TY - GEN
T1 - Adjustable gap rheometry for the rheological characterization of energetic formulations
AU - Kalyon, Dilhan
AU - Gevgilili, Halil
AU - Kowalczyk, James E.
AU - Prickett, Suzanne
AU - Murphy, Constance
PY - 2006
Y1 - 2006
N2 - It is difficult to characterize the rheological behavior of energetic suspensions due to their viscoplasticity and wall slip. The use of the rectangular slit geometry, as an on-line or off-line rheometer is advantageous provided that the surface to volume ratio of the slit die can be systematically varied to allow the wall slip corrections to be made. Here two rectangular slit rheometers designed and built to handle the rheological behavior of energetic suspensions are presented. The gap of these rheometers is variable to give the user the ability to vary the gap and the flow rate independently and hence obtain the wall shear stress as a function of the surface to volume ratio of the rheometer, thus enabling wall slip corrections to be made and the slip velocity behavior and the shear viscosity versus the deformation rate material function to be characterized. The slit rheometers rely on a series of pressure transducers, installed flush with the wall, which are used to determine the pressure drop over the fully-developed flow region and hence the wall shear stress directly from the fully developed pressure gradient. The ability to independently vary the mass flow rate and the gap opening allows one to carry-out the wall slip corrections and hence obtain the wall slip velocity versus the shear stress data, which can then be used as the boundary condition during the simulation of the die and extrusion flows and at the same time allow the determination of accurate shear viscosity data. A set of data systematically collected with an on-line slit rheometer with a continuously adjustable gap to characterize the wall slip velocity as well as the shear viscosity material function of a LOVA formulation as a function of deformation rate, solvent concentration and temperature is used to illustrate the working principles of the on-line and off-line adjustable-gap rheometers.
AB - It is difficult to characterize the rheological behavior of energetic suspensions due to their viscoplasticity and wall slip. The use of the rectangular slit geometry, as an on-line or off-line rheometer is advantageous provided that the surface to volume ratio of the slit die can be systematically varied to allow the wall slip corrections to be made. Here two rectangular slit rheometers designed and built to handle the rheological behavior of energetic suspensions are presented. The gap of these rheometers is variable to give the user the ability to vary the gap and the flow rate independently and hence obtain the wall shear stress as a function of the surface to volume ratio of the rheometer, thus enabling wall slip corrections to be made and the slip velocity behavior and the shear viscosity versus the deformation rate material function to be characterized. The slit rheometers rely on a series of pressure transducers, installed flush with the wall, which are used to determine the pressure drop over the fully-developed flow region and hence the wall shear stress directly from the fully developed pressure gradient. The ability to independently vary the mass flow rate and the gap opening allows one to carry-out the wall slip corrections and hence obtain the wall slip velocity versus the shear stress data, which can then be used as the boundary condition during the simulation of the die and extrusion flows and at the same time allow the determination of accurate shear viscosity data. A set of data systematically collected with an on-line slit rheometer with a continuously adjustable gap to characterize the wall slip velocity as well as the shear viscosity material function of a LOVA formulation as a function of deformation rate, solvent concentration and temperature is used to illustrate the working principles of the on-line and off-line adjustable-gap rheometers.
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M3 - Conference contribution
AN - SCOPUS:80053824851
SN - 081691012X
SN - 9780816910120
T3 - AIChE Annual Meeting, Conference Proceedings
BT - 2006 AIChE Annual Meeting
T2 - 2006 AIChE Annual Meeting
Y2 - 12 November 2006 through 17 November 2006
ER -