This document summarizes the history and current issues surrounding plastics from a scientific and global perspective. It describes how the beautiful science and engineering behind plastics like polyethylene has enabled both beneficial applications but also problematic overuse on a global scale. While plastics were initially developed for useful purposes, the ease of processing and low cost has led to massive worldwide production and usage, resulting in environmental issues like plastic waste in oceans that governments are now seeking to address through policies aimed at reducing, recycling, and finding more sustainable uses for plastics.

1. The Beauty and Nightmare of
Plastics
By
Malcolm Mackley,
Emeritus Professor, Department of Chemical Engineering
and Biotechnology
University of Cambridge
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Polyethylene “single crystals” “Plastic Free Kingsbridge”
Bath University. March 2019

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Several messages in the talk.
• The “beautiful” science and engineering in plastics.
• How “beautiful science” can result in problematic global technology.
• The “problem with plastics”.
• The beauty and nightmare of;
…(many Science to Global Technologies).

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1947
1957
1967
1977
1987
1997
2007
2017
Ipswich Suffolk Gravesend, Kent
Gravesend Technical SchoolBath Technical CollegeLeicester Univ
Leicester Univ Bristol University
Sussex UnivCambridge University
Cambridge University
Cambridge University
Cambridge University Salcombe, Devon
My own “brief history” time line.

4. Plastics are Polymers!
The plastic polyethylene (PE) is the world largest
commodity thermoplastic.
4

5. “Polymers (including plastics!) are beautiful and fantastic”
DNA, the stuff of life
Polyethylene (PE), a “man made polymer” 1934 discovery
5
Cellulose,
one of natures building blocks

6. Polyethylene (PE) has an incredible molecular structure.
Graphic courtesy of Alexi Likhtman, University of Reading
Total
Chaos
Perfect
Order
Random Coil,
in the melt or
rubbery solid
Perfect Crystal,
in fibre or tape
6

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Rubbery or MoltenTough and Strong solid
PE has a very wide range of mechanical properties
Macro.
mm-m
Micro.
µm
Nano.
nm
Molecular.
Angstrom
Semi crystalline solid
Diamond like
Perfect order Total chaos

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Polyethylene Molecular and Nanostructure.
(My Bristol Physics PhD Supervisors 1970s)
Sir Charles Frank (1911-1998)Andrew Keller (1925 –1999)

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“Beautiful” Polyethylene Crystal “Nanostructures”
Bristol Physics 1950-1970s
PE “single crystals”
PE “shish kebabs” nanofibres PE micro “Spherulites”
10 µm
10 nm

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Polyethylene
Unit cell
Diamond
If PE chain fully
aligned in crystal.
Expect PE Stiffness
E=285 GPa
Not usual
E=1 GPa
Frank 1970
C.W.Bunn 1945
Sir Charles Frank prediction; High Modulus Polyethylene 1970s
Towards Global Problems !
Step 1. Great Science; an example, High Modulus PE

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Step 2. The Technology; to produce High Modulus PE
Low Entanglement, Ultra High Molecular Weight (UHMWPE)
Gel Drawing 1980 Piet Lemstra
TU Eindhoven
Low entanglement UHMWPE
polymer gel. 1% polymer in
solvent
Unoriented Gel fibre
Quench bath
Unoriented Low entanglement semi crystalline fibre
. Hot draw
Oriented High Modulus
100 GPa Polyethylene
Solvent recovery
Piston
Ex Groningen Ex Bristol
Paul Smith.
ETH

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Step 3. Commercialisation.
Continuous Processing of DSM UHMWPE Dyneema fibre. late 1980s
Screw extruder
UHMWPE Polymer
powder
Solvent
Low entanglement polymer gel
Spinneret
Gel fibres
Quench bath
Low entanglement semi crystalline fibre
Hot draw
Solvent recovery
High Modulus
Polyethylene
Han Meijer. DSM & Eindhoven

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1. Science. Then…..
2. Technology. Then…..
3. Commercialisation. Then sometimes…
4. Global scale up. Then….
5. A problem?
Dyneema ropesDyneema and Endumax
Body armour
Endumax
Bomb protection
Step 4. Global Scale up.
High Modulus PE
1990- 2019
Endumax
sails

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Polyethylene (PE) Global manufacture.
1934-2019
Globally, 2018
> 100 million tonnes/annum
= Fill Salcombe Estuary / annum
with PE

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Westbury Wilts Cement Works 1960- 2010
(Where my father was Production Manager 1962- 1980)
700,000 tonnes cement/annum.
35 million tonnes of cement over 50 years.
25 million tonnes of chalk.
Global PE 100 million tonnes/annum;
enough to fill the chalk quarry
at least 4 times over/annum.
(Wiltshire Times)
Drone Photo
Simon Wright ‘Skynamite’

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Temperature
50 100 150 200
C0
∆H
Melt
Processing
The “good” and “bad” properties of PE
• Low melting point.
• Low density.
• High strength and toughness.
• “Low cost?”.
• Ease of processing.
Polyethylene £ 1000/tonne (Paper £ 300 /tonne)
• Relatively poor gas diffusion barrier.
Plastic floats!
Good for low temp
processing.
Bad for flammability.
Bad for some food packaging applications

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Ease of melt Processing ;
a reason why plastic is used so much.
1
10
100
1000
10000
1 10 100 1000 10000 100000 1000000
S7
S8
S9
S10
S11
S12
Apparent
Viscosity
Pas Entanglement
of chains
Shear Thinning
Simulation. Experiment.
Birefringence stress fields
Stress field birefringence
Cambridge Multipass Rheometer (MPR)
(David Hassell)
Strain rate

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Thirty years of research results for
example in the ability to mathematically
model and optimise plastic bottle blow
moulding.
Whilst at the same time…Thirty
years is enough time to create a global
plastic bottle nightmare.
Plastic Bottles !
UK; 35 million plastic bottles /day

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PE Applications
Sustainably “benign”
Tube and pipe extrusion.
Injection moulding.

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Plastic packaging and bottles are a Global problem
PE application; Film blowing and blow moulding

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“The birth” of single use plastic drinking cups?
Street Scenes whilst at a food conference
in San Antonio USA 2007
Photos used in my
2008-2011 Rheology lectures
suggesting this would become
a common sight in the UK too!
Single use plastics; in the beginning?

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2017. The World finally realised; “We have a problem.”
“The Plastic Bashers”
In the UK, recognition of problem,
Surfers Against Sewage (SAS).
Micro plastics in oceans.
Beach cleaning groups.
BBC Blue Planet programme.
China stopped accepting recycled plastic waste.
2018. local and National Politicians start to get involved.
National, European and Global policies starting to emerge.
2019. ?
The trouble with plastics

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This is a very well written
2018 Government paper
which has excellent ideas
that are unlikely to be acted
on?

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The Solutions!
• Collect separated used plastic.
• Recycle.
• Burn.
• Burn and recover energy.
• Go biodegradable.
• Restrict application areas for plastics.
• Tax manufacturers, processors, distributors,
users.
• Penalise inappropriate users of plastics.
• Educate populous to use plastics sensibly.

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The Bright side of Plastics.
The Dark side of Plastics.
A “man made” organic material that has very effective mechanical
and electrical properties.
Some applications have current environmental problems; however
Governments and users now realise these problems; but in
“poorer countries” remedial action has not been taken.
Some plastics manufacturers and processors are still in denial in terms
of genuine sustainability and using plastics to “make the world a better place”.

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Plastics are not alone !
Other technologies with global problems.
• Minerals. Mining
toxic tailings (waste pits)
• Mobile phones. 1 Billion/annum.
Materials recycle, Society and social aspects.
• CO2 Global warming
• Transportation.
• Mathematics!
• The internet of things.
• Drones.
• ……………….
Burst tailings dam. Brazil Jan 2019

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Wise words!
Peter Swinnerton Dyer (1927-2019)
ex Cambridge Vice Chancellor
“You can never observe Cambridge changing. You can only observe
that it has changed.”
We now know, fast developing Science and Global Technologies,
including plastics can have both a positive and negative effect on society.
Hopefully current and future generations will recognise this and ensure
a balanced approach to current and future technology changes.
Sustainable Innovation and design.

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Positive Future; “High Tech” applications of PE.
PE membranes PE Lithium ion battery membranes
Dyneema / Endumax body armour
PE Battery membranes
UHMWPE Hip Joints

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Collecting plastic
waste on the Thames
Plastic waste Product made from
recycled plastic
Energy recovery by burning plastics
Biodegradable plastic
Options; Recycle, Reuse, Burn or biodegrade