Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: ADVANCED STARCH-BASED MATERIALS FOR NON-FOOD APPLICATIONS

Location: Plant Polymer Research

2005 Annual 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? What does it matter?
The economic viability of the U.S. farmers is threatened by low commodity prices due to domestic and foreign production in excess of current demand. There is a growing demand for biobased materials to replace petroleum-based plastics. Starch and fibers derived from corn or wheat have potential to fill a large part of the approximately 70 billion lb/yr U.S. market for synthetic thermoplastics. To develop starch-based materials with functional properties, it is critical to better understand how starch interacts with other polymers and how these interactions can be modified and optimized. Development of new starch-based materials will increase market opportunities for biobased products and enhance the economic viability of U.S. agriculture. This research project will generate new uses for cereal grains and coproducts by discovery and development of value added biomaterials, and is part of the National Program 306, Quality and Utilization of Agricultural Products.

The development of new, higher value products from cereal grains and coproducts would boost farm income and help ensure that farmers remain competitive worldwide. Improved processes would reduce environmental impact of production of biobased materials. Market penetration of 1% of the current thermoplastics market in the U.S. would translate into approximately 700 million lbs/yr of biobased materials. If these new materials were 80% by weight starch, new markets would be created for approximately 100,000 acres of corn. Reduced environmental impact of solid waste disposal would provide significant positive societal impact. Improved methods of analysis of complex multicomponent systems will benefit other researchers in this broad field of study.

Potential products of this research include materials for applications such as disposable films, absorbents, adhesives, sensors, and materials responsive to changes in humidity, temperature, or pH. New fundamental knowledge of the interactions of starch with water and other additives will provide these basis for rational design of biobased materials.

Customers of this research project include scientists and engineers in academic and government labs who conduct research in carbohydrate biobased materials. Companies who develop, manufacture, or use biobased materials will also be customers of this research. Growers and grower organizations will benefit from increased markets for their products, and ultimately consumers will benefit from increased environmental benefits of biobased materials.


2.List the milestones (indicators of progress) from your Project Plan.
Objective 1.1: Conductive materials. 0-15 Months: Prepare and characterize conductive blends; demonstrate critical formulation variables. 15-30 months: Prepare and characterize graft copolymers; demonstrate efficacy of anti-corrosion materials. 30-45 months: Doping of graft copolymers. Transfer anti-corrosion technology; develop cost estimates of selected materials. 45-60 months: Scale-up of processing in pilot plant for targeted materials.

Objective 1.2: SM (shape memory) materials. 0-15 Months: Graft copolymer film study; initiate responsive material study; demonstrate critical variables controlling shrinkage. 15-30 months: Complete film study; begin larger cross-sections; develop cost estimates of film technology; demonstrate temperature-sensitive responsive materials. 30-45 months: Alternate monomers for grafting; complete thicker cross-sections; demonstrate pH responsive modulated materials. 45-60 months: Technology transfer of SM materials; complete pH sensitive materials; develop cost estimates of selected responsive materials.

Objective 1.3: Oriented materials. 0-15 months: Prepare and characterize oriented films. 15-30 months: Examine alternate orientation techniques; initiate epitaxy work. 30-45 months: Prepare oriented films by extrusion and characterize properties; develop cost estimates of selected film formulations. 45-60 months: Complete epitaxy work; pursue technology transfer.

Objective 1.4: Starch nanospheres. 0-15 months: Produce particles using dialysis method; demonstrate critical variables controlling particle size. Determine enzyme/acid treatments to weaken granules. Optimize viscosity ratios of starch and PLA (poly (lactic acid). 15-30 months: Optimize solvents and membrane to control particle size; develop cost estimates of solvent process. Ball mill treated starches into nanoparticle; develop cost estimates of milling process. Optimize extrusion parameters; develop cost estimates of extrusion process. 30-45 months: Characterize particles in solution; measure particle uptake of various chemicals for controlled release. Characterize ageing properties and demonstrate particle size effects; use materials based on optimized conditions. 45-60 months: Demonstrate uptake and release properties. Complete controlled release study; technology transfer efforts. Characterize ageing properties and demonstrate particle size effects; use materials based on optimized conditions.

Objective 2.1: DFT (Density Functional Theory). 0-15 months: DFT studies of glucose, maltose, cellobiose with 1-5 water molecules. 15-30 months: Glucose trimers and water; glucose with 10 water molecules. 30-45 months: Epimer solvation; larger glucose oligomers. 45-60 months: Vibration and NMR (Nuclear Magnetic Resonance) shifts; complete glucose study.

Objective 2.2: Water diffusion. 0-15 months: DP30 periodic box study; Tg (transition glass) and crosslinking. 15-30 months: DP100 periodic box study; include opimers. 30-45 months: Metal ion effects on water diffusion and conduction band. 45-60 months: Complete metal ion study.

Objective 2.3: Type B structure. 0-15 months: Complete preliminary periodic box study. 15-30 months: Determine structure to fix Xray data; complete study. (Final milestone for 2.3).

Objective 2.4: Epimers. 0-15 months: Complete mannose/allose structure; begin glucose/water. 15-30 months: Complete galactose/Idose structure; increase number of water with glucose. 30-45 months: Complete analog study; begin twisted boat solvation. 45-60 months: Determine vibrational frequencies and NMR shifts.

Objective 3: Chemometric methods. 0-15 months: Infrared and thermodynamic analyses to identify and quantify individual components and their interactions. 15-30 months: Utilize infrared spectra to characterize intermolecular interaction and hydrogen bonding between components. 30-45 months: IR (InfraRed) method for determination of concentrations of individual polymers. Develop chemometric models for infrared analysis of intermolecular interactions in multicomponent biopolymer materials. 45-60 months: Develop mathematical models to extract structure-property relationships in multicomponent biopolymers and optimize formulation parameters.


4a.What was the single most significant accomplishment this past year?
Starch nanoparticles. Use of starch in many material applications is limited by the inherent size of starch granules. Therefore, the development of starch nanoparticles is an area of active interest. Cornstarch was dissolved in water-dimethyl sulfoxide solvents and dialyzed against pure ethanol. The starch particles generated by this method had particle sizes ranging from 200 nanometers to 1 micron. For comparison, native corn starch granules are typically 10 microns or larger in size. Drying methods directly affected particle size. Particles that were air dried had the largest size whereas particles that were critical point dried while still in an ethanol suspension had the smallest size. Producing nano-particle starch will open new markets for starch by imparting novel properties not attainable with larger-particle starch.


4b.List other significant accomplishments, if any.
Although starch-based films have been studied for many years as a replacement for petroleum-based plastic films, they have yet to be used extensively as they suffer from brittleness and poor water resistance. One possible way to improve flexibility and water resistance is to induce orientation and crystallinity into starch films and fibers. Some methods for achieving starch orientation have been reported in the literature but these methods were not optimized and the effects of orientation on starch film properties were not characterized. Films from amylose (the linear component of starch) were prepared, partially oriented and characterization of film strength and flexibility was begun. The findings of this research should assist other researchers and companies involved in trying to make disposable, biodegradable starch-based plastic articles.

Wheat gluten was modified to add value by improving its viscoelaticity and other food end-use properties. In collaboration with Dr. Abdellatif Mohamed (CPF - Cereal Products & Food Science) to improve the properties of wheat protein, the effects of the enzymatic crosslinking upon native wheat gluten were examined by Modulated Differential Scanning Calorimetry (MDSC) and Fourier Transform Infrared Spectroscopy (FTIR). An FTIR spectroscopic method was devised to obtain evidence of molecular interaction between the gluten protein and the TRIS (hydroxymethyl)aminomethane) buffer used in the crosslinking reaction. It is well known that FTIR spectra of proteins are sensitive to their molecular conformations and environments. Therefore, FTIR spectroscopy of the crosslinked gluten in TRIS buffer provided definitive evidence that gluten-TRIS hydrogen bonding likely occurs at their molecular interface in aqueous systems and thus plays an important role in enzymatic crosslinking reactions. These MDSC and FTIR methods, especially when combined with potential spectral deconvolution strategies, have applications for distinguishing between levels of crosslinking in wheat gluten for studies in flour or dough rheology.

Since all natural carbohydrates (such as starch and cellulose) exist in the presence of water, successful computer modeling requires accurate methods of incorporating water. Various models of glucose (the structural building block of starch and cellulose) with water was simulated at a high level of theory. These structural studies of solvated carbohydrates are the first detailed examinations which describe how water changes conformational preferences, or shape, in amylose- and cellulose-like compounds. This work has great potential for improving our understanding of these biobased materials, with the goal of improved properties for commercial utility.

Thermoplastic starch-carbon black blends with up to 40 percent by weight carbon black prepared by extrusion. Films were evaluated for their electrial conductivity and mechanical properties. Conductivity with increasing carbon black content up to an optimum level after which it decreased. Strength and stiffness increased with increasing carbon black content while extensibility decreased. The materials retained their conductance values after 21 days of ageing. Strength and stiffness increased significantly with ageing time. These results demonstrate that starch-based materials with useful levels of conductivity and mechanical properties can be easily prepared using conventional techniques. This information is useful to other researchers developing biobased materials.

Successful development of new markets for biobased materials requires materials with novel properties. Starch graft copolymers, in which a synthetic polymer is chemically bonded to starch, were prepared and evaluated for use as responsive ("smart") materials. Initial results indicate that these starch-based materials respond to changes in relative humidity or temperature by changing shape. These responses are due to the starch component. These studies provide the basis for future work in this area, and suggest new opportunities for starch-based materials.


4c.List any significant activities that support special target populations.
None.


4d.Progress report.
Our ability to perform sophisticated computer simulations has been enhanced by the addition of a 16-processor, 64 bit word computer. This computer has increased the delivery of computational output and allowed molecular systems to be studied.


5.Describe the major accomplishments over the life of the project, including their predicted or actual impact.
This is the first year of this project. Starch nanoparticles. Use of starch in many material applications is limited by the inherent size of starch granules. Therefore, the development of starch nanoparticles is an area of active interest. Cornstarch was dissolved in water-dimethyl sulfoxide solvents and dialyzed against pure ethanol. The starch particles generated by this method had particle sizes ranging from 200 nanometers to 1 micron. For comparison, native corn starch granules are typically 10 microns or larger in size. Drying methods directly affected particle size. Particles that were air dried had the largest size whereas particles that were critical point dried while still in an ethanol suspension had the smallest size. Producing nano-particle starch will open new markets for starch by imparting novel properties not attainable with larger-particle starch.

Although starch-based films have been studied for many years as a replacement for petroleum-based plastic films, they have yet to be used extensively as they suffer from brittleness and poor water resistance. One possible way to improve flexibility and water resistance is to induce orientation and crystallinity into starch films and fibers. Some methods for achieving starch orientation have been reported in the literature but these methods were not optimized and the effects of orientation on starch film properties were not characterized. Films from amylose (the linear component of starch) were prepared, partially oriented and characterization of film strength and flexiblity was begun. The findings of this research should assist other researchers and companies involved in trying to make disposable, biodegradable starch-based plastic articles.

Wheat gluten was modified to add value by improving its viscoelaticity and other food end-use properties. In collaboration with Dr. Abdellatif Mohamed (CPF - Cereal Products and Food Science) to improve the properties of wheat protein, the effects of the enzymatic crosslinking upon native wheat gluten were examined by Modulated Differential Scanning Calorimetry (MDSC) and Fourier Transform Infrared Spectoscopy (FTIR). An FTIR spectroscopic method was devised to obtain evidence of molecular interaction between the gluten protein and the TRIS (hydroxymethyl)aminomethane) buffer used in the crosslinking reaction. It is well known that FTIR spectra of proteins are sensitive to their molecular conformations and environments. Therefore, FTIR spectroscopy of the crosslinked gluten in TRIS buffer provided definitive evidence that gluten-TRIS hydrogen bonding likely occurs at their molecular interface in aqueous systems and thus plays an important role in enzymatic crosslinking reactions. These MDSC and FTIR methods, especially when combined with potential spectral deconvolution strategies, have applications for distinguishing between levels of crosslinking in wheat gluten for studies in flour or dough rheology.

Since all natural carbohydrates (such as starch and cellulose) exist in the presence of water, successful computer modeling requires accurate methods of incorporating water. Various models of glucose (the structural building block of starch and cellulose) with water was simulated at a high level of theory. These structural studies of solvated carbohydrates are the first detailed examinations which describe how water changes conformational preferences, or shape, in amylose- and cellulose-like compounds. This work has great potential for improving our understanding of these biobased materials, with the goal of improved properties for commercial utility.

Thermoplastic starch-carbon black blends with up to 40 percent by weight carbon black prepared by extrusion. Films were evaluated for their electrical conductivity and mechanical properties. Conductivity with increasing carbon black content up to an optimum level after which it decreased. Strength and stiffness increased with increasing carbon black content while extensibility decreased. The materials retained their conductance values after 21 days of ageing. Strength and stiffness increased significantly with ageing time. These results demonstrate that starch-based materials with useful levels of conductivity and mechanical properties can be easily prepared using conventional techniques. This information is useful to other researchers developing biobased materials.

Successful development of new markets for biobased materials requires materials with novel properties. Starch graft copolymers, in which a synthetic polymer is chemically bonded to starch, were prepared and evaluated for use as responsive ("smart") materials. Initial results indicate that these starch-based materials respond to changes in relative humidity or temperature by changing shape. These responses are due to the starch component. These studies provide the basis for future work in this area, and suggest new opportunities for starch-based materials.

Customers for this research should be companies involved in making biobased products for applications such as disposable packaging, personal hygiene products, and edible films. This research will lead to greater understanding of structure-property relationships and the effects of composition and processing parameters. New knowledge created using chemometrics for characterization molecular modeling to predict property differences will enable the design of new biobased materials with predicted properties. Ultimately this research will lead to new materials with improved properties, and expanded uses of corn and other grains.


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?
Since this is the first year of this project, technology transfer activities have largely been publishing and presentations of research results at meetings and conferences. Initial discussions have been held with potential commercial partners interested in the oriented starch films and electroactive materials.


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).
None.


Review Publications
Finkenstadt, V.L., Willett, J.L. 2004. Preparation and characterization of functionalized electroactive biopolymers [abstract]. American Chemical Society. p.25.

Willett, J.L., Jasberg, B.K., Finkenstadt, V.L. 2004 CD-ROM. Effects of process parameters in reactive extrusion of starch [abstract]. BioEnvironmental Polymer Society.

Shogren, R.L., Biresaw, G. 2005. Surface properties of water soluble starch esters [abstract]. American Chemical Society. p.1 of 2, cell 27.

Bosma, W.B., Appell, M.D., Willett, J.L., Momany, F.A. 2004. Density functional study of cellobiose hydrates [abstract]. American Chemical Society. p.189.

Blair, N.M., Biswas, A., Adhvaryu, A., Gordon, S.H., Erhan, S.Z., Willett, J.L. 2004. Amine functionalized soybean oil [abstract]. American Chemical Society. p.108.

Berfield, J.L., Biswas, A., Parsons, J.D., Finkenstadt, V.L. 2004. Preparation of starch-graft-poly(itaconic acid) copolymers. American Chemical Society. p.177.

St Lawrence, S., Walia, P., Felker, F.C., Willett, J.L. 2004. Starch filled ternary polymer composites ii: room temperature tensile properties [abstract]. Journal of Polymer Engineering and Science. 44(10):1839-1847.

Lawton Jr, J.W. 2004. Native starch; uses of. Encyclopedia of Grain Science. 1-3:195-202.

Appell, M.D., Willett, J.L., Momany, F.A. 2005. Dft study of alpha- and beta-d-mannopyranose at the b3lyp/6-311++g** level. Carbohydrate Research. 340:459-468.

Shogren, R.L., Rousseau, R.J. 2005. Field testing of paper/polymerized vegetable oil mulches for enhancing growth of eastern cottonwood trees for pulp. Forest Ecology and Management. Available from: http://authors.elsevier.com/sd/article/S0378112704008229 ScienceDirect.

Willett, J.L., Felker, F.C. 2005. Tensile yield properties of starch-filled poly(ester amide) materials. Polymer. p.46.

Finkenstadt, V.L. 2005. Natural polysaccharides as electroactive polymers. Applied Microbiology and Biotechnology. 67:735-745.

Momany, F.A., Appell, M.D., Willett, J.L., Bosma, W.B. 2005. B3lyp/6-311++g** geometry optimization study of pentahydrates of alpha- and beta-d-glucopyranose. Carbohydrate Research. 340:1638-1655.

Last Modified: 4/18/2014
Footer Content Back to Top of Page