Progress 07/01/04 to 06/30/08
Outputs
Progress Report Objectives (from AD-416) Modification of zein is necessary to allow re-introduction into the fiber market. Work will be undertaken to improve zein's processability, physical properties and properties after exposure to moisture. After meeting the goals for each of these areas of research, melt spun fibers will be produced. Approach (from AD-416) Processability, physical properties and physical property retention may all be impacted by incorporating appropriate additives into zein. Zein will be dissolved or suspended in the appropraite solvent and allowed to react with the desired reagents. Zein flour will be mildly oxidized using various techniques (UV, ozone, chemical) which will generate radicals that will alter properties. Initial efforts to produce fibers will be undertaken on small scale melt spinning machines. Significant Activities that Support Special Target Populations Two approaches were evaluated to produce improved zein based articles. The modification of zein in the melt state using glyoxal as a cross- linking reagent was carried out. The articles produced having 1.75% glyoxal or higher were found to be resistant to dissolution by a variety of known solvents for zein. These same articles did not display improved tensile properties to the extent as from solution processes. It is known that compatible polymer blends may have improved properties relative to both base polymers. There are no known synthetic polymers that are compatible with zein. It was found that polyvinylpryrrolidone (PVP) of various molecular weights forms compatible blends with zein. Certain formulation had tensile strengths up to 24% higher than control. Dry spun electrospun fibers can be produced from these same blends. While dry spinning fibers is an industrially sound technology; melt spinning may have certain economic advantages. Zein formulations containing 30% plasticizer, and therefore not solvent resistant, could be melt spun producing fibers having a diameter of ~120 microns. While these fibers are much too large to be suitable for textile applications, it does provide a higher degree of confidence in the ability to form such fibers. Progress was monitored with Illinois Corn Marketing Board via meetings, presentations, phone calls, and e-mail. This research addresses NP 306, Component 2.
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Progress 10/01/06 to 09/30/07
Outputs
Progress Report Objectives (from AD-416) Modification of zein is necessary to allow re-introduction into the fiber market. Work will be undertaken to improve zein's processability, physical properties and properties after exposure to moisture. After meeting the goals for each of these areas of research, melt spun fibers will be produced. Approach (from AD-416) Processability, physical properties and physical property retention may all be impacted by incorporating appropriate additives into zein. Zein will be dissolved or suspended in the appropraite solvent and allowed to react with the desired reagents. Zein flour will be mildly oxidized using various techniques (UV, ozone, chemical) which will generate radicals that will alter properties. Initial efforts to produce fibers will be undertaken on small scale melt spinning machines. Significant Activities that Support Special Target Populations This report documents research conducted under a Cooperative Research and Development Agreement (CRADA) between Agricultural Research Services (ARS) and Illinois Corn Marketing Board (ICMB). Additional details of research can be found in the report for the parent project 3620-41000-119-00D, entitled "Nonfood Utilization of Cereal and Soy Based Co-products." The ability of glyoxal-reacted zein to be melt-processed was studied. Zein was processed in a rheometer with varying levels of glyoxal and NaOH (sodium hydroxide), and at varying temperatures and reaction times. The resulting doughs were ground and compression-molded, and were found to be solvent-resistant over a wide range of glyoxal and NaOH concentrations. Molded bars were resistant to acetic acid, dimethylformamide (DMF), tetrahydrofuran (THF), acetonitrile, dichloromethane, acetone, toluene, 80% ethanol, 8M urea, and 10% hydrochloric acid (HCI). Bars were not resistant to 10% NaOH and DMSO (dimethyl sulfoxide). Reactions containing the highest glyoxal levels (3-6%) yielded bars with improved tensile strength compared to control. Zein was also reaction extruded with glyoxal and base, followed by injection molding to produce standard Instron bars. These glyoxal/zein bars were also found to be solvent resistant, while bars containing only zein were not. Bars produced were not of a quality that could be used to determine physical properties. Additional studies of polymer blends of zein with polyvinylpyrrolidone (PVP) were conducted. Previous work included PVP with molecular weights of 10,000 and 55,000 daltons; this study used PVP with a molecular weight of 1.3 million. Cast films of zein with 10% added PVP1.3M showed a 37% increase in tensile strength compared to the control film with no added PVP. Electrospun fibers of zein containing 10% added PVP1.3M showed a 120% increase in tensile strength compared to control zein fibers, and the fibers are also significantly wider than control fibers. Differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy and confocal fluorescence microscopy have been used to test the compatability of zein/PVP films. All tests conducted to date show no incompatibility between zein and PVP in the films. Zein/glutaraldehyde (GDA) fibers have been created by electrospinning. Fibers containing 8% GDA had a tensile strength 130% higher than that of control zein fibers. Mats containing 4% and 2% GDA were improved by 83% and 57%, respectively. These fibers were rendered solvent-resistant by heating. Solvent resistance was determined as less than 30% loss when soaked in acetic acid for three hours. Zein fiber mats with 8% GDA were rendered insoluble by heating at 120 deg C for 40 minutes, while 2% GDA mats required 180 deg C for 5 minutes to become solvent resistant. This work is being monitored by meeting with the collaborator every 6 months and submitting yearly progress reports. This work was carried out in support of ARS National Program 306, Quality and Utilization of Agricultural Products and addresses Problem Statement 2c, New and Improved Processes and Feedstocks.
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Progress 10/01/05 to 09/30/06
Outputs
Progress Report 4d Progress report. This serves to document research conducted under a Cooperative Research and Development Agreement (CRADA) between ARS and the Illinois Corn Marketing Board (ICMB). Additional details of research can be found in the report for the parent CRIS 3620-41000-119-00D entitled Nonfood Utilization of Cereal and Soy Based Co-products. The effect of crosslinking reagents, such as glyoxal, methylglyoxal and formaldehyde, on the physical properties of zein films was studied. Zein was solubilized in 90% (v/v) aqueous ethanol and the pH was adjusted with either HC1 (hydrochloric acid) or NaOH (sodium hydroxide). Crosslinking reagents were added to the solution at 0.3, 1.0, 3.0 and 6.0% (w/w by zein weight), with the reactions carried out at 60 deg C. Triethylene glycol was added as a plasticizer. Films were cast and dried at room temperature, with cut bars stored at 50% and 70% relative humidity before testing. Films crosslinked with glyoxal
and formaldehyde showed a significant increase in tensile strength under certain pH conditions. Films of glyoxal reactions conducted at basic pH gave the highest overall tensile strength, with a 52% increase compared to the control film. Formaldehyde films had improved tensile strength when reacted at acidic or neutral pH. Methylglyoxal had no effect on the tensile strength of zein films. Films crosslinked with glyoxal were resistant to boiling water and were found to swell, rather than dissolve, when placed in solvents known to dissolve zein. Denaturing gel electrophoresis of glyoxal and formaldehyde reactions showed the presence of high molecular weight moieties when compared to control reactions. In an attempt to improve the tensile properties of zein articles, polymer blends of zein with various amounts of polyvinylpyrrolidone (PVP) were created and cast as thin films. Two different molecular weights of PVP were used (10kD and 55kD) at levels between 5 and 25% by zein weight.
Zein blends with the high molecular weight PVP showed a 20-25% increase in tensile strength. Blends with the low molecular weight PVP showed no such improvement in tensile strength, and actually showed a decrease in tensile strength with increasing PVP. Zein-PVP blends appear compatible by light microscopy and differential scanning calorimetry analysis. Zein fibers have been created using the process of electrospinning. A basic electrospinning set-up consists of a charged polymer solution that is fed through a small opening or nozzle (usually a needle or pipette tip) . Because of its charge, the solution is drawn as a jet toward a grounded collecting plate or rotating drum, typically 5-30 cm away. During the jet's travel, the solvent gradually evaporates, and a charged polymer fiber is left to accumulate on the grounded target. The resulting product is a non-woven fiber mat. If the target is allowed to move with respect to the nozzle position, specific fiber orientations can be
achieved. Zein has been electrospun under many different conditions, including differing voltages, concentrations, target distances, and with many different additives and crosslinkers. The fibers are birefringent and range from 0.1 to 10 micrometers in diameter.
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Progress 10/01/04 to 09/30/05
Outputs
4d Progress report. This report serves to document research conducted under a Cooperative Research and Development Agreement between ARS and the Illinois Corn Marketing Board (ICMB). Additional details of research can be found in the report of the parent research project #3620-41000-119-00D, Nonfood Utilization of Cereal and Soy Based Co-Products. Work continues on the decolorization of zein through low pressure column chromatography. Several sources of activated carbon as well as ion exchange have shown promise as large scale color removal agents. Although the yields from ion exchange chromatography are low, near 45%, it produces zein with the least amount of color. Investigations into an alternate source of ion exchange resin to improve yield are underway. Additionally, the NCAUR pilot plant facility for extracting and decolorizing zein from ground corn has been completed. The pilot-scale facility produced a white zein isolate with greater than 90% purity, but
zein yield was not as high as expected. The low yield is contributed to the lack of mechanical stirring during the protein extractions, which could be improved if a more sophisticated extraction vessel was purchased. The completion of this pilot plant facility is another step towards a new industrial process for recovering a value-added co-product from ethanol production.
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Progress 10/01/03 to 09/30/04
Outputs
4. What were the most significant accomplishments this past year? D. Progress Report. This report provides information regarding the research conducted under a Cooperative Research and Development Agreement (CRADA) between ARS and the Illinois Corn Marketing Board (ICMB). Additional information regarding this research can be found in the report for the parent project 3620-41000-105-00D, Chemistry and Processing of Cereal and Soy Based Co- products for Nonfood Utilization. The CRADA between ARS and ICMB was signed in June of 2004. Efforts have begun to recruit a postdoc in June 2004 to work fulltime on the project. Research efforts will be focused on modifying zein, the dominant corn protein which is currently underutilized, in order to produce a fiber suitable for the apparel market. Main product needs have been identified; these include deterioration of tensile strength on exposure to high moisture and improved mechanical processing. Routes to mitigate these
deficiencies will include the use of non-reactive additives and polymer modification. Polymer modification will be achieved through the use of chemical, mechanical and oxidative processes.
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