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Ramani Narayan, Michigan State University Tutorial on BIODEGRADABLE PLASTICS [email protected] & MATERIALS SCIENCE Ramani Narayan University Distinguished Professor If you use any of the slides/materials, please reference authorship and affiliation (Ramani Narayan, Michigan State University) – thank you Copyright Ramani Narayan
27

Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Sep 04, 2014

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Page 1: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

Tutorial on BIODEGRADABLE PLASTICS

[email protected]

&MATERIALS SCIENCE

Ramani NarayanUniversity Distinguished Professor

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

Copyright Ramani Narayan

Page 2: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

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

• Disposal environment (like composting, anaerobic digestor, marine

• 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)

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

Carbon footprint reduction strategy using bio content

Value proposition for biodegradable plastics/products

2

Page 3: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

TERMINOLOGY

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

Biodegradability – can be partial with break down products assimilated by the body, and the remaining polymer excreted from the body

ENVIRONMENTAL BIODEGRADABILITY – END-OF-LIFE scenario Biodegradability (Environmental) is a measure of the microbial utilization of (carbon) substrates in the selected environment

• Biodegradability must be Complete – otherwise serious consequences• Biodegradability in a measure, short time period – for composting it is 180

days

Page 4: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

Terminology (Contd)

BIODEGRADABLE (Complete)AND

PETRO/FOSSIL BASEDPLASTICS OR PRODUCTS

BIO (renewable) BASED

OR

BIOMASS BASED

PLASTICS OR PRODUCTS

NOT BIODEGRADABLE

Value proposition --Provides for a reduced

carbon footprint

BIODEGRADABLE (complete)AND

BIOBASEDPLASTICS OR PRODUCTS

BIOPLASTICS

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

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

the microorganisms as measured by the evolved CO2 (aerobic) and CO2 + CH4 (anaerobic)

Page 5: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

Carbon footprint reduction strategy using bio contentBiodegradability

5

Using biodegradability as an end-of-life option to completely remove single use short life disposable products from the environmentalcompartment in a safe and efficacious manner via microbial assimilation (microbial food chain)

• Disposal environment (like composting, anaerobic digestor, marine

• 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)

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

• Specification Standards ASTM D6400, D6868, D7021• Specification Standards EN 13432 (European Norm)• Specification Standards ISO 17088 (International Standard)

Page 6: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

What does Biodegradable Mean?Can the microorganisms in the target disposal system (composting, soil, anaerobic digestor) assimilate/utilize the carbon substrate as food source completely and in a short defined time period?

CO2 + H2O + Cell biomass

Completemicrobial assimilation

defined time frame, no residues

Hydrolytic

Polymer chains with susceptible linkages

EnzymaticOxidative

Oligomers & polymer fragments

Environment – soil, compost, waste water plant, marine

Biodegradation(Step 2): Only if all fragmented residues consumed by microorganisms as a food & energy source as measured by evolved CO2 in defined time and disposal environment

STEP 1

STEP 2

Page 7: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

Carbon footprint reduction strategy using bio contentMeasuring biodegradability

7

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; DG0’ = -686 kcal/molAEROBIC

ANAEROBIC

Glucose/C-bioplastic 2 lactate; ΔG0’ = -47 kcal/mol

CO2 + CH4

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

Page 8: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

More Biodegradation/Bioassimilation Facts The aerobic oxidation process (a highly specialized cellular phenomenon) requires the participation of three metabolically interrelated processes:

1. Tricarboxylic acid cycle (TCA cycle)2. Electron transport3. Oxidative phosphorylation

All of the processes take place inside the cell

For these processes to occur:The substrates needs to be transported inside the cell

Thus, molecular weight, hydrophobic/hydrophilic balance, other molecular and structural features govern transport across cell membrane into the cell for utilization of the C-substrate.

Page 9: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

Carbon footprint reduction strategy using bio contentMeasuring biodegradability

9

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

Time (days)

% C

con

vers

ion

to C

O2

(% b

iode

grad

atio

n)

lagphase

biodegradation phase

plateau phase

biodegradation degree O2

Compost & Test

Materials

CO2

Page 10: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

END OF LIFE OPTIONS

COMPOSTINGFACILITY

COMPOSTINGFACILITY RECYCLING

FACILITYRECYCLING

FACILITY

WASTE TO ENERGY FACILITY

WASTE TO ENERGY FACILITY

BiodegradablePlastics

BiodegradablePlastics

RECYCLED PRODUCTS

LAND APPLICATIONrecycling polymeric carbon

back to soilENERGY

INCINERABLE

Anaerobic digestion facility

Marine environment

Paper-biopolymer composite

Landfill

X

Unless managed for landfill gas recovery for energy

BIOBASED

PLASTICS

Page 11: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

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 --endocrine disruptors

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

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

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

– Takada et al Environ. Sci. Technol. 2001, 35, 318-324 – Blight, L.K. & A.E. Burger. 1997. Occurrence of plastic

particles in seabirds from the Eastern North Pacific. Mar. Poll. Bull. 34:323-325

– Phil. Trans. Royal. Soc. (Biology) July 27, 2009; 364

Page 12: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

THE NEED FOR COMPLETE BIODEGRADABILITY !

• 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

Page 13: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

Aliphatic-aromatic copolyester

Copolyester

C C

O O

O CH2 O C

O

CH2 C

O

m nx y z

Terephthalic acid Diol Aliphatic diacid

Tm ~ 110 -125 0C

Completely Biodegradable (microbial assimilation) under composting conditions

BASF (ECOFLEX & ECOVIO) Novamont (Eastman Chemcial) DuPontBayer (esteramide)Showa (BIONELLE, chain extension with isocyanate

C-14 label on aromatic ring carbon for monitoring biodegradability

Page 14: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

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

R - copolyester

Page 15: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

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

BiodegradableMaterials

BiodegradableMaterials

COMPOSTINGFACILITY

COMPOSTINGFACILITY

LAND APPLICATIONrecycling polymeric carbon

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

Waste water treatment

facility

ASTM D5271ISO 14851/14852

Anaerobic digestionbiogas energy plant

ASTM D5511ASTM D5526ISO 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

Page 16: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Narayan

Carbon footprint reduction strategy using bio content

16

Biodegradability under composting conditions

• Specification Standards ASTM D6400, D6868, D7021• Specification Standards EN 13432 (European Norm)• Specification Standards ISO 17088 (International Standard)

Biodegradability under marine conditions• Specification Standard D 7021

Biodegradability Test Methods – ASTM Standards• Soil D5988• Anaerobic digestors D 5511, ISO 15985

• Biogas energy plant• Accelerated landfill D 5526

• Guide to testing plastics that degrade in the environment by a combination of oxidation and biodegradation ASTM D 6954

Must provide results from the test methods – could be zero or 50 or 100 percent --- generally not provided but claim of complete biodegradability made

Page 17: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

Sorting through facts, hypes, claims (misleading)

GREEN WASHING

Page 18: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

MISLEADING BIODEGRADABILITY CLAIMS

Page 19: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

MISLEADING BIODEGRADABILITY CLAIMS

Page 20: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

Green Washing Claims -- Additive Technology• “Plastic products with our additives at 1% levels will fully

biodegrade in 9 months to 5 years wherever they are disposed like composting, or landfills under both aerobic and anaerobic conditions”

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.DATA DOES NOT SUPPORT THE CONCLUSIONS!

Page 21: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

MISLEADING CLAIMS – UNSUPPORTED BY DATA

Oxo-biodegradable polyethylene (PE) film claims – “The technology is based on a very small amount of prodegradant additive being introduced into the manufacturing process, thereby changing the behavior of the plastic and the rate at which it degrades. The plastic does not just fragment, but is then consumed by bacteria and fungi and therefore continues to degrade to nothing more than carbon dioxide, water and biomass with no toxic or harmful residues to soil, plants or macro-organisms”“Designed to interact with the microorganisms present in landfills, composters, and almost everywhere in nature including oceans, lakes, and forests. These microorganism metabolize the molecular structure of the plastic breaking it down into soil”“Combined with an oxo-biodegradable proprietary application method to produce films for bags. This product, when discarded in soil in the presence of microorganisms, moisture, and oxygen, biodegrades, decomposing into simple materials found in nature. Completely breakdown in a landfill environment in 12-24 months leaving no residue or harmful toxins and have a shelf life of 2 years”In each of the above cases scientific substantiation showing carbon conversion to CO2 using established standard test methods NOT PROVIDED

Page 22: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

“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.”

Page 23: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

Page 24: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

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?

Page 25: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

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

Biodegradability Factoids

• An independent study commissioned by the State of California’s Waste Management Board with a California public university showed that the “oxo-biodegradable” bags on the market showed no biodegradation ("Performance Evaluation of Environmentally Degradable Plastic Packaging and Disposable Service Ware," California Integrated Waste Management Board (CIWMB) Publications)

• http://www.ciwmb.ca.gov/Publications/Plastics/43208001.pdf (June 2007).

• This study, and the proliferation of unsubstantiated wild claims on biodegradability forced the State of California to put in place laws:

Page 26: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

Ramani Narayan, Michigan State University

GREEN WASHING

NAD (National Advertising Division of the Council of Better Business Bureaus) EXAMINES ADVERTISING FOR GP PLASTICS CORP.‘POLYGREEN’ PLASTIC BAGSNAD Recommends Marketer Modify, Discontinue Certain ‘Green’ Marketing Claims

US Federal procurement requires biodegradability claims to be substantiated by ASTM D6400 specification standard

State of California passed law AB 1972 that no claims of biodegradability should be made unless it meets ASTM D6400 & city of San FranciscoAB 2071 authorize a city, a county, or the state to impose civil liability, in specified amounts, for violations of the above provisions

NAD recommended the following claims be discontinued:• Enviroware is formulated to degrade in months when buried or discarded in a landfill• Enviroware cutlery, straws, hinged containers, plates, bowls and trays are 100%biodegradable and come with a certificate of biodegradability.Federal Trade Commission (FTC) recently brought action against three companies for scientifically unsubstantiated biodegradability claims that their products biodegrade within a reasonably short period of time (landfill

Page 27: Principles of Biodegradable PLASTICS the Science the Hype and the Misleading Claims

TAKE HOME MESSAGEBiodegradability is an end-of-life option for single use disposable, packaging and consumer plastics that harnesses microbes to completely utilize the carbon substrate and remove it from the environmental -- entering into the microbial food chain.

However, biodegradability must be defined and constrained by:• The disposal system – composting, anaerobic digestor, soil,

marine• Time required for complete microbial utilization in the selected

disposal environment – short defined time frame, and in the case of composting the time frame is defined as 180 days or less

• Complete utilization of the substrate carbon by the microorganisms as measured by the evolved CO2 (aerobic) and CO2 + CH4 (anaerobic) leaving no residues

Degradability, partial biodegradability, or will eventually biodegrade is not an option! – serious health and environmental consequences can occur as documented in literature