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Interfacial Properties (interfacial + property)
Selected AbstractsInfluence of [Ba + Ca]/[Ti + Zr] Ratio on the Interfacial Property of (Ba,Ca)(Ti,Zr)O3 (BCTZ) Powders in an Aqueous MediumJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2003Jaeho Lee We report findings on the electrokinetic and solubility behaviors of (Ba,Ca)(Ti,Zr)O3 (BCTZ) powders having three different [Ba + Ca]/[Ti + Zr] ratios: 0.995, 1.000, and 1.005. Electrokinetic and solubility properties of BCTZ powders in aqueous media are phenomenologically similar to BaTiO3. Ba and Ca ions, occupying primarily A-sites on the perovskite lattice, dissolve during acid titration, which results in surface depletion of A-site cations in the surface region of BCTZ particles. The electrokinetics of colloidal BCTZ powders reflects changes in the surface chemistry that occur as a result of dissolution and adsorption/reprecipitation of surface ions. An increase in [Ba + Ca]/[Ti + Zr] ratio results in an increase in the dynamic mobility at all pH values, an increase in the titration hysteresis, and an increase in the isoelectric pH. Each of these effects can be attributed to Ba and Ca in the near-surface region of BCTZ. [source] Interface Engineering for Organic ElectronicsADVANCED FUNCTIONAL MATERIALS, Issue 9 2010Hong Ma Abstract The field of organic electronics has been developed vastly in the past two decades due to its promise for low cost, lightweight, mechanical flexibility, versatility of chemical design and synthesis, and ease of processing. The performance and lifetime of these devices, such as organic light-emitting diodes (OLEDs), photovoltaics (OPVs), and field-effect transistors (OFETs), are critically dependent on the properties of both active materials and their interfaces. Interfacial properties can be controlled ranging from simple wettability or adhesion between different materials to direct modifications of the electronic structure of the materials. In this Feature Article, the strategies of utilizing surfactant-modified cathodes, hole-transporting buffer layers, and self-assembled monolayer (SAM)-modified anodes are highlighted. In addition to enabling the production of high-efficiency OLEDs, control of interfaces in both conventional and inverted polymer solar cells is shown to enhance their efficiency and stability; and the tailoring of source,drain electrode,semiconductor interfaces, dielectric,semiconductor interfaces, and ultrathin dielectrics is shown to allow for high-performance OFETs. [source] Increased Interface Strength in Carbon Fiber Composites through a ZnO Nanowire InterphaseADVANCED FUNCTIONAL MATERIALS, Issue 16 2009Yirong Lin Abstract One of the most important factors in the design of a fiber reinforced composite is the quality of the fiber/matrix interface. Recently carbon nanotubes and silicon carbide whiskers have been used to enhance the interfacial properties of composites; however, the high growth temperature degrade the fiber strength and significantly reduce the composite's in-plane properties. Here, a novel method for enhancing the fiber/matrix interfacial strength that does not degrade the mechanical properties of the fiber is demonstrated. The composite is fabricated using low-temperature solution-based growth of ZnO nanowires on the surface of the reinforcing fiber. Experimental testing shows the growth does not adversely affect fiber strength, interfacial shear strength can be significantly increased by 113%, and the lamina shear strength and modulus can be increased by 37.8% and 38.8%, respectively. This novel interface could also provide embedded functionality through the piezoelectric and semiconductive properties of ZnO. [source] The Effect of NaF In Vitro on the Mechanical and Material Properties of Trabecular and Cortical BoneADVANCED MATERIALS, Issue 4 2009Philipp J. Thurner High doses of sodium fluoride in bones lead to severe softening, by weakening interfacial properties between the inorganic minerals and the organic components, while leaving mineralization unchanged. This leads to reduction of microdamage and associated stress-whitening pointing to a change in failure mode. Accordingly, elastic modulus, failure stress, and indentation-distance increase are decreased, whereas failure strain is increased. [source] Nanobiomaterials and Nanoanalysis: Opportunities for Improving the Science to Benefit Biomedical Technologies,ADVANCED MATERIALS, Issue 5 2008W. Grainger Abstract Nanomaterials advocated for biomedical applications must exhibit well-controlled surface properties to achieve optimum performance in complex biological or physiological fluids. Dispersed materials with extremely high specific surface areas require as extensive characterization as their macroscale biomaterials analogues. However, current literature is replete with many examples of nanophase materials, most notably nanoparticles, with little emphasis placed on reporting rigorous surface analysis or characterization, or in formal implementation of surface property standards needed to validate structure-property relationships for biomedical applications. Correlations of nanophase surface properties with their stability, toxicity and biodistributions are essential for in vivo applications. Surface contamination is likely, given their processing conditions and interfacial energies. Leaching adventitious adsorbates from high surface area nanomaterials is a possible toxicity mechanism. Polydimethylsiloxane (PDMS), long known as a ubiquitous contaminant in clean room conditions, chemical synthesis and microfabrication, remains a likely culprit in nanosystems fabrication, especially in synthesis, soft lithography and contact molding methods. New standards and expectations for analyzing the interfacial properties of nanoparticles and nano-fabricated technologies are required. Surface science analytical rigor similar to that applied to biomedical devices, nanophases in microelectronics and heterogeneous catalysts should serve as a model for nanomaterials characterization in biomedical technologies. [source] Formation of Polyelectrolyte Multilayer Films at Interfaces Between Thermotropic Liquid Crystals and Aqueous Phases,ADVANCED MATERIALS, Issue 7 2006A. Lockwood Preparation of polyelectrolyte multilayer (PEM) films at fluid interfaces between aqueous solutions and liquid crystals is described. The orientation of the liquid crystals is coupled to the presence and organization of the PEM films (see figure). The PEM films can selectively mediate the interactions between solutes and the interfaces of the liquid crystals. PEM films offer a general method to tailor the interfacial properties of liquid crystals for chemical or biological sensing. [source] Photoinitiated polymerization in bicontinuous microemulsions: Fluorescence monitoringJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2006C. Peinado Abstract The photopolymerization of bicontinuous microemulsions was simultaneously monitored with differential scanning calorimetry and fluorescence. The kinetics and mechanism of the reaction were studied throughout the entire photopolymerization reaction. The role played by the surfactant in the kinetics and morphology was studied. The nature of the surfactant changed the autoacceleration process and final conversion. The behavior was explained as a result of the differences in the interfacial properties. Anionic cetyltrimethylammonium bromide (CTAB) gave rise to a more flexible interfacial film than anionic sodium dodecyl sulfate (SDS), resulting in competition between the intramolecular and intermolecular reactions in the former systems. As cyclization did not contribute to the increase in the degree of crosslinking, SDS photopolymerization gave solids with a more rigid microstructure. Fluorescence methodology was applied to monitor bicontinuous microemulsion polymerization and to reveal the microstructure and morphology development during photopolymerization. The microemulsion composition was designed to prepare nanoporous, crosslinked materials. Even though the nanostructure of the precursor microemulsions was not retained because of phase separation during polymerization, mesoporous solids were obtained. Their morphologies depended on the nature of the surfactant, and membranes with open cells were successfully prepared with CTAB, whereas more complex morphologies resulted with SDS. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5291,5303, 2006 [source] Compositionally Graded Aluminum Oxide Coatings on Stainless Steel Using Laser ProcessingJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2007Partha P. Bandyopadhyay A 1.5 mm thick fully dense alumina coating with a composition gradient from 100% Ni,20 wt% Cr at the substrate to 100% alumina on top has been developed on a 316 stainless steel sheet using Laser Engineered Net Shaping (LENSÔ). The gradient coatings showed hardness in the range of 1800,2000 Hv, one of the highest reported so far due to high-density layers. During laser deposition, ,-Al2O3 found to grow along the deposition direction with coarse columnar structure. The inherent advantage of this approach is to control simultaneously both location and composition leading to better interfacial properties of coatings. [source] Effect of Biodegradable Epoxidized Castor Oil on Physicochemical and Mechanical Properties of Epoxy ResinsMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 15 2004Soo-Jin Park Abstract Summary: Biobased epoxy materials were prepared from diglycidyl ether of bisphenol A (DGEBA) and epoxidized castor oil (ECO) initiated by a latent thermal catalyst. The physicochemical and mechanical interfacial properties of the DGEBA/ECO blends were investigated. As a result, the thermal stability of the cured epoxy blends showed a maximum value in the presence of 10 wt.-% ECO content, which was attributed to the excellent network structure in the DGEBA/ECO blends. The storage modulus and glass transition temperature of the blends were lower than those of neat epoxy resins. The mechanical interfacial properties of the cured specimens were significantly increased with increasing the ECO content. This could be interpreted in terms of the addition of larger soft segments of ECO into the epoxy resins and thus reducing the crosslinking density of the epoxy network, which results in increasing toughness in the blends. KIC values of the DGEBA/ECO blends as a function of ECO content. [source] Quartz Crystal Microbalance Studies on Conformational Change of Polymer Chains at InterfaceMACROMOLECULAR RAPID COMMUNICATIONS, Issue 4-5 2009Guangzhao Zhang Abstract The conformation of polymers at interface profoundly influences the interfacial properties. Quartz crystal microbalance with dissipation (QCM-D) is a newly developed technique to detect polymer behavior at interface in real time. In this article, we mainly review our QCM-D studies. Our focus is on temperature induced collapse and swelling of tethered polymer chains, pancake-to-brush transition and mushroom-to-brush of polymer chains. [source] Influence of interfacial adhesion on the structural and mechanical behavior of PP-banana/glass hybrid compositesPOLYMER COMPOSITES, Issue 7 2010Sanjay K. Nayak Hybrid composites of polypropylene (PP), reinforced with short banana and glass fibers were fabricated using Haake torque rheocord followed by compression molding with and without the presence maleic anhydride grafted polypropylene (MAPP) as a coupling agent. Incorporation of both fibers into PP matrix resulted in increase of tensile strength, flexural strength, and impact strength upto 30 wt% with an optimum strength observed at 2 wt% MAPP treated 15 wt% banana and 15 wt% glass fiber. The rate of water absorption for the hybrid composites was decreased due to the presence of glass fiber and coupling agent. The effect of fiber loading in presence of coupling agent on the dynamic mechanical properties has been analyzed to investigate the interfacial properties. An increase in storage modulus (E,) of the treated-composite indicates higher stiffness. The loss tangent (tan ,) spectra confirms a strong influence of fiber loading and coupling agent concentration on the , and , relaxation process of PP. The nature of fiber matrix adhesion was examined through scanning electron microscopy (SEM) of the tensile fractured specimen. Thermal measurements were carried out through differential scanning calorimetry (DSC) and the thermogravimetric analysis (TGA), indicated an increase in the crystallization temperature and thermal stability of PP with the incorporation of MAPP-treated banana and glass fiber. POLYM. COMPOS., 31:1247,1257, 2010. © 2009 Society of Plastics Engineers [source] Mechanical properties of injection molded long fiber polypropylene composites, Part 1: Tensile and flexural propertiesPOLYMER COMPOSITES, Issue 2 2007K. Senthil Kumar Innovative polymers and composites are broadening the range of applications and commercial production of thermoplastics. Long fiber-reinforced thermoplastics have received much attention due to their processability by conventional technologies. This study describes the development of long fiber reinforced polypropylene (LFPP) composites and the effect of fiber length and compatibilizer content on their mechanical properties. LFPP pellets of different sizes were prepared by extrusion process using a specially designed radial impregnation die and these pellets were injection molded to develop LFPP composites. Maleic-anhydride grafted polypropylene (MA- g -PP) was chosen as a compatibilizer and its content was optimized by determining the interfacial properties through fiber pullout test. Critical fiber length was calculated using interfacial shear strength. Fiber length distributions were analyzed using profile projector and image analyzer software system. Fiber aspect ratio of more than 100 was achieved after injection molding. The results of the tensile and flexural properties of injection molded long glass fiber reinforced polypropylene with a glass fiber volume fraction of 0.18 are presented. It was found that the differences in pellet sizes improve the mechanical properties by 3,8%. Efforts are made to theoretically predict the tensile strength and modulus using the Kelly-Tyson and Halpin-Tsai model, respectively. POLYM. COMPOS., 28:259,266, 2007. © 2007 Society of Plastic Engineers [source] The effect of interface characteristics on the static and dynamic mechanical properties of three-component polymer alloysPOLYMER COMPOSITES, Issue 3 2002I. Fisher The effect of interfacial characteristics on the structure-property relationships of ternary polymer alloys and blends comprising polypropylene (PP), ethylene-vinyl alcohol copolymer (EVOH) and glass beads (GB) or fibers (GF) was investigated. The systems studied were based on a binary PP/EVOH immiscible blend, representing a blend of a semi-crystalline apolar polymer with a semi-crystalline highly polar copolymer. The ternary systems studied consisted of filler particles encapsulated by EVOH, with some of the minor EVOH component separately dispersed within the PP matrix. Modification of the interfacial properties was done using silane coupling agents for the EVOH/glass interface and compatibilization using a maleic anhydride grafted PP (MA-g-PP) for the PP/EVOH interface. Both glass fillers increased the dynamic modulus and decreased the damping of the neat polymers and of their binary blends, especially in the rubbery region. GF has a more profound effect on both the modulus and the damping. Glass surface treatments and compatibilization have only a marginal effect on the dynamic mechanical behavior of the ternary blends. Yet, compatibilization shifted the polymers' TgS to higher temperatures. Both glass fillers increased the elastic modulus of the binary blends, where GF performed better than GB as a reinforcing agent. GF slightly increased the strength of the binary blends while, GB reduced it. Both fillers reduced the ductility of the binary blends. The blends' mechanical properties were related to the morphology and their components' crystallinity. The compatibilizer increases both stiffness and strength and reduces deformability. [source] Influence of melt-blending conditions on structural, rheological, and interfacial properties of polyamide-12 layered silicate nanocompositesPOLYMER ENGINEERING & SCIENCE, Issue 8 2006Pascal Médéric The influence of the melt-blending conditions on the structural, rheological, and interfacial properties of modified montmorillonite/Polyamide-12 nanocomposites has been studied performing transmission electron microscopy observation combined with X-Ray diffraction and rheological experiments. In the dilute regime, for short mixing times, the apparent aspect ratio of primary clay entities, determined from intrinsic viscosity measurements, is shown to increase with rotational speed. At high blade rotational speeds, the viscometric results suggest an almost achieved exfoliation, as confirmed by transmission electron microscopy micrographs. For longer mixing times, a significant drop of viscous dissipation is observed, which is very marked at high blade rotational speeds and attributed to a modification of the particle/matrix interface. In the concentrated regime, the rheological behavior of nanocomposites is attributed to the formation of a network of mesoscopic domains, composed of correlated clay entities. Upon increasing strain during mixing, the clay aggregates within these domains break into intercalated stacks and finally exfoliated layers, as shown by transmission electron microscopy micrographs and wide-angle X-ray diffraction patterns. The melt state elastic and viscous properties of the nanocomposites are mainly governed by the networked domains, and not by the nature and properties of the structure within the domains. POLYM. ENG. SCI. 46:986,994, 2006. © 2006 Society of Plastics Engineers. [source] | |||||||||||||||||||