Physical structure and thermal behavior of ethylcellulose
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The physical structure and properties of ethylcellulose (EC) powders of different molecular weights were examined. A molecular weight in the range of 20–144 kDa with a large polydispersity was determined. EC thermal analysis revealed a glass transition at ~130 °C and a melting temperature at ~180 °C. Glass transition temperatures increased with polymer molecular weight. Wide angle (WAXS) analysis detected an amorphous broad peak at q = 1.5 Å−1 and a distinct Bragg’s peak at 12.6 Å, which seems to be related to a supramolecular ordered structure of the polymer. These observations were confirmed using high temperature powder X-ray diffraction analysis where the crystalline peak disappeared above the melting temperature of the polymer. Ultra-small angle (USAXS) results were fitted to the Bouacage fractal unified model and fractals with an average size of 100–600 nm with a relatively smooth surface were predicted. This prediction was confirmed by transmission electron microscopy (TEM) images. According to our results, the EC polymer has a semi-crystalline structure, with crystalline domains within an amorphous background.
KeywordsEthyl cellulose Semi-crystalline Powder Fractal X-ray scattering
Research supported by the Ontario Ministry of Agriculture and Food (OMAF) and the Natural Sciences and Engineering Research Council of Canada (NSERC). We acknowledge the technical assistance of Fernanda Peyronel for setting up experiments and data analysis. The author wish to thank Dr. Jan Ilavsky from the APS sector 15ID-D USAXS/SAXS facility for his help conducting both SAXS and USAXS experiments. ChemMatCARS Sector 15 is principally supported by the National Science Foundation/Department of Energy under grant number NSF/CHE-0822838. Use of the Advanced Photon Source was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
- Atalla RH, Isogai A (1998) Recent developments in spectroscopic and chemical characterization of cellulose. In: Dumitriu S (ed) Polysaccharides: structural diversity and functional versatility, 2nd edn. Marcel Dekker, New York, pp 123–157Google Scholar
- Cavalcanti OA, Petenuc B, Bedin AC, Pineda EAG, Hechenleitner AAW (2004) Characterisation of ethylcellulose films containing natural polysaccharides by thermal analysis and FTIR spectroscopy. Acta Farm Bonaerense 23:53–57Google Scholar
- Ethylcellulose polymers technical handbook (2005). Dow Chemical Company, http://www.dow.com/dowwolff/en/pdfs/192-00818.pdf
- Knill CJ, Kennedy JF (1998) Cellulosic biomass-derived products. In: Dumitriu S (ed) Polysaccharides: structural diversity and functional versatility. Marcel Dekker, New York, pp 937–956Google Scholar
- Kondo T (1998) Hydrogen bonds in cellulose and cellulose derivatives. In: Dumitriu S (ed) Polysaccharides: structural diversity and functional versatility, 2nd edn. Marcel Dekker, New York, pp 69–98Google Scholar
- Perez S, Samain D (2010) Structure and engineering of celluloses. Adv Cacbohyd Chem Biochem 64:26–116Google Scholar
- Witten TA, Sander LM (1983) Diffusion-limited aggregation. Phys Rev B 27:5686–5697Google Scholar