poly(lactic acid)-based biodegradable mulches for...
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Poly(Lactic Acid)-Based Biodegradable Mulches for “Green” Agriculture
Douglas G. Hayes
Department of Biosystems Engineering and Soil Science,University of TennesseeKnoxville, TN USA 37996dhayes1@utk.edu
Nanjing Agricultural University, Nov 111
Douglas G. Hayes
• Professor of Biosystems Engineering, University of Tennessee
• Internationally recognized scientist with over 25 years experience
• Co-authored and produced 50 articles and 13 book chapters
• Editor of Biobased Surfactants and Detergents - Synthesis, Properties, and Applications published by AOCS press
• Serves on editorial board of Journal of the American Oil Chemists’ Society, Journal of Surfactants and Detergents, and Biological Engineering Transactions
• Research Areas:
• Biobased products produced via biocatalysis
• Complex fluids / soft colloids for protein purification and biocatalysis
• Biobased degradable agricultural mulches
Nanjing Agricultural University, Nov 112
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
Nanjing Agricultural University, Nov 113
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 product Root pruning eliminated http://www.ces.ncsu.edu/depts/hort/hil/hil-33.html
Nanjing Agricultural University, Nov 114
“Plastic” Agricultural Mulches: Disadvantages
Costly and laborious to remove ($600 per acre) Potential environmental hazard Black plastic (polyethylene) is not biodegradable or
compostable Its persistence in the ecosystem can increase local
pesticide and toxicant concentrations Greater initial costs More intensive irrigation management Increased soil erosion (between strips of mulch)
http://www.ces.ncsu.edu/depts/hort/hil/hil-33.html
Nanjing Agricultural University, Nov 115
Goals for Biodegradable Mulches in AgricultureCurrent NIFA-SCRI Project: Oct 1, 2009 – Sept 30, 2012 To assess agricultural, ecological, and economic
consequences of using biodegradable mulches in protected (High Tunnel, or HT) and Open Field (OF) specialty crop production systems.
To test Poly(Lactic Acid)- [PLA-] based nonwovens (Spunbond and Meltblown) as mulch prototypes.
To test PLA and commercial “biodegradable” mulches for their performance in growing tomatoes under HT and OF conditions at 3 different US sites .. in a controlled study
Provide data that may be useful for developing a standard for biodegradation of mulches
O
O
n
Nanjing Agricultural University, Nov 116
Sites for Investigation Washington State University, Mount Vernon and
Pullman Campuses Texas A&M / Texas Tech University, Lubbock, TX University of Tennessee, Knoxville, TN
Nanjing Agricultural University, Nov 117
SCRI Interdisciplinary Research Team
Materials Working Group, “WG” (UTK, WSU)Design new biodegradable mulches from PLA and
its biopolymer blends via nonwovens textile technology
Physico-Chemical Testing
Crops WG (WSU, UTK, TAMU/TTU)Assess use of biodegradable mulches in high
tunnels for specialty crop production systems: plant physiology, weeds, pests, and diseases
Outreach to specialty crop growers/ organic farming community
Nanjing Agricultural University, Nov 118
SCRI Interdisciplinary Research Team
Soils WG (WSU, UTK, TAMU)Assess the impact of biodegradable mulches on
soil ecosystem
Economics WG (WSU, TTU)Assess the economic impact of using
biodegradable mulches in high tunnels
Sociology WG (WSU, UTK)Better understand the needs and concerns of the
specialty crops growers / organic farming community,
Discover and address the barriers hindering increased use of biodegradable mulches and high tunnels Nanjing Agricultural University, Nov 119
Why PLA-Based Nonwovens as Mulches?
PLA: Biobased, commercially available, reasonably priced, compostable & biodegradable
PLA: monomer is a common metabolite
Nonwovens: high strength, low weight
Nonwovens: small fiber size Increased rate of hydrolysis
Nonwovens can be made inexpensivelyNanjing Agricultural University, Nov 1110
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 the
cultivation season .. would be easily retrieved from the soil at the end
of the growing season .. then would be composted
Nanjing Agricultural University, Nov 1111
Nonwovens Textiles
(Wikipedia) “fabric-like material made from long fibres, bonded together by chemical, mechanical, heat or solvent treatment”
“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
Nanjing Agricultural University, Nov 1112
Nonwovens Textiles: Spunbond (SB)
Thermoplastic polymers are melted;
extruded through spinnerets; fibers are cooled and
collected on a conveyer beltNanjing Agricultural University, Nov 1113 http://web.utk.edu/~mse/Textiles/
Nonwovens Textiles: Meltblown (MB)
Low viscosity polymers are melted and extruded from a spinneret;
A stream of high velocity hot air disperses and solidifies the extruded polymer
Nanjing Agricultural University, Nov 1114http://web.utk.edu/~mse/Textiles/
Assessment Tools1. Soil burial studies in greenhouse experiments
2. Utilization of mulches for cultivation of vegetables in high tunnel and open field studies
3. Weatherometry and biodegradability testing
Nanjing Agricultural University, Nov 1115
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
Nanjing Agricultural University, Nov 1116
Greenhouse Study I (UTK) 3 Mulches “Spunbond” = SB-PLA-2010-white “Meltblown” = MB-PLA-2010-white, Cellulosic (WeedGuardPlus)
3 Soil treatments (manure, lime, control)
2 Durations (10 wk, 29 wk) 3 Replicates
Mulches buried 2 cm below the soil surface
Soil from a certified organic farm 1.0 L of water per tray per 48 h
period
Nanjing Agricultural University, Nov 1117 Wadsworth et al, submitted (2011)
PLA Nonwoven Mulches (SEM Micrographs)
Molecular Weight: SP-PLA-2010: Mn =
132,000; PDI = 1.5MB-PLA-2010: Mn =
111,000, PDI = 1.5
Nanjing Agricultural University, Nov 1118
Cellulose: 20.8 ± 8.1 m
SB-PLA: 14.8 ± 0.8 m
MB-PLA: 6.3 ± 2.3 m
Wadsworth et al, submitted (2011)
10 weeks
Greenhouse Study IDeterioration of MB-PLA-10 Mulch: Lime Treatment
Nanjing Agricultural University, Nov 1119
29 weeksWadsworth et al, submitted (2011)
Evidence of Deterioration for MB-PLA-2010 Mulch:SEM Analysis (Greenhouse Study I)
Lime soil treatment29 weeks exposure
Nanjing Agricultural University, Nov 1120 Wadsworth et al, submitted (2011)
Deterioration of MB-PLA-10 Mulch (Greenhouse Study I)
Measurement Method 0 wk 10 wk, Control
10 wk, Lime
Mass, g m-2 ASTM D3776 82.58 ± 8.35 97.71 ± 7.57 96.66 ± 9.72
Thickness, mm ASTM D1777 0.435 ± 0.020 0.666 ± 0.109 0.679 ± 0.111
Air Permeability, cm3 s cm-2 ASTM D737 37.0 ± 2.1 56.2 ± 17.4 Not Tested
Breaking Load, N ASTM D4632 6.87 ± 3.26 2.05 ± 1.26 0.88 ± 0.51
Breaking Elongation ASTM D5035 5.98 ± 3.67 4.16 ± 3.20 3.82 ± 1.96
Mn, kDa GPC 93.5 ± 0.620 111± 8 112 ± 5
Nanjing Agricultural University, Nov 1121Wadsworth et al, submitted (2011)
Greenhouse Study II: Effect of Moisture Level
Nanjing Agricultural University, Nov 1122
Mulch and Treatment Breaking Load, gSB-PLA-11, as received 4190 ± 148
High Moisture 3820 ± 315Low Moisture 4200 ± 145
MB-100% PLA-11, as received 1820 ± 299High Moisture 639 ± 168Low Moisture 587 ± 222
MB 75% PLA/25% PHB-11 513. ± 252High Moisture 89.4 ± 45.8Low Moisture 70.0 ± 36.7
• Low and High Moisture: 1.0 L and 0.5 L per tray per 48 h, respectively• Soil from organic farm with compost added• Burial in soil for 10 wk• 3 replicates
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
Nanjing Agricultural University, Nov 1123
High Tunnel and Open Field Studies in TN, TX, and WA: Mulches (2010)
BioBag (Starch-Based), Palm Harbor, FL BioTelo, (Starch-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
Cellulose Control, “WeedGuardPlus,” SunShinePaper Company, LLC, Denver, CO USA, 107 g m-2
Control (no mulch)Nanjing Agricultural University, Nov 1124
Mulches for High Tunnel and Open Field Studies
Nanjing Agricultural University, Nov 1125
High Tunnel and Open Field Studies in TN, TX, and WA (2010): Methods and Conditions
Mulches laid 14 ft long, 2-3 ft wide and 5-6 ft apart in high tunnels or open fields
Tomatoes planted: ~April – September, 2010 Irrigated: 1 inch of water per week Continuous monitoring of soil & air temperature,
moisture, pests & diseases, etc. Several different physical and chemical test
conducted on retrieved mulches
Nanjing Agricultural University, Nov 1126
High Tunnels at WSU-Mount Vernon
Nanjing Agricultural University, Nov 1127
Nanjing Agricultural University, Nov 1128
High Tunnels at Univ. Tennessee
Maximum Load – Machine Direction for Mulches as Received
Nanjing Agricultural University, Nov 1129
High Tunnel and Open Field Studies (2010): Decrease of MW
Biobag BioTelo
SB-PLA
Greatest loss of MW occurs for High Tunnel, TN (thus far)
Loss of MW: Biobag > Biotelo >
Nanjing Agricultural University, Nov 1130
Comparison of Locations/Environment
Percent of Maximum Load at Time 3
Open Field High Tunnel Nanjing Agricultural University, Nov 1131
Comparison of Open Field & High Tunnel
Percent of Maximum Load at Time 3
Nanjing Agricultural University, Nov 1132
Comparison of Open Field & High TunnelPercent of Maximum Elongation
0
50
100
150
200
250
TN TX WA TN TX WA TN TX WA TN TX WA TN TX WA TN TX WA TN TX WA TN TX WA TN TX WA TN TX WA
BioBag BioTelo Cellulose Non-BDM SB PLA BioBag BioTelo Cellulose Non-BDM SB PLA
FIELD HT
Perc
enta
ge o
f Tim
e 0
Elon
gati
on (
%)
Time 1
Time 2
Time 3
Nanjing Agricultural University, Nov 1133
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
Nanjing Agricultural University, Nov 1134
Biodegradability and Weatherometry Four mulches investigated
Spunbond PLA 2010 – white Spunbond PLA 2010 – black Meltblown PLA 2010 (white) Meltblown 75% PLA / 25% polyhydroxyalkanoate (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
Nanjing Agricultural University, Nov 1135
Biodegradability and Weatherometry
Photodegradation of PLA: Norrish II mechanism of carbonyl polyester (Ikada E. , J Photopolym Sci Technol 1997:10(2):265-270.
Nanjing Agricultural University, Nov 1136
Preliminary Results: Weatherometry(GPC Analysis)
2-fold decrease of Mn for all mulches; polydispersityindex increases
Nanjing Agricultural University, Nov 1137
SB-PLA-black
SB-PLA-white MB PLA MB-PLA+PHA
Mn (g/mol)
0 day 39000 44000 44000 3100021 days 17928 18430 20701 14045Mn 0d/Mn 21 d 2.18 2.39 2.13 2.21
Mw (g/mol)
0 day 52000 56000 56000 4300021 days 42299 46834 48309 32451Mw 0d/Mw 21 d 1.23 1.20 1.16 1.33
PDI0 day 1.33 1.27 1.27 1.3921 days 2.36 2.54 2.33 2.31PDI 0 d/PDI 21 d 0.56 0.50 0.54 0.60
Preliminary Results: Weatherometry(GPC Analysis)
Nanjing Agricultural University, Nov 1138
10000
20000
30000
40000
50000
60000
0 5 10 15 20 25Ageing (days)
Mn
(g/m
ol)
BSBWSBMB PLAPLA/PHB
Preliminary Results: Weatherometry(Differential Scanning Calorimetry, DSC)
For all 100% PLA nonwovens, two melting peaks occurred after ageing different type and/or size of crystalline zones
From lowest to highest degradation): MB PLA > SB-PLA-2011-black > SB-PLA-2011-white > MB PLA/PHA
Nanjing Agricultural University, Nov 1139
Mulch Tg (°C) Tm (°C) ∆Hm (J/g)SB-PLA-black – Day 0 62 168 51.9SB-PLA-black – Day 21 59 (-5%) 150 / 159 (-10%/-5%) 38.0 (-27%)SB-PLA-white – Day 0 62 169 45.8SB-PLA-white – Day 21 60 (-3%) 155 / 162 (-8%/-4%) 39.2 (-14%)
MB PLA – Day 0 62 168 47.6MB PLA – Day 21 57 (-8%) 146 / 154 (-13%/-8%) 33.6 (-29%)
MB - PLA/PHB – Day 0 41 140 / 166 0.8 / 43.2MB - PLA/PHB – Day 21 40 (-2%) 142 / 164 (+1%/-1%) 0.6 / 44.4 (-25%/+3%)
Preliminary Results: Weatherometry(Differential Scanning Calorimetry, DSC)
Nanjing Agricultural University, Nov 1140
61.51°C(I)
58.83°C
62.26°C
102.11°C
92.95°C29.54J/g
167.90°C
162.58°C47.56J/g
56.69°C(I)53.73°C
58.02°C
112.50°C
102.84°C32.41J/g
153.87°C
148.19°C33.60J/g
146.17°C
-2.0
-1.5
-1.0
-0.5
0.0
0.5
Hea
t Flo
w (W
/g)
0 50 100 150 200 250
Temperature (°C)
MBPLA-0d.001––––––– MBPLA-21d.001–––––––
Exo Up Universal V4.3A TA Instruments
Preliminary Results: Weatherometry (FTIR) (SB-PLA-2010-black)
Nanjing Agricultural University, Nov 1141
Preliminary Results: Weatherometry (FTIR) (SB-PLA-2010-black)
Nanjing Agricultural University, Nov 1142
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
1900210023002500270029003100330035003700Wavenumber (cm-1)
Abs
orba
nce
Day 0Day 21
Hydroperoxidesand alcohols
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
1900210023002500270029003100330035003700Wavenumber (cm-1)
Abs
orba
nce
Day 0Day 21
Hydroperoxidesand alcohols
Summary Greenhouse Studies MB-PLA-10 in the presence of lime shows the
greatest extent of deterioration Mechanical strength: breaking load; elongation, SEM no significant change of MW
Long-Term High Tunnel & Open Field Studies Loss of mechanical strength greater for mulches used in the open field as compared to
high tunnels No universal trend based on mulch type and location
Nanjing Agricultural University, Nov 11
43
Ongoing Research Greenhouse Studies Focus upon moisture level, use of enzymes, new
PLA/poly(hydroxyalkanoate nonwovens (lower MW)
High Tunnel & Open Field Studies New Spunbond PLA mulch; Year 2 study is ongoing
Biodegradability and Weatherometry All mulches underwent deterioration via
weatherometry; biodegradability testing is ongoing
Nanjing Agricultural University, Nov 11
44
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
Nanjing Agricultural University, Nov 1145
Back-Up Slides
Nanjing Agricultural University, Nov 1146
Key Scientific Advisors and Stakeholders John Dorgan, Site Director, Colorado Center for
Biofuels and Biorefining (C2B2), Department of Chemical Engineering; Colorado School of Mines, Golden, CO
Ramani Narayan, Department of Chemical Engineering and Materials Science; Michigan State University, 2527 Engineering Building, East Lansing, MI
Robert Green, NatureWorks LLC, 402 Sir Walker Lane, Cary, NC
Terry Phillips, Mark Williams, BioBag USA, Palm Harbor, FL
Several members of the Specialty Crops Growers / Organic Farming Community of TN, TX, and WA
Nanjing Agricultural University, Nov 1147
Comparison of Locations/Environment
Percent of Maximum Elongation at Time 3
Open Field High Tunnel Nanjing Agricultural University, Nov 1148
Comparison of Open Field & High Tunnel
Percent of Maximum Elongation at Time 3
Nanjing Agricultural University, Nov 1149
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