Upload
others
View
18
Download
0
Embed Size (px)
Citation preview
Fabricating Biodegradable Mulches
Douglas G. Hayes
1, Larry C. Wadsworth 1, and Karen K. Leonas 2
1
Department of Biosystems Engineering and Soil Science,University of TennesseeKnoxville, TN USA 37996-45312
Department of Apparel, Merchandising, Design & Textiles, Washington State UniversityPullman, WA 99164-2020,
ASHS Conference, 31 July 20121
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
10 million ha of land used in China alone (80% of world market)
ASHS Conference, 31 July 20122
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.htmlASHS Conference, 31 July 20123
“Plastic”
Agricultural Mulches: Disadvantages
Potential environmental hazard: 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)ASHS Conference, 31 July 20124
Developed in the 1980’s
Ultimate goal: complete biodegradation at the end of the cultivation season, after being tilled into the soil
“.. the best choice appears to be a mulch material ..
with an outdoor service life which matches the crop duration, and
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
Organic agriculture: regulations differ between countries and states, affecting product use
Development of standards is challenging! long-term degradation processes that differ greatly with ecosystem & climate
Biodegradable Mulches
ASHS Conference, 31 July 20125
Molecular Structure of Polymers Employed in Agricultural Mulches
ASHS Conference, 31 July 20126
Paper Mulching
ASHS Conference, 31 July 20127
Used extensively prior to 1950 (Shogren, R. L. J. Sustain. Agric. 2000, 16, 33-47)
Are readily biodegradable (Shogren, R. L. J. Sustain. Agric. 2000, 16, 33-47)
Possess greater puncture resistance than plastic mulches
High weight & easily embrittled difficult to lay down in the field
Susceptible to tearing from the wind
Rapidly lose mechanical strength when wet
Commercially Available Polymers and Blends Employed in Biodegradable Agricultural Mulches
ASHS Conference, 31 July 20128
Product Name Polymer Manufacturer
Biocycle® Sucrose / PHA blend PHB Industrial (Brazil)
Bio-Flex PLA / copolyester FKUR, Willich (Germany)
Biomax TPS 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
ASHS Conference, 31 July 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
PBAT (Ecoflex®)
ASHS Conference, 31 July 201210
Mechanical properties similar to PE (high flexibility, good impact strength, and good melt processability)
Biodegradable under composting environments (55-58 oC)
Readily forms composites with cellulose, polysaccharides, PLA, and PHA
Field trials: mulches performed similarly to PE mulches: weed control and crop yield; slighly higher soil temperature (Ngouajio, et al., HortTechnol. 2008, 18, 605-610)
Undergoes photodegradation depolymerization & cross-link formation reduced extent of biodegradation (Kijchavengkul, et. al., Polym. Degrad. Stab. 2010, 95, 99-107)
Not biobased (“synthetic”)
Mater-Bi®
ASHS Conference, 31 July 201211
“is nowadays amongst the best developed products”
(Martin-Closas &Pelacho, Biopolymers 2011, 277-299)
Possible concern: weakness / susceptibility to tearing in the transverse direction (Briassoulis, Polym. Degrad. Stab. 2006, 91, 1256-127)
Not biobased (“synthetic”)
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
ASHS Conference, 31 July 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)
ASHS Conference, 31 July 201213
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
ASHS Conference, 31 July 201214
Nonwovens as Mulches?
Nonwovens: high strength, low weight
Nonwovens: small fiber size Increased rate of hydrolysis
Nonwovens can be made inexpensively
crystalline morphology, often
ASHS Conference, 31 July 201215
SB-PLA: 14.8 ±
0.8 m
MB-PLA: 6.3 ±
2.3 m
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 the growing season
.. then would be composted ASHS Conference, 31 July 201216
Conceptual Model for
Biodegradation of Mulches
ASHS Conference, 31 July 201217
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
ASHS Conference, 31 July 201218
10 weeks
Greenhouse Study IDeterioration of MB-PLA-10 Mulch: Lime Treatment
ASHS Conference, 31 July 201219
29 weeksWadsworth et al, submitted (2011)
Evidence of Deterioration for MB-PLA-2010 Mulch:SEM Analysis (Greenhouse Study I)
Lime soil treatment29 weeks exposure
ASHS Conference, 31 July 201220 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
ASHS Conference, 31 July 201221Wadsworth et al, submitted (2011)
Effect of Soil Moisture and Pineapple Juice: FTIR Analysis (Greenhouse Study II)
ASHS Conference, 31 July 201222
MB-PLA (85%) / PHA (15%)
30 wk of soil burial
High Moisture and Enzymes (Bromolain) enhance hydrolysis
High Tunnel and Open Field Studies in TN, TX, and WA: Mulches (2010)
BioBag (BioAgri, 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
Cellulose Control,
“WeedGuardPlus,”
SunShine Paper Company, LLC, Denver, CO USA, 107 g m-2
Control
(no mulch)ASHS Conference, 31 July 201223
ASHS Conference, 31 July 201224
High Tunnels at Univ. Tennessee
Maximum Load –
Machine Direction for Mulches as Received
ASHS Conference, 31 July 201225
Comparison of Locations/Environment
Percent of Maximum Load at Time 3
Open Field High Tunnel ASHS Conference, 31 July 201226
Biodegradability and Weatherometry
Photodegradation of PLA: Norrish II mechanism of carbonyl polyester (Ikada E. , J Photopolym Sci Technol 1997:10(2):265-
270.
ASHS Conference, 31 July 201227
Weatherometry Treatment
ASHS Conference, 31 July 201228
Summary
Conventional polyethylene mulches: the environmental fate at end-of-life is a major concern
Commercially available biodegradable mulches:
Many perform well (mechanical strength, biodegradability under specific conditions); but:
Are they applicable to all cultivation systems, climates, and soil types?
Are they truly environmentally benign under all circumstances?
Can they meet organic agriculture certifications?
Have they been sufficiently tested in large-scale agriculture to ensure environmental safety?
What will “third generation”
biodegradable mulches look like? (Can improved performance be commensurate with reduced cost?)
ASHS Conference, 31 July 2012
29
Summary
Greenhouse Studies
Meltblown-PLA / PHA in the presence of lime and/or compost shows the greatest extent of deterioration
Spunbond-PLA: excellent properties for long-use compostable material
Long-Term High Tunnel & Open Field Studies
Loss of mechanical strength: most visible parameter for assessment of physico-chemical changes
No universal trend based on mulch type and location
ASHS Conference, 31 July 2012
30
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)S. Dharmalingam , C. Tyler Pannel and R. Dunlap (UTK), Dr. William Klingeman, Phil Flanagan
1 25
SCRI Grant Award No. 2009-51181-05897
43 6
ASHS Conference, 31 July 201231
Hayes et al, Biodegradable Agricultural Mulches Derived from Biopolymers, in Degradable Polymers and Materials, Principles and Practice, 2nd Edition (ACS Symposium Series), in press.
Back-Up Slides
ASHS Conference, 31 July 201232
Important Definitions
ASHS Conference, 31 July 201233
Biobased: “.. composed in whole or in significant part of biological products or renewable domestic agricultural materials (http://www.biobased.us/)
Compostable plastic: “.. undergoes degradation by biological processes during composting to yield carbon dioxide, water, inorganic compounds, and biomass .. leaves no visible, distinguishable, or toxic residue”
(ASTM D6400)
Biodegradable plastic: “..degradation (change in its chemical structure) resulting from the action of naturally occurring microorganisms such as bacteria, fungi, and algae”
(ASTM D6400)
Important Definitions
ASHS Conference, 31 July 201234
Biobased: “.. composed in whole or in significant part of biological products or renewable domestic agricultural materials (http://www.biobased.us/)
Compostable plastic: “.. undergoes degradation by biological processes during composting to yield carbon dioxide, water, inorganic compounds, and biomass .. leaves no visible, distinguishable, or toxic residue”
(ASTM D6400)
Biodegradable plastic: “..degradation (change in its chemical structure) resulting from the action of naturally occurring microorganisms such as bacteria, fungi, and algae”
(ASTM D6400)
Important Definitions
ASHS Conference, 31 July 201235
Organic Agriculture:
“An ecological production management system that
promotes and enhances biodiversity, biological cycles, and soil biological activity .
.based on minimal use of off-farm inputs and
on management practices that restore, maintain, or enhance ecological harmony”
(USDA-NOSB)
Synthetic Material:
“A substance that is formulated or manufactured by a chemical process
or by a process that chemically changes a substance .. from a naturally occurring plant, animal, or mineral sources..”
(USDA-NOSB)
Important Definitions
ASHS Conference, 31 July 201236
Sustainable Agriculture:
“Integrated system of plant and animal production practices that will, over the long term:
satisfy human food and fiber needs;
enhance environmental quality and the natural resource base upon which the agricultural economy depends;
make the most efficient use of nonrenewable resources and on-farm resources ..
sustain the economic viability of farm operations;
and enhance the quality of life for farmers and society as a whole. “
(1990 USA Farm Bill)
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
ASHS Conference, 31 July 201237
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
ASHS Conference, 31 July 201238
Comparison of Locations/Environment
Percent of Maximum Elongation at Time 3
Open Field High Tunnel ASHS Conference, 31 July 201239
Comparison of Open Field & High Tunnel
Percent of Maximum Elongation at Time 3
ASHS Conference, 31 July 201240
Goals for Biodegradable Mulches in Agriculture Current 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
ASHS Conference, 31 July 201241
Sites for Investigation
Washington State University, Mount Vernon and Pullman Campuses
Texas A&M / Texas Tech University, Lubbock, TX
University of Tennessee, Knoxville, TN
ASHS Conference, 31 July 201242
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
ASHS Conference, 31 July 201243
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 ASHS Conference, 31 July 201244
Nonwovens Textiles: Spunbond (SB)
Thermoplastic polymers are melted;
extruded through spinnerets;
fibers are cooled and collected on a conveyer belt
ASHS Conference, 31 July 201245 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
ASHS Conference, 31 July 201246http://web.utk.edu/~mse/Textiles/
PHA
Biobased; not “synthetic”
Readily available
60,000 tonnes per year
High cost
Readily biodegradable, including in soil
Highly crystalline thermoplastic polymer susceptible to embrittlement & thermal
degradation
Incompatible with several other polymers
Susceptible to loss of elongation at break due to ultraviolet radiation produced by the sun
ASHS Conference, 31 July 201247
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
ASHS Conference, 31 July 201248 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
ASHS Conference, 31 July 201249
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)
Greenhouse Study II: Effect of Moisture Level
ASHS Conference, 31 July 201250
Mulch and Treatment Breaking Load, gSB-PLA-11, as received 4190 ±
148High Moisture 3820 ±
315Low Moisture 4200 ±
145MB-100% PLA-11, as received 1820 ±
299High Moisture 639 ±
168Low Moisture 587 ±
222MB 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
Mulches for High Tunnel and Open Field Studies
ASHS Conference, 31 July 201251
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
ASHS Conference, 31 July 201252
High Tunnels at WSU-Mount Vernon
ASHS Conference, 31 July 201253
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 >
ASHS Conference, 31 July 201254
Comparison of Open Field & High Tunnel
Percent of Maximum Load at Time 3
ASHS Conference, 31 July 201255
Comparison of Open Field & High TunnelPercent of Maximum Elongation
ASHS Conference, 31 July 201256
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 USA
2.
S. Dharmalingham, Drs. Doug Hayes and Larry Wadsworth, UTK
ASHS Conference, 31 July 201257
Preliminary Results: Weatherometry (GPC Analysis)
2-fold decrease of Mn for all mulches; polydispersity index increases
ASHS Conference, 31 July 201258
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)
ASHS Conference, 31 July 201259
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
ASHS Conference, 31 July 201260
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)
ASHS Conference, 31 July 201261
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-2011-black)
ASHS Conference, 31 July 201262
Preliminary Results: Weatherometry (FTIR) (SB-PLA-2011-black)
ASHS Conference, 31 July 201263
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
Biodegradability and Weatherometry
Four mulches investigated
Spunbond PLA 2011 –
white
Spunbond PLA 2011 –
black
Meltblown PLA 2011 (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
ASHS Conference, 31 July 201264
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
ASHS Conference, 31 July 2012
65