ABSTRACT
Rheological modifers are materials which are used to modify the flow properties of fluids (liquids, suspensions, emulsions, creams, etc.). In general, materials which increase the viscosity of formulations/systems are referred to as thickeners or rheological additives. There are both marketing and technical reasons for using rheological additives in various products. The first one is consumer appeal [1]. The users expect a thick product to be more concentrated and richer than a thin one. The second reason for thickening is the suspension stabilization. In suspensions, the rheological additives delay the separation of suspended solid particles during storage. The third reason is that the rheological additives in fluids, such as liquids and creams, confer thixotropic properties in order to improve their mobility during application and facilitate the ease of spreading on the surface, such as skin and hair. Thixotropy allows the product to be mobile or low in viscosity during application, followed by restoration of the internal structure to ensure adhesion and minimize drainage from the site of application. There are also some production reasons for thickening liquid products such as shampoos. Too thin a liquid shampoo in a bottle is more likely to leak through an improperly fitted cap than a thick viscous liquid.
