1 The oxo-biodegradable option for Plastics Packaging – is it a

Wells Plastics Ltd. - A Company Profile
The oxo-biodegradable option
for Plastics Packaging – is it a
viable technology?
Walmart, Bentonville March 2009
Large Product Portfolio includes :
• Antiblocks.
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Antimicrobials.
Antimicrobials.
Antioxidants.
Antistatics.
Blowing Agents.
Flame Retardants.
Fragrances.
Process Aids.
Slips.
UV stabilisers.
Combinations.
• Biodegradables.
• Speciality polymer
compounder.
• 25 years of experience.
• Manufacture all products
in-house.
• Have own R&D facility.
• This backward integration differentiates Wells
from other oxobiodegradable additive suppliers.
• Oxobioplast are our Reverte partners in USA.
Biodegradable Product Range
Wells has developed and manufactures a product range based on intrinsically
biodegradable polymers (hydrobiodegradables) such as PLA, PCL etc.
We have also developed our own ranges of oxobiodegradable addit ives –
both for conventional polymers and to enhance the breakdown of
hydrobiodegradables.
We always endeavour to recommend and supply the most suitable solution to
meet a client ’s requirements.
It’s “horses for courses”! Sometimes the best solution is based on
hydrobiodegradable technology and
other times it’s based
on
oxobiodegradables.
I find the so called schism between the two technologies fairly risible! Wells
manages to straddled both camps without any problems and has developed a
good understanding and familiarity with both product groups.
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For Example :
If there is a thin section composting requirement then hydrobiodegradables
Various BD Terminologies
1. “ Degradable”
This term is somewhat out of fashion but was used to describe a simple
prodegradant additive.
currently offer the only option.
2. “ Compostable”
However, thicker section hydrobiodegradable products (>150 to 200 µm) can
fail to meet industrial composting specifications.
A product that will compost within the timeframes required by Industrial
composters. Basically these are intrinsically hydro-biodegradable
polymers.
Reverte additives can facilitate this shortfall!
If the ability to recycle is important then again hydrobiodegra dables cannot be
recommended.
However, if ease of use, low cost and the ability to seamlessly integrate into
both manufacturing and disposal infrastructures are paramount th en
oxobiodegradables become the technology of choice.
3. “ Biodegradable”
A product that will ultimately be broken down by microbes to form CO2
(maybe CH4 ), H2 O and biomass (humus).
4. “ Oxo-biodegradable”
Used to describe a product that is initially broken down through
oxidation and which subsequently becomes available for microbial
based biodegradation.
Reverte falls into this category!
Is terminology important?
Yes!
It is important to recognise the difference between biodegradation and
compostability.
Everything that is compostable is biodegradable ….
…BUT everything that is biodegradable is not compostable. It’s all about
timescale.
Various BD Methods / Specifications
There are a number of international test methods and specifications
including :
• EN 13432 - 90% in 6 m – European composting specification.
• DIN V 54900 - Very similar to EN 13432 but 60% - again composting.
• ISO 14855 - 60% in 6 m - composting test method.
Industrial composters like very rapid composting – ≥
60% in 180 days.
• ASTM D6400 – 60% in 6 m– US composting specification.
But this means rapid evolution of Carbon dioxide with all the attendant
disadvantages.
• GB/T 20197 -2006 – Chinese oxo -bio test specification.
IN COMPARISON
• BS 8472 – proposed EU oxo -bio test method (specification to follow).
Oxobiodegradation is SLOW – breaking down more like woody materials.
CO2 evolution occurs at a more natural rate and so is more likely to be
utilised by plants.
• ASTM D6954-04 – US oxo- bio test method (not a specification).
Most specifications are geared towards industrial composting, not
simple biodegradation. We must not confuse the two!
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ASTM
ASTM D6954
D6954 - D6400
This Northern American favoured composting test method comprises :
• Toxicity
Degradation of Polymers
• The natural degradation of polymers, such as polyethylene, polyp ropylene, and
• Disintegration / breakdown
other polyolefins occurs relatively haphazardly and at a low rate.
• Germination (“cress test”)
• Compostability – tested to ASTM D 6400
• Reverte containing products pass toxicity – heavy metals (CONEG
plus) and global food approvals. All independently certified.
• The breakdown is generally instigated by exposure to heat and/or UV light, but
subsequent microbial biodigestion remains very, very slow due to the polymer’s
high molecular weight and intrinsic hydrophobicity.
• However, microbial digestion (biodegradation) can commence when the polymer
molecular weight is sufficiently reduced by initial degradation.
• Disintegration – polyolefins pass.
• Cress test – virtually everything passes this!
• Compostability – PE/PP can be shown to ultimately compost but
fail the time frame for industrial composting.
• Oxo-biodegradable additives have been developed to enhance, accelerate and
control this degradation process in many standard polymers.
The problem is we are relying on a composting specification to
define biodegradation!
Controlled Degradation of Polymers
through OxoOxo -biodegradation.
eg POLYETHYLENE
[CH 2 – CH2]
Measurement
Measurement of
of initial
initial degradation
degradation
FTIR spectra of PE Film – After heat/UV exposure in an ageing cabinet at 50 oC.
n
Typically n = approximately 250,000
Chain scission can be achieved through the free radical initiated catalytic
oxidation by certain metal ions :
.
+
R / M / O2
O
+
+ M+
Oxidative degradation causes chain scission. A carbonyl group is formed at each
break point. The carbonyl level can be measured to chart the reaction kinetics.
The Metal ion catalyst is regenerated allowing reaction to continue and chain
lengths to become progressively smaller.
When the MW is reduced to 4,000 to 10,000 then microbial attack can occur.
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Measurement
Measurement of
of initial
initial degradation
degradation
FTIR spectra of PE Film – After heat/UV exposure in an ageing cabinet at 50 oC.
Measurement
Measurement of
of initial
initial degradation
degradation
FTIR spectra of PE Film – After heat/UV exposure in an ageing cabinet at 50 oC.
Measurement
Measurement of
of initial
initial degradation
degradation
FTIR spectra of PE Film – After heat/UV exposure in an ageing cabinet at 50 oC.
Measurement
Measurement of
of initial
initial degradation
degradation
FTIR spectra of PE Film – After heat/UV exposure in an ageing cabinet at 50 oC.
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Measurement
Measurement of
of initial
initial degradation
degradation
Evaluation of Performance : Initial degradation profile.
FTIR spectra of PE Film – After heat/UV exposure in an ageing cabinet at 50 oC.
PE Film – After heat/UV exposure in an ageing cabinet at 50oC.
Initial Degradation Profile of HDPE bag + 1% Reverte BD 92845
Degree of E mbritt lement( %)
250
200
150
Embrittlement Point
100
Control
Sample + Reverte
50
0
0
3
6
9
12
15
18
21
24
Calculated time in months at 20oC
Applying Arrhenius principles has given a distinct dwell time of 3 to 4 months
followed by an embrittlement time of around 12 months at 20 oC.
Evaluation of Performance : Initial degradation profile.
Biodegradable Additive Masterbatches
BOPP Film – After heat/QUV exposure in an ageing cabinet at 50oC.
Degr ee of Embrittle ment
(%)
Degradation of BOPP independentlydetermined by
Smithers RAPRA.
What makes Reverte different?
Reverte additive masterbatches have three performance enhancing features :
100.0
1. A metal ion prodegradant package to controllably reduce the polymer chain
length but giving a clearly defined “dwell time”.
80.0
Control Film
Test film
2. A photoinitiation package to protect product from premature breakdown
before disposal.
60.0
40.0
3. Secondary biodegradation promoters to initiate and enhance subsequent
biodegradation rates.
20.0
0.0
0
50
100
150
QUV Ageing time in hours
200
Independent confirmation of Reverte induced degradation.
In addition Reverte additives :

Do not utilise any toxic heavy metals in their formulation.

Products pass EC and FDA food contact specifications.
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Photoinitiation
Photoinitiation Stage
Stage explained
explained
Secondary microbial degradation
Degradation Profiles of PE films with and without a photo-trigger.
From studies performed by Dr Iza Radecka at Wolverhampton University
200
Degr eeo f Embr ittlement ( %)
180
Standard LDPE Film – Incubated
for 5 weeks with A.niger in
nutrient free non-Carbon agar.
160
Control film
1% Reverte
No Trigger
140
LDPE + Reverte – Incubated for 5
weeks with A.niger in nutrient free
agar medium.
120
Embrittlement Point
100
80
60
40
20
0
-24
-18
-12
-6
0
6
12
18
24
30
36
42
48
Calculated time in months at 20oC
1. With no phototriggering the product does not portray any enhanced breakdown within an
18 - 24 month period and then breaks down to embrittlement over a further 47 month
period.
2. Once triggered it gives a 5 – 10 month dwell time followed by embrittlement after a further
10 to 12 months.
3. The control film is projected to reach only a low level of e mbrittlement over a 6 year
period.
Biodegradable film challenged with A. niger
PE Film + REVERTE incubated for 5 weeks with A niger.
Virtually unaffected but small
level of activity can be seen.
High level of growth with
thriving colonies.
Micrograph of Biodegraded PE film
PE Film + REVERTE incubated for 13 weeks with A niger.
Extensive
hypha growth
Large cracks
appearing
Extensive hypha growth throughout
film sample.
Acute degradation with extensive cracking
evident.
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Bacterial Challenge
Standard LDPE Film – Incubated
for 5 weeks with B. cereus in
nutrient free non -Carbon agar.
Virtually unaffected but small
level of activity can be seen.
LDPE + REVERTE – Incubated for 5
weeks with B. cereus in nutrient
free non-carbon agar.
Biodegradable film inoculated with
Baccillus cereus (bacterial challenge).
Close-up of B. cereus growth on PE film + REVERTE after 5 weeks incubation.
High level of growth with
thriving colonies.
Successful bacterial colonisation of film can be seen.
Micrograph of biodegraded film.
Scanning electron micrograph of modified PE film after 13 weeks of incubation
Mineralization of prepre-degraded
degraded PE
PE film
film
PE Film – After heat/UV exposure in an ageing cabinet at 50o C to
embrittlement.
with B.cereus inoculum.
MIneralisation Curve for pre-oxidised PE film.
60
% Mi ner alisation
50
40
30
20
10
0
0
50
100
150
200
250
300
350
400
Composting days at 50oC
Data source - Wells' in-house testing following pre-oxidation at 50oC
This demonstrates that a bacterial challenge alone has been very
effective at breaking down the film with a large amount of micro and
macro cracking.
It can be seen that after approximately 400 days of laboratory composting at 50oC, 60% of
the available Carbon had been mineralised..
Source : In-house data from Wells’ laboratories
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Mineralization
Mineralization of
of prepre- degraded PP Sheet
Independent testing of PP thermoformed Sheet – After heat/UV exposure in an
ageing cabinet to embrittlement at 55oC
Mineralization of pre- degraded PP Sheet
Chinese Test Report
Mineralisation of pre-oxidised PP sheet containing Reverte Additive
masterbatch
35
30
% M in e ralisa tio n
25
20
15
10
5
0
0
20
40
60
80
100
120
Composting time in days at 55oC
Source : Independent testing by Professor W eng, China National Centre for Quality Supervision & Test of Plastics Products.
This experiment was terminated when a value of approximately 33% was achieved.
Food Contact Suitability
Biodegradable Additive Masterbatches
Recycling
• All Reverte grades have been formulated to be suitable for food
contact applications.
• The major food contact specification bodies include the European
Community (through EC directives including 2002/72/EC), Canada
(CFIA) and, in America, the FDA.
• Reverte masterbatches, various polymer films and many products
containing Reverte have been independently verified for food contact
suitability under the European, Canadian and North American
directives.
• Smithers-RAPRA have undergone independent examination and
testing of all categories of Reverte products and have found them
suitable for food contact as above.
1. We consider recycling to be paramount.
2. Reverte technology has been developed to be compatible with
recycling schemes.
3. APR and their associated bodies are quite rightly concerned about
any possibilities of recyclate stream contamination – we totally
agree with them!
4. We are in communication with APR and currently putting Reverte
containing products through their testing protocol.
5. Results will be published as soon as the testing has been completed.
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Suitability
Suitability for
for Recycling.
Recycling.
Biodegradable Additive Masterbatches
Effect of Recycling Reverte film.
Toxicity / Heavy metals
140
1. In the USA heavy metals are regulated through the CONEG legislation.
0% Reverte film
10% Reverte film
120
20% Reverte film
2. A representative selection of Reverte grades have been independently
analysed (EPA 3052) and assessed by Smithers-RAPRA.
% cf contr ol
100
80
60
3. All have been found to comply with the CONEG legislation with NO
regulated heavy metals found in the masterbatches.
40
20
4. In addition Smithers-RAPRA analysed for the presence of Cobalt and
Manganese (both non- regulated metal ions) under the EPA 3051
protocol and have certified that these are not present either.
0
MFI
Elongation
Modulus
Tensile strength
Relative
Embrittlement
Time
1. Film waste containing 1% Reverte was added to 100% non-Reverte waste at 10% and 20%.
5. We should all be assured that products that gain direct food contact
approvals in the USA and the EC do not contain toxic entities!
2. Various film properties were determined including an accelerated ageing test.
3. No significantly detrimental differences were found.
Landfills – aerobic
aerobic vs
vs anaerobic.
anaerobic.
Landfill phases
1. Richard Hanson, Thomas Hanson(1996) Methanotrophic Bacteria
MICROBIOLOGICAL REVIEWS, June 1996, p. 439–471 Vol. 60, No. 2
1996, American Society for Microbiology
Phase 1
Methanotrophic bacteria that
convert CH4 to CO 2 do so via a
low acidity oxidative process
so an anaerobic environment
would preclude this.
Phase 4
High pH low
acidity
Steady state aerobic /
anaerobic decomposition
CO2 + CH 4 released
This sole state is only
achieved in relatively
undisturbed landfills
Aerobic
chain scission / oxidation
CO2 released
As landfill is disturbed /
new- layered / reoxygenated then
mechanism reverts to
Phase 1.
Hydrocarbons
and
carbohydrates
oxidised to acidic
species
2. Barlaz, M.A. (1989). Bacterial Population development and Chemical
Characteristics of Refuse Decomposition in a Simulate Sanitary
Landfill. Applied Environmental Microbiology. 55: 55-65
Phase 2
Anaerobic
Acid formation
CO2 + H2 released
Low pH, high
acidity
Phase 3
Anaerobic
Acid consumption
CH4 released
Recommended reading
3. Senior, Eric (Ed.).(1995) Microbiology of Landfill Sites. Boca Raton:
Lewis Publishers
Acid neutralisation
stage
“Due to the fact that refuse is placed in a landfill at different times and consists of different
types of solid waste at different moisture content, all four phases of degradation may be
occurring simultaneously within the landfill”
4. Neil Kirkpatrick, Jenny Will, and James McGaughey. Tetracycline
Resistance in Aerobic and Anaerobic Bacteria Recovered from Land fill
Leachate. Biological Sciences Department, Eastern Illinois University,
Charleston, IL
Source : Agency for Toxic Substances and Disease Registry US Government (2009)
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Misleading Claims
Oxo--biodegradable Additives
Oxo
Credibility.
We have seen claims by suppliers of other additive masterbatches that their products can impart
biodegradation properties to polymers so that rapid breakdown and even composting norms can
be met.
Some such claims are backed up by what appears to us to be pseudo-scientific or
misrepresented data.
Wells Plastics / Oxobioplast abhor any attempts to mislead and wish to dissociate ourselves from
any such unsubstantiated claims.
Why worry?
Unwarrantably raising private and public technical expectations can damage a hugely beneficial
product concept.
Some examples of Reverte
Applications
Putting uncompostable products into the composting waste stream can only alienate composting
facilities and detract from valuable recycling.
We strongly support recycling, landfill volume reduction and slo w release of greenhouse gases
but offer a credible insurance policy against the incorrect disc arding of plastic products – let’s
ensure we progress on a solid and substantiated technical base!
used in check-out bags in China
Polyethylene blend
check-out bags
containing Reverte
used in supermarkets.
used in checkcheck-out
out bags
bags in
in India
India
Five examples of
check-out bags
containing Reverte
used in Indian
supermarkets.
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used in loop handle carrier bags
Branded carrier bags
containing Reverte
produced for high
specification
application (loop
handles).
Polyethylene Rubbish bags
Polyethylene rubbish
bags containing
Reverte are formulated
to biodegrade after
their useful life has
been completed.
used
used in
in Food
Food bags
bags
“5-a-day” produce
bags containing
Reverte used in
supermarkets.
Fruit netting
Formulated to give a
long dwell time before
the onset of rapid
degradation.
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Bubble Wrap
Agricultural Mulch Film
Example of Field covered with
Reverte Film
The film rapidly fragments under the first
stage of the oxo-biodegradation pathway.
Often shorter term use
packaging - ideal for
an oxo-biodegradable
application.
Reverte has been used in many
different crop types including
tobacco, maize, potatoes and
peanuts.
At a slower rate the film is
completely bio-digested,
eventually producing CO2, H 2O
and Biomass.
Oxo--biodegradable
Oxo
biodegradable Additive
Additive Masterbatches
Masterbatches
SUMMARY
• Oxobiodegradable
additives can offer a low cost option with a se amless
introduction into existing manufacturing and disposal infrastructures.
• The
technology can be shown to be sound – independent studies have
demonstrated and confirmed controlled fragmentation followed by
mineralisation.
• The technology is not suitable for composting and test specifications
requiring rapid mineralisation are simply not relevant.
• There is substantial independent evidence that the products are non-toxic and
contain no regulated heavy metals.
• Products readily pass EC, FDA and other food contact specifications.
• Studies have demonstrated no effect on recycling streams but work continues
with APR to attain their approval.
• Oxobiodegradable products are used extensively throughout the world and
their value has been globally recognised.
www.wellsplastics.com
www.oxobioplast.com
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