Polymers rheological representations

Fig. 5 When representing mechanical elements with equivalent circuits, elements which are placed in series to each other, physically, have to be drawn as parallel elements in the circuit representation because currents (speeds) are additive for parallel electrical elements. Conversely, mechanical elements which are physically placed in parallel have to be represented in series because the voltage (force) is additive for electrical elements placed in series. In the literature on polymer rheology, springs and dashpots are depicted as on the right-hand side, but connected to each other as on the left-hand side. This convention differs from the convention chosen here. It amounts to a different set of Kirchhoff rules...

Lyotropic SCLCP are far less well studied by rheology than lyotropic MCLCPs. An example is the discotic SCLCP, as mentioned in Chap. 6 (Fig. 6.15), by Franse et al. (2002-2004). Fig. 16.37 gives a schematic representation of side chain discotic polymers (Franse, 2002). In solution the polymers have a tendency to form networks due to interaction between the discotic side chains. From viscoelastic measurements (G and G" as functions of angular frequency) it appeared that the networks formed in a 13% solution in 1,1,2-trichloroethane are very fragile, with a rubber modulus of not more than IN/m2. 

The model representation of the filled polymer mixture shows a very important feature of filled polymer mixtures The properties of a binary matrix between two filler particles are not the same as for the initial unfilled mixture. In analyzing rheological properties of the filled binary melt, one should keep in mind that relative changes of the viscosity in the filler presence should be considered in relation to the matrix properties changed under the influence of the filler. Such an approach was developed for filled melts by Droste and Dibenedetto [15]. 

Figure 9.6. A schematic representation of the thickening mechanism of (a) conventional water-soluble polymers and (b) associative rheology modifiers in a simplified latex paint system. The...

If we assume the existence of a network of disclinations (idealized representation), then the analogy arises with respect to concentrated solutions and melts of polymers in which the existence of networks of linkages is possible and with fill systems in which there is a network of contacts with the filler. For this reason, based on the concept of the network, it is possible to approach the description of the rheological properties of the individual systems from a unified point of view and their mixtures firom the point of view of the superposition of... 

Figure 11.15 Schematic representation of mesophase types. (From Ref. 47.) Reprinted with permission from Wissbrun, K. F., Rheology of Rod-Like Polymers in the Liquid Crystalline State, J. Rheol., 25, 619-662, 1981.

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