Polymer chain size

Flory exponent for the polymer chain size Flory radius... 

We assume here that the concentrations of monomer and initiator remain essentially constant during polymerization and that any dependence of termination rate constants on polymer chain size and concentration or autoacceleration effects can be neglected. Molecular weight distributions derived under these conditions will not obviously apply to commercial polymers, whose polymerizations are often finished at high conversions. These high-conversion polymers may have distributions that differ from those calculated here. A later section discusses the size distributions of such polymers. 

The properties of polymers are dependent on many factors including inter-and intrachain bonding, the nature of the backbone, processing events, presence/absence of additives including other polymers, chain size and geometry, and molecular weight distribution. 

An alternative approach has been shown by Mu and Winey (131), who observed that, while the molecular weight of the polymer matrix has no significant effect on the degree of SWNT dispersion or alignment in the composite, it plays an important role in the load transfer at the SWNT-polymer interface. Therefore, even without functional groups attached to the nanotube, when the polymer chain size is large compared to the nanotube diameter the elastic modulus of the composite greatly increases. 

Fig. 17.1. Diagrammatic representation of the close approach of two flat plates in a polymer solution (a) corresponds to a distance of separation greater than the size of the polymer chains whereas (b) corresponds to a plate separation less than the polymer chain size (Feigin and Napper, 1980a).

Yosida and Cohen (2004) suggested that the separation performance of PVAc-silica membrane can be increased by reducing the water flux via denser surface chain coverage and by increasing the grafted polymer chain size relative to the native membrane pore size. 

The effect of sodium hydroxide on the low-shear viscosity can be explained as follows HPAM undergoes further hydrolysis in the presence of strong alkalis (base hydrolysis). As the polymer is hydrolyzed, the number of the carboxylate groups (i.e., the number of negative charges) on the polymer chain increases. Consequently, the electrostatic repulsion increases, and the chain size increases. This increase in the polymer chain size enhances the viscosity of the polymer solution in deionized... 

Another measure of polymer chain size is the end-to-end length, the length of the vector pointing through space from one end of the chain to the other, when the chain is in a given conformation (see Figure 32.1(b)). The end-to-end length varies from one chain conformation to the next. The end-to-end vector r is the vector sum over the bonds Sj for bonds i = 1,2,3,...,N ... 

The molecular weiyftt of the polymer. Polymers with higher molecular weight exhibited lower degradation rates because the molecular weight has a direct relation with the polymer chain size [85] ... 

It is well-known that the Flory mean-field theory of the polymer self-excluded volume problem yields excellent results. If R is some scalar measure of the polymer chain size, such as the radius of gyration, and N is the number of monomer units in the chain, then R scales with N as... 

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