Water activity of aqueous solutions of ethylene oxide-propylene oxide block copolymers and maltodextrins

• Autor(a) principal: Carareto,N. D. D.
• Data de Publicação: 2010
• Outros Autores: Monteiro Filho,E. S., Pessôa Filho,P. A., Meirelles,A. J. A.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Brazilian Journal of Chemical Engineering
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322010000100015
• topic: Water activity; Excess Gibbs energy; Phase equilibrium; Flory-Huggins; UNIFAC

The water activity of aqueous solutions of EO-PO block copolymers of six different molar masses and EO/PO ratios and of maltodextrins of three different molar masses was determined at 298.15 K. The results showed that these aqueous solutions present a negative deviation from Raoult's law. The Flory-Huggins and UNIFAC excess Gibbs energy models were employed to model the experimental data. While a good agreement was obtained with the Flory-Huggins equation, discrepancies were observed when predicting the experimental behavior with the UNIFAC model. The water activities of ternary systems formed by a synthetic polymer, maltodextrin and water were also measured and used to test the predictive capability of both models.