poly(lactic acid) / poly(hydroxyalkanoate) nonwovens as...
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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
* dhayes1@utk.edu
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
BEPS Conference, Denton, TX, Sept 20122
“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)
BEPS Conference, Denton, TX, Sept 20123
“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
BEPS Conference, Denton, TX, Sept 20124
“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)
BEPS Conference, Denton, TX, Sept 20125
“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
BEPS Conference, Denton, TX, Sept 20127
Commercially Available Polymers and Blends Employed in Biodegradable Agricultural Mulches
BEPS Conference, Denton, TX, Sept 20128
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
BEPS Conference, Denton, TX, Sept 20129
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
BEPS Conference, Denton, TX, Sept 201210
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
BEPS Conference, Denton, TX, Sept 201211
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
BEPS Conference, Denton, TX, Sept 201212
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
BEPS Conference, Denton, TX, Sept 201213
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
BEPS Conference, Denton, TX, Sept 201214
Conceptual Model for
Biodegradation of Mulches
BEPS Conference, Denton, TX, Sept 201215
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)
BEPS Conference, Denton, TX, Sept 201216
Greenhouse Expt II: Effect of Soil Moisture and Hydrolases (Bromelain)
BEPS Conference, Denton, TX, Sept 201217
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)
BEPS Conference, Denton, TX, Sept 201218
Molecular Weight Analysis (Greenhouse Study II)
FTIR Analysis of MB-PLA (75%) – PHA (25)
BEPS Conference, Denton, TX, Sept 201219
Effect of Soil Moisture and Pineapple Juice: FTIR Analysis (Greenhouse Study II)
BEPS Conference, Denton, TX, Sept 201220
MB-PLA (75%) / PHA (25%)
30 wk of soil burial
High Moisture enhances hydrolysis
SEM Analysis (Greenhouse Study II)
BEPS Conference, Denton, TX, Sept 201221
MB-PLA LMPJ MB-PLA (85%) + PHA (25%) LM
MB-PLA (75%) + PHA (25%) HMPJ
SB-PLAHM
Fiber bond breakage
BEPS Conference, Denton, TX, Sept 201222
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
BEPS Conference, Denton, TX, Sept 201223
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
BEPS Conference, Denton, TX, Sept 201224
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)
BEPS Conference, Denton, TX, Sept 201225
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
BEPS Conference, Denton, TX, Sept 201226
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
BEPS Conference, Denton, TX, Sept 201228
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
BEPS Conference, Denton, TX, Sept 201229
Biodegradability and Weatherometry
Photodegradation of PLA: Norrish II mechanism of carbonyl polyester (Ikada E. , J Photopolym Sci Technol 1997:10(2):265-270).
BEPS Conference, Denton, TX, Sept 201230
Effect of Weatherometry on Molecular Weight
BEPS Conference, Denton, TX, Sept 201231
Effect of Weatherometry on Tensile Strength
BEPS Conference, Denton, TX, Sept 201232
Biodegradability of Weatherometry-Treated Mulches (ASTM D5338)
BEPS Conference, Denton, TX, Sept 201233
Weatherometry (FTIR Analysis) MB-PLA (75%) + PHA (25%)
BEPS Conference, Denton, TX, Sept 201234
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
BEPS Conference, Denton, TX, Sept 201235
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
BEPS Conference, Denton, TX, Sept 2012
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
BEPS Conference, Denton, TX, Sept 201237
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