The Mesoscopic Theory of Polymer DynamicsOur brutal century of atom bombs and spaceships can also be called the century ofpolymers. In any case, the broad spreading ofsynthetic polymer materials is one of thesigns of our time. A look at the various aspects of our life is enough to convince us that polymeric materials (textiles, pl- tics, rubbers) are as widely spread and important in our life as are other materials (metals and non-metals) derived from small molecules. Polymers have entered the life of the twentieth century as irreplaceable construction materials. Polymers differ from other substances by the size of their molecules which, appropriately enough, are referred to as macromolecules, since they consist of thousands or tens of thousands of atoms (molecular weight up to -4 6 10 ormore) andhave a macroscopic rectilinear length (upto 10 cm). The atoms ofa macromolecule are firmly held together by valence bonds, fo- ing a single entity. In polymeric substances, the weaker van der Waals forces have an effect on the components of the macromolecules which form the system. The structure of polymeric systems is more complicated than that oflow-molecular solids or liquids, but there are some common features: the atoms within a given macromolecule are ordered, but the centres ofmass of the individual macromolecules and parts of them are distributed randomly. Remarkably, the mechanical response of polymeric systems combines the elasticity of a solid with the fluidity of a liquid. |
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anisotropy approximation behaviour Birefringence Brownian particles calculated characteristic quantities characteristic viscosity co-ordinates components concentrated Solutions consider constitutive equations constitutive relation deformation dependence determined dilute solution dimensionless dumbbell dynamic modulus dynamic viscosity dynamo-optical coefficient elastic elongational entangled system equilibrium estimate expression Flory formula frequencies friction coefficient glassy hydrodynamic interaction internal variables internal viscosity intramolecular Kuhn segments length linear macromole macromolecular coil matrix mean orientation memory functions mesoscopic mode molecular weight molecules moments motion neutron scattering non-linear number density parameters permittivity tensor phenomenological Pokrovskii polymer polymer Solutions polymer system polystyrene Pyshnograi refractive index relative permittivity relaxation branches relaxation processes reptation second-order Section segments set of relaxation shear modulus shear viscosity single macromolecule ſº solvent stress tensor subchain taking into account temperature theory tion uvik values velocity gradients viscoelastic liquid viscous liquid weakly-coupled