Submitted to: Microscopy and Microanalysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 15, 2008
Publication Date: August 3, 2008
Citation: Wood, D.F., Chiou, B., Glenn, G.M., Hoffmann, D.F., Williams, T.G., Yee, E., Imam, S.H., Orts, W.J. 2008. Fine Structure of Starch-Clay Composites as Biopolymers. Microscopy and Microanalysis. 14(Suppl 2):1500-1501. Interpretive Summary: Bio-based polymer nanocomposites were made from renewable resources by adding montmorillonite nanoclays to native wheat starch. The polymer composites were produced in a twin-screw extruder. The physical properties were previously characterized by rheology, x-ray diffraction, tensile, water absorbance, and water vapor transmission. Structure and function are often related, therefore, an understanding of the ultrastructure is necessary in order to further characterize the composites. In this study. methods were developed for the observation of these biopolymers using transmission electron microscopy.
Technical Abstract: Midsol 50 wheat starch and 5% Cloisite clay with or without the addition of glycerin were used to prepare biopolymers in a twin-screw extruder. Early trials of sectioning the unembedded biopolymer resulted in the immediate absorption of water and subsequent dissolution of the sample due to the the great hydrophilic properties of our biopolymer. Collecting of dry sections without benefit of a water bath was impossible because the tiny fragments could not be collected with any degree of precision. Cryo-sectioning was tried on a single sample and yielded good results. However, because the equipment was not readily available, a method of embedding and sectioning the bioploymers was needed in order to get reproducible results. The trials included the use of standard recommended procedures for Epon, Spurr's, Durcupan and LR White resins. The standard procedures produced inconsistent results. The successful trial for all samples included the use of Spurr's and infiltration and embedding under partial vacuum (0.5 atm).