Cone-plate viscometry

The principal difference between cone-plate viscometry and rotational viscometry is in the materials that are most suitable for investigation by each method. In contrast to the... 

Cone/Plate Viscometry Co-Axial Cylinder Viscometry Parallel Plate Viscometry Tensile or Extensional Viscometry Dynamic or Oscillatory Rheometry Morphological Analysis... 

The poly(oxyethylene)-poly(oxypropylene)-poly(oxyethylene) block copolymers were also used to gel the continuous aqueous phase. Poloxamers may be used as the secondary hydrophilic surfactant in the preparation of the w/o/w system, and the finished emulsion is then irradiated. The polymerisation reaction can be monitored by cone-and-plate viscometry. Fig. 9 shows the flow curve obtained for a water/isopropyl myristate/water emulsion as a function of the radiation dose. As the dose of y-irradiation is increased, the viscosity of the w/o/w emulsion increased up to a gel-point1. The gel-point of the emulsion is dependent on the type and concentration of poloxamer. In the example shown, prepared using a mixture of 5% (w/v) Pluronic F87 and 5% (w/v) Pluronic F88 in the external phase, the gel-point was reached at 4.2 (Fig. 9). Fig. 10 shows the changes in the properties of irradiated systems on storage. 

The cure of a thermosetting adhesive is usually measured by techniques such as cone and plate viscometry, or by a vibrating needle system. From these measurements, important characteristics such as the gelation point and the point of the final cure can be determined. The time from mixing of an adhesive to the gelation point gives the useful... 

Petera, J. and Nassehi, V., 1995. Use of the finite element modelling technique for the improvement of viscometry results obtained by cone-and-plate rheometers. J. Non-Newtonian Fluid Mech. 58, 1-24. 

The decision was taken in favour of a cone-and-plate apparatus, as such a type of apparatus has proven to be very suitable for the viscometry of polymer melts. Afterwards, as a consequence of the experiences gathered with this apparatus, it is felt that also a concentric cylinder apparatus would be useful, viz. for the investigation of the flow birefringence in... 

A study, relevant to recirculation behaviour in a RRIM machine, of polyol and polyol slurry rheology at shear rates in the range 0-103 s 1. This study is based on viscometry with modified cone and plate geometry. 

But though rotational viscometry seems simple in principle, in practice it turns out there are so many sources of error to consider and corrections to be made that an operating rotational viscometer of good accuracy is a rather complicated apparatus. Many commercial instruments, operating either on the continuous rotation principle or the oscillating principle, are described in the monograph by Van Wazer et al. [2]. To illustrate the application of the principles of rotational viscometry to operating instruments, we shall examine the details of two instruments the first practical rotational viscometer, devised by Couette [9], and the Per ranti-Shirley cone-and-plate viscometer. 

Viscometry is the science of the measurement of viscosity. Such viscometric measurements generally have to do with appl3ong either a force F or a velocity V at a surface in contact with a contained test liquid. The response of this liquid to either the velocity or the force is measured at that surface or at some other nearby surface which is also in contact with the liquid. Examples of the geometries used for this purpose include tubes, parallel plates, cone-and-plate arrangements, and concentric cylinders. Sometimes artefacts arise whereby the presence of these surfaces interferes with the local liquid microstructure, giving apparent slip effects—these win be discussed in detail later. 

Expressions for other specimen geometries and higher damping are reviewed by Nielson [9]. Solid or rubbery samples are twisted as illustrated in the form of rods, tubes, strips, etc. Liquids or soft solids may be contained in one of the geometries described for rotational viscometry earher (Couette, cone-and-plate, etc.). 

Figure 14.10 shows capillary viscometry data at 150°C for the lUPAC A LDPE considered earlier in Figure 14.7. It is apparent that these data blend nicely with the data generated using a cone-and-plate viscometer. At shear rates greater than about 1 sec , the viscosity-versus-shear rate behavior is linear. Consequently, one can say that the shear stress x (where subscripts have been dropped for convenience) is given by...

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