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Cationic polyelectrolytes are water-soluble polymers bearing positive ionic groups along the backbone or in side chains. These cationic polymers are synthesized by free radical polymerization of acrylamide and their derivatives by the copolymerization method, which includes solution, precipitation, and emulsion techniques. The Mannich reaction is another important method by which the cationic polymers can be processed. In this review paper, the preparation methods, interaction mechanisms of these polymers, and their popular industrial applications are summarized. These polymers open a lot of applications in different fields such as paper-making processes, water and wastewater treatment, oil and drilling industries, mineral separation, paint and food industries, cosmetics, and pharmacy. In addition, these polymers are widely used as flocculants and rheology control agents. These polymers are especially employed in oil field operations as viscosity control agents for enhanced oil recovery, drilling fluid additives, and also for modifying flow and stability properties of aqueous solutions and gels. They are used as super-plasticizers, which affect the rheological properties of dense cement suspensions. Mining processes also benefit from the use of acrylamide derivative polymers to flocculate solids in aqueous dispersions. The cationic polymers may interact with different components in the system such as inorganic/organic particles in aqueous dispersions in several ways, which may result in the stability or instability of dispersion. The particles can be destabilized through three different main mechanisms which promote flocculation: polymer bridging, charge neutralization, and polymer adsorption.

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Nowadays, chemical and physical thermoplastic elastomers have found many applications in different industries. Compatibilizer and co-continuous composition are among the important factors which control the optimum properties of a number of physical blends. Morphology, mechanical and rheological properties of various blends of polystyrene (PS) and polybutadiene were investigated. The results show that the co-continuous composition for these blends is located in-between 24 and 35 wt% of PS. These blends show a negative deviation from the viscosity logarithmic additivity rule. This observation suggests an improvement in the interactions between the phases in co-continuous composition. Rheological and mechanical properties were used in determination of the co-continuous phase.