There is a growing interest of extrusion drug and polymer together to manufacture various solid dosages. In those cases, the drug's release profiles are greatly affected by the miscibility of two materials. The goal of this study is to test the drug's solubility in molten polymer and obtain the mixture's rheological properties for the purpose of optimizing the extrusion process. The dynamic and steady viscosities of APAP-PEO mixture were determined using oscillatory and capillary rheometers. The curves of viscosity vs. drug loading generally have a "V" shape, and the minimal point gives the APAP's solubility in PEO. The test results suggest that different dynamic methods lead to essentially the same solubility data. At high shear rates, the mixtures show shear thinning behavior and the viscosity becomes less sensitive to the drug loading. In other words, it is desirable to use a low shear rate in order to deduce the drug's solubility in polymer from the viscosity data. On the other hand, viscosity data at high shear rates are more representative of the materials' rheological properties during extrusion. (C) 2011 Elsevier B.V. All rights reserved.

When it is desirable that a product contain the maximum volume percentage of selected solids within a fluid matrix, which in turn gels or solidifies, it may be desirable to consider an infusion process. An infusion process permits achievement of a higher solids loading than can be obtained utilizing a pourable premixed slurry. However, infusing a viscous fluid into a bed of fine powder is a daunting task. The wide size distributions and non-uniform shapes frequently encountered with many powders make the classical equations for fluid flow through packed beds difficult or impossible to use. An alternate approach is proposed whereby the mechanism is characterized as flow through parallel capillary channels, rather than just as flow over the particle surfaces. A simple test system can be used to define the effective capillary size, from which the pressure and time required to infuse a fluid into powder mixtures can be predicted as a function of the viscosity of the fluid and the geometry of the vessel into which it is being pumped. The predictability is particularly important when the fluid is a polymerizable monomer with only a narrow operating window before it sets up, such as some potting compounds and energetic applications. Examples are given with various fluid/powder systems. Introduction The current art of manufacturing energetic products, such as propellants and explosives, usually involves mixing of the ingredients for long periods to achieve a uniform distribution of the solid ingredients in a binder matrix that is still pourable but eventually slowly polymerizes or gels into a solid mass. The slurry paste becomes very viscous because of the generally high loading of solids. The increase in viscosity caused by the solids loading frequently sets the maximum solids content that can be processed. The high viscosity of the mixture requires substantial torque to blend. The power to mix combined with long mixing times result in inefficient mixing and high power consumption, and can lead to potentially undesirable and dangerous heat buildup. For example, mixing for the solid propellants such as used in the space shuttle program typically contain 12.6 % by volume aluminum powder as fuel (10 to 20 microns), 63.5 % ammonium perchlorate as oxidant, generally bimodal size distribution (about 20 microns and about 300 microns), and 23.9 % polymerizable mixture of prepolymer and plasticizer. Mixing the above formulation may be done in large planetary change-can mixers. The recent ACE wet manufacturing process described by Gogos et al [1] involves similar energetic products for the opposite end of the size spectra, namely long narrow metal tubes known as burster tubes. The ACE process achieves higher solids loading by replacing the slurry-mix-and-pour step by preconditioning the solids and dry filling the burster tube with the solid mixture, followed by infusing and curing of the binder fluid. The work described herein concerns the time and pressure required to achieve complete infusion before gelling occurs. Pressure Drop through Packed Beds Flow of fluids through packed beds has been well investigated by the Ergun [2] equation in the creeping flow regime. 2 1 3 2 2 1 1 3 1 3 2 1 ) 1 ( 150 1 75 . 1 ) 1 ( 150 sv sv g sv d U d U d U p p L p μ ε ε ρ ε ε μ ε ε − ≈ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎣ ⎡ − + − = Δ (1) Where, μ, viscosity of the fluid, E, fraction void, ∆p, pressure drop across bed, dsv, surface volume of the packing particles, U, superficial velocity, ρ, fluid density, L, bed depth. Since the superficial flow velocity dt dL U ε = 1 , thus infusion time t can be rearranged as: 2 2 2 3 2 ) 1 ( 75 kL L d p t sv = ⎭ ⎬ ⎫ ⎩ ⎨ ⎧ × Δ − = μ ε ε (2) Appling the Ergun equation to predict the time vs. infusion length for packed beds of widely differing particle sizes and shapes is difficult. Figure 1, 2 and 3 show size distributions representive of two of the solids used in these tests. Figure 1 Photomicrograph of Dechlorane Plus 515 particles Figure 2 Particle size distribution of Dechlorane Powders Figure 3 Particle size distribution of KCl crystals Instead of trying to describe the flow pattern based on the sizes of the particles around which the binder fluid has to flow, we decided to simplify the model for any packed bed of powder by characterizing the flow as many parallel passages with an equivalent capillary diameter, Φ, which can be determined from the same ∆p vs. L data. For a Newtonian fluid, the flow in a capillary channel follows the formula: μ ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ Φ = ΦΔ V L p 8 4 (3) in which Φ is the effective capillary diameter, and V is the velocity of the fluid

Domain size of 10% dispersed polystyrene in polyethylene was followed in a 34-mm intermeshing counter-rotating twin screw extruder. Variables studied included the effects of barrel temperature, screw speed, viscosity ratio of dispersed-to-continuous phase, and parallel melt versus preblended solids feeds. After steady state was achieved, die samples were quenched for later photomicrographing. The extruder was then stopped and quenched, with subsequent pulling of the screws. From 7 to 12 additional samples were taken along the 18/1 L/D extruder for determination of the mechanism of dispersion and dispersed phase domain size by optical microscopy. At low temperatures, the polystyrene tended to fracture with sharp edges. The fine particles formed in the initial breakup underwent no further size reduction. At higher temperatures, fractured segments had rounder edges, but the size of the small domains remained constant throughout the axial length. There was some evidence of flocculation and coalescence prior to exit through the die. © 2006 Wiley Periodicals, Inc. Adv Polym Techn 25: 81–89, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20065

This chapter contains sections titled: Introduction Pretreatment of Fillers Feeding Melting Introduction of Solids and Mixing Venting Pressure Generation Process Examples Further Information References

An experimental investigation was conducted to evaluate the performance of three single-screw mixing elements: a Maddock; a Pineapple; and a Twente mixer. The study was designed to focus on the mixers' performance in the mixing of immiscible polymers in the molten state. Two independently controlled melt streams were fed to the mixer and the evaluation of the mixer performance was based on the following criteria: (i) the processing characteristics, namely the pressure drop/rise across the mixer for specific machine and material operating variables; and (ii) the resulting quality of mixing as determined by image analysis of phase morphology on samples collected at the die. The mixing performance was judged both qualitatively, in terms of spatial material distribution, as well as quantitatively, by analysis for the size of the dispersed phase. The blending tests were conducted using three pairs of LDPE/PS systems having different rheological properties. In addition to the experimental work, the flow in the Maddock mixer was simulated using a commercial finite element package (FIDAP). The calculations were done using the experimental conditions and the properties of a pure LDPE phase. The simulation results were used to explain the dispersion data obtained experimentally. © 1998 John Wiley & Sons, Inc. Adv in Polymer Techn 17: 1–17, 1998

AIChE JournalVolume 40, Issue 2 p. 383-383 Book Review Mixing in polymer processing edited by Chris Rauwendaal, Marcel Dekker, new york, 1991, 496pp., $160.00 Costas G. Gogos, Costas G. Gogos Chemistry and Chemical Engineering Dept. Stevens Institute of Technology Hoboken, NJ 07030Search for more papers by this authorDavid B. Todd, David B. Todd Polymer Processing Institute Hoboken, NJ 07030Search for more papers by this author Costas G. Gogos, Costas G. Gogos Chemistry and Chemical Engineering Dept. Stevens Institute of Technology Hoboken, NJ 07030Search for more papers by this authorDavid B. Todd, David B. Todd Polymer Processing Institute Hoboken, NJ 07030Search for more papers by this author First published: February 1994 https://doi.org/10.1002/aic.690400224AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume40, Issue2February 1994Pages 383-383 RelatedInformation

Journal of Polymer Science Part A: Polymer ChemistryVolume 31, Issue 5 p. 1343-1344 Book Review Mixing in polymer processing, by Chris Rauwendaal ed., Marcel Dekker, Inc., New York, 1991, 496 pp. price: $160.00 David B. Todd, David B. Todd Polymer Processing Institute, Hoboken, New Jersey 07030Search for more papers by this author David B. Todd, David B. Todd Polymer Processing Institute, Hoboken, New Jersey 07030Search for more papers by this author First published: April 1993 https://doi.org/10.1002/pola.1993.080310534AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume31, Issue5April 1993Pages 1343-1344 RelatedInformation

This work was undertaken to develop an additional and improved mode of control for twin‐screw compounding equipment, to increase the capability for the compounder to “fine tune” his equipment to accommodate changes in feed rate and feed properties without having to alter screw configeration.

TransfusionVolume 6, Issue S1 p. 401-403 Clinical Use of Dextran-40 in Extracorporeal Circulation—A Summary of 5 Years' Experience David M. Long Jr., David M. Long Jr.Search for more papers by this authorDavid B. Todd, David B. ToddSearch for more papers by this authorRobert A. Indeglia, Robert A. IndegliaSearch for more papers by this authorRichard L. Varco, Richard L. VarcoSearch for more papers by this authorC. Walton Lillehei, C. Walton LilleheiSearch for more papers by this author David M. Long Jr., David M. Long Jr.Search for more papers by this authorDavid B. Todd, David B. ToddSearch for more papers by this authorRobert A. Indeglia, Robert A. IndegliaSearch for more papers by this authorRichard L. Varco, Richard L. VarcoSearch for more papers by this authorC. Walton Lillehei, C. Walton LilleheiSearch for more papers by this author First published: November 1966 https://doi.org/10.1111/j.1537-2995.1966.tb04814.xCitations: 4AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume6, IssueS1November 1966Pages 401-403 RelatedInformation