MODIFICATION OF NATURAL POLYMERS BY THERMO-MECHANICAL PROCESSING

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
511	1510	2000	90%
511	1549	2000	10%

Progress 06/16/04 to 06/15/09

Outputs
Progress Report Objectives (from AD-416) The overall goal is to develop processes to enhance the conversion of cereal crops into value added polymers and chemicals, and thus generate expanded markets for cereals and reduce dependence on petroleum. Approach (from AD-416) Investigate the effects of stirring during cooling on the rheological properties of hot dispersions prepared by jet cooking starch in both the presence and absence of non-starch additives. Further investigate the structure, properties and end-use applications of spherocrystals formed in slowly-cooled solutions of jet-cooked starch. Modify laboratory techniques to permit commerical scale-up of processes used for deposition of thin starch coatings onto plastic surfaces and modification of these coatings by graft polymerization. Prepare starch esters having low to high degree of substitution and controlled substitution patterns with high efficiency and minimal byproducts. Characterize structure-property relationships and identify applications. Prepare new, inexpensive hydrophobic starches by reaction of starch with unsaturated hydrocarbons and characterize utility as adhesives. Prepare starch graft copolymers by reactive extrusion. Significant Activities that Support Special Target Populations The overall goal of this project is to develop processes to enhance the conversion of cereal crops into value added polymers and thus generate expanded markets and reduce dependence on petroleum. Modified corn starches with novel properties are prepared by chemical, enzymatic and physical techniques. Completed research on the adsorption of polyethylene onto starch film surfaces (see accomplishment). Manuscript has been accepted for publication in the Journal of Applied Polymer Science. Initiated research on the incorporation of silver particles into extruded films of starch-poly(methyl acrylate) graft copolymers to yield films with good electrical conductivity. Silver particles were incorporated into graft copolymer films by immersing the films in aqueous solutions of silver nitrate, converting silver nitrate to water-insoluble silver chloride by reaction with sodium chloride, and then reducing silver ion to metallic silver by reaction with sodium borohydride. We are working to prepare starch graft copolymer films that will not fragment and disperse when they are immersed in aqueous solutions, and that can be extrusion processed in amounts sufficient for a more complete study. Initiated research on the incorporation of electrically conductive carbon black into films cast from aqueous dispersions of starch-poly(methyl acrylate) graft copolymers. Aqueous dispersions of graft copolymer and carbon black were treated with ultrasound to minimize particle size and were air-dried to yield continuous films with good electrical conductivity. We are examining experimental variables to maximize both the conductivity and physical properties of the films. Starch graft copolymers (SGP) have applications as superabsorbents, coatings and thickeners. However, the catalysts normally used to make these can be hazardous and high temperatures may also be required. Preliminary experiments showed that horseradish peroxidase, a common natural enzyme, catalyses the graft copolymerization of starch with acrylic acid in the presence of a small amount of acrylamide. These novel findings should stimulate more research on SGP's and lead to greater acceptance of starch based materials. Through the reaction of starch with itaconic anhydride, suitable olefinic species have been placed on the starch backbone and can be taken advantage of using the polymerization through technique. By carrying out a standard acrylamide polymerization using a RAFT reagent to control polydisperisty in dimethylsulfoxide in the presence of a small amount of this modified starch, the graft density of the starch was greatly increased. To date, there was one polyacrylamide graft per 200 glucose units. This level of density is much higher than typically found in the literature. The molecular weight and polydispersity for these grafts were much lower than those typically found in the literature at approximately 90,000 and 1.6 respectively. These basic and applied research results will assist industrial and academic scientists to design products and applications that utilize starch and other biobased polymers to replace petroleum- based products in a cost-competitive manner. Technology Transfer Number of Invention Disclosures submitted: 1 Number of New Patent Applications filed: 1

Impacts
(N/A)

Publications

Stevens, E.S., Willett, J.L., Shogren, R.L. 2007. Thermoplastic starch- kraft lignin-glycerol blends. Journal of Biobased Materials and Bioenergy. 1(3):351-359.
Shogren, R.L. 2008. Scandium triflate catalyzed acetylation of starch under mild conditions. Carbohydrate Polymers. 72(3):439-443.
Peterson, S.C., Eller, F.J., Fanta, G.F., Felker, F.C., Shogren, R.L. 2008. Comparison of the effects of critical fluid and reflux-extracted techniques on cornstarch pasting properties. Carbohydrate Polymers. 71(1) :74-79.
Biswas, A., Sharma, B.K., Willett, J.L., Erhan, S.Z., Cheng, H.N. 2008. Room-temperature self-curing ene reactions involving soybean oil. Green Chemistry. 10(3):298-303.
Stevenson, D.G., Inglett, G.E., Chen, D., Biswas, A., Eller, F.J., Evangelista, R.L. 2008. Phenolic content and antioxidant activity of supercritical carbon dioxide-treated and air-classified oat bran concentrate microwave-irradiated in water or ethanol at varying temperatures. Food Chemistry. 108(1):23-30.
Biswas, A., Brajendra, S.K., Willett, J.L., Adhvaryu, A., Erhan, S.Z., Cheng, H.N. 2008. Azide derivatives of soybean oil and fatty esters. Journal of Agricultural and Food Chemistry. 56(14):5611-5616.
Fanta, G.F., Felker, F.C., Shogren, R.L., Salch, J. 2008. Preparation of spherulites from jet cooked mixtures of high amylose starch and fatty acids. effect of preparation conditions on spherulite morphology and yield. Carbohydrate Polymers. 71(2):253-262.
Shogren, R.L. 2007. Effect of orientation on the physical properties of amylose and high amylose starch films. Biomacromolecules. 8:3641-3545.
Shogren, R.L., Gonzalez, S.O., Willett, J.L., Graiver, D., Swift, G. 2007. Preparation of sorbitol citrate polyesters by reactive extrusion and application as inhibitiors of calcium carbonate precipitation. Journal of Biobased Materials and Bioenergy. 1(2):229-237.
Biswas, A., Sharma, B.K., Willett, J.L., Erhan, S.Z., Cheng, H. 2008. Soybean Oil as a Renewable Feedstock for Nitrogen-Containing Derivatives. Energy and Environmental Science. 1:639-644. Available: http://xlink.rsc. org/?doi=B809215J.
Biswas, A., Cheng, H., Selling, G.W., Willett, J.L., Kendra, D.F. 2009. Synthesis of Phenyl-Adducted Cyclodextrin through the Click Reaction. Carbohydrate Polymers. 77(2009):681-685.
Saha, B.C., Biswas, A., Cotta, M.A. 2008. Microwave Pretreatment, Enzymatic Saccharification, and Fermentation of Wheat Straw to Ethanol. Journal of Biobased Materials and Bioenergy. 2(3):210-217.
Kim, W., Ho, H., Nelson, R.L., Krishnan, H.B. 2008. Identification of Several gy4 Nulls from the USDA Soybean Germplasm Collection Provides New Genetic Resources for the Development of High-Quality Tofu Cultivars. Journal of Agricultural and Food Chemistry. 56:11320-11326.
Biresaw, G., Shogren, R.L. 2008. Friction Properties of Chemically Modified Starch. Journal of Synthetic Lubrication. 25(1):17-30.
Patil, D.R., Fanta, G.F., Felker, F.C., Salch, J. 2008. Application of Hydrophilic Starch-based Coatings to Polyethylene Surfaces. Journal of Applied Polymer Science. 108(5):2749-2755.
Byars, J.A., Fanta, G.F., Felker, F.C. 2009. Rheological Properties of Dispersions of Spherulites from Jet-Cooked High-Amylose Corn Starch and Fatty Acids. Cereal Chemistry. 86(1):76-81.
Finkenstadt, V.L., Mohamed, A., Biresaw, G., Willett, J.L. 2008. Mechanical Properties of Green Composites with Poly(caprolactone) and Wheat Gluten. Journal of Applied Polymer Science. 110(4):2218-2226.
Mohamed, A., Finkenstadt, V.L., Gordon, S.H., Biresaw, G., Palmquist, D.E., Rayas-Duarte, P. 2009. Thermal Properties of Extruded Injection-Molded Polycaprolactone/Gluten Bioblends Characterized by TGA, DSC, SEM and Infrared Photoacoustic Spectroscopy. Journal of Applied Polymer Science. 110(5):3256-3266.
Shogren, R.L., Willett, J.L., Westmoreland, D., Gonzalez, S., Doll, K.M., Swift, G. 2008. Properties of Copolymers of Aspartic Acid and Aliphatic Dicarboxylic Acids Prepared by Reactive Extrusion. Journal of Applied Polymer Science. 110:3348-3354.
Shogren, R.L., Willett, J.L., Biswas, A. 2008. HRP-Mediated Synthesis of Starch-Polyacrylamide Graft Copolymers. Carbohydrate Polymers. 75(1):189- 191.
Shogren, R.L. 2009. Flocculation of Kaolin by Waxy Maize Starch Phosphates. Carbohydrate Polymers. 76(1):639-644.
Biswas, A., Shogren, R.L., Willett, J.L., Erhan, S.Z., Cheng, H.N. 2008. Enzymatic Products from Modified Soybean Oil Containing Hydrazinoester. American Chemical Society Symposium Series. 999(1):76-85.
Biswas, A., Selling, G.W., Woods, K.K., Evans, K.O. 5009. Surface Modification of Zein Films. Industrial Crops and Products. 30(169):168-171.

Progress 10/01/06 to 09/30/07

Outputs
Progress Report Objectives (from AD-416) The overall goal is to develop processes to enhance the conversion of cereal crops into value added polymers and chemicals, and thus generate expanded markets for cereals and reduce dependence on petroleum. Approach (from AD-416) Investigate the effects of stirring during cooling on the rheological properties of hot dispersions prepared by jet cooking starch in both the presence and absence of non-starch additives. Further investigate the structure, properties and end-use applications of spherocrystals formed in slowly-cooled solutions of jet-cooked starch. Modify laboratory techniques to permit commerical scale-up of processes used for deposition of thin starch coatings onto plastic surfaces and modification of these coatings by graft polymerization. Prepare starch esters having low to high degree of substitution and controlled substitution patterns with high efficiency and minimal byproducts. Characterize structure-property relationships and identify applications. Prepare new, inexpensive hydrophobic starches by reaction of starch with unsaturated hydrocarbons and characterize utility as adhesives. Prepare starch graft copolymers by reactive extrusion. Significant Activities that Support Special Target Populations Cooperative research was conducted with Binghamton University under the non-funded cooperative agreement "Starch-Lignin Blends Materials". A manuscript on this has been accepted by J. Biobased Materials and Bioenergy. Cooperative research was conducted with Bradley University under the non-funded cooperative agreement "Nano-Structured Materials from Starch". Accomplishments Simple method for preparation of starch-fatty acid esters. Starch-fatty acid esters are difficult to prepare by conventional chemical routes but can have useful properties and applications. It was found that fatty acid esters of starch can be prepared simply by heating starch under mild conditions (75 deg C) with certain ionic liquids and vinyl stearate or stearic acid. The starch fatty ester can then be isolated by precipition in water or ethanol. The ionic liquid can be subsequently recovered by evaporating the solvent and reused. This easy, green synthesis should facilitate more studies and applications of starch fatty esters and result in greater adoption of materials based on safe, renewable resources (starch from corn and fatty acids from soybean oil). Novel catalyst for making starch esters. Corn starch has potential applications in biodegradable packaging, adhesives, coatings, dispersants, etc. but usually needs to be chemically modified. New methods of chemical modifying corn starch are needed to improve the properties of starch for these applications. It was found that a novel catalyst called scandium triflate was able to cause starch to react with acetic acid at fairly low temperatures. This is the first time that such a reaction has been reported. A novel starch having acetic groups on the surface of the starch particles only was also prepared. These findings should facilitate the preparation of new starch esters under mild "green" conditions. Critical fluid extraction of native lipids from cornstarch. Critical fluid extraction with 75% ethanol/water as the solvent removed over 99% of the native lipid from cornstarch. The percentage of native lipid extracted depended upon the starch/solvent ratio. The pasting properties and shear storage modulus of defatted, critical fluid-extracted cornstarch differed from those of cornstarch defatted with hot 75% propanol/water, even though both samples contained only trace amounts of residual native lipid. The amount of soluble starch in pasted samples of critical fluid-extracted starch was higher than that observed with un- extracted starch. The discovery of this non-toxic method for extracting native lipids from cereal starch could lead to new end-use applications, due to the unique pasting and gelling properties of the extracted starches. Modification of Natural Polymers by Novel Processes. A novel method for the preparation of cellulose acetate was developed involving the concurrent use of iodine, acetic anhydride and microwave. The method is simple, rapid, efficient, and solvent-less. With this method, cellulose acetates have been synthesized in minutes. This solvent-free method that we discovered would help the cellulose acetate manufacturers to prepare cellulose acetate in an environment friendly way. This method reduces the use of solvents and acids. The collaborator for this work was Eastman Chemical Company, Research Laboratories, Kingsport, TN. Developing new synthetic techniques for starch derivatization. An improved method is needed for incorporating appropriate groups onto starch that will allow the use of controlled techniques to deliver higher value starch based materials. We have modified our synthetic approach and we have been able to place bromo-acetyl groups on starch which may serve as initiating sites for polymerization. We have also performed similar substitutions, in higher yields/grafting efficiencies, onto pullulan and cyclodextrin. End result will be a method to produce starch graft co-polymers with unique properties derived from the low polydispersity of the grafts on starch. These grafts may also have block architecture. All of 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. Technology Transfer Number of New CRADAS and MTAS: 1 Number of Active CRADAS and MTAS: 1 Number of Non-Peer Reviewed Presentations and Proceedings: 3 Number of Newspaper Articles,Presentations for NonScience Audiences: 3

Impacts
(N/A)

Publications

Willett, J.L., Finkenstadt, V.L. 2006. Reactive extrusion of starch- polyacrylamide graft copolymers using various starches. Polymers and the Environment. 14:125-129.
Shogren, R.L., Hochmuth, R.C. 2004. Field evaluation of watermelon grown on paper/polymerized vegetable oil mulches. HortScience. p. 1588-1591.
Biswas, A., Sharma, B.K., Willett, J.L., Vermillion, K., Erhan, S.Z., Cheng, H.N. 2007. Novel modified soybean oil containing hydrazino-ester: synthesis and characterization. Green Chemistry. 9:85-89.
Biswas, A., Adhvaryu, A., Stevenson, D.G., Sharma, B., Willett, J.L., Erhan, S.Z. 2007. Microwave irradiation effects on the structure, viscosity, thermal properties and lubricity of soybean oil. Industrial Crops and Products. 25:1-7.
Shogren, R.L., Biswas, A. 2006. Preparation of water-soluble and water- swellable starch acetates using microwave heating. Carbohydrate Polymers. 64:16-21.
Biswas, A., Shogren, R.L., Stevenson, D.G., Willett, J.L., Bhowmik, P.K. 2006. Ionic liquids as solvents for biopolymers: acylation of starch and zein protein. Carbohydrate Polymers. 66:546-550.
Shogren, R.L., Biresaw, G. 2007. Surface properties of water soluble starch, starch acetates and starch acetates/alkenylsuccinates. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 298(3):170-176.
Peterson, S.C., Eller, F.J., Fanta, G.F., Felker, F.C., Shogren, R.L. 2007. Effects of critical fluid lipid extraction on the gelatinization and retrogradation of normal dent cornstarch. Carbohydrate Polymers. 67(3):390- 397.
Fanta, G.F., Felker, F.C., Shogren, R.L., Salch, J. 2006. Effect of fatty acid structure on the morphology of spherulites formed from jet cooked mixtures of fatty acids and defatted cornstarch. Carbohydrate Polymers. 66:60-70.
Stevenson, D.G., Biswas, A., Jane, J., Inglett, G.E. 2007. Changes in structure and properties of starch of four botanical sources dispersed in the ionic liquid, 1-butyl-3-methylimidazolium chloride. Carbohydrate Polymers. 67(1):21-31.
Shogren, R.L., David, M. 2007. Biodegradable paper/polymerized vegetable oil mulches for propagation of tomatoes and peppers. Applied Horticulture Consulting. 8(1):92-94.
Biswas, A., Selling, G.W., Appell, M.D., Woods, K.K., Willett, J.L., Buchanan, C.M. 2007. Iodine catalyzed esterification of cellulose using reduced levels of solvent. Carbohydrate Polymers. 68(3):555-560.

Progress 10/01/05 to 09/30/06

Outputs
Progress Report 1. What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? Why does it matter? This project contributes to ARS National Program 306, Quality and Utilization of Agricultural Products. The need to develop new and expanded industrial markets for cereal grains, such as corn, is driven by continued production in excess of demand. For many applications, starch must be physically and/or chemically modified to impart desired characteristics. Reactions of water solutions of starch with water- insoluble organic compounds are difficult to carry out because of the incompatibility between water and organic phases. This limits the number of new, useful starch derivatives that can be economically prepared using practical processing techniques. Starch is produced annually in the U.S., primarily from corn, in amounts exceeding current market needs. Methods of converting these starch surpluses to new value-added products are, therefore, urgently needed. Novel and inexpensive methods, with minimal environmental impact, are needed to increase the compatibility and reactivity of starch with non- starch materials, if new starch products are to be produced and marketed. 2. List by year the currently approved milestones (indicators of research progress) FY 2005 (15 months) 1a. Determine effect of stirring during cooling on rheology of jet cooked dispersions. 1b. Separate large and small sphero-crystals; isolate complexed lipids to determine effect of lipid type on structure. 1c. Demonstrate effect of starch concentration, cooling rate and volume. 2a. Scale up preparation of starch acetates; prepare new starch citrates and aspartates. 2b. Demonstrate feasibility by forming C-O (carbon-oxygen) bond by grafting dicyclopentadiene to starch. 2c. Demonstrate extent of penetration of CO2 (carbon dioxide) into starch granules. 3a. Demonstrate effects of extrusion parameters on starch-polyacrylamide copolymer properties. 3b. Develop lab techniques using model compounds. 4a. Screen different reactions and enzymes (+ or -). 4b. Screen different alcohols and enzymes (+ or -). 4c. Screen enzymes in aqueous suspension or DMF (dimethylformaide). FY 2006 & 2007 (30 months) 1a. Isolate and compare crystallites formed with and without oil. 1b. Measure surface area and pore volumes. Investigate end-use applications. 1c. Evaluate other plastic substrates; expand graft polymerization studies. 2a. Characterize starch acetate, citrate structure and properties, demonstrate a practical use. 2b. Explore grafting with butadienes, styrene. Characterize graft copolymer structure. 2c. Determine effect of sc CO2 on OSA-starch reaction efficiency. 3a. Initiate reactive extrusion using other monomers and initiators. 3b. Optimize synthetic techniques using corn starch. 4a. Select most efficient (>5%) reactions, optimize conditions. 4b. Optimize reaction conditions. 4c. Optimize reaction conditions, characterize prod. FY 2008 (45 months) 1a. Determine effect of stirring during cooling on crystallite type, size and morphology. 1b. Add lipids such as palmitic and linoleic acids, study crystallite type formed and optimize yields. 1c. Study effect of co-jet cooking with oils and lipids. 2a. Determine which other starch esters can be made efficiently; investigate other solvents, catalysts. 2b. Optimize reaction yields and evaluate properties for usefulness in products. 2c. Characterize interaction of gelatinized starch and sc CO2 (supercritical carbon dioxide). 3a. Initiate reactive extrusion of other substrates. 3b. Apply new methods to reactive extrusion processes. 4a. Prepare larger lab-scale quantities of products (gram size). 4b. Determine effect of starch physical treatments. 4c. Scale up reactions with mixer or extruder. FY 2009 (60 months) 1a. Carry out similar experiments using mixtures of starch, pectin and xanthan. 1b. Determine effect of cooling rate and starch concentration on spherocrystal type and yield. 1c. Develop practical production methods and commercial applications. 2a. Prepare regiospecifically substituted starches; identify applications and transfer technology. 2b. Identify applications, file patent and transfer technology. 2c. Finish work on enzymatic esterification of starch in sc CO2. 3a. Characterize graft copolymers from other substrates, transfer technology. 3b. Characterize products and transfer technologies. 4a. Characterize structure and properties. 4b. Characterize structure and properties. 4c. Determine physical properties and assess applications. 4a List the single most significant research accomplishment during FY 2006. SORBITOL CITRATE POLYESTERS AS ANTISCALANTS. This research contributes to ARS National Program 306, Quality and Utilization of Agricultural Products and addresses Problem Statement 2c, New and Improved Processes and Feedstocks. It has been shown that sorbitol citrate polyesters have antiscalant activity (prevent calcium carbonate precipitation) similar to polyacrylic acid and that the former can be efficiently prepared by reactive extrusion or batch mixer methods. Replacing a non-degradable, petroleum based polymer like polyacrylic acid with biodegradable sorbitol citrate will reduce potential toxicity to people and the environment, reduce the need for imported petroleum, and create higher value products from corn. These results should be of interest to companies making and using water treatment polymers, especially in the detergent industry. This work was carried out under a CRADA (Cooperative Research and Development Agreements) between USDA/ARS/NCAUR and Folia, Inc. 4b List other significant research accomplishment(s), if any. PREPARATION OF NANOPARTICULATE STARCH-FATTY ACID COMPLEXES. This research contributes to solving problems in support of ARS National Program 306, Quality and Utilization of Agricultural Products and addresses Problem Statement 2a, New Product Technology. Conditions were developed to maximize yields of spherulites formed in jet cooked amylose/fatty acid mixtures. When high amylose cornstarch was jet cooked with sufficient palmitic acid to complex all of the amylose in the starch sample, the yield of spherulites was 55-60%, based on total starch. Spherulite morphology depended upon the rate of cooling and also upon whether or not the dispersions were stirred during the cooling period. Slow cooling over a 22 hr. period with stirring yielded the usual mixture of torus-shaped and spherical/lobed spherulites. Slow cooling in the absence of stirring also produced small, spherical particles about 500 nanometers in diameter. When jet cooked dispersions were cooled rapidly in an ice bath with stirring, the 500 nanometer spherulites were the only particles observed. High spherulite yields and the ability to control spherulite morphology by varying cooling conditions will enable us to examine end use applications of these materials. MODIFICATION OF CELLULOSE BY NOVEL PROCESSES: A novel method for the preparation of cellulose acetate was developed involving the concurrent use of iodine and acetic anhydride. The method is simple, rapid, efficient, and solvent-less. With this method, cellulose acetates have been synthesized. This solvent-free method that we discovered would help the cellulose acetate manufacturers to prepare cellulose acetate in an environment friendly way. This method reduces the use of solvents and acids. The collaborator for this work was Charles Buchanan, Eastman Chemical Company, Kingsport, TN. 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. MODIFICATION OF NATURAL POLYMERS BY ENZYMES. Efforts were made in this work to use bio-based materials to produce potential products. In particular, soybean oil was reacted with diethylazodicarboxylate to form an -ene reaction product, which was then hydrolyzed chemically and enzymatically. The chemical hydrolysis gives hydrazino-fatty acids, whereas the enzymatic hydrolysis gives the fatty acids derivatized with the diethyl-azadicarboxylate functionality. These are useful synthons for further reactions to yield new materials. These new materials perhaps can be used as lubricants and as ingredients in coatings, cosmetics, biodiesel fuel, and oil-based or oil-containing chemical products. These hydrazino acids may even have pharmaceutical activities. The following manuscript was submitted for publication and Dr. Atanu Biswas has been invited to give a talk at the ACS San Francisco meeting. The collaborator for this work was Dr. H.N. Cheng, Hercules Incorporated, Wilmington, DE. 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. HYDROPHOBIC STARCH ESTERS BY ENZYMATIC CATALYSIS. Fatty acid esters of starch were prepared by lipase catalysis in an ionic liquid solvent under mild (low temperature) conditions. The ionic liquid was recovered after reaction by extraction with ethanol. Such novel modified starches are difficult to prepare using conventional catalysis and should have utility in a number of applications. 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. PREPARATION OF STARCH WITH UNSATURATED GRAFTS. Have produced significant quantities of starch grafted with either itaconic anhydride or maleic anhydride. This has introduced conjugated unsaturation onto the starch. A water soluble ATRP (atom transfer radical pulmerization) initiator was also synthesized. These materials will be combined with waste soluble monomers, copper bromide and ligand to allow grafting to take place via a "polymerization through" technique. When successful, this technique, and variants of it, will allow us to produce starch-graft copolymers with defined grafts having more consistent graft molecular weights and higher graft densities. Previous work on placing halo- initiators onto starch has been problematic - other routes continue to be explored to provide "grafting from" techniques. This work was carried out in support of ARS National Program 306, Quality and Utilization of Agriculatural Products and addressed Problem Statement 2c, New and Improved Processes and Feedstocks. REACTIVE EXTRUSION OF STARCH GRAFT COPOLYMERS. New starch-based materials were prepared using a continuous reactive extrusion process. In addition to acrylamide, acrylic acid and acrylamide-2-methyl- propanesulfonic acid were also used to produce materials for applications such as hydrogels and superabsorbents. The efficacy of water-soluble initiators other than ammonium persulfate (used in prior work) was demonstrated. Reactions with other monomers and initiators were characterized for reaction and grafting efficiency, graft molecular weight, water absorbency, and other properties. Production and properties of starch-polyacrylic acid graft copolymers were conducted under a CRADA between ARS and Absorbent Technologies, Inc., in order to develop continuous methods for production of starch graft copolymers. These results expand the range of monomers and initiators which can be used in reactive extrusion of starch, and demonstrate the functional properties of the graft copolymers produced by this process. 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. PREPARATION OF POLYASPARTATES BY REACTIVE EXTRUSION. Copolymers of aspartic and other comonomers were prepared via reactive extrusion under a CRADA (Cooperative Research and Development Agreement) between ARS and Folia, Inc. Such a continuous process for making polyaspartates is likely to be more economical than current procedures. This should allow greater acceptance of polyaspartates in the marketplace and thus create new markets for aspartic acid (a fermentation product of corn starch). 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. SURFACE TENSION OF MODIFIED STARCHES. Finding new, high value uses for corn starch will depend on a better understanding of the physical behavior of starch. Specifically, the surface tension of starch in water or its tendency to spread over other surfaces is critical to applications as coatings, adhesives and dispersing agents. However, previous studies of the surface properties of starch and chemically modified starches have been conflicting and incomplete. This work has used a newer technique to determine values for the surface tension of starch and modified starches which are probably much closer to the correct values than previous studies. In addition, one of the modified starches acted as a good emulsifier for soybean oil. This work should help scientists and engineers in the food and industrial sectors predict how to improve the effectiveness of starch coatings, adhesives and dispersants. This work was carried out in support of ARS National Program 306, Quality and Utilization of Agricultural Products and addresses Problem Statement 2a, New Product Technology. KRAFT LIGNIN-REINFORCE STARCH FILMS. Flexible cornstarch films with improved strength were prepared by extrusion with kraft lignin and glycerol under a non-funded cooperative agreement between USDA/ARS/NCAUR and State University of New York at Binghamton. The lignin appeared to be finely dispersed into particles of 1 micrometer or less in size and thus acted as a reinforcing filler. These results may be important to industrial and academic researchers interested in improving the mechanical properties of starch films and coatings as well as preparing small (nanoparticulate) sized lignin particles. Since the latter are dark brown in color, they may also have some potential to replace carbon black as a colorant or filler. This work was carried out in support of ARS National Program 306, Quality and Utilization of Agricultural Products and addresses Problem Statement 2a, New Product Technology. SUPERCRITICAL (sc) FLUID EXTRACTED STARCH. Very little lipid was extracted from starch with sc CO2 but sizeable amounts were extracted with pressurized ethanol and sc CO2/ethanol mixtures. Lipid extraction had significant effects on the rheology of gelantinized starch dispersions. Thus, lipid extraction may represent an additional way to vary the properties of starch to fit new applications. 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. 4d Progress report. Research progress in FY2006 is documented in Questions 4a and 4b. SY position 1W1213 was abolished in FY2006 due to fiscal constraints. As indicated in Question 3a, this has impacted the accomplishment of Objectives 4a and 4b and represents a reduction in the MU's (management unit) research capacity. 5. Describe the major accomplishments to date and their predicted or actual impact. We have observed that the viscosities of jet cooked starch dispersions are greater if the hot dispersions are stirred as they are allowed to cool. This method for altering the viscous properties of starch dispersions will expand their range of end-use applications. By adjusting the composition and cooling conditions of jet cooked starch- fatty acid dispersions, very uniform micro- and nano-sized starch particles were prepared. After extraction with alcohol, hollow nano- tubes were formed. These new starch morphologies could have several new applications. A commercially viable procedure was developed to deposit thin coatings of jet cooked starches onto surfaces of normally water repellent plastics such as polyethylene. Such hydrophilic starch coated plastics would have utility for water based printing inks, reduced electrostatic charging and improved biocompatibility. Microwave processing was used to prepare water soluble and water swellable starch acetates quickly and without added catalyst or solvent. It was also discovered that iodine efficiently catalyses the acetylation of cellulose without added solvent or catalyst. These findings should help reduce the cost and amount of waste products involved in commercial production of starch and cellulose acetates. Sorbitol citrates and polyaspartic acid copolymers were prepared in an efficient and continuous manner by reactive extrusion. These biodegradable polycarboxylates can substitute for petroleum derived polymers such as polyacrylic acid in applications such as detergent additives and oilfield uses. Several companies are currently evaluating these materials in their products and processes. The feasibility of preparing novel hydrophobic starch esters using enzyme catalysis was also demonstrated. Starch-polyacrylamide copolymers were prepared in a rapid and efficient manner by reactive extrusion. Modified starches having conjugated unsaturation were produced by grafting itaconic and maleic anhydrides onto starch. It is expected that these will have new functionality and applications. In summary, farmers will derive benefits from the expansion of markets for agricultural commodities. New and expanded markets for cereal grains will reduce federal outlays for surplus commodity support and will improve the profitability of American agriculture. Multi-billion bushel carry-overs of corn each year will provide a vast source of raw material. This work was carried out in support of ARS National Program 306, Quality and Utilization of Agricultural Products and addresses Problem Statements 2a, New Product Technology, and 2c, New and Improved Processes and Feedstocks. 6. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? 1. CRADA with a research corporation interested in marketing the starch coating technology to the private sector: The purpose of the CRADA is to develop commercially viable methods for applying starch coatings to plastic surfaces to make them more hydrophilic. Work under this CRADA has resulted in three U.S. patent applications. 2. CRADA with an industrial partner: The purpose of this CRADA is to provide research support to ATI in its efforts to manufacture and market the starch graft copolymer superabsorbent (Super Slurper). 3. CRADA with an industrial partner: The purpose of the agreement was to prepare and characterize starch/aspartic acid copolymers and to seek applications for these in the industrial sector.

Impacts
(N/A)

Publications

Peterson, S.C., Fanta, G.F., Adlof, R.O., Felker, F.C. 2005. Identification of complexed native lipids in crystalline aggregates formed from jet cooked cornstarch. Carbohydrate Polymers. 61(2):162-167.
Shogren, R.L., Biswas, A. 2005. Preparation of starch esters using efficient processes [abstract]. International Chemical Congress of Pacific Basin Meeting. p.117.
Shogren, R.L., Fanta, G.F., Felker, F.C. 2006. X-ray diffraction study of crystal transformations in spherulitic amylose/lipid complexes from jet- cooked starch. Carbohydrate Polymers. 64(3):444-451.
Biswas, A., Saha, B.C., Lawton Jr, J.W., Shogren, R.L., Willett, J.L. 2006. Process for obtaining cellulose acetate from agricultural by-products. Carbohydrate Polymers. 64:134-137.
Doll, K.M., Shogren, R.L., Willett, J.L., Swift, G. 2006. Solvent free polymerization of citric acid and D-sorbitol. Journal of Polymer Science A. 44:4259-4267.
Byars, J.A., Fanta, G.F., Felker, F.C. 2006. The influence of oil on the properties of slowly-cooled jet-cooked normal corn starch dispersions. Carbohydrate Polymers. 63(3):316-322.

Progress 10/01/04 to 09/30/05

Outputs
1. What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? What does it matter? The need to develop new and expanded industrial markets for cereal grains, such as corn, is driven by continued production in excess of demand. For many applications, starch must be physically and/or chemically modified to impart desired characteristics. Reactions of water solutions of starch with water-insoluble organic compounds are difficult to carry out because of the incompatibility between water and organic phases. This limits the number of new, useful starch derivatives that can be economically prepared using practical processing techniques. Starch is produced annually in the U.S., primarily from corn, in amounts exceeding current market needs. Methods of converting these starch surpluses to new value-added products are, therefore, urgently needed. Novel and inexpensive methods, with minimal environmental impact, are needed to increase the compatibility and reactivity of starch with non-starch materials, if new starch products are to be produced and marketed. 2. List the milestones (indicators of progress) from your Project Plan. Objective 1a: Effect of stirring on jet-cooked starch. 15 months: Determine effect of stirring during cooling on rheology of jet cooked dispersions. 30 months: Isolate and compare crystallites formed with and without oil. 45 months: Determine effect of stirring during cooling on crystallite type, size and morphology. 60 months: Carry out similar experiments using mixtures of starch, pectin and xanthan. Objective 1b: Investigate properties of starch spherocrystals. 15 months: Separate large and small spherocrystals; isolate complexed lipids to determine effect of lipid type on structure. 30 months: Measure surface area and pore volumes. Investigate end-use applications. 45 months: Add lipids such as palmitic and linoleic acids, study crystallite type formed and optimize yields. 60 months: Determine effect of cooling rate and starch concentration on spherocrystal type and yield. Objective 1c: Scale-up of starch coatings on plastics. 15 months: Demonstrate effect of starch concentration, cooling rate and volume. 30 months: Evaluate other plastic substrates; expand graft polymerization studies. 45 months: Study effect of co-jet cooking with oils and lipids. 60 months: Develop practical production methods and commercial applications. Objective 2a: Prepare and characterize starch esters. 15 months: Scale up preparation of starch acetates; prepare new starch citrates and aspartates. 30 months: Characterize starch acetate, citrate structure and properties, demonstrate a practical use. 45 months: Determine which other starch esters can be made efficiently; investigate other solvents, catalysts. 60 months: Prepare regiospecifically substituted starches; identify applications and transfer technology. Objective 2b: Prepare hydrophobic starch esters. 15 months: Demonstrate feasibility by forming C-O bond by grafting dicyclopentadiene to starch. 30 months: Explore grafting with butadienes, styrene. Characterize graft copolymer structure. 45 months: Optimize reaction yields and evaluate properties for usefulness in products. 60 months: Identify applications, file patent and transfer technology. Objective 2c: Starch-sc CO2 interactions. 15 months: Demonstrate extent of penetration of CO2 into starch granules. 30 months: Determine effect of sc CO2 on OSA-starch reaction efficiency. 45 months: Characterize interaction of gelatinized starch and sc CO2. 60 months: Finish work on enzymatic esterification of starch in sc CO2. Objective 3a: Prepare starch graft copolymers by reactive extrusion. 15 months: Demonstrate effects of extrusion parameters on starch- polyacryl-amide-copolymer properties. 30 months: Initiate reactive extrusion using other monomers and initiators. 45 months: Initiate reactive extrusion of other substrates. 60 months: Characterize graft copolymers from other substrates, transfer technology. Objective 3b: Develop methods for controlling graft molecular weight. 15 months: Develop lab techniques using model compounds. 30 months: Optimize synthetic techniques using corn starch. 45 months: Apply new methods to reactive extrusion processes. 60 months: Characterize products and transfer technologies. Objective 4a: Enzymatic starch modification in water. 15 months: Screen different reactions and enzymes (+ or -). 30 months: Select most efficient (>5%) reactions, optimize conditions. 45 months: Prepare larger lab-scale quantities of products (gram size). 60 months: Characterize structures and properties. Objective 4b: Enzymatic starch modification with alcohol, sugar. 15 months: Screen different alcohols and enzymes (+ or -). 30 months: Optimize reaction conditions. 45 months: Determine effect of starch physical treatments. 60 months: Characterize structures and properties. Objective 4c: Transesterification of starch and polyesters. 15 months: Screen enzymes in aqueous suspension or DMF. 30 months: Optimize reaction conditions, characterize product. 45 months: Scale up reactions with mixer or extruder. 60 months: Determine physical properties and assess applications. 3a List the milestones that were scheduled to be addressed in FY 2005. For each milestone, indicate the status: fully met, substantially met, or not met. If not met, why. 1. Objective 1a: Determine effect of stirring during cooling on rheology of jet cooked dispersions. Milestone Fully Met 2. Objective 1b: Separate large and small spherocrystals; isolate complexed lipids to determine effect of lipid type on structure. Milestone Fully Met 3. Objective 1c: Demonstrate effect of starch concentration, cooling rate and volume. Milestone Substantially Met 4. Objective 2a: Scale up preparation of starch acetates; prepare new starch citrates and aspartates. Milestone Fully Met 5. Objective 2b: Demonstrate feasibility by forming C-O bond by grafting dicyclopentadiene to starch. Milestone Not Met Other 6. Objective 2c: Demonstrate extent of penetration of CO2 into starch granules. Milestone Substantially Met 7. Objective 3a: Demonstrate effects of extrusion parameters on starch- polyacrylamide copolymer properties. Milestone Fully Met 8. Objective 3b: Develop lab techniques using model compounds. Milestone Fully Met 9. Objective 4a: Screen different reactions and enzymes (+ or -). Milestone Not Met Other 10. Objective 4b: Screen different alcohols and enzymes (+ or -). Milestone Not Met Other 11. Objective 4c: Screen enzymes in aqueous suspension or DMF. Milestone Substantially Met 3b List the milestones that you expect to address over the next 3 years (FY 2006, 2007, and 2008). What do you expect to accomplish, year by year, over the next 3 years under each milestone? Objective 1a: Effect of stirring on jet-cooked starch. FY2006: Cornstarch will be jet cooked in both the presence and absence of oil to determine how the presence of oil droplets influences the size and shape of the spherulites formed. A range of starch concentrations will be examined. FY2007: Cornstarch will be jet cooked in the presence of oil at several starch concentrations, and the effects of stirring during cooling on the rheology of the cooled starch/oil dispersions will be determined. Spherulites formed in the cooled dispersions will be examined microscopically to determine the effect of stirring on morphology. FY2008: Natural gums such as pectin and xanthan will be added to cornstarch to determine their effect on the rheology of jet cooked dispersions and the morphology of the spherulites formed. Objective 1b: Investigate the properties of starch spherocrystals. FY2006: Pure fatty acids, such as palmitic, linoleic and stearic will be added to defatted cornstarch to determine the influence of fatty acid structure on spherulite morphology. FY2007: High amylose cornstarch will be jet cooked at a range of concentrations with different amounts of fatty acid. This study will allow us to maximize spherulite yields and will provide us with sufficient quantities of spherulites to examine end-use applications. FY2008: Surface areas and pore volumes of spherulites will be examined, and end-use applications of spherulites will be investigated. Objective 1c: Scale-up of starch coatings on plastics. FY2006: Practical methods, suitable for large-scale commercial processing, will be developed for applying starch coatings to polyethylene surfaces. The effects of adding other components in minor quantities to jet cooked starch dispersions will be investigated with the goal of maximizing adhesion of the starch coating to the polyethylene surface. FY2007: Starch will be jet cooked with varying amounts of lipids, and the effects of lipid structure on the properties and adhesion of the starch coating will be determined. FY2008: The application of graft polymerized starch and other starch derivatives to polyethylene surfaces will be investigated. Application of starch to the surfaces of plastics other than polyethylene will also be examined. Objective 2a: Prepare and characterize starch esters. FY2006: Characterization of surface properties of starch acetates will be completed. Starch esters prepared under CRADA with Folia will be characterized and practical uses will be demonstrated. FY2007: The potential of preparing other types of starch esters will be studied along with novel catalysts and ionic liquid solvents. FY2008: Regiospecifically modified starch esters will be prepared. Objective 2b: Prepare hydrophobic starch esters. FY2006: Explore grafting with butadienes, styrene. Characterize graft copolymer structure. FY2007: Optimize reaction yields and evaluate properties for usefulness in products. FY2008: Identify applications, file patent and transfer technology. Objective 2c: Starch-sc CO2 interactions. FY2006: The effect of supercritical carbon dioxide and/or ethanol on the reaction of starch with long chain alkenylsuccinic anhydrides will be studied. FY2007: The effect of supercritical carbon dioxide on the gelatinization process of starch in water and subsequent precipitation will be studied. FY2008: The feasibility of performing enzymatic esterifications in supercritical carbon dioxide will be assessed. Objective 3a: Demonstrate effects of extrusion parameters on starch- polyacrylamide copolymer properties. FY2006: Prepare and characterize starch graft copolymers by reactive extrusion using water soluble monomers other than acrylamide. Pursue technology transfer efforts with potential partners. FY2007: Prepare starch graft copolymers using other agriculturally- derived substrates such as corn fiber and proteins. Pursue technology transfer efforts. FY2008: Pursue technology transfer efforts. Expand range of substrates and monomers. Objective 3b: Develop methods for controlling graft molecular weight. FY2006: Optimize synthetic techniques using corn starch - other controlled radical polymerization techniques will be evaluated to select the most robust process for desired monomers. Polymerization 'to' and 'from' techniques will be evaluated to determine preferred technique. FY2007: Apply new methods to reactive extrusion processes - desired grafting process will be modeled in a torque rheometer and scaled to full size extruder. FY2008: Characterize products and transfer technologies - experimental conditions will be explored to develop various products that will be fully characterized. Objective 4a: Enzymatic starch modification in water. FY2006: Screen different reactions and enzymes (+ or -). FY2007: Select most efficient (>5%) reactions, optimize conditions. FY2008: Prepare larger lab-scale quantities of products (gram size). Objective 4b: Enzymatic starch modification with alcohol, sugar. FY2006: Screen different alcohols and enzymes (+ or -). FY2007: Optimize reaction conditions. FY2008: Determine effect of starch physical treatments. Objective 4c: Transesterification of starch and polyesters. FY2006: Continue preparation of starch-polycaprolactone graft copolymers using lipase catalysis. Compare reaction efficiency using granular and nanoparticulate starches. FY2007: Optimize reactions and begin characterization of product structure and properties. FY2008: Scale up reactions using mixer or extruder. 4a What was the single most significant accomplishment this past year? A commercially viable procedure was developed to deposit thin coatings of starch onto the surfaces of normally water repellent plastics such as polyethylene. These starch coatings impart water receptive properties to the plastic surface. Absorption of water-based dyes and inks, reduced electrostatic charging, and compatibility with aqueous reagents and biological fluids are some of the useful properties that are imparted to plastic materials when the surfaces are modified to make them water- compatible. This technology will be of interest to companies that produce plastic containers, biomedical devices, and wrapping materials for sensitive electronic components. 4b List other significant accomplishments, if any. We have observed that the viscosities of jet cooked starch disperions are greater if the hot dispersions are stirred as they are allowed to cool. This method for altering the viscous properties of starch dispersions will expand their range of end-use applications. Identification of complexed native lipids in the small (toroidal) and large (spherical) spherulite species will allow us to control the size and morphology of these particles by adding fatty acids of different composition to the starch prior to jet cooking. This will allow us to tailor the structures of these materials for specific end use applications. Microwave processing was used to prepare starch acetates quickly and without added catalyst or solvent. These starch acetates were very soluble in cold water over long periods of time and had low viscosities, making them useful as coatings and adhesives. Starch acetates made by current commercial procedures result in much byproduct and are generally poorly soluble in water or precipitate from solution over time. Thus, starch acetates produced by microwave processing have new functionality which could be useful to companies making coatings for paper, textiles, etc. Novel starch and polyol esters prepared under a CRADA were shown to have functionality similar to a non-degradable petroleum-based polymer. The latter is used commercially in fairly large quantities and may accumulate in the environment and potentially cause problems. A U.S. patent application covering this technology was filed in February, 2005. Scale up activities are in progress. The stability of starch/lipid spherocrystals was studied under different drying, hydration and solvent conditions. It was found that the lipid component of these crystals can be largely removed by extraction with alcohols, leaving the structure of the hollow starch helix intact. Such hallow "nanotubes" could have new uses as selective absorbents and catalysts. A novel solvent-less method to esterify polysaccharides was discovered which utilizes a highly efficient catalyst (iodine). The results described in this paper may impact the way 1.5 billion pounds of starch and cellulose acetates are globally manufactured every year. This solvent-free method that we discovered would help the starch/cellulose acetate manufacturers to prepare starch or cellulose acetate in an environment friendly way. This method eliminates the use of solvents and acids. A novel method for the rapid preparation of starch esters was developed by the use of microwave. The rapid reaction of starch and maleic anhydride in DMSO was achieved under microwave irradiation. Starch ester manufacturers may potentially benefit from this work. Controlled radical polymerization techniques were explored using copper based atom transfer polymerization of styrene. Initial experiments did not give polymer. After review of pertinent literature and discussion with academic resources, techniques utilized were modified which provided polystyrene. Resulting polystyrene is substituted in the terminal position by a bromide. By using standard organic chemistry techniques this polymer will be grafted onto starch in the near future which will illustrate that the polymerization 'to' technique is a valid approach for grafting a polymer made using controlled molecular weight techniques. 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. This was the first year of the project. Farmers will derive benefits from the expansion of markets for agricultural commodities. New and expanded markets for cereal grains will reduce federal outlays for surplus commodity support and will improve the profitability of American agriculture. Multi-billion bushel carry-overs of corn each year will provide a vast source of raw material. New starch-based materials will be of interest to companies that produce plastic containers, wrapping materials for electronic components, biomedical devices, hydrogels, controlled release agents, and other materials for water-based applications. 6. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? CRADA with a company interested in marketing the water-receptive starch coating technology to the private sector. The goal of this research is to develop commercially viable methods for applying starch coatings to plastic surfaces. Work under this CRADA has resulted in the filing of two U.S. Patents. CRADA with Absorbent Technologies, Inc. The goal of this research is to investigate new methods for producing starch graft copolymer superabsorbents. CRADA with Folia, Inc. to prepare and characterize starch/aspartic acid copolymers and to seek applications for these in the industrial sector. 7. List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below). 1. Peterson, S.C., Fanta, G.F., Adlof, R.O., and Felker, F.C. Identification of complexed native lipids in crystalline aggregates formed from jet cooked cornstarch. Carbohydrate Polymers 2005 (in press). Log #168706. 2. Abstract. Felker, F.C., Fanta, G.F., Shogren, R.L., and Salch, J.H. Fatty acid type influences morphology of spherulites formed from jet- cooked fatty acid/defatted starch mixtures. AACC Meeting, Orlando, FL. Log #178605. 3. Abstract. Peterson, S.C., Fanta, G.F., Eller, F.J., and Felker, F.C. Effects of supercritical fluid extraction on the pasting properties of cornstarch. AACC Meeting, Orlando, FL. Log #178445.

Impacts
(N/A)

Publications

Fanta, G.F., Felker, F.C., Shogren, R.L., Byars, J.A., Salch, J. Crystalline particles formed in slowly-cooled cornstarch dispersions prepared by steam jet cooking. The effect of starch concentration, added oil and rate of cooling. Carbohydrate Polymers. 2005. v.61(2):222-230.
Finkenstadt, V.L., Willett, J.L. Reactive extrusion of starch- polyacrylamide graft copolymers: effects of monomer/starch ratio and moisture content. Macromolecular Chemistry and Physics. 2005. v.206:1648- 1652.
Momany, F.A., Willett, J.L. 2004. Molecular dynamics simulations of amylose fragments with cross-linking reagents:glass transition temperatures of epichlorohydrin bridged complexes [abstract]. American Chemical Society. 190:416.
Parsons, J.D., Willett, J.L., Finkenstadt, V.L. 2004. Comparison of molecular weight of starch-graft-poly(acrylamide) produced by batch reaction and reactive extrusion [abstract]. American Chemical Society. p. 196:435.
Shogren, R.L., Petrovic, Z., Liu, Z., Erhan, S.Z. 2004. Biodegradation behavior of some vegetable oil-based polymers [abstract]. Polymers and the Environment. 12(3):492351:173-178.
Kim, S., Willett, J.L. 2004. Isolation of amylose from starch solutions by phase separation*. Starch/Starke. 56:29-36.
Finkenstadt, V.L., Willett, J.L. 2004. Natural polysaccharides as electroactive biomaterials [abstract]. BioEnvironmental Polymer Society. p. 133:355.
Finkenstadt, V.L. 2005. Edging into the synthetic electroactive polymer (eap) market: solid polymer electrolytes using renewable biomaterials [abstract]. American Chemical Society. p.87.
Bosma, W.B., Bartelt, R.J., Momany, F.A. 2005. Calculations to determine the experimental conformation of a cyclic insect pheromone using a novel multi-faceted ab initio approach [abstract]. Midwest Theoretical Conference. p.10.
Appell, M.D., Cote, G.L., Dunlap, C.A., Willett, J.L., Momany, F.A. 2004. B3lyp/6-311++g**study of conformational preferences and thermodynamic properties of disaccharides [abstract]. American Chemical Society. 189:413.
Shogren, R.L. 2004. Preparation, properties and non-food uses for starch esters of moderate degree of substitution [abstract]. Nordic Starch Network. p.9:33.
Biswas, A., Shogren, R.L., Willett, J.L. 2004. Synthesis of starch maleate half-esters under microwave irradiation [abstract]. American Chemical Society Meeting. p.5:132.
Haig, R.L., Parsons, J.D., Finkenstadt, V.L. 2004. Enzyme digestion of starch-graft-copolymers [abstract]. American Chemical Society. p.176:371.
Finkenstadt, V.L., Willett, J.L. 2004. Direct current electroactivity via ion-conduction in thermoplastic starch and other biopolymers [abstract]. United States Japan Natural Resources. p.59-63.