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United States Department of Agriculture

Agricultural Research Service

Research Project: MODIFICATION OF NATURAL POLYMERS BY THERMO-MECHANICAL PROCESSING

Location: Plant Polymer Research

Title: Preparation and Physical Properties of Starch Stearates of Low to High Degree of Substitution

Authors
item Shogren, Randal
item Biswas, Atanu
item Willett, Julious

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 20, 2010
Publication Date: March 21, 2010
Citation: Shogren, R.L., Biswas, A., Willett, J.L. 2010. Preparation and Physical Properties of Starch Stearates of Low to High Degree of Substitution. Meeting Abstract. Carb 106.

Technical Abstract: Starch stearates of degree of substitution (DS) 0.07-2.40 were prepared by heating dry starch and vinyl stearate in the ionic liquid BMIM dca at 75 Degrees C. Starch stearate of low DS (0.07) was insoluble in water but formed a gel and absorbed over seven times its weight of water. Starch stearate with high DS (2.4) was soluble in chloroform or toluene and had a high degree of swelling in hydrocarbons such as hexane. Films cast from starch stearates had water contact angles of 84-93 Degrees, indicating a very hydrophobic surface. X-ray diffraction and DSC of DS > 0.6 indicated some short-range crystallization of the stearate side chains. Optical birefringence was noted at moderate to high DS, suggesting liquid crystal formation. Starch stearates of DS ~0.6 showed intense birefringence resembling starch granules in DMSO while cholesteric liquid crystalline behavior was observed in toluene (reflected blue light). Blue light reflection disappeared on heating to >60-80 Degrees C then reformed on cooling. These results suggest that starch stearates have some interesting structural ordering and have potential applications as water absorbents, hydrocarbon/oil absorbents, water resistant coatings and liquid crystalline materials.

Last Modified: 7/30/2014
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