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

Tutorial on BIODEGRADABLE PLASTICS

Ramani Narayan University Distinguished Professor

& MATERIALS SCIENCE [email protected] you use any of the slides/materials, please reference authorship and affiliation (Ramani Narayan, Michigan State University) thank you Copyright Ramani NarayanRamani Narayan, Michigan State University

Carbon footprint reduction strategy using bio content

Value proposition for biodegradable plastics/products 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

Ramani Narayan, Michigan State University

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TERMINOLOGY

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 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

Ramani Narayan, Michigan State University

Terminology (Contd)BIOPLASTICS

BIO (renewable) BASED OR BIOMASS BASED PLASTICS OR PRODUCTS NOT BIODEGRADABLE Value proposition -Provides for a reduced carbon footprint

BIODEGRADABLE (complete) AND BIOBASED PLASTICS OR PRODUCTS

BIODEGRADABLE (Complete) AND PETRO/FOSSIL BASED PLASTICS OR PRODUCTS

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)

Ramani Narayan, Michigan State University

Carbon footprint reduction strategy using bio content

Biodegradability

Using biodegradability as an end-of-life option to completely remove single use short life disposable products from the environmental compartment 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 completelyassimilated 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)5

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?

Environment soil, compost, waste water plant, marine Hydrolytic Oxidative Enzymatic

STEP 1 Oligomers & polymer fragmentsComplete

Polymer chains with susceptible linkages

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

microbial assimilation

defined time frame, no residues STEP 2

CO2 + H2O + Cell biomass

Ramani Narayan, Michigan State University

Carbon footprint reduction strategy using bio content

Measuring biodegradability

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 AEROBIC Glucose/C-bioplastic + 6 O2 ANAEROBIC Glucose/C-bioplastic 2 lactate; G0 = -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 6 CO2 + 6 H2O; DG0 = -686 kcal/mol

Ramani Narayan, Michigan State University

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More Biodegradation/Bioassimilation FactsThe aerobic oxidation process (a highly specialized cellular phenomenon) requires the participation of three metabolically interrelated processes: 1. Tricarboxylic acid cycle (TCA cycle) 2. Electron transport 3. 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.Ramani Narayan, Michigan State University

Carbon footprint reduction strategy using bio content

Measuring biodegradabilityCO2

100

% C conversion to CO2 (% biodegradation)

90 80

biodegradation degree

O2

plateau phase70 60 50 40

biodegradation phase30 20 10 0 0 20 40 60 80 100 120 140 160 180 200

Compost & Test Materials

lag phase

Time (days)

Ramani Narayan, Michigan State University

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END OF LIFE OPTIONS

LandfillAnaerobic digestion facility

Unless managed for landfill gas recovery for energy Marine environment

X

COMPOSTING COMPOSTING FACILITY FACILITY

Biodegradable Biodegradable Plastics Plastics INCINERABLE

Paper-biopolymer composite

RECYCLING RECYCLING FACILITY FACILITY

recycling polymeric carbon back to soil

LAND APPLICATION

WASTE TO ENERGY WASTE TO ENERGY FACILITY FACILITY ENERGY

RECYCLED PRODUCTS

BIOBASED PLASTICS

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

Phil. Trans. Royal. Soc. (Biology) July 27, 2009; 364Ramani 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 2004Ramani Narayan, Michigan State University

Aliphatic-aromatic copolyesterC-14 label on aromatic ring carbon for monitoring biodegradability

O C

O C x O CH2 O m y Diol Copolyester

O C CH2 n

O C z

Terephthalic acidTm ~ 110 -125 0C

Aliphatic diacid

Completely Biodegradable (microbial assimilation) under composting conditions

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

Ramani Narayan, Michigan State University

R - copolyesterRamani Narayan, Michigan State University, www.msu.edu/~narayan

Cradle to Cradle Concept for Material Design(Integration of Biodegradable Materials with Disposal Infrasructures) TEST METHOD ASTM D5338; ISO14855 1 & 2 ISO16939 (disintegration) ASTM D6340 C-14 SPECIFICATIONS ASTM D6400; EN 13432 ISO 17088 ASTM D6868 paper coatings COMPOSTING COMPOSTING FACILITY FACILITY ASTM D 5988 Soil Soil Mulch film Mulch film Agriculture appl Agriculture appl ASTM D 6691,6692 D 7021 specification Marine & fresh water

Biodegradable Biodegradable Materials Materials

Anaerobic digestion biogas energy plant ASTM D5511 ASTM D5526 ISO 15985

recycling polymeric carbon back to soil

LAND APPLICATION

Waste water Waste water treatment treatment facility facility ASTM D5271 ISO 14851/14852

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

Carbon footprint reduction strategy using bio content

Biodegradability under composting conditions Specification Standa