Progress 10/01/05 to 09/30/09
Outputs
OUTPUTS: Presentations have been made to 6 major pesticide producers or formulators including visits/tours on the Cornell Campus, WebEx presentations and teleconferences. Research results have been presented at the American Chemical Society meetings in St. Louis and in New Orleans. Confidentiality and Material Transfer agreements have been signed with 3 major pesticide producers and continuation of research and development is being pursued. One patent application has been filed: "Biodegradable Chemical Delivery System", Application Number PCT/US09/59076; Filing Date 09/30/2009. PARTICIPANTS: (1) Margaret W. Frey, Associate Professor, Fiber Science and Apparel Design. Michael P. Hoffmann, Professor, Entomology (2)Mr. Jeffrey Gardner, Enotomology Ms. Silvie Pitcher, Entomology Dr. Chunhui Xiang, Fiber Science and Apparel Design Collaborators and contacts: Alan G. Taylor,Professor, Horticultural Sciences TARGET AUDIENCES: Pesticide formulators and pesticide producers. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
PLA/cellulose nanocomposite fibers were electrospun at elevated temperature from Poly(lactic acid) (PLA) in dimethylformamide (DMF) solutions containing suspended cellulose nanofibrils. Cellulose nanofibrils were prepared by sulfuric acid hydrolysis. The rod-like morphology of cellulose nanofibrils was studied by transmission electron microscopy (TEM). Electrospinning conditions were optimized to form PLA/cellulose nanocomposite fibers with uniform diameters and smooth morphology at cellulose nanofibril content loadings of 0%, 1wt% and 10 wt% (on the weight of PLA). Surface elemental composition analysis confirmed the presence of cellulose nanofibrils at the surface of PLA nanocomposite fibers. Incorporation of cellulose nanofibrils increased PLA crystallinity in the resulting nanocomposite fibers. As the cellulose nanofibril content increased, the electrospun non-woven fabrics became increasingly hydrophilic. The strength of the electrospun non-woven fabrics was improved by the incorporation of cellulose nanofibrils into PLA. The elongation of the electrospun non-woven fabrics was decreased as the cellulose nanofibrils incorporated into PLA. Nanocomposite fibers electrospun from poly(lactic acid) (PLA) containing 0%, 1%, and 10% cellulose nanocrystals were used as chemical delivery systems targeted for controlled release delivery of pesticides. Columbia Blue, a hydrophobic dye with a molecular weight within the pesticide range, was used as a model pesticide for examining release rate profiles of the electrospun nanocomposite fibers. Fifty percent of Columbia Blue (based on the weight of PLA) was incorporated into the nanocomposite fibers during electrospinning. Columbia Blue was released from the electrospun nanocomposite fibers through both a diffusion-controlled mechanism and a degradation-controlled mechanism. The electrospun nanocomposite fibers containing Columbia Blue formed different crystalline polymorphs than the dye-free nanocomposite fibers. During the release experiments, Columbia Blue was identified by liquid chromatography / mass spectroscopy (LC/MS), and the LC/MS confirmed that Columbia Blue did not degrade during the 16 week release experiments. Columbia Blue which was released by diffusion-controlled mechanism followed Fickian transport (n = 0.5). The release profiles of Columbia Blue by degradation-controlled mechanism followed zero-order, time- independent Case П kinetics (n = 1.0). The rate of release by both diffusion controlled and degradation controlled mechanisms increased with increasing cellulose content of the fibers. Degradation of the PLA was confirmed by measured decrease in the molecular weight of PLA during the degradation experiments. Green house trials confirmed that imidichloprid delivered from PLA nanofiber non-woven fabrics successfully controlled white fly populations on Kentucky Wonder pole bean plants.
Publications
- Xiang, C. 2006. Biodegradable non-woven fabrics electrospun from renewable polymers for controlled release delivery of chemicals, M.S. Thesis, Cornell University.
- Xiang, C.,Frey, M.W.,Taylor, A.G., Rebovich, M.E., 2007. Selective chemical absorbance in electrospun nonwovens, Journal of applied polymer science. 106(4): 2363.
- Xiang, C. 2009. Biodegradable non-woven fabrics electrospun from renewable polymers for controlled release of pesticides, Ph.D. Dissertation, Cornell University.
- Xiang, C., Joo, Y.L., Frey, M.W., 2009. Nanocomposite Fibers Electrospun from Poly(lactic acid)/Cellulose Nanocrystals, J. Biobased Materials and Bioenergy 3: 147-155.
- Hall, S., 2009. New method applies pesticides in nanofibers to keep chemicals on target, Cornell Chronicle, http://www.news.cornell.edu/stories/March09/fiberPesticides.sh.html
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: Results of laboratory experiments were presented at the American Chemical Society (ACS) national meeting in New Orleans, LA in the Cellulose and Renewable Materials Division Sessions (April, 2008). "Nanocomposite fibers electrospun from biodegradable polymers" Chunhui Xiang and Margaret W. Frey, Fiber Science and Apparel Design, Cornell University, Cornell University, Ithaca, NY 14853. Based on laboratory and green house results, an invention disclosure was filed with the Cornell Center for Technology, Enterprise and Commercialization (CCTEC). "Controlled Release Agricultural Chemical Delivery System" Patent Application number: 61/101,915 Application date: 01-Oct-08. Inventors: Margaret Frey, Michael Hoffmann, Alan Taylor, Chunhui Xiang PARTICIPANTS: Individuals: Margaret W. Frey, P.D., Associate Professor, Department of Fiber Science and Apparel Design, College of Human Ecology, Cornell University. Michael P. Hoffmann, co-P.D., Professor, Department of Entomology, College of Agriculture and Life Sciences, Cornell University. Jeffrey Gardner, Department of Entomology, College of Agriculture and Life Sciences, Cornell University. Collaborator: Alan G. Taylor, Professor and Chair, Department of Horticultural Sciences, Geneva Experiment Station, Cornell University. Training: Ms. Chunhui Xiang, Graduate Student, Fiber Science, College of Human Ecology, Cornell University TARGET AUDIENCES: Agricultural pesticide formulators and users. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Nanocomposite fibers electrospun from poly(lactic acid) (PLA) containing 0 percent, 1 percent, and 10 percent cellulose nanocrystals were used as pesticide carriers in this study. Columbia Blue, a hydrophobic dye with a molecular weight within the pesticide range, was used as a model pesticide for examining release rate profiles of the electrospun nanocomposite fibers. Fifty percent of Columbia Blue (based on the weight of PLA) was incorporated into the nanocomposite fibers during electrospinning. Columbia Blue was released from the electrospun nanocomposite fibers through both a diffusion-controlled mechanism and a degradation-controlled mechanism. The electrospun nanocomposite fibers containing Columbia Blue had did not form the same crystal structures as the dye-free nanocomposite fibers. During the release experiments, Columbia Blue was identified by liquid chromatography / mass spectroscopy (LC/MS), and the LC/MS confirmed that Columbia Blue did not degrade in the release medium with time. Release of Columbia Blue into water followed a diffusion controlled mechanism while release into a buffer solution at elevated temperature followed a mechanism controlled by the PLA degradation rate. Columbia Blue which was released by diffusion-controlled mechanism followed Fickian transport (n equals 0.5). The release profiles of Columbia Blue by degradation-controlled mechanism followed zero-order, time- independent Case П kinetics (n equals 1.0). Increasing cellulose nanocrystal content of the nanocomposite nanofibers increased both the biodegradation rate of the fibers and the rate of diffusion of Columbia Blue from the fibers. The faster the nanocomposite fiber degraded, the higher Columbia Blue release rate. Thiamethoxam was loaded into PLA fibers at 50 percent w/w PLA and electrospun into non-woven fabrics. Fabrics were planted in soil with sprouted Kentucky Wonder pole bean seeds. Rates tested were: control (PLA only), 50 percent, 100 percent and 200 percent of the manufacturer recommended thiamethoxam application rate. A piece of non-woven fabric approximately 2 mm by 2 mm square was required to provide 100% of the manufacturer's recommended application rate. A cage containing 20 white flies was placed on the first leaf of the pole bean plant and white fly mortality was monitored over a 10 day period. White fly mortality increased with increasing thiomethoxam rate.
Publications
- No publications reported this period
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Progress 10/01/06 to 09/30/07
Outputs
OUTPUTS: To determine the ability of electronspun Polylactic acid (PLA) fabrics to incorporate and release active agricultural chemicals, a model system was devised in which metaldehyde and caffeine (know molluscicides) were incorporated into the PLA fabrics and tested in order to determine the efficacy of the fiber mats in either achieving slug mortality or at least serving as a deterrent. In order to accomplish this, initial trials were conducting using a electrospinning apparatus which was capable of producing a single small square of PLA fabric. These squares were then soaked in a bath of either metaldehyde or caffeine until maximum loading was achieved and then washed so as to remove excess chemicals. These samples were then each taken and placed in square, 2 qt., plastic containers with tops. The containers served as arenas in which 6 slugs were placed. In addition to the PLA samples, potting soil for substrate and copper bands were also placed in the arenas. The copper sheets
were cut and placed around the perimeter of the arenas in order to keep the slugs not only from escaping the arenas, but also to restrict them to the substrate at all times. Finally, Classic Rabbit Food Pellets from LM Animal Farms were placed onto the PLA squares as the only food source in the arenas. Each arena was then observed daily and watered accordingly in order to prevent desiccation. In subsequent trials, metaldehyde was added through inclusion in the fibers rather than absorption onto the fibers and trials were set up in order to determine whether there would be a difference between metaldehyde that was absorbed. Metaldehyde was included in the fibers at loadings of 1 percent, 2 percent, and 4 percent by mass. Nanocomposite nanofibers containing PLA and cellulose were prepared. Cellulose nanofibrils were prepared by sulfuric acid hydrolysis and incorporated into dimethylformamide (DMF) by ultrasonication to obtain a stable suspension. The morphology of cellulose nanofibrils
was studied by TEM. Nanocomposite fibers were electrospun at elevated temperature from PLA/DMF solutions containing suspended cellulose nanofibrils and collected as randomly oriented non-woven fabrics. Fiber morphology was optimized by the PLA concentration in DMF. Effects of the cellulose nanofibril content on the electrospun non-woven fabrics on the fabric physical properties and morphology were studied. Crystallinity of the electrspun nanocomposite fibers was investigated by a differential scanning calorimeter (DSC) and by a wide angle X-ray diffraction (WAXD).
PARTICIPANTS: Margaret Frey (PI) Michael Hoffmann (co-PI) Jeffrey Gardner (Entomology research associate designed and conducted slug trials) Kyle Dumont (Entomology research associate designed and conducted slug trials) Chunhui Xiang (Graduate Student, prepared fabrics for slug trials, prepared and analyzed PLA/cellulose nanocomposite nanofibers)
Impacts
Both a decline in slug weight and an increase in slug mortality were statistically greater in the experimental trials than in the controls. Also, declines in slug weight and increases in slug mortality were observed to be greater in the metaldehyde trials than in the caffeine trials. Data from the starvation controls confirms that the lack of feeding has a negligible effect on slug mortality and weight loss compared to exposure to metaldehyde and caffeine Cellulose nanofibrils were successfully produced by hydrolysis. PLA/cellulose nanocomposite fibers were produced by elevated temperature electrospinning. Strength of the electrospun non-woven fabrics was improved by the incorporation of cellulose nanofibrils into PLA. Elongation of electrospun non-woven fabrics was decreased by the incorporation of cellulose nanofibrils into PLA. Average fiber diameter was not significantly affected by the addition of cellulose nanofibrils. The degree of crystallinity was increased by
the incorporation of cellulose nanofibrils, which indicated that cellulose nanofibrils acted as nucleating agent of PLA crystallization. Water contact angle decreased as cellulose nanofibrils concentration increased in the electrospun nanocomposite fibers.
Publications
- Xiang, C., Frey, M.W., Taylor, A.G., Rebovich, M. 2007. Selective chemical absorbance in electrospun nonwovens. Journal of Applied Polymer Science, 106: 2363-2370.
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Progress 01/01/06 to 12/31/06
Outputs
Materials for absorbance and release of agricultural chemicals are under development. Suitability of materials for this application was assessed by measuring the absorption and holding capacity of fabrics as a function of the fabric porosity, hydrophilicity and surface area. Surface area was controlled by varying the size of fibers comprising the fabrics. All materials used are derived from rapidly renewable resources and are biodegradable. Absorbance of liquids and compounds with varying degrees of hydrophilicity into electrospun fabrics and conventional fabrics has been measured. Electrospun cellulose and polylactic acid (PLA) fabrics had comparable fiber diameters and pore spacing between fibers. Woven cotton and polyester (PET) fabrics had pore spacing between fibers 10 to 20 times larger than the electrospun fabrics. Absorbance of liquids and chemicals with varying water/octanol solubility onto the hydrophobic (PET and PLA) and hydrophilic (cellulose and cotton)
fabrics was compared. Both surface chemistry of the fibers and pore size in the fabrics were found to affect liquid uptake with smaller pores and like chemistry resulting in the greatest liquid absorbance. Absorbance of chemical compounds also increased with decreasing fabric pore size, increasing surface to volume ratio and compatible surface chemistry of the fabric. Preliminary molluscicide trials were conducted. Delivery systems were prepared by filling electrospun PLA envelopes with either metaldehyde or caffeine. Empty PLA envelopes were used as control. Native slugs were used as test subjects. Treatment effects were evident. Further trials to determine longevity of effects are planned.
Impacts
Biodegradable controlled release systems for agricultural chemical application are expected to decrease the overall amount of chemicals required, decrease drift of chemicals and decrease labor required to apply chemicals to plant crops. Agricultural chemicals delivered by this system could include pesticides, herbicides or fertilizers. Delivery of the chemicals will occur by both diffusion of the chemicals from the fiber based carrier and by breakdown of the fiber based carrier during biodegradation. Materials used in this project, cellulose and polylactic acid, biodegrade via aerobic and anaerobic pathways.
Publications
- No publications reported this period
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