Entanglement Molecular Weight

In some literature, entanglement molecular weight A is discussed as a material property that characterizes magnitudes of entanglement for polymeric liquids. However, M, was introduced as a model parameter for theories that explain the plateau modulus, and the value is model dependent. A value of A may induce misleading analysis if it is presented without noting the underlying theoretical model. Meanwhile, attempts in molecular simulations allow us to extract A from a snapshot of entwining molecules via the topological analysis. However, the relation has not been fully clarified yet between the extracted network and the entangled polymer dynamics; the latter is the retarded molecular motion observed for dense polymeric liquids with high molecular weight. Analysis of the reduction of entanglement density under deformations is also a matter of discussion since some molecular theories can reproduce non-linear rheology with stable entanglement density.