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United States Department of Agriculture

Agricultural Research Service


Location: Plant Polymer Research

2008 Annual Report

1a.Objectives (from AD-416)
The goal of this research is to develop new biobased materials from starch and new fundamental knowledge of their properties. Objectives of this work fall into three topic areas: materials development, molecular modeling and simulations, and analysis techniques.

1b.Approach (from AD-416)
Develop new biobased materials from starches with novel properties, utilizing the inherent properties of starch so that it is an active component rather than a low cost, biodegradable filler. Develop molecular modeling tools for use in rational design approaches. Develop novel sophisticated instrumental analytical techniques to characterize the structures and properties of multicomponent biobased materials.

3.Progress Report
Preliminary experiments were conducted with a fiber drawing line to extrude oriented polylactic acid (PLA) and PLA/starch blend fibers. Preliminary experiments were carried out to characterize the absorption of low molecular weight amylose onto isotropic and oriented films of polylactic acid, poly(3-hydroxybutyric acid), and other polymers. No orientation in the amylose phase was measured by polarized Fourier Transform Infrared Spectroscopy (FTIR) although FTIR would not detect very thin layers of oriented material. Our computational program to determine the importance of water on carbohydrate structure is providing new fundamental results. The inclusion of explicit and implicit solvent models has provided optical, vibrational, energetic, chemical shift, and other structural properties of carbohydrates, unavailable from any other source. Our constant energy Density Functional Theory and COnductor-like Screening MOdel (DFT+COSMO) molecular dynamics study of different conformations of maltose led to a better understanding of the structural fluctuations expected when studying dynamic structures in solution. Questions of the effect of solvent on conformation of larger amylose fragments are being addressed. We have shown that hydroxyl orientation is strongly solvent dependent, and becomes more important as the number of glucose residues increases. These studies are important to the understanding of material properties of starch like materials, and to provide fundamental basis for future simulations of larger systems. Novel starch-based hydrogels have been developed which respond to changes in temperature or solvent quality. By controlling composition and processing parameters, large changes in volume can be realized by increasing temperature or adding ethanol. The amount of swelling or deswelling can be controlled as well. These new biobased materials may have applications as sensors, actuators, or in control devices. Corrosion of metals is one of the most challenging problems faced by industry. Using electrochemical analyses, we identified several bacterial exopolysaccharides, as well as other bio-based polymer coatings, that exhibit corrosion inhibition behavior when applied to SAE 1010 steel and that are environmentally benign and cost comparative to existing measures. Initial methods involved casting films onto the metal substrates. We have developed a method to spray coat very thin layers using commercially available equipment. Effectiveness of coating varies with coating material and thickness. This research fits under NP 306, Component 2.

1. Calculation of degree of orientation in amylose/starch films. There has been considerable interest recently in developing starch-based fibers and films for use as biodegradable packaging and hygiene products. Previous work has shown that stretching amylose films (the linear polymeric component of starch), so that the molecules are pointed in one direction (oriented) gives films that are much stronger and more flexible. It has been difficult to determine, however, if starch films are fully oriented or not. This research showed the theoretical birefringence (an optical characteristic) for a perfectly oriented starch crystal. The degree of orientation of a real starch film can then be estimated based on the measured birefringence. These results should help companies and university scientists develop new starch-based materials for disposable consumer products to replace those derived from imported petroleum. This work was carried out in support of NP 306, Component 2, Problem Area 2c.

5.Significant Activities that Support Special Target Populations

6.Technology Transfer

Number of Non-Peer Reviewed Presentations and Proceedings1

Review Publications
Mohamed, A., Finkenstadt, V.L., Palmquist, D.E. 2008. Thermal properties of extruded-injection molded poly (lactic acid) and bio-based composites. Journal of Applied Polymer Science. 107(2):898-908.

Holser, R.A., Willett, J.L., Vaughn, S.F. 2008. Thermal and physical characterization of glycerol polyesters. Journal of Biobased Materials and Bioenergy. 2(1):1-3.

Schnupf, U., Willett, J.L., Bosma, W., Momany, F.A. 2007. DFT studies of the disaccharide, a-maltose: relaxed isopotential maps. Carbohydrate Research. 342(15):2270-2285.

Schnupf, U., Willett, J.L., Bosma, W., Momany, F.A. 2008. DFT conformational studies of alpha-maltotriose. Journal of Computational Chemistry. 29(7):1103-1112.

Momany, F.A., Schnupf, U., Willett, J.L., Bosma, W. 2007. DFT study of alpha-maltose: influence of hydroxyl orientations on the glycosidic bond. Structural Chemistry. 18(5):611-632.

Han, J., Heaven, M.C., Schnupf, U., Alexander, M.H. 2008. Experimental and theoretical studies of the CN-Ar van der Waals complex. Journal of Chemical Physics. 128(10):104308.

Willett, J.L. 2008. Humidity-responsive starch-poly (methyl acrylate) films. Macromolecular Chemistry and Physics. 209(1):764-772.

Last Modified: 4/18/2014
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