Orthogonal rheometer

Steady-State Maxwell Orthogonal Rheometer Flow [Warner and Bird (75)J... 

Fig. 10. Schematic diagram of the orthogonal rheometer [Maxwell and Chartoff (55)) both circular disks rotate with the same steady angular velocity Q...

The quantities in Eqs. (21.6) and (21.7) are tj (Q) and tj"(Q) where tj and rf are the quantities defined in 7 for the small amplitude oscillatory experiment. Hence when the limit is taken as T->0, xXJ(—QY) - rj and xyJ(— QY)->t)". The same limiting result was obtained for this flow by Bird and Harris (4) using an integral continuum model. Thus, this gives additional support to the argument that the Maxwell orthogonal rheometer flow provides the possibility of measuring the dynamic properties of fluids. 

As an example of a flow which is neither a shearing flow or an elon-gational flow we consider the Maxwell orthogonal rheometer flow (see Fig. 10). In this flow the velocity profile is = — Q y — Yz), = Qx, and Uj = 0 where T = ajl. Here the diffusion equation is obtain from Eq. (3.9) with the first line of the right side omitted, and Eqs. (3.11) and (3.12) with Q, YQ, and k = Q ... 

Viscous and elastic moduli with small-amphtude sinusoidal shear can be determined by using an orthogonal rheometer [2]. Small-amplitude sinusoidal shear, using cone-and-plate or paraUel-plate test methods, can determine rheological behavior for normal stresses in shear flow, as well as for shear strain. 

Maxwell, B. and Chartoff, R.P. (1965) Studies of polymer melts in an orthogonal rheometer, Trans. Soc. RJieol, 9,41-52. 

Another area of current research deals with combining the earlier work on production of polymer blends in the elastic melt extruder and the observation of the maximm in melt elasticity as a fimction of composition as fo md in the orthogonal rheometer studies on blends. It would be expected that as the melt elasticity increased the forces required for melt orientation would also increase. This has been confirmed in current studies of melt tension in fiber spinning experiments. The important point is that the composition of the blend can be used to control the molecular orientation. 

Studies of a Polymer Melt in an Orthogonal Rheometer," with... 

Gent (1960) first published an ERD experiment using vulcanized rubber. He reports that his inspiration came from Maxwell s rotating cantilever rod experiments. Mooney (1934) also tried the geometry on gum rubbers. Maxwell and Chartoff (1965) carried out the first tests on polymer melts. Maxwell s (1967) experiments caused the geometry to become known as the Maxwell orthogonal rheometer. 

Note that in the literature this geometry js called the Maxwell orthogonal rheometer or eccentric rotating disks, ERD (Macosko and Davis, 1974 Bird, et al., 1987, also see Chapter 5). Usually, the coordinates X2 = > and X3 = z are used. 

FIGURE 16.10 Analysis of the orthogonal rheometer (a) relative displacement vector between point 1 on the center of the lower disk and point 2 immediately above it at ojt = 0 (b) geometry of the displacement vector and its components. 

In the Maxwell orthogonal rheometer (Fig. 18.18), material is sheared between two parallel disks of radius R, separated from one another by a distance h, each rotating at the same steady angular frequency a>, but with their axes of rotation displaced by a distance d. Transducers are set up to measure three steady, orthogonal force components (hence the name) on one of the disks, f, Fy, and Fg. 

NMR applied to polymer structure analysis Maxwell, orthogonal rheometer... 

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