Chain entanglements rheological properties

Unique architecturally driven properties that may be expected from hyperbranched polymers will be largely derived from their (a) amplified number of terminal functional groups, (b) new rheological properties based on less chain entanglement and (c) new architectural arrangements that may modulate crystallinity, flow characteristics and glass transition properties in designed systems. 

In a celebrated series of papers, Doi and Edwards [80] used the reptation, or tube model, to develop a theory for the rheological properties of entangled chains. In this model, the dynamics of a chain is described by the tube of entanglements. The configuration of the... 

Very large micelles may also form in binary surfactant systems. These are long wormlike micelles that become entangled at higher concentrations, giving rise to rheological properties similar to those in polymer solutions. Such systems have been examined by H band shape analysis [52,53]. The protons of the surfactant hydrocarbon chain form a very large dipolar coupled spin system with an essentially continuous distribution of transverse relaxation rates. The distribution of relaxation rates is related to the distribution of order... 

Figure 5.132 illustrates that mesophases can also be identified by rheological properties. The crystals of PTFE show a highly anisotropic flow parallel to the molecular axes, a property often found in smectic liquid crystals. As soon as the molecules start to melt, however, the shear-stress increases abruptly because of the chain-entanglement that occurs during melting. On a microscopic basis, PTFE... 

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