The Effect of Starch Structure on Starch-based Nanocomposite
J.H. Zhou and M.A. Hanna
South China Agricultural University, CN
starch, nanocomposite, plasticizer, intercalacation, nanoclay
The effect of starch structure on starch based nanocomposite Starches, including high amylose cornstarch, normal cornstarch, and waxy cornstarch, were gelatinized and mixed with nanoclay aqueous dispersion and different amount plasticizer. The mixtures were then cast onto Teflon plate and allowed to dry naturally. The dried film were conditioned in an environmental chamber at 25, and 50% relative humidity for more than 24 hours before tested for water permission, mechanical strength and XRD. The intercalation of starches into nanoclay depended on the chain length of starch main chain and side chain in absence of plasticizer. The shorter the chain length of starch was, the higher the degree of intercalation. However, the films prepared in absence of plasticizer were very brittle. Plasticizers had much smaller molecular weight than that of starch, plasticizer instead of starch intercalated into the nanoclay as shown by XRD when starch films were prepared in the presence of plasticizer. Even though starch could not intercalate into the nanoclay itself, the introduction of nanoclay increased the mechanical strength and reduced elongation the same way in synthetic polymer nanocomposite, but to a lower extent. The introduction of nanoclay did not change the water permission significantly due to the factor that nanoclay was hydrophilic itself. Chain length played an important role in the non-specific intercalation of nanoclay films. Plasticizer repelled starch chain from intercalation into the nanoclay but it still showed positive effect in increasing the mechanical and water permission properties. Acknowledgements: Project 20106004 supported by NSFC and China Scholarship Council.
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Nanotech 2007 Conference Program Abstract