Poly(Lactic Acid) / Poly(Hydroxyalkanoate) Nonwovens as ...agsyst.wsu.edu/Scri/Hayes-BEPS-PLA-mulches.pdfPLA: Disadvantages Hard embrittlement & poor thermostability Highly crystalline

Poly(Lactic Acid) / Poly(Hydroxyalkanoate) Nonwovens as

Biodegradable Agricultural Mulches

Douglas G. Hayes1,*, Larry C. Wadsworth1, Sathiskumar Dharmalingam1, Karen K. Leonas2, Carol Miles3, Debra A.

Inglis3, Elodie Hablot4, and Ramani Narayan4

1University of Tennessee, Knoxville, TN; 2 Washington State University (WSU), Pullman, WA; 3 WSU Northwestern Washington Research & Extension Center, Mount Vernon, WA; 4 Michigan State University, East Lansing, MI

* [email protected]

BEPS Conference, Denton, TX, Sept 20121

Outline1. Introduction, Goals, and Approaches

2. Soil burial / greenhouse studies

3. Performance assessment in high tunnel and open field studies

4. Weatherometry and biodegradability testing

5. Conclusions


“Plastic” Agricultural Mulches

Started in the 1950s Its cost (~240 USD / ha) offset by

increased crop yield 2.6 million metric tonnes of plastic

mulches / yr worldwide 10 million ha of land used in China

alone (80% of world market)


“Plastic” Agricultural Mulches: Advantages

Reduced weed problems Enhanced moisture control Increased soil temperature extension of growing season increased plant growth rate

Reduced soil compaction Reduced fertilizer leaching Cleaner specialty crop product Root pruning eliminated http://www.ces.ncsu.edu/depts/hort/hil/hil-33.html


“Plastic” Agricultural Mulches: Disadvantages Undesirable end-of-life alternatives: black plastic

(polyethylene, “PE”) slowly biodegradable or compostable Harmful biodegradation products Becomes brittle debris can tarnish crops; affect

drainage of water; increase local pesticide / toxicant levels

petroleum-derived poor sustainability Costly and laborious to remove

(250 USD / ha) Greater initial costs Intensive irrigation management Soil erosion (between strips)


“Plastic” Agricultural Mulches: Disadvantages

BEPS Conference, Denton, TX, Sept 20126 Photo courtesy of Ramani Narayan, MSU

Developed in the 1980’s Ultimate goal: complete microbial assimilation at the

end of the growingn season, after being tilled into the soil

“.. the best choice appears to be a mulch material ..o with an outdoor service life which matches the crop

duration, and o which would later be incorporated by the agricultural

system” (Martin-Closas, et al Biopolymers 2011, 277-299.)

High cost compared to conventional PE mulches, 2.54 x What are acceptable standards? (X% conversion of C

CO2 in Y days)

“Biodegradable” Agricultural Mulches


Commercially Available Polymers and Blends Employed in Biodegradable Agricultural Mulches


Product Name Polymer Manufacturer

Biocycle® Sucrose / PHA blend PHB Industrial (Brazil)

Bio-Flex PLA / copolyester FKUR, Willich (Germany)

BiomaxTPS Starch DuPont (USA)

Biomer L PHA Biomer (Germany)

Bionolle PBS Showa High Polymer (Japan)

Biopar Starch co-polyester Biop (Germany)

BiosafeTM PBAT/starch blend; PBS; PBSA Xinfu Pharmaceutical Co (China)

Eastar BioTM PBAT / starch blend Novamont (Italy)

Eco-Flex® PBAT / starch blend BASF (Germany)

Ecovio Ecoflex® + PLA BASF (Germany)

Envio Ecoflex® +PLA+starch blend BASF (Germany)

Green = Biobased

From Hayes et al, in in Degradable Polymers and Materials, Principles and Practice, 2nd Edition (ACS Symposium Series),K.C. Khemani and C.n Scholz, Eds., Washington, DC, American Chemical Society, in press


Product Name Polymer Manufacturer

EnPol PBS IRE Chemical (Korea)

GreenBio PHA Tianjin GreenBio Materials (China)

Ingeo® Starch + PLA; PBS + PLA Natureworks (USA)

Mater-Bi® PCL + starch blend Novamont (Italy)

Mirel® PHA Metabolix (USA)

Paragon Starch + thermoplastic starch Avebe, (Netherlands

ReNew PHA Danimer Scientific (USA)

Skygreen® Terephthalic acid co-polyester SK Chemicals (Korea)

Commercially Available Polymers and Blends Employed in Biodegradable Agricultural Mulches

Green = Biobased

Nonwovens Textiles “manufactured sheet, web or bat of

directionally or randomly oriented fibers, bonded by friction, and/or cohesion and/or adhesion” (http://web.utk.edu/~mse/Textiles/)

Not woven or knitted; not paper-based Examples: Medical surgical

gowns; HEPA air filters, disposable clothing

Note: Almost all agricultural plastics are films


Nonwovens as Agricultural Mulches?

Nonwovens: high strength, low weight

Nonwovens: small fiber size Increased rate of hydrolysis & microbial assimilation

Nonwovens can be made inexpensively

crystalline morphology, often


Spunbond-PLA: 14.8 ± 0.8 m

Meltblown-PLA: 6.3 ± 2.3 m

PLA: Advantages

Biobased Readily available 140,000 metric tonnes at the Blair, NE USA facility

operated by NatureWorks, LLC Global production: 800,000 metric tonnes by 2020

Reasonably priced 2.1 USD / kg Compostable Possesses good mechanical strength


PLA: Disadvantages

Hard embrittlement & poor thermostability Highly crystalline Hydrophobic A “synthetic” (produced via chemical

catalysis of biobased lactic acid) slowly biodegrades under ambient conditions

in soil (Tokiwa, et al. Int. J. Mol. Sci. 2009, 10, 3722-3742) Enriched microbial community nearly complete

disintegration of PLA in soil at 30oC (Hakkarainen et al. Polymer 1999, 41, 2331-2338)

Blends formed (PBAT, PCL, and common plasticizers such as lactic acid, glycerol, and citrate esters), or copolymers


Ultimate Goal

Prepare a biobased agricultural mulch .. that will perform well for specialty crop cultivation .. that would undergo slow deterioration during the

cultivation season (~March – October) .. that would be tilled into the soil at the end of the

cultivation season (~November) .. and would be completely mineralized by the

beginning of the next cultivation season (March) Alternate Goal: ..would not undergo fragmentation during a long

cultivation season .. would be easily retrieved from the soil at the end

of its use .. then would be composted


Conceptual Model for

Biodegradation of Mulches


Outline1. Introduction, Goals, and Approaches2. Soil burial / greenhouse studies3. Performance assessment in high tunnel and open field studies4. Weatherometry and biodegradability testing5. Conclusions

Key Participants S. Dharmalingham, T. Washington, T. Pannell, Prof. Doug

Hayes, Prof. Larry Wadsworth, UTK J. Martin, Prof. Annette Wszelaki, UTK R. Raley, Prof. Jaehoon Lee, UTK

Greenhouse Study 1: Wadsworth et al, JEFF J, in press (2012)


Greenhouse Expt II: Effect of Soil Moisture and Hydrolases (Bromelain)


2 Soil Moisture Levels 2 burial times (10 and 30 wk) 2 enzyme treatments (pineapple juice = PJ; no PJ) 4 Mulches

Spunbond (SB)-PLA-2011-black (Natureworks Ingeo® 6252D)

Meltblown (MB)-PLA-2011 (Ingeo® 6252D) MB-PLA(85%)+PHA(15%); (Ingeo® 6251D + GreenBio®) MB-PLA(75%)+PHA (25%)

2 replicates 64 trays Analyses: GPC, FTIR, SEM, Tensile strength (breaking load

and elongation); soil properties (pH, CEC)


Molecular Weight Analysis (Greenhouse Study II)

FTIR Analysis of MB-PLA (75%) – PHA (25)


Effect of Soil Moisture and Pineapple Juice: FTIR Analysis (Greenhouse Study II)


MB-PLA (75%) / PHA (25%)

30 wk of soil burial

High Moisture enhances hydrolysis

SEM Analysis (Greenhouse Study II)


MB-PLA LMPJ MB-PLA (85%) + PHA (25%) LM

MB-PLA (75%) + PHA (25%) HMPJ

SB-PLAHM

Fiber bond breakage


Effect of Soil Moisture and Pineapple Juice: Tensile Strength (Greenhouse Study II)

SB-PLA underwent no loss of Peak Load

Results: Greenhouse II1. MB-PLA (75%) + PHA (25%) underwent the greatest

extent of deteriorationA. 90% loss of tensile strengthB. 13% decrease of MWC. Ester bond cleavage

2. SB-PLA underwent minimal deterioration good candidate for compostable plastics for long-term agriculture

3. Moisture level, addition of pineapple juice, had minimal effect on hydrolysis of ester bonds


Outline1. Introduction, Goals, and Approaches2. Soil burial / greenhouse studies3. Performance assessment in high tunnel and open

field studies4. Weatherometry and biodegradability testing5. Conclusions

Key Participants Profs. Debra Inglis and Carol Miles, and their groups (WSU, NW

REC, Mount Vernon, WA USA) Prof. Russell Wallace’s group (Texas AgriLife REC, Lubbock,

TX USA) J. Martin, Prof. Annette Wszelaki, UTK Prof. Karen Leonas and her group; Prof. Doug Hayes and his

group


High Tunnel and Open Field Studies in TN, TX, and WA: Mulches (2010)

BioBag (Mater-Bi -Based), Palm Harbor, FL BioTelo, (Mater-Bi -Based), Dubois Agrinovation, Waterford,

Ontario SB-PLA-2010-white, PLA donated by NatureWorks, Blair NE

USA; made at Saxon Textile Institute (STFI), Germany, white, 90 g m-2

Black Plastic Polyethylene, Pliant Corp, Schaumburg, IL USA Cellulose Control, “WeedGuardPlus,” SunShine Paper

Company, LLC, Denver, CO USA, 107 g m-2

Control (no mulch)


High Tunnel and Open Field Studies in TN, TX, and WA (2010): Methods and Conditions

Mulches laid 14 ft long, 2-3 ft wide & 5-6 ft apart in high tunnels or open fields

Tomatoes planted: ~Apr – Sept 2010 Irrigated: 1 inch of water per week Continuous monitoring of soil & air temp-

erature, moisture, pests & diseases, etc. Several different physical and chemical

test conducted on retrieved mulches


Comparison of Locations/Environment

Percent of Maximum Load at Time 3

Open Field High Tunnel BEPS Conference, Denton, TX, Sept 201227

Outline1. Introduction, Goals, and Approaches2. Soil burial / greenhouse studies3. Performance assessment in high tunnel and open field studies4. Weatherometry and biodegradability testing5. Conclusions

Key Participants1. Dr. Elodie Hablot, Prof. Ramani Naryan, and his

group, Michigan State Univ, East Lansing, MI USA2. S. Dharmalingham, Drs. Doug Hayes and Larry

Wadsworth, UTK


Biodegradability and Weatherometry Four mulches investigated

SB-PLA 2010 – white SB-PLA 2011 – black MB-PLA 2011 (white) MB-75% PLA / 25% PHA

All mulches treated by weatherometry Ci4000 Xenon Weather-Ometer, Standard = ASTM G155-05a Exposure Cycle: 102 min light at 63°C; 18 min light and water

spray Exposure time: 21 d (504 h) Irradiance: 0.35 W m-2 nm-1

Wavelength: 340 nm All mulches analyzed for biodegradability (ASTM D5833), before

and after weatherometry treatment


Biodegradability and Weatherometry

Photodegradation of PLA: Norrish II mechanism of carbonyl polyester (Ikada E. , J Photopolym Sci Technol 1997:10(2):265-270).


Effect of Weatherometry on Molecular Weight


Effect of Weatherometry on Tensile Strength


Biodegradability of Weatherometry-Treated Mulches (ASTM D5338)


Weatherometry (FTIR Analysis) MB-PLA (75%) + PHA (25%)


Results: Weatherometry1. MB-PLA (75%) + PHA (25%) underwent the greatest

extent of deteriorationA. 97% loss of tensile strengthB. 40% decrease of MW

2. SB-PLA-White and MB-PLA underwent slightly greater deterioration SB-PLA-Black (Tensile Strength, CO2 release)

3. All mulches are undergoing microbial assimilation under compost conditions


Summary

Spunbond PLA is a good candidate as a long-term agricultural plastic cover (high strength, low degradation)

Meltblown PLA+PHA is the best candidate to date for a mulch that can be plowed into the soil


36 BEPS Conference, Denton, TX, Sept 2012

Biodegradable Mulches for Specialty Crops Produced Under Protective Covers

Debra Inglis and Carol Miles (Project Directors)1;Andrew Corbin, Ana Espinola‐Arredondo, Annabel Kirschner, Karen Leonas, Tom Marsh and Tom Walters1;

Doug Hayes, Bobby Jones, Jaehoon Lee, Larry Wadsworth and Annette Wszelaki2; Jennifer Moore‐Kucera3; Russ Wallace4; Marion Brodhagen5 ; and Eric Belasco6;

NatureWorks (PLA Donation)Saxon Textile Institute (Germany)

Biax Fiberfilm (WI USA)Dr. William Klingeman (UTK)

Phil Flanagan (UTK)

1 25

SCRI Grant Award No. 2009-51181-05897

43 6


Documents

Poly(Lactic Acid) / Poly(Hydroxyalkanoate) Nonwovens as ...agsyst.wsu.edu/Scri/Hayes-BEPS-PLA-mulches.pdfPLA: Disadvantages Hard embrittlement & poor thermostability Highly crystalline