Viscous-cohesive products

Based on our own study results, we propose a partial revision of the viscoelastic substance grouping/classification proposed by Arshinoff, to be based on the rheologic and physicochemical characteristics of viscoelastic substances obtained in cooperation with the Max-Planck Institute for Polymer Research, Department of Rheology, in Mainz, Germany. Furthermore, a new product, the so-called "viscous cohesion dissociated high molecular weight viscoelastic", better known by its product name, Healon 5 (Fig. 2), is now at our disposal. Healon 5 is formulated to fulfill specific requirements for use in phacoemulsification (i.e., with both cohesive and dispersive characteristics). 

The super-viscous cohesive agents facilitated surgical maneuvers and endothelial protection more than viscous cohesive agents. By combination of different properties, Healon 5 combines advantages of cohesive and dispersive properties. From the rheological standpoint it is the most ideal product for each step of the phacoemulsification procedure compared to Healon and Healon GV. 

Hydrated food products exhibiting adhesive or cohesive properties are generally highly viscous or plastic and, therefore. 

Plastic solids derive their functionality from their unique plastic nature. Three conditions are essential for plasticity (5) (1) both liquid and solid phases must be present (2) the solid phase must be so finely dispersed that the entire solid-liquid matrix can be effectively bound together by internal cohesive forces and (3) proper proportions must exist between the phases. Incorrect phase ratios adversely influence product rheology. For example, deficient solids content may result in oil separation, whereas excessive solids can cause hardness or brittleness instead of the desired viscous flow. 

Pressure sensitive adhesives (PSA) are highly viscous, viscoelastic liquids which adhere to virtually aU surfaces when pressed down gently. They are used in manufacturing easy to apply self-adhesive products, such as labels and tapes. Pressure sensitive adhesives typically have permanent tack and adequate cohesion, so that further curing operations after applying the tape or label are generally unnecessary. 

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