Hydroxyethylcellulose (HEC) is a nonionic water soluble polymer derived from cellulose, it is used as a thickener, protective colloid, binder, stabilizer, and suspending agent in a variety of industrial applications. The HEC attracted a considerable attention in food industry, detergents, cosmetics, decorative and protective coatings , pharmaceuticals, textiles, paper, adhesives , emulsion polymerization, ceramics, drilling mud and many miscellaneous uses (Cahn and Lai 2006), (Li 1999). Literature has reported some progress in this basic concern. The hydroxyethyl cellulose (HEC) was used as a retardation of the cement hydration  (Pourchez J. 2006),(Singh 2003). The addition of the HEC to coating colors was investigated to improve his water retention properties, (G. Fadat 1988) studied his influence on water drainage from the colors and they discussed the effect of the polymer on the rheological properties of a clay based coating color.(Wencong Wang 2015) studied the hydrodynamic properties and gelation of HEC as function of molar substitution (MS) concentration and temperature, the authors showed that the intrinsic viscosity and the gelation time of HEC solutions decreases with temperature, (Carico RD (1978) )solutions in the same solvent. The success of drilling a well depends essentially on the right choice of fluid used.In order to preserve the environment, cellulose derivatives are often used as additives to drilling fluid in various oil and gas well drilling processes (Benyounes, Mellak et al. 2010). Rheological studies of cellulosic derivatives are important for estimating and understanding on a molecular basis the function of these components in the drilling fluid, they have proven their effectiveness in drilling wells in less time and providing minimal permeability during drilling and completion operations  (Himes and 1991. 1991; Tuttle RN 1974; Carico RD (1978) ; Cole RC (1995)), and hydroxyethylcellulose (HEC) has proven its high performance in this field.

Moreover, such characteristics are interest in many other industrial areas and a further development of the utilization of this polymer may be expected from these studies. Particularly Cellulose derivative polymers are intensively used in pharmaceutical applications to modify the release of drugs in tablets and capsule formulations and to improve their dissolution in the gastrointestinal fluids. This process is called “hydrophilization”. (Kamel, Ali et al. 2008) showed that both low and high viscosity grade cellulose ether polymers can be mixed uniformly, in different proportions, in order to produce matrices with modulated drug release properties. The study of(S. C. NAIK and 1976) confirms

that the aqueous solutions of HEC have high degrees of pseudo plasticity and stability over long periods. (Castelain, Doublier et al. 1987) studied the flow behavior of two types of cellulose derivatives (CMC and HEC) in aqueous solution, they showed that the viscous behavior is roughly similar with two critical concentrations c* and c**, delimiting three flow regions, and a third critical concentration ce, intermediate between c* and c**, determined from the variation of the relaxation time with concentrations.  

Rheological studies of cellulose derivative are of importance for estimating and understanding on a molecular basis, the function of these components in food systems. Several works were carried to improve the stability of emulsions by adding natural cellulose derivatives to increase the viscosity of the medium (Radi and Amiri 2013), (Yaseen, Herald et al. 2005), to perform and control the texture of foodstuffs, they are also used as thickener, binder, stabilizer suspending and water retaining agent (Mirhosseini, Tan et al. 2008), (Menezes, Marques et al. 2010). The polymer-surfactant interaction has been the subject of several studies. (H. Lauer 1999; L.G.Patruyo 2002) were interested in studying the interaction between HEC and three of its drifts with the SDS; they showed that these interactions lead to phase separation in an intermediate concentration range of SDS and, for higher concentrations of surfactants, when a homogeneous phase has been obtained, these interactions lead to higher apparent shear and expansion viscosities.

The addition of other surfactants eventually reduces hydrophobic interactions due to electrostatic repulsion between the micelles, causing shear viscosities to be even lower than those of the original polymer solution. In terms of our work, we were interested in the rheological aspect of HEC by studying the effect of temperature and concentration on the rheological properties of water-based solutions.