@misc{desimone_siripurapu_khan_spontak_royer_2010, title={Nano-and micro-cellular foamed thin-walled material, and processes and apparatuses for making the same}, volume={7,658,989}, number={2010 Feb. 9}, author={DeSimone, J. M. and Siripurapu, S. and Khan, S. A. and Spontak, R. J. and Royer, J.}, year={2010} }
 @misc{royer_roberts_2006, title={Continuous method and apparatus for separating polymer from a high pressure carbon dioxide fluid stream}, volume={7,063,839}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Royer, J. R. and Roberts, G. W.}, year={2006} }
 @misc{royer_roberts_2004, title={Continuous method and apparatus for separating polymer from a high pressure carbon dioxide fluid stream}, volume={6,806,332}, number={2004 Oct. 19}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Royer, J. R. and Roberts, G. W.}, year={2004} }
 @misc{desimone_khan_royer_spontak_walker_gay_siripurapu_2004, title={Methods of making foamed materials of blended thermoplastic polymers using carbon dioxide}, volume={6,790,870}, number={2004 Sept. 14}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={DeSimone, J. M. and Khan, S. A. and Royer, J. R. and Spontak, R. J. and Walker, T. A. and Gay, Y. J. and Siripurapu, S.}, year={2004} }
 @article{siripurapu_gay_royer_desimone_spontak_khan_2002, title={Generation of microcellular foams of PVDF and its blends using supercritical carbon dioxide in a continuous process}, volume={43}, ISSN={["1873-2291"]}, DOI={10.1016/S0032-3861(02)00407-X}, abstractNote={Use of supercritical carbon dioxide (scCO2) as a blowing agent to generate microcellular polymer foams (MPFs) has recently received considerable attention due to environmental concerns associated with conventional organic blowing agents. While such foams derived from amorphous thermoplastics have been previously realized, semicrystalline MPFs have not yet been produced in a continuous scCO2 process. This work describes the foaming of highly crystalline poly(vinylidene fluoride) (PVDF) and its blends with amorphous polymers during extrusion. Foams composed of neat PVDF and immiscible blends of PVDF with polystyrene exhibit poor cell characteristics, whereas miscible blends of PVDF with poly(methyl methacrylate) (PMMA) yield foams possessing vastly improved morphologies. The results reported herein illustrate the effects of blend composition and scCO2 solubility on PVDF/PMMA melt viscosity, which decreases markedly with increasing PMMA content and scCO2 concentration. Morphological characterization of microcellular PVDF/PMMA foams reveals that the cell density increases as the PMMA fraction is increased and the foaming temperature is decreased. This study confirms that novel MPFs derived continuously from semicrystalline polymers in the presence of scCO2 can be achieved through judicious polymer blending.}, number={20}, journal={POLYMER}, author={Siripurapu, S and Gay, YJ and Royer, JR and DeSimone, JM and Spontak, RJ and Khan, SA}, year={2002}, month={Sep}, pages={5511–5520} }
 @misc{desimone_khan_royer_spontak_walker_2002, title={Method of making foamed materialsUSing surfactants and carbon dioxide}, volume={6,403,663}, number={2002 Jun. 11}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={DeSimone, J. M. and Khan, S. A. and Royer, J. R. and Spontak, R. J. and Walker, T. A.}, year={2002} }
 @article{royer_gay_adam_desimone_khan_2002, title={Polymer melt rheology with high-pressure CO2 using a novel magnetically levitated sphere rheometer}, volume={43}, ISSN={["0032-3861"]}, DOI={10.1016/S0032-3861(01)00804-7}, abstractNote={A magnetically levitated sphere rheometer (MLSR) designed to measure viscosity of fluids exposed to high-pressure carbon dioxide has been developed. This device consists of a magnetic sphere submerged inside a test fluid within a high-pressure housing and levitated at a fixed point. The housing is constructed from an optically transparent sapphire tube. The cylindrical tube can be moved vertically to generate a shear flow around the levitated sphere. The difference in magnetic force required to levitate the sphere at rest and under fluid motion can be directly related to fluid viscosity. Rheological properties, specifically zero shear viscosities, of transparent high-pressure materials can be measured to a precision of about 5% and over a wide range of viscosities. In addition, operation at constant pressure, in concentration regimes from a pure polymer to an equilibrated polymer/supercritical fluid solution, and at shear rates over several orders of magnitude is possible, eliminating many of the disadvantages associated with other high-pressure rheometers. Experiments performed at different temperatures with a poly(dimethylsiloxane) melt at atmospheric pressure are compared with data from a commercial Couette rheometer to demonstrate device sensitivity and viability. Measurements of a PDMS melt plasticized by high-pressure CO2 are performed to illustrate the utility of the new rheometer under high-pressure conditions. Experimental data are obtained at 30 °C, for pressures up to 20.7 MPa and CO2 concentrations reaching 30 wt%. Viscosity reductions of nearly two orders of magnitude compared with the pure polymer viscosity at atmospheric pressure are observed. Additionally, the effects of pressure on a polymer/CO2 system are directly investigated taking advantage of the constant pressure operation mode of the MLSR. This allows us, for the first time in experiments of polymers with supercritical fluids, to decouple the effects of CO2 concentration and pressure in a single device.}, number={8}, journal={POLYMER}, author={Royer, JR and Gay, YJ and Adam, M and DeSimone, JM and Khan, SA}, year={2002}, month={Apr}, pages={2375–2383} }
 @article{royer_desimone_khan_2001, title={High-pressure rheology and viscoelastic scaling predictions of polymer melts containing liquid and supercritical carbon dioxide}, volume={39}, ISSN={0887-6266 1099-0488}, url={http://dx.doi.org/10.1002/polb.10057}, DOI={10.1002/polb.10057}, abstractNote={Abstract}, number={23}, journal={Journal of Polymer Science Part B: Polymer Physics}, publisher={Wiley}, author={Royer, Joseph R. and DeSimone, Joseph M. and Khan, Saad A.}, year={2001}, pages={3055–3066} }
 @article{martinache_royer_siripurapu_henon_genzer_khan_carbonell_2001, title={Processing of polyamide 11 with supercritical carbon dioxide}, volume={40}, ISSN={["0888-5885"]}, DOI={10.1021/ie010410b}, abstractNote={The supercritical carbon dioxide induced swelling and plasticization of polyamide 11 were investigated. The swelling kinetics exhibit an initial region of large swelling, in which the diffusion of CO2 into the polymer follows Fickian behavior, and a subsequent region of small volume increase that asymptotically approaches an equilibrium swelling value. The diffusion coefficient of CO2 in polyamide 11 was calculated from the initial slope of the swelling kinetics data. CO2, injected up to 3 wt % using an extrusion rheometer, is shown to be an effective plasticizer for polyamide 11, lowering the viscosity of the polymer melt by as much as 50%. The use of CO2 as a blowing agent was also investigated, and we report preliminary foaming attempts using a batch process. We obtained homogeneously distributed foams, featuring well-defined closed cells with an average diameter of 30 μm that had an unfoamed skin layer.}, number={23}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Martinache, JD and Royer, JR and Siripurapu, S and Henon, FE and Genzer, J and Khan, SA and Carbonell, RG}, year={2001}, month={Nov}, pages={5570–5577} }
 @article{royer_gay_desimone_khan_2000, title={High-pressure rheology of polystyrene melts plasticized with CO2: Experimental measurement and predictive scaling relationships}, volume={38}, number={23}, journal={Journal of Polymer Science. Part B, Polymer Physics}, author={Royer, J. R. and Gay, Y. J. and Desimone, J. M. and Khan, S. A.}, year={2000}, month={Dec}, pages={3168–3180} }
 @article{mccormick_royer_hwang_khan_2000, title={Tailored rheology of a metallocene polyolefin through silane crafting and subsequent silane crosslinking}, volume={38}, DOI={10.1002/1099-0488(20000915)38:18<2468::AID-POLB140>3.0.CO;2-7}, abstractNote={Polymer modification through silane grafting and its subsequent crosslinking allows the rheological properties of a polymer to be tuned from those of a viscous melt to those of a crosslinked elastic network. In this study, a metallocene polyolefin resin is grafted with vinyl trimethoxy silane (VTMS) using dicumyl peroxide (DCP) as the initiator and is subsequently crosslinked in an oxidative environment. Dynamic rheological experiments are conducted to elucidate the effects of DCP and VTMS concentrations on the grafting and ensuing crosslinking processes. We find that the addition of VTMS alone to the polymer produces no grafting. In contrast, the presence of DCP by itself leads to direct crosslinking between polymer chains as suggested by an increase in elastic modulus and complex viscosity. Samples containing both DCP and VTMS undergo silane grafting, with the extent of grafting increasing with increasing DCP concentration. This conclusion is borne out by both rheological and Fourier transform infrared measurements. The grafted samples undergo silane crosslinking only in an oxidative environment and at temperatures equal to or greater than 190 °C. During crosslinking, the samples undergo a transition from a viscous melt with frequency-dependent moduli to a gel exhibiting frequency-independent moduli with the elastic modulus exceeding the viscous modulus. However, the kinetics of crosslinking and the extent of the modulus increase are a function of the DCP concentration, with both exhibiting a maximum at a specific DCP and VTMS combination.}, number={18}, journal={Journal of Polymer Science. Part B, Polymer Physics}, author={McCormick, J. A. and Royer, J. R. and Hwang, C. R. and Khan, Saad}, year={2000}, pages={2468–2479} }
 @article{royer_desimone_khan_1999, title={Carbon dioxide-induced swelling of poly( dimethylsiloxane)}, volume={32}, ISSN={["0024-9297"]}, DOI={10.1021/ma9904518}, abstractNote={A new experimental device is used to monitor in situ the swelling behavior of poly(dimethylsiloxane) melts in contact with supercritical carbon dioxide. The effects of pressure, temperature, and sample molecular weight on the kinetics and extent of swelling are examined using this experimental technique. The swelling kinetics of all polymer samples exhibit two distinct regimes:  an initial region of large swelling in which the diffusion of CO2 into the polymer follow Fickian behavior and a subsequent region of small volume increase asymptotic to an equilibrium swelling value. Diffusion coefficients of CO2, obtained from the initial swelling kinetics data, are found to be relatively insensitive to pressure, increase with temperature, and decrease with polymer molecular weight with the latter exhibiting a power-law dependence with an exponent of ∼−2. The extent of swelling increases with both pressure and molecular weight but exhibits different trends with temperature depending on system pressure. For press...}, number={26}, journal={MACROMOLECULES}, author={Royer, JR and DeSimone, JM and Khan, SA}, year={1999}, month={Dec}, pages={8965–8973} }
 @article{walker_raghavan_royer_smith_wignall_melnichenko_khan_spontak_1999, title={Enhanced miscibility of low-molecular-weight polystyrene polyisoprene blends in supercritical CO2}, volume={103}, ISSN={["1089-5647"]}, DOI={10.1021/jp990551f}, abstractNote={While ongoing efforts continue to explore the high-pressure phase equilibria of polymer blends, few studies have attempted to address the impact of a supercritical (sc) fluid on such equilibria. In this work, we report on the phase behavior of an upper critical solution temperature (UCST) polymer blend in the presence of supercritical carbon dioxide (scCO2), a nonselective plasticizing agent. Blends composed of low-molecular-weight polystyrene and polyisoprene have been examined as a function of temperature in scCO2 by visual inspection, small-angle neutron scattering, and spectrophotometry. In the presence of scCO2, the cloud point temperature is depressed by as much as 28 °C, depending on both blend composition and CO2 pressure. Complementary studies performed with nitrogen decouple the plasticization efficacy of CO2 from free-volume compression due to hydrostatic pressure. Existence of a pressure yielding a maximum in CO2-induced cloud point depression is established. These results provide evidence for...}, number={26}, journal={JOURNAL OF PHYSICAL CHEMISTRY B}, author={Walker, TA and Raghavan, SR and Royer, JR and Smith, SD and Wignall, GD and Melnichenko, Y and Khan, SA and Spontak, RJ}, year={1999}, month={Jul}, pages={5472–5476} }
 @misc{khan_roberts_royer, title={CO2-assisted deploymerization, purification and recycling of step-growth polymers}, volume={6,919,383}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Khan, S. A. and Roberts, G. W. and Royer, J. R.} }
 @misc{royer_desimone_roberts_khan, title={Methods of CO2-assisted reactive extrusion}, volume={6,900,267}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Royer, J. and DeSimone, J. M. and Roberts, G. W. and Khan, S. A.} }
 @article{royer_gay_adam_desimone_khan, title={Polymer melt rheology with high-pressure co<inf>2</inf> using a novel magnetically levitated sphere rheometer}, volume={43}, number={8}, journal={Polymer}, author={Royer, J. R. and Gay, Y. J. and Adam, M. and DeSimone, J. M. and Khan, S. A.}, pages={2375–2383} }