2. I love realism. I don't like plastics - Michael Jackson, 1982
Plastic artefacts will be the most important witnesses to our
time- Biefer and Zgraggen, 1991
1920 1960 2015
2015 2018
1970
2021
3. what are plastics, chemically speaking?
why do plastics break down and how are
their lifetimes measured?
can research into degradation of heritage
plastics help us better understand plastic
pollution?
and find solutions?
6. ingredients for making cellulose acetate
+
triphenyl
phosphate-
fire retardant
+
diethyl
phthalate-
plasticizer
cellulose acetic
acid
+
7. 1945 – today: production of synthetic
plastics
plasticizers
antiageing
additives,
lubricants
colour
+
8.
9. how long do plastics last?
hint: the first synthetic plastic is 70 years old
*based on predictions and modeling
10. 20 years
loss of original significance of cultural heritage
loss of function of product during use
loss of physical integrity after use-microplastics
2 years
1 year
11.
12. plastics industry uses accelerated ageing to
test products within a convenient period
Q10 = 2 - rate of reaction doubles for every 10°C increase in temperature
13. darkening of PVC tubing
at 70°C over 4 months
new 1 month 2months 3 months 4 months
Physical bonding of plasticizers ( )
to PVC polymer
+
16. • how long does
plastic litter take to
degrade to
microplastics
(smaller than 5mm)?
• can all plastics form
microplastics?
• which environments
promote
microplastics?
18. accelerated thermal ageing
24 months at 70⁰C = ca. 50 years at 20⁰C
LDPE
PP
PS
PS
PVC
PET
PUR ether
PLA
formed MPs after 15 months
formed MPs after 16 months
PLA
27. 730 days Danish Weather
730 days heat aging
TDI
isomers
loss of flame retardant
GC-MS examines additives and degradation products
loss of antioxidant
30. plastic type, colour and environment are significant factors for
rate of degradation
degradation in environments:
thermal ageing (70°C) >Danish weather > surface seawater >
under seawater >sediment
PLA, PUR foam,PVC, PE, PS, PET and rubber showed chemical
degradation within 24 months
polyurethane sponges least stable
polyester and nylon are the most stable
Results
31. Skodprojektet
cigarette butts are the greatest source of
plastic pollution in Denmark
ca. 8 million butts on Danish streets daily
it costs 2kr per cigarette butt to clean up!
they contain water-soluble toxins
32. what are cigarette filters?
• filters for particles and tar from tobacco
• cellulose acetate fibres wrapped in a brown
paper
33. cellulose acetate produces acetic acid
and eventually becomes paper again
degradation rate doubles at pH 4
34. cigarette butts exposed to 8 environments
earth
air
seawater
pH 2
tap water
pH 7
soap water
pH 12
freezer
-20°C oven
70°C
35. all plastics degrade
it is essential to understand the causes
and rates of their degradation
museums are a unique source of
knowledge and experience because we
preserve everything-including plastics!
research into plastics in cultural heritage
can be transferred directly to plastics
pollution
36. I am grateful to
the Velux
Foundation and
KrogagerFonden
for their financial
support