Rheological characterization

Step 1 The first conseqnence of an increase of temperature is a decrease in both modnlus and viscosity dne to the rednctionof the plasticizer viscosity. 

Step 3 The increase in modnlus and viscosity is observed until all of the plasticizer and PVC have interacted, reaching a maximum at temperature between 130 and 170°C, which is a temperature at which gelation has been conclnded and thermal expansion and fusion of PVC microcrystalhtes began, provoking a pronounced decrease in modnlns and viscosity. 

The extent of changes and temperatures at which these steps occm is strongly infln-enced by the type and the concentration of plasticizer, as well as by the type of resin and additives in formulatiom The effect of the plasticizer type has been studied by different authors resulting in different behaviors observed for plasticizers of different solvent power. The gelation takes place at lower temperatures for a more compatible plasticizer. Nakajima stated that depending on the plasticizer type and its concentration, some deviations in behavior can be observed. 

Particle size and particle size distribution strongly affect initial viscosity of plastisol but less likely the gelation rate. The viscosity of plastisol between 90 and 160°C is also influenced by these variables. In this range of temperatures, plastisols containing PVC having lower particle sizes develop higher viscosities. The higher the number of fine 

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In shear studies, the most commonly used type of device for the generation of well-defined flow fields is the rotational viscometer. The use of these devices for the rheological characterization of liquids is well established [137]. Compared with the capillary and jet devices (Sects. 5.1 and 5.2), rotational viscometers allow the investigation of the effects of continuous rather than intermittent shearing. 

S. N. Shah, P. C. Harris, and H. C. Tan. Rheological characterization of borate crosslinked fracturing fluids employing a simulated field procedure. In Proceedings Volume. SPE Prod Technol Symp (Hobbs, NM, 11/7-11/8), 1988. 

Manoi, K. and Rizvi, S. S. H. (2008). Rheological characterizations of texturized whey protein concentrate-based powders produced by reactive supercritical fluid extrusion. Food Res. Int. 41, 786-796. 

D Peressini, A Sensidoni, B de Cindio. Rheological Characterization of Traditional and light mayonnaises. J Food Eng 35(4) 409-417, 1998. 

Shah, S.N. Harris, P.C. Tan, H.C. "Rheological Characterization of Borate Crosslinked Fracturing Fluids Employing A Simulated Field Procedure" SPE Paper 18589, 1988 SPE Production Technology Symposium, Hobbs, N.M. 

Prud homme, R.K. "Rheological Characterization of Fracturing Fluids," Final Report API PRAC Project 84-45, American Petroleum Institute, Dallas, TX (1985). 

Jiang, T.Q., Young, A.C., and Metzner, A.B. "The Rheological Characterization of HPG Gels Measurement of Slip Velocities in Capillary Tubes," Rheol Acta 25 397-404 (1986). 

Guillot, D Dunand, A. "Rheological Characterization of Fracturing Fluids Using Laser Anemometry" SPE paper 12030, 1983 58th Annual Technical Conference and Exhibition, San Francisco, October 5-8. 

Alvarez, M. D., Canet, W. (1998h). Rheological characterization of fresh and cooked potato tissues (cv. Monalisa). Z. Lebensm. Unters. Forsch. A., 207, 55-65. 

Further factors influencing rheological characterization of filled polymers include changes in the degree of filler dispersion or inter-particle structure forma-... 

The field gradient spin echo methods appear now to have amply proven their validity and usefulness in the study of polymer systems. This early work has been understandably academic in flavor, but there seems to be no impediment to the use of FGSE measurements for routine rheological characterization, e.g., to... 

Kampf, N. and Nussinovitch, A. 1997. Rheological characterization of carrageenan soy milk gels. Food Hydrocoil. 11 261 -269. 

T.Q. Jiang, A.C. Young and A.B. Metzner, The Rheological Characterization of HPG gels Measurement of slip velocities in capillary tubes, Rheol. Acta, 25 397 (1986). 

Seong DG, Kang TJ, Youn JR (2005) Rheological characterization of polymer-based nanocomposites with different nanoscale dispersions. e-Polymers 5... 

Abdel-Goad M, Potschke P (2005) Rheological characterization of melt processed polycarbonate-multiwalled carbon nanotube composites. J Non-Newtonian Fluid Mech 128 2-6... 

Finally, at higher particulate loadings, above 50% vol, the rheological behavior of filled melts is dominated by particle-to-particle interactions, due to both interparticle forces and physical flow-caused movement hindrances of the suspended particulates, particularly during pressure flows. One consequence of this is the creation of a particulate-free wall film that creates a lubricity slip layer and pluglike flows. Such slip velocities have to be considered in flow rate versus pressure drop design expressions, as well as the viscometric rheological characterization (91). 

Chen, X., Knight, D.P., and Vollrath, F. "Rheological characterization of Nephila spidroin solution". Biomacromolecules 3(4), 644—648 (2002b). 

Wayne, J.E., Shoemaker, C.F. 1988. Rheological characterization of commercially processed fluid milks. J. Texture Stud. 19, 143-152. 

Rheological characterization of an organoleptic property (unctuousness). J. Text. Stud. 

The fundamental rheological characterization of a material requires the experimental determination of a constitutive equation (a rheological equation of state) that mathematically relates stress and strain, or stress and strain rate. The constants in the constitutive equation are the rheological properties of the material. 

Since one of the main reasons to incorporate bubbles into foods is to impart particular textural characteristics, the rheological characterization of the dispersion is absolutely critical to the nature of the dispersion formed as well as to the product... 

The purpose of this paper is to present a technique whereby manufacturing process dynamics for structural polymers can be accurately defined through efficient laboratory rheological characterization. Structural polymers, in this paper, refer principally to the thermosetting epoxides, phenolics and polyimides. This type of test pattern, however, is generally applicable to the production and utilization of most polymers. The engineering applications associated with these polymers involves primary and secondary aerospace articles. In this situation, failure to meet performance criteria could result in catastrophic loss of the vehicle and associated cargo. 

A complete rheological characterization of a material is very time consuming and expensive and much of the data will be irrelevant to any particular process or problem. 

Measurement of the linear viscoelastic properties is the basic rheological characterization of polymer melts. These properties may he evaluated in the time domain (mainly creep and relaxation experiments) or in the frequency domain in this case we will talk about mechanical spectroscopy, where the sample experiences a harmonic stimulus (either stress or strain). 

One may use the linear viscoelastic data as a pure rheological characterization, and relate the viscoelastic parameters to some processing or final properties of the material inder study. Furthermore, linear viscoelasticity and nonlinear viscoelasticity are not different fields that would be disconnected in most cases, a linear viscoelastic function (relaxation fimction, memory function or distribution of relaxation times) is used as the kernel of non linear constitutive equations, either of the differential or integral form. That means that if we could define a general nonlinear constitutive equation that would work for all flexible chains, the knowledge of a single linear viscoelastic function would lead to all rheological properties. 

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