A TPD study of H2 ON Ru/SiO2 and Ru-Cu/SiO2

In H₂ TPD from Ru/SiO₂, two desorption peaks were observed. Both exchanged H for D in sequential dosing experiments. These hydrogen adsorption states were also found for Ru-Cu/SiO₂, along with another, higher temperature state at 400–500 K. This last state was neither exchangeable with nor replaceable by deuterium subsequently dosed at 150 K. The three chemisorption states are attributed to hydrogen held at the interface between Ru and SiO₂ (< 300 K), adsorbed on Ru particles (310–380 K), and held at the Ru-Cu interface (> 400 K).     

Constitutive modeling for intercalated PMMA/clay nanocomposite foams

A constitutive model for tensile behavior of PMMA/clay nanocomposite foams was developed in this study. The elastic modulus of the nanocomposites is affected by the form of clays embedded in the polymer matrix. The reinforcing effect by intercalation of the clays and the detrimental effect by clay agglomeration were considered for the determination of the elastic modulus of the nanocomposites. A viscoelastic model was adapted for the tensile behavior of the material. The developed constitutive equation is expressed in terms of clay morphology and material properties. The aspect ratio of clays and the expansion of clay layer spacing in the intercalated clay clusters were proved to play a vital role in the reinforcing mechanism. For the verification of the constitutive model, Poly(methyl‐methacrylate) (PMMA)/clay nanocomposite foams were manufactured by batch process method and their uniaxial tensile test results were compared with theoretical predictions. Compared with the experimental results, the proposed constitutive equation showed agreement with the experimental test results. POLYM. ENG. SCI. 46:1787–1796, 2006. © 2006 Society of Plastics Engineers.     

Effect of solvent or hydrophilic polymer on the hydration melting behavior of polyacrylonitrile

The effect of solvent, DMF, and hydrophilic polymer on the hydration melting behavior of Tae Kwang polyacrylonitrile-based copolymer (T-PAN) was investigated by DSC measurement. The melting temperature (T_m) of T-PAN was sharply lowered by incorporating water under autogenous pressure, but leveled off above a critical water content: 23 wt %. However, an additional incorporation of DMF into the hydrated T-PAN further lowered the T_m, even above the critical water content. On the other hand, addition of water-soluble poly(acrylic acid), poly(vinyl alcohol), and poly(ethylene glycol) or water-swellable starch to the hydrated PAN slightly raised the T_m. © 1994 John Wiley & Sons, Inc.     

Comparison of vertical and horizontal slot die coatings

Comparison of vertical and horizontal slot coatings was carried out experimentally using aqueous glycerin solutions with varying viscosity on a laboratory‐scale slot coater. The maximum coating speeds achieved in vertical slot coating were found to be higher than those of horizontal slot coating for low‐viscosity solutions. The coating defects observed below the minimum wet thickness changed from ribbing to air entrainment at a critical solution viscosity of around μ = 75 mPa s. Above this critical viscosity, a lower minimum wet thickness was obtained for the horizontal coating but not for vertical coating. The difference between vertical and horizontal coating was mainly the length of the coating bead. The dimensionless minimum wet thickness was correlated as a function of Reynolds number. There existed three regions of minimum wet thickness depending on Reynolds number. Initially, the dimensionless wet thickness increased in the low Reynolds number region (Region I), then reached a plateau in the intermediate Re region (Region II), finally dropped off sharply in the high Re region (Region III). The boundaries of these three regions were identified by two critical Reynolds numbers, i.e., Re = 1 and 20. Only Regions I and II of the wet thickness could be found for horizontal coating, while mainly Regions II and III were obtained for vertical coating, depending on the viscosity of the coating solution. POLYM. ENG. SCI., 47:1927–1936, 2007. © 2007 Society of Plastics Engineers     

Transesterifications in a polyblend of poly(butylene terephthalate) and a liquid crystalline polyester

Transesterfication between a liquid crystalline polyster and poly(butylene terephthalate) was followed quantitatively by analyzing ¹³C-NMR spectra of the 50:50 blend after heat treatmetn at 290°C for varying lengths of time. Differential scanning nalysis was employed to follow the interchange reactions. From analysis of triad sequences of the transesterified blends, it was clear that measurable exchange reactions occurred when the blend was kept at 290°C for 20 min. The distribution of sequences tends to approach that of a statistical binary copolymer as the heat treatment period is increased. The results ontained from this investigation show that polyblends between an LC polyesterand conventional polyesters must be handled carefully. Otherwise, ester interchange reactions are inevitable.     

Synthesis of organic–inorganic hybrid polymeric nanocomposites for the hard coat application

An organic–inorganic hybrid polymeric nanocomposite has been synthesized for making UV‐curable hard coats. This nanocomposite consists of nano‐sized colloidal silica functionalized with vinyltriethoxysilane (VTES) and dendritic acrylic oligomers (DAO) which have been formed earlier via a reaction of ethylenediamine (EDA) with trimethylopropane triacrylate (TMPTA). Applied as a hard coat on top of a polyethylene terephthalate (PET) film, this nanocomposite has a short UV‐cure time and the cured coat has an enhanced thermal decomposition temperature (T_d), 89–90% transparency, increased hardness up to 3H, better adhesion up to 4B, and a flat surface with a root mean square roughness of 2–4 nm. The preparation as well as the characterization of the constituting species and the final hybrid are described in detail. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3985–3993, 2007     

A Weighted Delaunay Triangulation Framework for Merging Triangulations in a Connectivity Oblivious Fashion

Simplicial meshes are useful as discrete approximations of continuous spaces in numerical simulations. In some applications, however, meshes need to be modified over time. Mesh update operations are often expensive and brittle, making the simulations unstable. In this paper we propose a framework for updating simplicial meshes that undergo geometric and topological changes. Instead of explicitly maintaining connectivity information, we keep a collection of weights associated with mesh vertices, using a Weighted Delaunay Triangulation (WDT). These weights implicitly define mesh connectivity and allow direct merging of triangulations. We propose two formulations for computing the weights, and two techniques for merging triangulations, and finally illustrate our results with examples in two and three dimensions.     

Extending the field of view: a human-centred design perspective on 360° TV

Omnidirectional video (ODV) is a type of video that presents viewers with a new type of interactivity. It enables people to look around in a 360° view of the recorded dynamic scene as if they are controlling the camera themselves. ODV presents opportunities for new interactive television formats. The development of such new formats, however, is accompanied by challenges in terms of user experience and technical and creative development. In this article, we discuss issues and opportunities tied to televising ODV from a user perspective. These findings are the result of a human-centred design study. In this study, we introduced 20 potential users to ODV, as this was new to them. We gathered their feedback on the demonstration, and then encouraged them to envision suitable ODV-based enhancements of television genres. This article offers a discussion of both the methodology (including a form of laddering) applied in the study and the user research findings. We found that people see an added value in ODV under certain conditions (e.g. enabling exploration), but that there are also a number of bottlenecks such as the concern to miss key parts of a television programme while looking around.     

Influence of processing conditions on the morphological and mechanical properties of compatibilized PP/LCP blends

The main aim of this work is to study the influence of the application of different processing conditions on the morphological and mechanical properties of thermoplastic/LCP blends, in which the viscosity ratios are inferior to unity and decrease with increasing temperature. The way the microstructure evolves along the extruder determines the final morphology and thus, the mechanical performance of the systems. In the present case, the mechanical properties are related with the degree of fibrillation in the final composites. The best degree of fibrillation was obtained for low screw speeds and temperatures and for intermediate outputs. The use of high screw speeds and processing temperatures results in a decrease of the viscosity ratio, in the former case via an increase in the viscous dissipation, at the regions of higher shear rates (kneading‐elements). The application of a lower processing temperature is advantageous for deformation, break‐up, and fibrillar formation because of the higher viscosity ratios and higher shear stresses involved. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Ethanolysis of castor and cottonseed oil: A systematic study using classical catalysts

Several classical catalytic systems for the transesterification reaction have been used to produce FA ethyl esters (FAEE) from castor and cottonseed oils The effects of the amount and nature of the catalyst, and of the reaction temperature, on the yields of FAEE were determined. The most efficient transesterification of castor oil was achieved in the presence of methoxide and acid catalysts, whereas for cottonseed oil, which has a composition that is much more similar to most vegetable oils than is castor oil, the highest yields of FAEE were obtained following base-catalysed ethanolysis.