Concentration viscoelastic behavior affected

Although taking place over a somewhat wider range of c[ij], this transition parallels the variation of JeR from Zimm-like to Rouse-like behavior at low concentrations (15). It also supports the contention (Section 5) that coil overlap is the principal structural variable affecting viscoelastic behavior at low to moderate concentrations. 

Absorption of a solute liquid or vapor into a polymer film can profoundly affect the viscoelastic behavior of the polymer. The magnitude of this effect depends on the nature of the solute/polymer interactions and on the amount of solute absorbed. The solute/polymer interactions can range fttun simple dispersion to hydrogen-bonding and other specific interactions. The extent of absorption can be described by the partition coefficient, AT, which quantifies the thermcxlynamic distribution of the solute between two phases (K = coiKentration in polymer divided by die concentration in the liquid or vapor phase in contact with the polymer). It has long been known that acoustic wave devices can be used to probe solubility and partition coefficients (53,67). Due to the relevance of these topics to chemical sensors, more comprehensive discussions of these interaction mechanisms and the significance of the partition coefficient are included in Chapter 5. 

This section presents the factors that affect polymer viscoelastic behavior. These factors include polymer concentration, salinity, surfactant, and temperature. The viscoelastic behavior in a typical Daqing solution is also presented. 

The change of viscoelastic behavior of ciosslinked elastomers on swelling depends on polymer physical network. This, in turn, depends on the concentration and nature of the plasticizer in the material expressed by parameter m describing the ability of liquid to affect physical network of elastomer. 

The mechanism of preferentially blocking high-permeability channels is controversial (Seright, 2006 Chang et al., 2006). The research work done so far has been focused more on formulation selection, improvement of properties, and determination of factors that affect gel performance, but less on flow behavior (Ma et al., 2005). The viscoelasticity of a low concentration HPAM/ AlCit crosslinked system was mathematically described by Sun et al. (2005). 

For these transient networks formed by the interaction of an ABA triblock copolymer and a microemulsion it has been shown that their principal viscoelastic properties are not affected significantly by the chemical nature of the microemulsion, i.e., they are similar for systems with both nonionic and ionic surfactants. Also it should be noted that the phase behavior of the corresponding microemulsion is qualitatively preserved, i.e., the reversible aggregation of the nanodroplets and the phase transitions to lyotropic liquid crystalline phases remain essentially unchanged (although the concentrations at which they occur might... 

---