Viscoelastic behavior factors that affect

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). 

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 authors also describe the effect of temperature on the Payne effect. With increasing temperature the amplitude of the Payne effect decreases significantly (Fig. 12). Very surprisingly, enhanced Payne-like behavior was observed for rubber vulcanizates at room temperature where filler-filler and filler-polymer interaction are not observed in comparison to the typically filled vulcanizates. The authors concluded that in addition to the contribution from the filler-filler network, there are many other factors that affect the nonlinear viscoelastic behavior. Nevertheless, the Payne effect is assumed to arise from the elementary mechanism consisting of adsorption-desorption of polymer chains from the surface of the particles [50]. Besides the experimental investigation, the authors have applied the Maier... 

In an earlier section, we have shown that the viscoelastic behavior of homogeneous block copolymers can be treated by the modified Rouse-Bueche-Zimm model. In addition, the Time-Temperature Superposition Principle has also been found to be valid for these systems. However, if the block copolymer shows microphase separation, these conclusions no longer apply. The basic tenet of the Time-Temperature Superposition Principle is valid only if all of the relaxation mechanisms are affected by temperature in the same manner. Materials obeying this Principle are said to be thermorheologically simple. In other words, relaxation times at one temperature are related to the corresponding relaxation times at a reference temperature by a constant ratio (the shift factor). For... 

We have approached the subject in such a way that the book will meet the requirements of the beginner in the study of viscoelastic properties of polymers as well as those of the experienced worker in other type of materials. With this in mind. Chapters 1 and 2 are introductory and discuss aspects related to chemical diversity, topology, molecular heterodispersity, and states of aggregation of polymers (glassy, crystalline, and rubbery states) to familiarize those who are not acquainted with polymers with molecular parameters that condition the marked viscoelastic behavior of these materials. Chapters 1 and 2 also discuss melting processes and glass transition, and factors affecting them. 

Researchers have examined the creep and creep recovery of textile fibers extensively (13-21). For example, Hunt and Darlington (16, 17) studied the effects of temperature, humidity, and previous thermal history on the creep properties of Nylon 6,6. They were able to explain the shift in creep curves with changes in temperature and humidity. Lead-erman (19) studied the time dependence of creep at different temperatures and humidities. Shifts in creep curves due to changes in temperature and humidity were explained with simple equations and convenient shift factors. Morton and Hearle (21) also examined the dependence of fiber creep on temperature and humidity. Meredith (20) studied many mechanical properties, including creep of several generic fiber types. Phenomenological theory of linear viscoelasticity of semicrystalline polymers has been tested with creep measurements performed on textile fibers (18). From these works one can readily appreciate that creep behavior is affected by many factors on both practical and theoretical levels. 

The process characteristic of the Sulzer SMX-L mixer is for the 5% CMC solution identical to that for the Kenics mixer for L/D> 30, see expression (8.19). The value for glycerine lies about 20% above that for PAA. The viscoelastic viscosity behavior affected heat transfer negatively. The pressure drop characteristic Cf Re — const (for Re < 1 X lO ) has been confirmed for SMX-L, the constant being about a factor of 10 higher than for an empty pipe. 

Molecular weight distribution (MWD) is an important factor affecting the rheological behavior of a polymer solution. The effects of MWD on polymer blend and melt were studied previously by many groups. Struglinski el al [1] analyzed the linear viscoelastic properties of the binary polydispersed entangled polymers. They concluded that the behavior of the binary mixture depends both on the relaxation time and weight fraction of the individual component. The zero shear viscosity pA of the mixture is dominated by the... 

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