Crossed-slot device

If the duration and intensity of the elongational stress are sufficiently large, the macromolecule can be stretched to a greater extent. Keller was able to prove this using a cross-slot device producing a planar elongational flow field with the aid of flow diffraction. 

Many devices other than those mentioned above have been designed for measuring extensional viscosities. These include crossed-slot devices, opposed jets, and others described in Keller and Odell (1985) and Macosko (1994). 

In extensional flows at high Deborah numbers, szi > 1, long polymer molecules can fracture (Keller and Odell 1985 Rabin 1987 Kausch 1985). If the strain is large, the breakage usually is near the middle of the molecule, indicating that fracture occurs after the molecule has undergone a coil-stretch transition (Keller and Odell 1985). For polystyrene of molecular weight 20 million in a low-viscosity solvent (dekalin), fracture occurs at extension rates above about 1000 sec In the crossed-slot device, the critical extension rate for... 

The demarcation line between (7) and (8) is not absolute, even in the same flow apparatus. Islam and co-workers studied the effect of inertia [136], as characterized by Re (1), on the scission of polyethylene oxide (PEO) in cross-slot devices. As shown in Fig. 11, in a 50 50 aqueous glycerol mixture 10pure water (910 [Pg.152]

Swartjes et al. [38] used an in-house designed crossslot flow and analyzed their results experimentally using birefringence and X-ray methods (the cross-slot device was equipped with special diamond windows), showing the existence of a highly oriented narrow region of crystalline fiber-like structures on the outflow center line. 

In addition, stagnation point (it is a point at which the net magnitude of velocity is zero, such as at the midpoint of a cylinder or a sphere in cross flow) devices, such as the dough roll mill, cross slot flow, and opposing jet devices can be used in which an area of intense extensional flow is created without the need to sustain a continuous filament. The latter technique is illustrated in Figure 3-27. Clark (1997) obtained extensional viscosity data on syrups and food gums dispersions using creation of... 

If the slots in the anode are not resonating, the tube is no longer a linear magnetron. If many nonresonating slots are cut in the anode block, then the device is a travehng wave tube. This type of traveling wave tube is termed a crossed field amplifier (CFA) or crossed field device (CFD). 

Devices used for flow-induced crystallization (FIC) experiments are aU types of rheometers rotational plate/plate, cone/plate, Couette, sliding plates, capillary rheometers, including the multipass rheometer (MPR) [24-26], and shear devices in-house built [27], Linkam shear cell [28,29], fiber pull-out [30-34], FS, and complex flows and contraction/expansion and cross-slot [35-38]. 

Historically the most common gas disperser for cross-flow plates has been the bubble cap. This device has a built-in seal which prevents liquid drainage at low gas-flow rates. Typical bubble caps are shown in Fig. 14-20. Gas flows up through a center riser, reverses flow under the cap, passes downward through the annulus between riser and cap, and finally passes into the liquid through a series of openings, or slots, in the lower side of the cap. 

The open area for these plates ranges from 15 to 30 percent of the total cross section compared with 5 to 15 percent for sieve plates and 8 to 15 percent for bubble-cap plates. Hole sizes range from 6 to 25 mm (1/4 to 1 in), and slot widths from 6 to 12 mm (14 to V2 in). The Turbogrid and Ripple plates are proprietary devices. 

The magnetic sensor is placed into a slot cut into the core and the current carrying conductor or wire is placed through the hole. The magnetic field from the current is then trapped in the core and crosses the sensor at the slot, yielding an analog Hall output signal proportional to the current. This type of direct current sensor is called an open-loop device. 

The balance is made of an articulated beam, suspended on a torsion wire. A rod is fixed in the middle of a beam and is coming with a window in the upper part. Four magnets are mounted in the middle part of the rod. Each of them is plunging in a solenoid fixed on the mechanical frame. On the same frame, a device of optical detection delivers a light that is fully crossing the slot of the window. The light signal is measured by means of a photodiode. 

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