This paper deals with the effect of solvent on the viscoelastic properties and microstructure of cellulose acetate (CA) by means of rheological measurements, dynamic-mechanical analysis and scanning electron microscopy. Acetone, acetic acid, dimethylacetamide (DMAc) and dimethylformamide (DMF) were used as good solvents and water as a non-solvent. The addition of water in the cellulose acetate/solvent mixture led to the development of an intense shear thinning behavior, as it caused the formation of CA agglomerates which were disrupted in a steady shearing condition. Apart from this, a three-dimensional elastic gel behavior in the CA/DMF/water and CA/DMAc/water solutions was observed during dynamical rheological analysis. The formation of CA agglomerates was controlled by the solvent type and resulted in microstructure changes, going from a dense structure to a porous one, and also influenced the CA chain rigidity and consequently the glass transition temperatures of the CA films. © 2013 Elsevier Ltd. All rights reserved.49927302737Balser, K., Hoppe, L., Eicher, T., Wandel, M., Astheinmer, H.J., Cellulose esters (1986) Ullmann's Encyclopedia of Industrial Chemistry, 5 A, pp. 438-457. , W. Gerhartz, Y.S. Yamamoto, VCH WeinheimChandra, R., Rustgi, R., Biodegradable polymers (1998) Prog Polym Sci, 23, pp. 1273-1335Edgar, K.J., Buchanan, C.M., Debenham, J.S., Rundquist, P.A., Seiler, B.D., Shelton, M.C., Advances in cellulose ester performance and application (2001) Prog Polym Sci, 26, pp. 1605-1688Ray, S.S., Bousmina, M., Biodegradable polymers and their layered silicate nanocomposites: In greening the 21st century materials world (2005) Prog Mater Sci, 50, pp. 962-1079Williams, C.K., Hillmyer, M.A., Polymers from renewable resources: A perspective for a special issue of polymer reviews (2008) Polymer Reviews, 48, pp. 1-10Basu, S., Khan, A.L., Cano-Odena, A., Liu, C., Vankelecom, I.F.J., Membrane-based technologies for biogas separations (2010) Chem Soc Rev, 39, pp. 750-768Appaw, C., Gilbert, R.D., Khan, S.A., Viscoelastic behavior of cellulose acetate in a mixed solvent system (2007) Biomacromolecules, 8, pp. 1541-1547Guenet, J.-M., (1992) Thermoreversible Gelation of Polymers and Biopolymers, , Academic Press LondonKadla, J.F., Korehei, R., Effect of hydrophilic and hydrophobic interactions on the rheological behavior and microstructure of a ternary cellulose acetate system (2010) Biomacromolecules, 11, pp. 1074-1081Matsuyama, H., Nishiguchi, M., Kitamura, Y., Phase separation mechanism during membrane formation by dry-cast process (2000) J Appl Polym Sci, 77, pp. 776-782Sivakumar, M., Malaisamya, R., Sajitha, C.J., Mohana, D., Mohana, V., Rangarajan, R., Ultrafiltration application of cellulose acetate polyrethane blend membranes (1999) Eur Polym J, 35, pp. 1647-1651Lee, H., Chaudhuri, S.R., Krantz, W.B., Hwang, S.-T., A model for evaporative casting of polymeric membranes incorporating convection due to density changes (2006) J Membr Sci, 284, pp. 161-172Kawanishi, H., Tsunashima, Y., Okada, S., Horii, F., Change in chain stiffness in viscometric and ultracentrifugal fields: Cellulose diacetate in N,N-dimethylacetamide dilute solution (1998) J Chem Phys, 108, pp. 6014-6025Schulz, L., Seger, B., Burchard, W., Structures of cellulose in solution (2000) Macromol Chem Phys, 201, pp. 2008-2022Tabe-Mohammadi, A., Villaluenga, J.P., Kim, H.J., Chan, T., Rauw, V., Effects of polymer solvents on the performance of cellulose acetate membranes in methanol/methyl tertiary butyl ether separation (2001) J Appl Polym Sci, 82, pp. 2882-2895Shieh, J.-J., Chung, T.S., Effect of liquid-liquid demixing on the membrane morphology, gas permeation, thermal and mechanical properties of cellulose acetate hollow fibers (1998) J Membr Sci, 140, pp. 67-79Li, Z., Ren, J., Fane, A.G., Li, D.F., Wong, F.-S., Influence of solvent on the structure and performance of cellulose acetate membranes (2006) J Membr Sci, 279, pp. 601-607Qian, J.W., An, Q.F., Wang, L.N., Zhang, L., Shen, L., Influence of the dilute-solution properties of cellulose acetate in solvent mixtures on the morphology and pervaporation performance of their membranes (2005) J Appl Polym Sci, 97, pp. 1891-1898Vaessen, D.M., McCormick, A.V., Francis, L.F., Effects of phase separation on stress development in polymeric coatings (2002) Polymer, 43, pp. 2267-2277Appaw, C., Gilbert, R.D., Khan, S.A., Kadla, J.F., Phase separation and heat-induced gelation characteristics of cellulose acetate in a mixed solvent system (2010) Cellulose, 17, pp. 533-538Hao, J.H., Wang, S., Calculation of alcohol-acetone-cellulose acetate ternary phase diagram and their relevance to membrane formation (2001) J Appl Polym Sci, 80, pp. 1650-1657Reuvers, A.J., Altena, F.W., Smolders, C.A., Demixing and gelation behavior of ternary cellulose acetate solutions (1986) J Polym Sci Part B: Polym Phys, 24, pp. 793-804Iiyina, E., Daragan, V., Self-diffusion of dimethyl sulfoxide and dimethyformamide in solutions and gels of cellulose acetates by pulsed field gradient NMR (1999) Macromolecules, 27, pp. 3759-3763Hong, P.-D., Chou, C.-M., Huang, H.-T., Phase separation behavior in polyvinyl alcohol/ethylene glycol/water ternary solutions (2000) Eur Polym J, 36, pp. 2193-2200Hong, S.-J., Hong, P.-D., Chen, J.-C., Shih, K.-S., Effect of mixed solvent on solution properties and gelation behavior of poly(vinyl alcohol) (2009) Eur Polym J, 45, pp. 1158-1168Fujii, S., Sasaki, N., Nakata, M., Rheological studies on the phase separation of hydroxypropylcellulose solution systems (2001) J Polym Sci: Polym Phys, 39, pp. 1976-1986Lizaso, E., Munoz, M.E., Santamaria, A., Formation of gel in ethylcellulose solutions. An interpretation from dynamic viscoelastic results (1999) Macromolecules, 32, pp. 1883-1889Kadla, J.F., Korehei, R., Tuning the morphology of cellulose acetate gels by manipulating the mechanism of phase separation (2011) Biomacromolecules, 12, pp. 43-49Brandrup, J., Immergut, E.H., (1989) Polymer Handbook, , John Wiley & Sons New YorkBarton, A.F.M., (1985) Handbook of Solubility Parameters and Other Cohesion Parameters, , CRC Press Boca RatonSato, T., Sakurai, K., Norisuye, T., Fujita, H., Collapse of randomly coiled schizophyllan in mixtures of water and dimethylsulfoxide (1983) Polym J, 15, pp. 87-96Yanaki, T., Tabata, K., Kojima, T., Melting behaviour of a triple helical polysaccharide schizophyllan in aqueous solution (1985) Carbohydr Polym, 5, pp. 275-283Macosko, C.W., (1994) Rheology: Principles, Measurements and Applications, , Wiley-VCH New YorkRomero, R.B., Leite, C.A.P., Gonçalves, M.C., The effect of the solvent on the morphology of cellulose acetate/montmorillonite nanocomposites (2009) Polymer, 50, pp. 161-170Cassu, S.N., Felisberti, M.I., Poly(vinyl alcohol) and poly(vinyl pyrrolidone) blends: Miscibility, microheterogeneity and free volume change (1997) Polymer, 38, pp. 3907-3911