ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 1 Effect of Temperature and a Non-Solvent Addition on the Specific Volume of Poly (sodium-4-styrene sulfonate) in Water Ons Zoghlami, Moez Guettari * and Tahar Tajouri Unité de recherche « RMN dans les polymères et dans les composites » Institut préparatoire aux études d’ingénieurs de Tunis. Université de Tunis. Tunisie * Author’s emails Moez Guettari : gtarimoez@Yahoo.fr Abstract The effect of temperature and a non-solvent, ethanol, addition on the specific volume of poly (sodium 4-styrene sulfonate) in water was investigated. The refractive indices of the studied solutions were measured over the 298.15 K to 323.15 K temperature range. Then the specific volumes of the polyelectrolyte were calculated according to the Lorentz-Lorenz and Gladstone- Dale equations. The relative deviations of the specific volumes between measured and calculated according to these equations didn’t exceed 2.5%. Several empirical equations were deduced to describe the variations of the refractive index increment and the specific volume versus the temperature and the mixture composition. Keywords Poly (sodium 4-styrene sulfonate), refractive index increment, specific volume, solvent-non- solvent mixture.