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Introduction. Polymer nanocomposites are of scientific and commercial interest because of their potential for enhanced properties compared to neat polymer. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] For example, improvements in mechanical properties are expected when highaspect-ratio nanofillers are well-dispersed or exfoliated in polymer; 7,8 prototypical nanofillers include layered silicates (clay) 9-14 and carbon nanotubes. 15-18 A carbon-based material of intense, recent focus in nanotechnology is graphite. 19 Despite its natural abundance and use since the Middle Ages, 19 graphite and its derivatives have only recently emerged as a nanomaterial of choice, as exceptional mechanical and electrical properties are observed when the sp 2 -hybridized carbon layers termed "graphene sheets" are isolated or in "paper" form. 20-23 Chemically similar to carbon nanotubes and structurally analogous to layered silicates, graphite has the potential to be an outstanding nanofiller in the form of individual graphene layers or nanoscale layered stacks.Despite potential advantages, there are relatively few reports of graphite-based polymer nanocomposites. 23-37 This is because effective dispersion or exfoliation of graphite is practically impossible with melt processing. Most polymer-graphite hybrids are made from chemically or thermally pretreated graphite, e.g., graphite oxide, expanded graphite, or thermally exfoliated graphite oxide. 23-36 Even with pretreatment, nanocomposite production by conventional processing is challenging due to thermodynamic and/or kinetic limitations, sometimes leading to limited property enhancement.Here we employ solid-state shear pulverization (SSSP) to produce polymer-graphite nanocomposites that are not subject to the thermodynamic/kinetic limitations associated with conventional processes. With SSSP, a modified twin-screw extruder applies shear and compressive forces to solid-state materials; this process has previously yielded blend compatibilization and nanoscale dispersion in polymer blends and organoclay-based nanocomposites. [38][39][40][41][42][43][44] We now demonstrate that the continuous, scalable SSSP process can result in well-dispersed unmodified, as-receiVed graphite in polypropylene (PP), leading to a 100% increase in Young's modulus and a ∼60% increase in yield strength in comparison with neat PP. Experimental Section. Polypropylene (Total Petrochemicals, MFI ) 1.8 g/10 min at 230°C) and unmodified, as-received graphite (ARG) (Asbury Carbons) were used without pretreatment. Polypropylene pellets and graphite particles (3.0 wt %) were manually blended prior to being fed to a Berstorff ZE-25P pulverizer, in which they were copulverized to yield a powder output. References 38-44 provide details on the SSSP process and equipment; parameters (screw design, barrel size, feed rate, etc.) were chosen to yield moderately harsh shear/ compression conditions. For comparison, composite material with similar filler content was fabricated via single-screw melt extrusion...

Liquid core and wall film flow rates have been measured in a pilot plant scale Venturi scrubber of Pease-Anthony design for liquld-to-gas flow ratios varying between 3 and 14 U.S. gal of H20/1000 SCF of air. The gas throat velocities were 150, 200, and 250 ft/s. The initial momentum of the injected scrubbing liquid has been found to be an important parameter in defining the maldistributions of liquid throat coverage. Experimental results have been compared to predictions from a two-dimensional model accounting for initial liquid momenta and turbulent diffusion.

An annular flow pressure drop model has been developed and compared with experimental data obtained on a pilot-plant-size Pease-Anthony-type venturi scrubber. Droplet and film accelerations as well as wall friction, based on the two-phase Lockhart-Martinelli correlation, are considered. Excellent agreement with experimental data is demonstrated for a wide range of throat gas velocities, liquid to gas ratios, and film flow rates for a single scrubber geometry. Venturi scrubbers have been recognized widely for their high particulate matter collection efficiencies. Fine-particle collection generally requires elevated pressure drops. The primary objective of this study was to develop a realistic mathematical model for prediction of pressure drop in a PeaseAnthony venturi scrubber.Flow losses are predicted by accounting for frictional effects and acceleration of liquid drops and the liquid films flowing on the walls. Recovery in the diffuser is also considered. Model validation involved measurement of pressure gradients, film flow rates, liquid to gas ratios, and throat gas velocities for a pilot-plant-scale venturi. A comparison is made among three widely used correlations using experimental data taken from the pilot-plant-scale venturi scrubber. CONCLUSIONS AND SIGNIFICANCEAn annular flow model is developed for accurate prediction of pressure drops in Pease-Anthony venturi scrubbers. This model-which considers the primary design parameters of liquid to gas ratio, throat gas velocity, venturi geometry, and liquid film flow rate-accurately predicted the measured pressure gradients and overall energy losses.The Hesketh (1974) correlation underestimated pressure drops at all liquid to gas ratios and throat gas velocities tested. The Calvert modified model (Yung et al., 1977a) predicted overall pressure drops lower than those experimentally measured for liquid to gas ratios below 8.0 X lod4 m3 liquid/m3 air, and greater magnitudes for liquid to gas ratios exceeding 1.3 xThe region of good agreement was achieved in spite of the neglect of wall friction, converging section losses, and diffuser pressure recovery when these effects compensated each other.Boll 's model (1973) consistently overpredicted the experimental pressure drops. The deviation increased with increasing liquid to gas ratios. Since film flow was not considered, the droplet acceleration component was always overestimated. The frictional losses, which were predicted using a homogeneous model (Wallis, 1969), were overestimated.

The maximum centreline penetrations, l**, of cross‐current liquid jets in a Venturi scrubber were measured for orifice diameters, d, of 1.397, 2.108, 2.565 and 3.860 mm. The data are correlated by for the range of conditions, 36 ≤ gas throat velocity Vg ≤ 125 m/s; 1.2 ≤ liquid injection velocity Vj ≤ 18 m/s; 0.06 ≤ liquid to gas ratio