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Your search keyword '"Sierakowski, Maria R."' showing total 17 results
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17 results on '"Sierakowski, Maria R."'

16. Properties of starch/layered compound composites

Author

Wilhelm, Helena-M, Sierakowski, Maria-R, Souza, Gabriel P, and Wypych, Fernando

Abstract

Glycerol-plasticized starch films were modified by addition of various layered compounds as fillers, two being of natural origin (kaolinite, a neutral mineral clay, and hectorite, a cationic exchanger mineral clay) and two synthetic (layered double hydroxide, LDH, an anionic exchanger, and brucite, having a neutral structure). The effects of the filler type and the plasticizer were analyzed by X-ray diffraction, dynamic mechanical analysis and thermogravimetry. The storage modulus was higher for kaolinite > brucite > hectorite than for LDH starch composites. However, only the hectorite filler presented a shift of the interplanar basal distance to higher values, which represents the intercalation of glycerol molecules between the clay layers. The glycerol intercalation is minimized in plasticized-oxidized starch films where the oxidized starch chains are preferentially intercalated. Copyright © 2003 Society of Chemical Industry

Published
2003
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17. Hydrophilicity improvement of mercerized bacterial cellulose films by polyethylene glycol graft.

Author

da Silva R, Sierakowski MR, Bassani HP, Zawadzki SF, Pirich CL, Ono L, and de Freitas RA

Subjects
Animals, Cell Line, Materials Testing, Mice, Molecular Weight, Nanostructures chemistry, Polymerization, Bacteria chemistry, Cellulose chemistry, Hydrophobic and Hydrophilic Interactions, Polyethylene Glycols chemistry
Abstract

In this work, polyethylene glycol (PEG), of tree distinct molar masses (200, 300 and 400 g mol(-1)), was grafted onto mercerized bacterial nanocellulose (BNCm) and applied to produce nanofilms (BNCm-PEG). The products BNCm-PEG were characterized by NMR and thermal analysis. Solid-state NMR and X-ray diffraction analyses exhibited no significant differences in index of BNCm-PEG derivatives compared to BNCm, indicating that grafting reaction did not modify the BNCm crystalline structure. The apparent contact angle of the films showed that BNCm-PEG films exhibited a pronounced increase in the polar components (BNCm: 8.1 mN m(-1) vs BNCm-PEG400: 29.4 mN m(-1)), and a decrease in dispersive components (BNCm: 41.7 mN m(-1) vs BNCm-PEG400: 35.2 mN m(-1)) of the surface free energy. The BNCm-PEG films were more hydrophilic than BNCm and retained the biocompatibility with L929 fibroblast cells culture., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Published
2016
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