The Effect of Processing Conditions and Composition on Starch Microcellular Foam Properties.

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dc.contributor.advisor Dr. Richard A. Venditti, Committee Chair en_US
dc.contributor.advisor Dr. Joel J. Pawlak, Committee Co-Chair en_US
dc.contributor.advisor Dr. Martin A. Hubbe, Committee Member en_US Patel, Sameerkumar Vasantlal en_US 2010-04-02T18:19:19Z 2010-04-02T18:19:19Z 2009-04-23 en_US
dc.identifier.other etd-03242009-094441 en_US
dc.description.abstract Starch microcellular foams (SMCF) are prepared by pore preserving drying or formation processes and contain pores in the micron size range. SMCF have high specific surface area and are useful for applications such as opacifying pigments or as adsorbent materials. The objective of this research was to determine how the processing conditions and use of a sizing and crosslinking agent would affect the foam structure and properties. To produce SMCF materials in this research, cooked starch solutions were subjected to different solvent exchange processes involving the exchange of water for ethanol. Drying from the low surface tension ethanol allows pore formation on drying to produce low density and high opacity microcellular foams; if the starches are dried from water, large capillary forces destroy the pore structure, producing dense translucent solids. It was found that the microcellular foam density passed through a minimum with respect to the solvent exchange times. SMCF (crosslinked and uncrosslinked) were prepared from molded aquagels and carbon dioxide extruded samples separately and then solvent exchanged. Extruded samples showed macroscopic pores whereas samples from aquagels showed a much finer micro pore structure. Aquagel based SMCF samples had lower density and higher brightness than extruded samples. The starch foams with micro pore structure had low density and high brightness. The solvent exchange process was the most important variable in generating a microcellular structure. Micro pores and not macro pores contributed to increased brightness of these materials. The brightness and density of the foams were found to be linearly related. Crosslinking with epichlorohydrin imparted significant water resistance to the extruded samples as evidenced in lower water swelling and higher contact angles. Equilibrium moisture content was correlated with the micro-porous structure. In order to investigate the effect of adding a hydrophobicizing agent on the water sensitivity several samples of SMCF-AKD were produced and the results showed that the samples had similar brightness, higher density, and higher water contact angle than starch foams alone. SMCF materials blended with Kymene, a common wet strength agent for paper and a crosslinking component for carbohydrates, did not show a significant increase in water resistance. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dis sertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject Kymene en_US
dc.subject AKD en_US
dc.subject solvent exchange en_US
dc.subject starch en_US
dc.subject foam en_US
dc.title The Effect of Processing Conditions and Composition on Starch Microcellular Foam Properties. en_US MS en_US thesis en_US Wood and Paper Science en_US

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