Daniel J. Klingenberg

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The rheological properties of acid hydrolyzed corn stover at high solids concentration (20-35 wt.%) were investigated using torque rheometry. These materials are yield stress fluids whose rheological properties can be well represented by the Bingham model. Yield stresses increase with increasing solids concentration and decrease with increasing hydrolysis(More)
Enzymatic hydrolysis of lignocellulosic biomass in a high shear environment was examined. The conversion of cellulose to glucose in samples mixed in a torque rheometer producing shear flows similar to those found in twin screw extruders was greater than that of unmixed samples. In addition, there is a synergistic effect of mixing and enzymatic hydrolysis;(More)
A microscopic model is employed to relate the dielectric tensor to the microstructure of isotropic amorphous or cubic crystalline materials. Electrostriction is characterized by dielectric parameters that describe how the dielectric tensor varies with deformation and the resulting change in the microstructure. These dielectric parameters are obtained for(More)
A two-fluid continuum model is developed to describe mass transport in electro- and magnetorheological suspensions. The particle flux is related to the field-induced stresses. Solutions of the resulting mass balance show column formation in the absence of flow, and stripe formation when a suspension is subjected simultaneously to an applied electric field(More)
Additives were tested for their ability to modify the rheology of lignocellulosic biomass. Additive types included water-soluble polymers (WSPs), surfactants, and fine particles. WSPs were the most effective rheological modifiers, reducing yield stresses of concentrated biomass by 60–80% for additive concentrations of 1–2 wt. % (based on mass of dry biomass(More)
Effects of nonmagnetic interparticle forces on the on- and off-state behavior of magnetorheological fluids are investigated experimentally and with particle-level simulations. Suspensions of iron particles in an aliphatic oil are modified by surface-active species. The modifications significantly alter the off-state properties, but have little impact on the(More)
An electro-acoustic method for measuring volume charge distributions in dielectric films (50 lm–0.2 mm thick) is described. A high voltage (.1 kV) sinusoidal signal (frequency ; 2 kHz) is applied across the dielectric sample. The charges inside the dielectric material will mechanically respond to the input electric signal and excite acoustic waves. The(More)