Effect of Aging on the Microstructure of Plasticized Cornstarch Films
Simão, Renata A.; Andrade, Cristina T.; Thiré, Rossana M. S. M.
http://dx.doi.org/10.1590/S0104-14282005000200013
Polímeros: Ciência e Tecnologia, vol.15, n2, p.130-133, 2005
Abstract
Aging of cornstarch films prepared by casting was investigated. Water and glycerol-plasticized cornstarch films were stored at 50% relative humidity over a period of 330 days. Aging was followed by X-ray diffraction (XRD) and atomic force microscopy (AFM). XRD spectra indicated development of B-type crystallinity even for fresh films and that the crystallinity index increased from 0.06 to 0.28 as a function of storage time. AFM images of 270-day-old films revealed that the general morphology and the overall roughness have not changed due to aging. AFM phase contrast images at higher magnification showed an increasing number of ordered domains at the surface of these films, which may be attributed to recrystallization of amylose. No morphological change was observed at least at the surface of the granular region, which is enriched in amylopectin.
Keywords
Cornstarch films, Aging, Atomic force microscopy, X-Ray diffraction
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