance such as maize or corn is treated with yeast to produce
ethanol by fermentation. Ethanol is purified and undergoes dehydration to form
ethene. Ethene undergoes addition polymerisation to form bioderived
polyethylene. {2}

Question 25

The figure below details annual world plastic production. Comment on the trend shown and explain why there is a need for a global move towards more sustainable manufacture and use of plastics. {2}

Answer 25

Graph demonstrates the increased global production of plastics. {1} This results in an increased demand for and use of finite natural resources such as oil needed for plastic production. {1}

Question 26

Explain the term ‘sustainable manufacture of plastics. {2}

Answer 26

Sustainable manufacture of plastics refers to design and development that incorporates replenishable raw materials. {1} Together with efficient manufacturing and production techniques. {1}

Question 27

• They can be manufactured using renewable materials. • They reduce environmental pollution. Describe how each of the points above can be considered as an advantage. {4}

Answer 27

Manufacture using renewable raw materials; • Renewable raw materials are readily replaced unlike fossil fuels {1} that are used during current production, so the process is more sustainable {1}. • There is greater security of supply of feedstocks {1} as there is less reliance on crude oil which can come from politically unstable regions {1}. • Finite crude oil supplies are conserved for future generations energy needs {1} and for other uses such as transport {1}. • Biodegradable plastics break down {1} so there is less of a build-up of plastics in the environment. This benefits wildlife and reduced the impact on ecosystems {1}. • The manufacture and disposal of biodegradable plastics produces fewer harmful gases and emissions {1} so there is a lower impact on global warming {1}. • Less plastic in the environment reduced littering {1} and therefore reduces the clean-up costs associated with this {1}.

Question 28

Assess the need for a global move towards the more sustainable manufacture and use of plastics. Your answer should include three different factors. {6}

Answer 28

Any three factors such as; * The manufacturing process is energy intensive and releases pollutants into the environment {1}. Alternative manufacturing processes are required which have less of an environmental impact {1}. * The lack of biodegradability {1} means that plastics accumulate in the environment causing damage to marine and land habitats and the organisms they support {1}. * They are made from non-renewable raw materials (crude oil) {1} so alternative, renewable feedstocks will need to be found as crude oil is expected to run out {1}.

Question 29

“Manufacturers have long chosen plastic for their products on the basis of price and functionality. But creating a more sustainable relationship with plastics will require a new dexterity on our part. It will require us to think about the entire life cycle of the products we create and use. ’’ Discuss how we can move towards the more sustainable manufacture and use of plastic. Include two discussion points on sustainable manufacture and one point on sustainable use. Sustainable manufacture: 1: _________________ {2} 2: ________________ {2} Sustainable use: 1: ________________ {2}

Answer 29

1: Current manufacture uses non-renewable crude oil. Sustainable manufacture means moving to renewable raw materials such as plant materials. {2} 2: Lack of biodegradability leads to build-up of plastic in the environment. Manufacturing processes need to be modified to enhance the degradability of plastics. {2} Sustainable use: Global pollution problems – increase in use of single-use plastics globally means an increase in pollution. Sustainable use must include strategies for reducing, reusing and recycling. {2}