Rheology research needs

Rheology is increasingly being coupled to other analytical test methods for more comprehensive material characterizations. Many of these developments are driven by research needs for broadened characterization capability. For fundamental studies of detergent systems this offers a broad suite of methods to probe surfactant mesophases and internal microstructure. 

High-solids research needs to be focused on two fronts. One is synthetic, where the distribution of species from random copolymerization cannot be tolerated in oligomers. The other is rheological. Concentrated solution rheology needs to be elucidated as well as it has for dispersions and for conventional solution coatings. For papers in this area, the works of Ericksen (86). Schoff (87). and Lamb (88) are recommended. 

Molecularly motivated empiricisms, such as the solubility parameter concept, have been valuable in dealing with mixtures of weakly interacting small molecules where surface forces are small. However, they are completely inadequate for mixtures that involve macromolecules, associating entities like surfactants, and rod-like or plate-like species that can form ordered phases. New theories and models are needed to describe and understand these systems. This is an active research area where advances could lead to better understanding of the dynamics of polymers and colloids in solution, the rheological and mechanical properties of these solutions, and, more generally, the fluid mechaiucs of non-Newtonian liquids. 

This review has shown that most studies on barley starches have been focused on understanding the fine structures, particle size distribution, chemical composition, gelatinization properties and susceptibility towards enzyme hydrolysis. However, there is a dearth of information on the rheological and retrogradation characteristics of barley starches from different cultivars. Furthermore, the response of small and large barley starch granules towards physical and chemical modification needs investigation. Research in the above areas is underway in our laboratories. It is hoped that this study may improve the utilization of different types of barley starches for specific products within the food and paper industry. 

We review the research on preparation, morphology, especially physical properties and applications of polyurethane (PU)/carbon nanotube (CNT) nanocomposites. First, we provide a brief introduction about the preparation of PU/CNT nanocomposites. Then, the functionalization and the dispersion morphology of CNTs as well as the structures of the nanocomposites are also introduced. After that, we discuss in detail the effects of carbon nanotubes on the physical properties (including mechanical, thermal, electrical, rheological and other properties) of PU/CNT nanocomposites. The potential applications of these nanocomposites are also addressed. Finally, the challenges and the research that needs to be done in the future for achieving high-performance polyurethane/carbon nanotube nanocomposites are prospected. 

The realisation of very high solids contents in commercial latexes through inventive control of particle size distribution has created a need for both theoretical and experimental research into the rheological behaviour of polymer colloids at high particle volume fractions. 

Research scientists and engineers involved in successful development and manufacture of commercial products have different rheology needs. Advanced technology emphasis may be on fundamental studies of interactions of product... 

From R D to quality control, rheology measurements for each phase of the product development life cycle involve raw materials, premixes, solutions, dispersions, emulsions, and full formulations. Well-equipped laboratories with stress- and strain-controlled oscillatory/steady shear rheometers and viscometers can generally satisfy most characterization needs. When necessary, customized systems are designed to simulate specific user or process conditions. Rheology measurements are also coupled with optic, thermal, dielectric, and other analytical methods to further probe the internal microstucture of surfactant systems. New commercial and research developments are briefly discussed in the following sections. 

Rheology (the study of deformation and flow of materials) provides the fundamental understanding needed to develop technologies for processing macromolecular materials to fabricate coatings, films, molded objects, and fibers. Research efforts strive to correlate macromolecular structure with viscosity (melt and solution) and modulus (stiffness) as a function of frequency and temperature. Polymer physics and molecular modeling of macromolecular structure and diffusion are fundamental to advances in this field. 

Here At is the time interval after the area expansion. An interpretation using the relaxation model given by Eqs. (4.115) to (4.118) is impossible as serum is a mixture of quite a number of surface active compounds of unknown concentrations. After admission to the hospital the elasticity is very low and even decreases a bit in the beginning of the therapy, while x is maximum. After haemodialysis the elasticity goes through a maximum and levels off then at values close to the normal determined as standard for persons of this age and sex. The relaxation time decreases to less than half of the initial value. The results allow to conclude that rheological studies provide an interesting tool for medical practice and research, in particular due to the fact that very small quantities of a sample are needed. 

Though perfect monodisperse dendrimers have very interesting material properties, for use as engineering materials they are far too complicated and costly to produce. This was soon realized by several researchers at DuPont Experimental Station working on dendritic polymers as rheology control agents and as spherical multifunctional initiators. The need to obtain the material rapidly and in large quantities forced them to develop a route for a one-step synthesis of dendritic polymers. These polymers... 

The results allow one to conclude that rheological studies provide an interesting tool for medical practice and research, in particular due to the fact that very small quantities of a sample are needed. 

It is hoped that this book will provide all the necessary background needed to understand the various aspects relating to the rheology of filled pol)rmer systems so that even new entrants to this exciting field may benefit from the information. For those who have already whetted their appetite with a taste for this research area, it is hoped that this book v l provide complete details imder one cover and entice them to probe into vacant areas of research that may become obvious to them on reading this book. 

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