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Interfacial Reaction (interfacial + reaction)
Selected AbstractsEffect of Interfacial Reaction on the Thermal Conductivity of Al,SiC Composites with SiC DispersionsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2001Chihiro Kawai The effect of interfacial reactions between Al and SiC on the thermal conductivity of SiC-particle-dispersed Al-matrix composites was investigated by X-ray diffraction and transmission electron microscopy (TEM), and the thermal barrier conductance (hc) of the interface in the Al,SiC composites was quantified using a rule of mixture regarding thermal conductivity. Al,SiC composites with a composition of Al (pure Al or Al,11 vol% Si alloy),66.3 vol% SiC and a variety of SiC particle sizes were used as specimens. The addition of Si to an Al matrix increased the thermal barrier conductance although it decreased overall thermal conductivity. X-ray diffraction showed the formation of Al4C3 and Si as byproducts in addition to Al and SiC in some specimens. TEM observation indicated that whiskerlike products, possibly Al4C3, were formed at the interface between the SiC particles and the Al matrix. The thermal barrier conductance and the thermal conductivity of the Al,SiC composites decreased with increasing Al4C3 content. The role of Si addition to an Al matrix was concluded to be restraining an excessive progress of the interfacial reaction between Al and SiC. [source] Distributive mixing profiles for co-rotating twin-screw extrudersADVANCES IN POLYMER TECHNOLOGY, Issue 3 2001Gifford Shearer Distributive mixing was experimentally measured during polymer melt blending along the length of a co-rotating twin-screw extruder. A mixing limited interfacial reaction between two reactive polymer tracers was employed to gain direct evidence of the generation of interfacial area. Model reactions were performed to validate this novel experimental method. In particular, the conversion was a direct indicator of the interfacial area available for the reaction. Specially designed sampling ports were used to obtain polymer samples along the length of the extruder during its continuous operation. The mixing capabilities of conveying sections and kneading blocks were compared over a wide range of operating conditions. In conveying sections, distributive mixing was controlled by the fully filled fraction. The mixing in kneading blocks depended on the combination of the operating conditions and the stagger angle. © 2001 John Wiley & Sons, Inc. Adv Polym Techn 20: 169,190, 2001 [source] Interfacial formation of porous membranes with poly(ethylene glycol) in a microfluidic environmentJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008Dongshin Kim Abstract In a microfluidic environment, the liquid,liquid interface, formed by laminar flows of immiscible solutions, can be used to generate thin membranes via interfacial polymerization. Because these thin nylon membranes have a very small pore size or lack porosity entirely, their utilization in some biological applications is greatly limited. We introduce an in situ fabrication method using the interfacial reaction of a two-phase system to generate a porous nylon membrane. The membranes were characterized with scanning electron microscopy and fluorescent beads. Scanning electron microscopy micrographs verified the asymmetrical structure of the porous membrane, and the membrane pore sizes ranged from 0.1 to 1 ,m. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008. [source] Polyamides nanocapsules: Modeling and wall thickness estimationAICHE JOURNAL, Issue 6 2006K. Bouchemal Abstract This work provides a better understanding for effective control of the nanocapsules wall thickness. Polyamides based nanocapsules are prepared by interfacial polymerization combined with spontaneous emulsification. A clear guideline of how factors such as monomer concentration, diffusion, interfacial reaction, or water swelling influence the capsule formation is very important to the control of capsule wall structure and release performance. In this goal, the macroscopic planar models of the interfacial polycondensation between diethylenetriamine and sebacoyle chloride are studied experimentally and theoretically. This planar model is developed to examine the kinetics of the reaction and to perform the estimation of parameters thanks to the experiment measurements. The effect of the operating conditions on the wall thickness is also studied. The model is shown to be consistent with the experimental data. Next, the spherical model is deduced from the first one. The results obtained with this model are in accordance with some observations of wall thickness. From this model, the increase of the wall thickness is predicted for several operating conditions. © 2006 American Institute of Chemical Engineers AIChE J, 2006 [source] Phase Evolution During Formation of SrAl2O4 from SrCO3 and ,-Al2O3/AlOOHJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2007Yu-Lun Chang Through the execution of experimental investigation, thermogravimetry, X-ray diffractometry, Fourier transform-infrared spectrometry, transmission electron microscopy, and energy-dispersive spectrometry, a variant reaction mechanism model was proposed for the solid-state reaction between SrCO3 and Al2O3/AlOOH for formation of SrAl2O4 material. The solid-state reaction is observed to be dependent on the calcination temperature. At temperatures lower than the transformation temperature of SrCO3 from orthorhombic to hexagonal (920°C), the reaction is attributed to the interfacial reaction between SrCO3 and alumina. Conversely, at temperatures higher than that, the solid-state reaction is dominated by the diffusion of Al3+ ions into the SrCO3 lattice. In this mechanism, two metastable species, hexagonal SrCO3 and hexagonal SrAl2O4, were observed. The activation energies of SrCO3 decomposition in the solid-state reaction also support these results. The interfacial reaction at low temperatures is characterized by a high activation energy of ,130 kJ/mol; whereas, in the reaction at higher temperatures, the activation energy of SrCO3 decomposition decreases to 34 kJ/mol. [source] Effect of Interfacial Reaction on the Thermal Conductivity of Al,SiC Composites with SiC DispersionsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2001Chihiro Kawai The effect of interfacial reactions between Al and SiC on the thermal conductivity of SiC-particle-dispersed Al-matrix composites was investigated by X-ray diffraction and transmission electron microscopy (TEM), and the thermal barrier conductance (hc) of the interface in the Al,SiC composites was quantified using a rule of mixture regarding thermal conductivity. Al,SiC composites with a composition of Al (pure Al or Al,11 vol% Si alloy),66.3 vol% SiC and a variety of SiC particle sizes were used as specimens. The addition of Si to an Al matrix increased the thermal barrier conductance although it decreased overall thermal conductivity. X-ray diffraction showed the formation of Al4C3 and Si as byproducts in addition to Al and SiC in some specimens. TEM observation indicated that whiskerlike products, possibly Al4C3, were formed at the interface between the SiC particles and the Al matrix. The thermal barrier conductance and the thermal conductivity of the Al,SiC composites decreased with increasing Al4C3 content. The role of Si addition to an Al matrix was concluded to be restraining an excessive progress of the interfacial reaction between Al and SiC. [source] Dependence of the interfacial reaction and morphology development on the functionality of the reactive precursors in reactive blendingMACROMOLECULAR SYMPOSIA, Issue 1 2003Z. Yin Abstract PMMA containing 50 wt% of anthracene-labeled PMMA chains end-capped by a phthalic anhydride group (anth-PMMA-anh) has been melt blended at 180°C with PS containing 33 wt% of chains end-capped by an aliphatic primary amine (PS-NH2) and PS bearing 3.5 pendant amine groups (as an average) along the chains (PS-co-PSNH2), respectively. The reactive chains have been synthesized by atom transfer radical polymerization. Conversion of anth-PMMA-anh into PS-b-PMMA and PS-g-PMMA copolymers has been monitored by SEC with a UV detector. The interfacial reaction mainly occurs in the initial melting and softening stage (<1.0 min.), although at a rate which strongly depends on the number of reactive groups attached to PS chains, the higher conversion being observed for the PS-co-PSNH2 containing blends. The phase morphology depends on the architecture of the in-situ formed copolymer. Indeed, a coarser phase dispersion is observed in case of the graft copolymer compared to the diblock. [source] Effect of chirality on PVP/drug interaction within binary physical mixtures of ibuprofen, ketoprofen, and naproxen: A DSC studyCHIRALITY, Issue 8 2009Ivan T. Ivanov Abstract We report on the thermal behavior of freshly prepared binary drug/polymer physical mixtures that contained ibuprofen, ketoprofen, or naproxen as a drug, and polyvinylpyrrolidone (PVP), hydroxyethylcellulose (HEC), or methylcellulose (MC) as excipient. At 6,10°C/min heating rates the DSC detected a sharp, single endotherm that corresponds to the melting of drug. On heating physical mixtures of PVP and racemic ibuprofen or ketoprofen at lower heating rates, another endotherm was registered in front of the original one. To observe the additional endotherm, specific minimal values of the heating rate and of PVP weight fraction were needed; for ibuprofen and ketoprofen they were 1.5 and 2.0°C/min, and 5 and 15% (w/w), respectively. At greater PVP weight fractions the top temperatures, Tmp, of both peaks were reduced almost linearly indicating strong solid-state interfacial reaction between the drug particles and PVP matrix. The additional endotherm was abolished at greater heating rates (2°C/min for ibuprofen, 3°C/min for ketoprofen), by replacing the racemate with respective S(+)-enantiomer and by replacing PVP with HEC and MC. Hence, the possible inclusion of enantioselective component within the PVP/drug interaction, responsible for the amorphization of physical mixture over storage, is assumed. Chirality, 2009. © 2008 Wiley-Liss, Inc. [source] Interface Reactions in Ultrathin Functional Dielectric Films,ADVANCED ENGINEERING MATERIALS, Issue 4 2009Dieter Schmeißer The functional properties of shrunken materials should not be influenced by the reduction of the dimensions. Here, an important consideration is the control of interfacial reactions. We report on synchrotron-based spectroscopic analysis of interfaces of ultrathin functional materials (thickness <10 nm). Examples of high- k oxides, as well as of a ferroelectric polymer, are shown. We demonstrate that our spectroscopic findings are also reflected in the electric properties of thin-film devices. [source] Local Electrochemical Functionality in Energy Storage Materials and Devices by Scanning Probe Microscopies: Status and PerspectivesADVANCED MATERIALS, Issue 35 2010Sergei V. Kalinin Abstract Energy storage and conversion systems are an integral component of emerging green technologies, including mobile electronic devices, automotive, and storage components of solar and wind energy economics. Despite the rapidly expanding manufacturing capabilities and wealth of phenomenological information on the macroscopic device behaviors, the microscopic mechanisms underpinning battery and fuel cell operations in the nanometer,micrometer range are virtually unknown. This lack of information is due to the dearth of experimental techniques capable of addressing elementary mechanisms involved in battery operation, including electronic and ion transport, vacancy injection, and interfacial reactions, on the nanometer scale. In this article, a brief overview of scanning probe microscopy (SPM) methods addressing nanoscale electrochemical functionalities is provided and compared with macroscopic electrochemical methods. Future applications of emergent SPM methods, including near field optical, electromechanical, microwave, and thermal probes and combined SPM-(S)TEM (scanning transmission electron microscopy) methods in energy storage and conversion materials are discussed. [source] An overview of the mathematical modelling of liquid membrane separation processes in hollow fibre contactorsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 11 2009E Bringas Abstract Liquid membranes have traditionally been employed for liquid/liquid mass transfer and have found applications in industrial, biomedical and analytical fields as well as in hydrometallurgical processes, wastewater treatment and remediation of polluted groundwater. However, in spite of the known advantages of liquid membranes, there are few examples of industrial application. The development of reliable mathematical models and design parameters (mass transport coefficients and equilibrium or kinetic parameters associated with the interfacial reactions) is a necessary step for design, cost estimation, process optimisation and scale-up. This work reports an overview of the different approaches that have been proposed in the literature to the mathematical modelling of liquid membrane separation processes in hollow fibre contactors providing, at the same time, a useful guideline to characterise the mass transport phenomena and a tool for the optimal design and intensification of separation processes. Copyright © 2009 Society of Chemical Industry [source] Effect of Interfacial Reaction on the Thermal Conductivity of Al,SiC Composites with SiC DispersionsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2001Chihiro Kawai The effect of interfacial reactions between Al and SiC on the thermal conductivity of SiC-particle-dispersed Al-matrix composites was investigated by X-ray diffraction and transmission electron microscopy (TEM), and the thermal barrier conductance (hc) of the interface in the Al,SiC composites was quantified using a rule of mixture regarding thermal conductivity. Al,SiC composites with a composition of Al (pure Al or Al,11 vol% Si alloy),66.3 vol% SiC and a variety of SiC particle sizes were used as specimens. The addition of Si to an Al matrix increased the thermal barrier conductance although it decreased overall thermal conductivity. X-ray diffraction showed the formation of Al4C3 and Si as byproducts in addition to Al and SiC in some specimens. TEM observation indicated that whiskerlike products, possibly Al4C3, were formed at the interface between the SiC particles and the Al matrix. The thermal barrier conductance and the thermal conductivity of the Al,SiC composites decreased with increasing Al4C3 content. The role of Si addition to an Al matrix was concluded to be restraining an excessive progress of the interfacial reaction between Al and SiC. [source] Valorization of poly(butylene terephthalate) wastes by blending with virgin polypropylene: Effect of the composition and the compatibilizationPOLYMER ENGINEERING & SCIENCE, Issue 8 2008Najoua Barhoumi Blends of recycled poly(butylene terephthalate) (PBT) parts obtained from scrapped cars, and virgin polypropylene (PP), were prepared in a twin-screw extruder at different compositions. Selected compositions were also prepared with the presence of ethylene- co -glycidyl methacrylate copolymer (E-GMA) and ethylene/methyl acrylate/glycidyl methacrylate terpolymer (E-MA-GMA) compatibilizers. The effect of the composition and the type of compatibilizer, as well as the mixing conditions, on the morphology phase, thermal, viscoelastic behavior, and mechanical properties of the blends has been investigated. Blends PP/PBT of various composition exhibit a coarse morphology and a poor adherence between both phases, resulting in the decrease of ductility, whereas at weak deformation, PBT reinforced the tensile properties of PP. Addition of E-GMA and E-MA-GMA to the PP/PBT blend exhibited a significant change in morphology and improved ductility because of interfacial reactions between PBT end chains and epoxy groups of GMA that generate EG- g -PBT copolymer. Moreover, thermal and viscoelastic study indicated that the miscibility of PP and PBT has been improved further and the reactions were identified. The E-MA-GMA results in the best improvement of ductility. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] | |||||||||||||||||||||||||