Ramani Narayan, Michigan State University UNDERSTANDING BIODEGRADABILITY ROLE IN PLASTICULTURE MYTHS...

Ramani Narayan, Michigan State University

UNDERSTANDING BIODEGRADABILITYROLE IN PLASTICULTURE

MYTHS & REALITY

Ramani NarayanUniversity Distinguished Professor

MICHIGAN STATE UNIVERSITY

[email protected]

If you use any of the slides/materials, please reference authorship and affiliation (Ramani Narayan, Michigan State University) – thank you

Copyright Ramani Narayan

&MATERIALS SCIENCE


PLASTICULTURE TECHNOLOGY

plastic mulch is standard practice used in agriculture to control weeds, increase crop yield, and shorten time to harvest

contributes significantly to the economic viability of farmers

Disposal is an issue – contributes to cost, and impacts on the environment

SOLUTION

DEGRADABILITY AND BIODEGRADABILITY DEGRADABILITY


The “VALUE PROPOSITION” FOR USING BIORESINS (BIOBASED AND OR BIODEGRADALBE)

• Using biodegradability as an end-of-life option to completely remove single use short life disposable plastics from the environmental compartment in a safe and efficacious manner via microbial assimilation

• Degradable, partial biodegradable not acceptable – serious health and environmental consequences

• Disposal environment (like composting, anaerobic digestor, marine

• Time to complete biodegradation

• Using bio/renewable feedstock (as opposed to petro/fossil feedstock:

• Reduces our carbon footprint and moves us to zero carbon or carbon neutral footprint

• Reduce CO2 emissions --- global warming climate change

• Provides a positive environmental footprint/profile (document using LCA tools)


TERMINOLOGY

BIOBASED (RENEWABLE)

Organic material containing in whole or part biogenic (biological sources) carbon

Refers to using biomass or crop feedstock (New carbon) vs petroleum or fossil feedstock (Old carbon)

Reducing carbon footprint

BIODEGRADABILITY – END-OF-LIFE option • functional property attribute to be designed and engineered into a biobased product

when needed or necessary!! • need to identify the (end-of-life)disposal system like composting, anaerobic digestion,

marine, soil • using microbes to completely utilize the carbon substrate and removing it from the

environmental compartment • Time to complete microbial utilization – no residue remaining

BIOMATERIALS -- Biomedical applications

Refers to:

Any material (metal, plastic, ceramic) implanted in the body -- design and engineering considerations different; biodegradability considerations different


TERMINOLOGY

Biobased plastics or productsOrganic material(s) containing in whole or part

biogenic carbon -- carbon from contemporary (non-fossil) biological sources – NEW CARBON

CO2 + H2O (CH2O)x + O2

Organic material(s) – IUPAC terminologyMaterial(s) containing carbon based compound(s) in whichthe carbon is attached to other carbon atom(s), hydrogen, oxygen, or other elements in a chain, ring, or three dimensional structure

Thus, to be classified biobased or biomass based, or renewable , the material must be organic and contain biogenic carbon (from biological sources)


Terminology (Contd)

BIOBASED

OR

BIOMASS BASED

OR

RENEWABLLY SOURCED

PLASTICS OR PRODUCTS

NOT BIODEGRADABLE

BIODEGRADABLE (Complete)

Petro based not biobased

PLASTICS OR PRODUCTS

BIOBASED AND

BIODEGRADABLE (complete!)PLASTICS OR PRODUCTS

BIOPLASTICS

IMPORTANT:Biodegradability MUST be defined/ constrained by:• the disposal system – composting, anaerobic

digestor• Time – 180 days ; max 1 year• Complete utilization of the substrate carbon by

the microorganisms as measured by the evolved CO2


DESIGNING FOR BIODEGRADABILITY – WHEN, & WHY?

• Durable Products – BIOBASED [reduced carbon footprint]

• biodegradability is not required element for reasons of performance, safety and long product life

• alternate methods of disposal needs to be identified

• Example -- BIO polyurethanes for automotive and farm vehicles

• Example -- Biofiber composites for industrial and automotive applications

• Example – Biopolyethylene ethanol to ethylene to PE

• BIODEGRADABILITY – For single use, short-life (controlled-life time), disposable products [end-of-life option]

• Like packaging, disposable plastics, agricultural films, marine disposable

• Designed for disposal systems like composting, anaerobic digestion, marine and soil disposal

• BIOBASED is added positive attribute

• IMPORTANT -- Must define environment and time required to ensure complete removal from the environmental compartment otherwise serious environmental and human health consequences


BIODEGRADABILITY -- END OF LIFE OPTIONS

COMPOSTING FACILITY

COMPOSTING FACILITY RECYCLING

FACILITY

RECYCLING FACILITY

WASTE TO ENERGY FACILITY


BiodegradablePlastics


RECYCLED PRODUCTS

LAND APPLICATIONrecycling polymeric carbon

back to soil

ENERGY

INCINERABLE

Anaerobic digestion facility

Marine environment

Paper-biopolymer composite

Landfill

X

Unless managed for landfill gas recovery for energy

BIOBASED

PLASTICS

Standards in place for Biodegradability as end-of-life option (Integration of Biodegradable Materials with Disposal Infrasructures)

BiodegradableMaterials


COMPOSTING FACILITY

COMPOSTING FACILITY


back to soil

TEST METHODASTM D5338; ISO14855 1 & 2 ISO16939 (disintegration)ASTM D6340 C-14 SPECIFICATIONSASTM D6400; EN 13432 ISO 17088ASTM D6868 – paper coatings

Waste water treatment

facility


facility

ASTM D5271ISO 14851/14852

Anaerobic digestionbiogas energy plant

ASTM D5511ISO 15985

Soil Mulch film

Agriculture appl

Soil Mulch film

Agriculture appl

ASTM D 5988

Marine&fresh water

ASTM D 6691,6692D 7021 specification

Ramani Narayan, Michigan State University, www.msu.edu/~narayan


Global Standards for Biodegradability

DIN CERTCOGERMANYBPS

J APAN

USA

Memorandum of UnderstandingCross Certification Program

www.bpiworld.org

EBPATaiwan K BPA

K orea

Composting AssnUK

BPSChina

BPSBrazil


J APAN

USA


www.bpiworld.org

EBPATaiwan K BPA

K orea

Composting AssnUK

BPSChina

BPSBrazil


J APAN

USA


www.bpiworld.org

EBPATaiwanEBPA

Taiwan K BPAK oreaK BPAK orea

Composting AssnUK

BPSChinaBPS

China

BPSBrazilBPS

Brazil

ISO 17088Specification for

compostable plastic


What is this all about?Myths and Green Washing – where is the data?

Industry debates: What’s biodegradable?

Plastics News October 6, 2006

• Oxobiodegradation is a process by which polyolefins can be accelerated to break down into low molecular weight species. Through the action of microbes , the material is transformed into CO2, water and biomass

• Have been used for many years in corn fields – no build of the films in the soil is evident, nor are there any issues with plant growth.

• Company claims that the material meets ASTM D5209, D5338 standards for biodegradability

• Products that conform to D6954 standard which allows for slower breakdown of materials wont get through

“PERF GO GREEN Bags will completely break down in a landfill environment in 12-24 months leaving no residue or harmful toxins and have a shelf life of 2 years.”


Claims of biodegradability


Claims of biodegradability

Basic Technology

– All of the commodity plastic resins used in the world today will take hundreds of years or more to degrade naturally in the environment

– Plastic products with our additives will biodegrade to become some of the soils’ organic components in a hundredth of that time or less

•Biodegrade

Conclusion

• Make all PE and PP products fully biodegradable• No toxic residue• Manufacture clear or in any color with no appreciable change

in physical properties• FDA compliant for use in applications with food contact• Products can be marketed as “biodegradable” because they

will biodegrade aerobically or anaerobically and without the need for additional reaction to heat, light or physical stress and therefore will biodegrade wherever there is other biodegradation occurring.


Quote from Industry website

“The two main types are oxo-biodegradable and hydro-biodegradable. In both cases degradation begins with a chemical process (oxidation or hydrolysis), followed by a biological process. Both types emit CO2 as they degrade, but hydro biodegradable can also emit methane”

The plastic does not just fragment, but is consumed by micro-organisms after the additive has reduced the molecular weight to sub 40,000 Daltons, and it is therefore "biodegradable." This process continues until the material has biodegraded to nothing more than CO2, water, humus, and trace elements.

Oxo-biodegradable plastics Association

www.biodeg.org; Sept 08, 2008


The 50% Bio-Batch film did not degrade as completely or as quickly as the cellulose. At the end of the test, 19% of the film had degraded.

The results of the aerobic degradation tests indicate that, in time, plastics produced using Bio-Batch pellets will biodegrade in aerobic conditions.


BIODEGRADABILITY CLAIMS Chem. Commun., 2002, (23), 2884 - 2885

– A hypothesis was developed, and successfully tested, to greatly increase the rates of biodegradation of polyolefins, by anchoring minute quantities of glucose, sucrose or lactose, onto functionalized polystyrene (polystyrene-co-maleic anhydride copolymer) and measuring their rates of biodegradation, which were found to be significantly improved

PRESS Sugar turns plastics biodegradable. Bacteria make a meal of sweetened polythene and

polystyrene.

weight loss of only 2-12%,

Only sugar is being assimilated, PE chain intact – Is this a genuine example of biodegradable plastic?


WHAT IS THE VALUE PROPOSITION FOR BIODEGRADABILITY?

End-of-life option for complete removal of the plastic product from the environmental compartment in a safe and efficacious manner – enter into the microbial food chain!!!

Need to define disposal systems or environment like composting (compostable plastic), anaerobic digestor, soil, marine)

Need to define TIME to complete biodegradation (90%+ of the carbon substrate should be completely assimilated by the microorganisms present in the disposal within a short time period (one year or less)

Degradability, partial biodegradability, or will eventually biodegrade is not an option! – serious health and environmental consequences

ASTM D6400, D6868, D7021 (U.S. Govt procurement law, State of CA, San Francisco India , China, Korea)

EN 13432 European Packaging Directives

ISO 17088 (China, Korea, India)


Why Biodegradable Plastics? How does it work?

Low-temperature electron micrograph of a cluster of E. coli bacteria, magnified 10,000 times. Each individual bacterium is oblong shape http://emu.arsusda.gov/default.html

Harness the power of microbes in soil to completely remove the carbon based plastics from the environment.

How?

By ensuing that it is completely consumed by the microorganisms (as its carbon food) for driving its life processes in a short and defined time frame and in the specified environment

the carbon product is taken inside the microbial cell and biologically oxidized to CO2 which releases energy that is utilized by the microorganism for its life processes – to multiply and grow and populate the soil for biological activity


Microorganisms extract chemical energy for use in their life

processes by the aerobic oxidation of glucose and other

utilizable substrates – BIODEGRADBLE PLASTICS, food waste, paper,

forest residues biological matter

Glucose/C-bioplastic + 6 O2 6 CO2 + 6 H2O; G0’ = -686 kcal/mol

AEROBIC

CO2 is the quantitative measure of the ability of the microrganisms present in the disposal environment to utilize/assimilate the test C-bioplastic, which is the sole C-source available for the microorganisms -- biodegradation/bioassimilation

METRIC FOR BIODEGRADABILITY

ANAEROBIC

Glucose/C-bioplastic 2 lactate; G0’ = -47 kcal/mol

CO2 + CH4


0

20

40

60

80

100

0 4 8 12 16 20 24 28 32 36 40 44

% C conversion to CO2

time (d)

lag-phase plateau phase

biodegradation degree 65%

biodegradation curve

degradation phase

O2

Compost & Test

Materials

CO2

Radiolabelling methodology – longer duration, can use active compost environment (90+% of carbon converted to CO2 absolute or relative to cellulose/positive control

Cellulose curve must plateau and the time period for control and test material must be the same


FUNDAMENTALS -- BASICS

BIODEGRADATION -- BIODEGRADABILITY

Composting

Compostable plastic

Soil Anaerobic digestor

landfills marine

ENVIRONMENT

IN

IN WHAT TIME?


BIODEGRADABILITY/BIODEGRADATION

In simple terms, biodegradability measures the capacity of microorganisms present in the disposal environment to completely consume the bio carbon product within reasonable and defined time frame in the specified environment.

Composting is one such environment under which biodegradability occurs (compostable plastic) – In the composting environment:

the description of the environment the degree of microbial utilization (percent biodegradation) the time frame within which it occurs

are specified through ASTM D6400 (for plastic products), and ASTM D6868 (for coatings on plastic substrates) standards.

– In the marine environment the requirements are specified in ASTM D7081


HYDRO, OXO, PHOTO PREFIX DOES NOT MATTER!! Test method is material independent

HYDROLYTIC OXIDATIVE

COMPLETE BIOASSIMILATION/BIODEGRADTION IN

DISPOSAL ENVIRONMENT IN SPECIFIED TIME

Carbon chain polymers

QUESTION IS -- Can the microbial population in the disposal environment completely assimilate/utilize the C-material in one year time frame???

Time & Disposal Environment is the KEY

PVOH – YES

PE/PS + ADDITIVES – NO, NOT IN THE DISPOSAL ENVIRONMENT AND NOT IN ONE-TWO YEAR TIME FRAME

PET –NOPBAT, PBS -- YESCELLULOSE TRIACETATE –NOCA ( around 2.0 ds – yes)PLA (YES, crystallinity is key)

Specification StandardsD6400, D6868, D7021EN 13432ISO 17088


END OF LIFE OPTIONS

COMPOSTING FACILITY

COMPOSTING FACILITY RECYCLING

FACILITY

RECYCLING FACILITY





RECYCLED PRODUCTS


back to soil

ENERGY

INCINERABLE

Anaerobic digestion facility

Marine environment

Paper-biopolymer composite

Landfill

X

Unless managed for landfill gas recovery for energy

BIOBASED

PLASTICS


Cradle to Cradle Concept for Material Design(Integration of Biodegradable Materials with Disposal Infrasructures)



COMPOSTING FACILITY

COMPOSTING FACILITY


back to soil

TEST METHODASTM D5338; ISO14855 1 & 2 ISO16939 (disintegration)ASTM D6340 C-14 SPECIFICATIONSASTM D6400; EN 13432 ISO 17088ASTM D6868 – paper coatings


facility


facility

ASTM D5271ISO 14851/14852

Anaerobic digestionbiogas energy plant

ASTM D5511ISO 15985

Soil Mulch film

Agriculture appl

Soil Mulch film

Agriculture appl

ASTM D 5988

Marine&fresh water

ASTM D 6691,6692D 7021 specification



DEGRADABLEVS

BIODEGRADABLE

Biodegradability claim must be qualified by identifying the disposal environment, ensuing complete utilization of the carbon substrate by the microorganisms present in the disposal environment in a short time period – one year or less, and substantiated by the appropriate ASTM, or ISO standards

Degradability, partial biodegradability, or will eventually biodegrade is not an option! – serious health and environmental consequences


BIODEGRADABILITY

Define Time – complete and short (one growing season)

Define Disposal Environment like composting

Degradability, partial biodegradability, or will eventually biodegrade is not an option! – serious environmental consequences


Problems with Degradables – Toxic Chemicals Transport

plastic pieces can attract and hold hydrophobic elements like PCB and DDT up to one million times background levels. As a result, floating plastic is like a poison pill -- toxins are carried up the food chain – birds, fishes, and eventually human

– From Algalita Marine Research Foundation – www.algalita.org/pelagic_plastic.html

Plastic residues function as a transport medium for toxic chemicals in the marine environment.

PCBs, DDE, and nonylphenols (NP) were detected in high concentrations in degraded polypropylene (PP) resin pellets collected from four Japanese coasts.

– Mato et al Environ. Sci. Technol. 2001, 35, 318-324


Captain Charles Moore

Algalita Marine Research Foundation

Plastic fragments with toxins colonized and consumed by birds fishesTransport of toxins up the food chain


Major Problems/Issues with Degradable Materials/Products

Thompson, R.C. et al. 2004. Lost at sea: Where is all the plastic? Science 304, 838, 2004

Plastic debris around the globe can erode (degrade) away and end up as microscopic granular or fiber-like fragments, and that these fragments have been steadily accumulating in the oceans

fragments come from several sources, the researchers suggest. These include mechanical erosion of nondegradable plastic bottles and packaging, nondegradable parts of biodegradable plastics, and plastic pieces used as abrasives in cleaning agents.

FLOTSAM Lab experiments show that marine animals consume microscopic bits of plastic, as seen here in the digestive tract of an amphipod. © Science 2004


Biodegradable Plastic Products Space Confusion Misunderstanding Misinformation Claims without scientific substantiation GETTING BETTER/MUCH BETTER

– ASTM Standards in place D6400 for composting, D6868 for paper coatings modifiers and

additives, D 7021 for marine – specification standards– Certification by BPI based on strict compliance with Standards– Regulations like in CA– Pioneering programs like the one at the city of San Francisco

enforcing compliance of Standards– California Waste Management Board study at Chico State showing

the applicability of Standards and demonstrating “true completely biodegradable plastics in composting conditions”

– Other Community, State, mandates – U.S. Composting Council



ASTM D6954

7.1 The reporting section must clearly and objectively include the proposed real world applications and disposal environments for which the plastic is being developed with indicated exposure and lifetime expectancies.

7.2 Tier 1—The report must identify the following: 7.2.1 Resin grade plus the commercial name of the formulation additive or

percent of catalyst concentrations. NOTE 8—Identification of test samples needs to be sufficient to inform readers of

the commercial identification of the formulation and of the additives and their availability in the marketplace.

7.2.2 The proposed disposal medium or media for the plastic must be indicated with anticipated life expectancy noted.

7.2.3 The exposure conditions such as temperature, time, moisture, and oxygen concentrations need to be reported.

7.2.4 The exposure conditions and time of exposure (kJ/m 2·nm at 340 nm) to radiation, if used, must be recorded.

7.2.5 Molecular weight and polydispersity index, tensile elongation, and percentage of gels of the samples before and after the indicated time for abiotic test exposure should be reported.

7.2.6 Complete mass balances are to be reported.


ASTM D6954 (Contd) 7.3 Tier 2—The report must state the following: 7.3.1 Extent of biodegradation (carbon dioxide evolution profile to plateau as

per standards) and expressed as a percentage of total theoretical carbon balance.

7.3.2 Percentage of gel or other nondegradable fractions. 7.3.3 Volatiles produced by the oxidation process. 7.3.4 Temperature and moisture conditions. 7.3.5 Additions of inoculants and moisture and their timing and any additional

mixing procedures. 7.4 Resulting data from Tier 1 combined with data from Tier 2 for comparison

and ranking of polymers under test.

7.5 Tier 3—The report shall include the following: 7.5.1 Detailed description of preparation of material for testing. 7.5.2 Specific testing performed as described in 6.9 with particular emphasis on

any deleterious effects of the soil or aquatic additive. 7.5.3 Regulated metal concentrations, pH, and ability to hold and percolate

water before and following oxobiodegradation testing.

NOTE 5—For determining biodegradation rates under composting conditions, Specification D 6400 is to be used, including test methods and conditions as specified.


ASTM D 6954 contd -- NOTE

NOTE 5—For determining biodegradation rates under composting conditions, Specification D 6400 is to be used, including test methods and conditions as specified.

At least one temperature must be reasonably close to the end use or disposal temperature, but under no circumstances should this be more than 20°C away from the removed that temperature. It must also be established that the polymer does not undergo a phase change, such as glass transition temperature (Tg) within the temperature range of testing

Standard Guide for Exposing and Testing Plastics that Degrade in the Environment by a Combination of Oxidation and Biodegradation


ASTM D6400 identified 3 criteriaMineralization (D5338):

Conversion to carbon dioxide, water & biomass via microbial assimilation

60% of carbon conversion to CO2 for homopolymer & 90% carbon conversion to CO2 for block, segmented copolymers, and blends, including addition of low MW additives

Same rate as natural materials Leaves, paper, grass & food scraps

Time -- 180 days or less; if radiolabeled polymer is used 365 days or less

Disintegration <10% of test material on 2mm sieve

– Safety No impacts on plants, using OECD Guide 208 Regulated (heavy) metals less than 50% of EPA

(USA, Canada) prescribed threshold

Specification Standard for Biodegradable/Compostable Plastics

Basis for standards inEurope, Japan, China,

Korea, Taiwan

O2

Compost & Test

Materials

CO2


TERMINOLOGYBIOBASED (RENEWABLE)Organic material containing in whole or part biogenic (biological sources) carbonRefers to using biomass or crop feedstock (New carbon) vs petroleum or fossil feedstock (OLD carbon)Reducing carbon footprint

BIODEGRADABILITYEND-OF-LIFE option – integrated with disposal systems like composting, and anaerobic digestion or marine or soilfunctional property attribute to be designed and engineered into a biobased product when needed or necessary!!

BIOMATERIALS Refers to:Any material (metal, plastic, ceramic) implanted in the body -- design and engineering considerations different; biodegradability considerations differentBiomedical applications

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Ramani Narayan, Michigan State University UNDERSTANDING BIODEGRADABILITY ROLE IN PLASTICULTURE MYTHS...

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