Effect of the reference chain dimensions in the molecular theory of viscoelastic behavior of polymer networks

Abstract

synopsisMooney's version of the molecular theory of polymer networks has been generalized to the case when the external strain applied in the isotropic state is different from that at network formation. As in the theory of equilibrium behavior of the polymer networks, this generalization allows inclusion in the viscoelastic functions of effects connected with the temperature dependence of internal energy of the chains and with the strain effect of the solvent. From viscoelastic functions thus generalized, it is possible to derive a relation for calculation of the monomeric friction coefficient. It also suggests the possibility of superposing data obtained at various temperatures, degrees of swelling, and condition of network formation.

Collapse of polyelectrolyte networks induced by their interaction with oppositely charged surfactants

“…It can be seen that the increase of the degree of cross-linking results in smoother gel collapse. Comparison of curves 1, 4, and 5 shows that the increase of the concentration of monomers at the preparation conditions which results in appearance of additional topological entanglements (refs 17 and 18) also leads to smoothening of the collapse. Thus, both the increase of the content of chemical cross-links and of topological entanglement affect the collapse in the same manner.…”

Linear thermoviscoelasticity and characterization of noncrystalline EPDM rubber networks

“…These calculated curves are given in Figure 10, together with the theoretical prediction for crosslinked networks with an energy elastic component such as EPDM. 27 In addition, G'(0,435) is tabulated in column 3 of Table 11. Strangely enough, the variation of G'(0,T) with temperature is very much dependent on the cure level.…”

The thermorheological complexity of photoelastic behaviour of 2-hydroxyethyl methacrylate — dodecyl methacrylate copolymers

“…The optical relaxation function (strain-optical function) B(t) = An(t)/e = 6 (t) to/2z d (20 = 546.1 nm is the wavelength of light, d is the sample thickness) was determined from the time dependence of optical retardation 6(t); the stress-optical function C(t) = B(t)/E(t) was also calculated. From the molecular theory of photoelastic behaviour [13,14] which allows for the fact that conditions of (2) the logarithms of their absolute values are plotted in Figure 2.…”

“…The superimposed curves of mechanical and optical functions Ep(t), Bp(t) and Cp(t) to To (= 230 k for PDMA and 329 K for PHEMA) were constructed using corresponding curves measured at experimental temperatures T by applying the time-temperature superposition according to relations [13,14] …”

“…Modification of Rouse's molecular theory for polymer networks involving the effect of the reference state of network [13] has led to a conclusion that the configurational rearrangement of an elastically active network chain (EANC) by applying an external force gives the relaxation spectrum H in the form H(r) --= (2~c) -1 v,a <a~d> 312 (P Co ~ kT/6) v2 r-1/2 = Ho ~-l/2 (4) where P is the degree of polymerization of EANC, via is the number of chains in the dry isotropic state, Co is the monomeric frictional coefficient, k is the Boltzmann constant, <ce~a> = ~ia/~ is the dialation factor (#a being the mean square end-to-end EANC distance in the isotropic state), and v is the relaxation time. If the network volume is independent of deformation, we have from the phenomenological theory of linear viscoelastic behaviour [2] and from Equation (4) …”