bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of the Organoclay Structure on Morphology and Rheological Response of PBT Nanocomposites
Authors: Scarfato P. , Scatteia L. , Costa G. , Acierno D. 
Published: September 2005

AbstractIn this paper the effect of different organoclays on the structure and the rheological properties of poly(butyleneterephtalate)–clay nanocomposites produced by melt compounding was investigated. The study was carried out using as nanometric fillers four commercial montmorillonites, treated with different organic modifiers and having similar interlayer spacing and organo‐modifier concentration. Each organoclay was melt compounded with PBT (at 3%, 6% and 9% by weight of clay) using a twin screw extruder. Using the same processing conditions, hybrid samples containing the unmodified silicate were also prepared for comparison purposes. All the obtained nanocomposite samples were submitted to physico‐chemical (XRD, TEM and FT‐IR), and rheological measurements in order to evidence the role of polymer‐clay affinity on the morphology and on the viscoelastic response of the materials. The results have pointed out that, with the used processing conditions, all nanocomposites exhibit a mixed intercalated/exfoliated structure; nevertheless, the clay dispersion homogeneity and the exfoliation level reached in the samples are higher for Nanofil 919 and Dellite 43B fillers, the organic modifiers of which may favorably interact with PBT matrix.
Fabrication and Characterization of Sensitive Polymer (Nano)Composites
Authors: Loffredo Fausta , Quercia Luigi , Massera Ettore , Di Francia Girolamo 
Published: September 2005

AbstractWe report on the fabrication process of a polymer sensing device based on a thin film composite obtained by spinning or casting a carbon fillers/thermoplastic polymer dispersion on a glass substrates. In this work we produce thin composite films characterized by different grade of dispersion of carbon black in polymer matrix (Poly(methyl‐methacrylate), Poly(2 hydroxy‐ethyl‐methacrylate) and atactic poly(styrene)). We discuss, in particular the effect of the polymer and filler characteristics on the thin film morphology. Device material response towards different analytes will be also discussed. Size distribution of filler in polymer suspension and deposition method type strongly influence homogeneity and conductivity of corresponding polymer composite films and finally their sensor properties.
Practical and Theoretic Analysis of Resin Flow in Vacuum Assisted Resin Transfer Molding Processes
Authors: Tuccillo F. , Antonucci V. , Calabrò A.M. , Giordano M. , Nicolais L. 
Published: September 2005

AbstractIn this study, the non‐isothermal resin infiltration during the VARTM process has been analyzed and characterized.In particular, the resin flow through the fibers has been described by the Darcy law and introducing the degree of saturation, the percent of void effectively occupied by the resin within a control volume, as variable in order to account for the moving boundary nature of the problem.Some preliminary tests to measure the advancement of a reference substance, pure water, between the reinforcement fibers with embedded optic fibers sensors, show the capability of a new sensorial technology, based on use of non intrusive fiber optic COTS components, assembled into an original way. These sensors will be used for real time monitoring of the resin flow during the experimental infusion tests and for in‐situ demonstration of the capability and the reliability of the model, in the aim to assure a “process repeatability”.Due the effectiveness lack of repeatability of VARTM, the Authors propose an approach to extract a parameter during the process, meaning a “Deviation” of modelized output (MOD Modelized Output Deviation). This parameter, obtained by use of optic fibers technology, may improve the standard quality of the production, analyzing and correcting with feed‐back capability the efficiency of the moulded manufactured devices.
Non‐Conventional Curing of Organic‐Inorganic Hybrids
Authors: Leonelli Cristina , Messori Massimo , Pilati Francesco , Veronesi Paolo 
Published: September 2005

AbstractInfrared and microwave curing of organic–inorganic hybrid materials was studied, in order to achieve the maximum conversion without detrimental effects due to the overheating or to the long‐time permanence at high temperature.Partially cured poly(ethylene oxide)/silica hybrids were prepared by hydrolysis and subsequent condensation of precursors for 30 minutes isothermal heat treatment at 70°C. The conversion after the preliminary treatment is still low and requires an additional heating to complete the reaction. Three different thermal treatments were investigated: conventional heating, infrared heating and microwave heating.DSC characterisation of the obtained samples evidenced a drastic reduction of the treatment time when microwaves were used, requiring only a few seconds, compared to the hours‐lasting conventional treatments.
Fracture Behaviour and Deformation Mechanisms of Polyimide/Silica Hybrids
Authors: Ragosta Giuseppe , Musto Pellegrino , Abbate Mario , Russo Pietro , Scarinzi Gennaro 
Published: September 2005

AbstractFilms of particulate polyimide‐silica hybrids were produced by a sol‐gel process and were examined in terms of morphological structure and fracture properties at different temperatures, varying from 20 to 250 °C.The fracture toughness characteristics were studied by the “Essential Work of Fracture” method using double edge‐notched specimens of different ligament lengths. The results showed that the fracture toughness, expressed through the essential (we) and non‐essential work of fracture (βwp) parameters increased when submicron silica particles were dispersed in the polyimide matrix. In particular, it was found that both we and βwp increased with temperature to a larger extent than the parent polyimide. This enhancement in the fracture toughness was attributed to extensive cavitations and shear yielding originating at the particle interface and within the matrix.
Impact of cognitive task on the posture of elderly subjects with Alzheimer's disease compared to healthy elderly subjects
Authors: Manckoundia Patrick , Pfitzenmeyer Pierre , d'Athis Philippe , Dubost Véronique , Mourey France 
Published: September 2005

AbstractThe aims of this study were to analyze the effects of cognitive task on static posture in Alzheimer's disease (AD) and in healthy elderly (HE) subjects and to evaluate whether those effects were greater in AD subjects than in HE subjects. We performed a posturographic analysis on 13 subjects with mild AD (mean age, 79.7 ± 5.1 years, Mini‐Mental State Examination scores between 18 and 23) and on 17 HE subjects (mean age, 78.5 ± 4.4 years). After watching a video sequence, the subjects were asked to maintain a stable upright posture while standing on a force platform. Then, the postural sway was measured during the following two conditions: (1) quiet standing and (2) both standing and answering questions about the video sequence. We were interested in the center of pressure (CoP) area and path. For each group, the single task was compared to the dual task for the CoP area and path. We also compared the variability of both CoP area (variation of the CoP area between the single and the dual task) and path (variation of the CoP path between the single and the dual task) between the two groups. We showed that there was no significant difference between the single and the dual task in HE subjects concerning the CoP area and path, in contrast to the AD group, and that variability of both the CoP area and path were significantly greater in the AD subjects than in the HE subjects. This finding may contribute to the risk of falls in AD patients. © 2005 Movement Disorder Society
Undersampling k‐space using fast progressive 3D trajectories
Authors: Spiniak Juan , Guesalaga Andres , Mir Roberto , Guarini Marcelo , Irarrazaval Pablo 
Published: September 2005

AbstractIn 3D MRI, sampling k‐space with traditional trajectories can be excessively time‐consuming. Fast imaging trajectories are used in an attempt to efficiently cover the k‐space and reduce the scan time without significantly affecting the image quality. In many applications, further reductions in scan time can be achieved via undersampling of the k‐space; however, no clearly optimal method exists. In most 3D trajectories the k‐space is divided into regions that are sampled with shots that share a common geometry (e.g., spirals). A different approach is to design trajectories that gradually but uniformly cover the k‐space. In the current work, successive shots progressively add sampled regions to the 3D frequency space. By cutting the sequence short, a natural undersampled method is obtained. This can be particularly efficient because in these types of trajectories the contribution of new information by later shots is less significant. In this work the performance of progressive trajectories for different degrees of undersampling is assessed with trajectories based on missile guidance (MG) ideas. The results show that the approach can be efficient in terms of reducing the scan time, and performs better than the stack of spirals (SOS) technique, particularly under nonideal conditions. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Quantitation and localization of blood‐to‐brain influx by magnetic resonance imaging and quantitative autoradiography in a model of transient focal ischemia
Authors: Knight Robert A. , Nagaraja Tavarekere N. , Ewing James R. , Nagesh Vijaya , Whitton Polly A. , Bershad Eric , Fagan Susan C. , Fenstermacher Joseph D. 
Published: September 2005

AbstractThe ability of gadolinium‐diethylenetriaminepentaacetic acid (Gd‐DTPA) enhanced MRI to localize and quantitate blood–brain barrier (BBB) opening was evaluated against quantitative autoradiographic (QAR) imaging of 14C‐α‐aminoisobutyric acid (AIB) distribution. The blood‐to‐brain transfer constant (Ki) for Gd‐DTPA was determined by MRI in rats after 3 h of focal cerebral ischemia plus 2.5 h of reperfusion (n = 9), and that of AIB was determined by QAR shortly thereafter. Tissue regions of interest (ROIs) for Gd‐DTPA leakage were identified by ISODATA segmentation of pre‐ and post‐Gd‐DTPA Look–Locker (L‐L) T1 maps. Patlak plots were constructed using time course of blood and tissue T1 changes induced by Gd for estimating Ki. Among the nine rats, 14 sizable regions of AIB uptake were found; 13 were also identified by ISODATA segmentation. Although the 13 MRI‐ROIs spatially approximated those of AIB uptake, the segmentation sometimes missed small areas of lesser AIB uptake that did not extend through more than 60% of the 2.0‐mm‐thick slice. Mean Ki's of AIB were highly correlated with those of Gd‐DTPA across the 13 regions; the group means (±SD) were similar for the two tracers (7.1 ± 3.3 × 10−3 and 6.8 ± 3.5 × 10−3 ml.g−1 · min−1, respectively). In most instances, Gd‐DTPA MRI accurately localized areas of BBB opening. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Low density polyethylene and grafted lignin polyblends using epoxy‐functionalized compatibilizer: mechanical and thermal properties
Authors: Sailaja RRN 
Published: September 2005

AbstractLignin was graft copolymerized with methyl methacrylate using manganic pyrophosphate as initiator. This modified lignin was then blended (up to 50 wt%) with low density polyethylene (LDPE) using a small quantity of poly[ethylene‐co‐(glycidyl methacrylate)] (PEGMA) compatibilizer. The mechanical properties of the blend were substantially improved by using modified lignin in contrast to untreated lignin. Differential scanning calorimetry studies showed loss of crystallinity of the LDPE phase owing to the interaction between the blend components. Thermogravimetric analysis showed higher thermal stability of modified lignin in the domain of blend processing. This suggested that there is scope for useful utilization of lignin, which could also lead to the development of eco‐friendly products. Copyright © 2005 Society of Chemical Industry
Hydrophilic–hydrophobic AB diblock copolymers containing poly(trimethylene carbonate) and poly(ethylene oxide) blocks
Authors: Feng Yakai , Zhang Shifeng 
Published: September 2005

AbstractAB‐type block copolymers with poly(trimethylene carbonate) [poly(TMC); A] and poly(ethylene oxide) [PEO; B; number‐average molecular weight (Mn) = 5000] blocks [poly(TMC)‐b‐PEO] were synthesized via the ring‐opening polymerization of trimethylene carbonate (TMC) in the presence of monohydroxy PEO with stannous octoate as a catalyst. Mn of the resulting copolymers increased with increasing TMC content in the feed at a constant molar ratio of the monomer to the catalyst (monomer/catalyst = 125). The thermal properties of the AB diblock copolymers were investigated with differential scanning calorimetry. The melting temperature of the PEO blocks was lower than that of the homopolymer, and the crystallinity of the PEO block decreased as the length of the poly(TMC) blocks increased. The glass‐transition temperature of the poly(TMC) blocks was dependent on the diblock copolymer composition upon first heating. The static contact angle decreased sharply with increasing PEO content in the diblock copolymers. Compared with poly(TMC), poly(TMC)‐b‐PEO had a higher Young's modulus and lower elongation at break. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4819–4827, 2005
New developments in the synthesis and characterization of phosphate esters of linear (per)fluoropolyether monofunctional and difunctional macromonomers
Authors: Russo Antonio , Tonelli Claudio , Barchiesi Emma 
Published: September 2005

AbstractThe synthesis of (per)fluoropolyether phosphate esters prepared by the reaction of phosphorus pentoxide and fluorinated alcohols has been investigated. The reactivity strongly depends on the structure of the fluorinated alcohol, generally decreasing with increasing acidity. Moreover, the addition of a modulated amount of water to the starting fluorinated alcohol allows the fine‐tuning of the monoalkylester and dialkylester contents in the final products. Therefore, when difunctional perfluoropolyether macromonomers are considered, the polymerization degree can be varied, and phosphate oligoesters of different molecular weights can be obtained in high yields, even if, as in this study, the synthesis is focused on low‐molecular‐weight oligomers. This easy control of the oligoester composition in the final product makes it possible to address the synthesis of phosphate oligoesters having a well‐defined equivalent weight, which also depends on the average molecular weight of the starting alcohol. The full characterization of the products is made possible by the combination of different NMR techniques (1H, 19F, 31P, 13C, and two‐dimensional NMR: 31P–1H and 31P–13C). This synthetic route shows great potential and opens the way to a new family of interesting candidates for the treatment of different organic or inorganic substrates to impart phobic properties against both polar and apolar substances. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4790–4804, 2005
Side‐chain terpyridine polymers through atom transfer radical polymerization and their ruthenium complexes
Authors: Tzanetos Nikos P. , Andreopoulou Aikaterini K. , Kallitsis Joannis K. 
Published: September 2005

AbstractPolymers containing side‐chain terpyridine ligands of well‐defined architectures and controllable molecular weights and molecular weight distributions are reported. These polymers were synthesized by the atom transfer radical polymerization (ATRP) of a newly synthesized terpyridine monomer with three functional initiators. The obtained polymers were characterized with 1H NMR and gel permeation chromatography techniques. The efficiency of the ATRP technique and the overall control of the molecular characteristics of the polymers were demonstrated by a kinetic study of the polymerization reaction. Subsequently, the ruthenium(III)/ruthenium(II) complexation chemistry was employed for the attachment of bis(dodecyloxy)‐functionalized terpyridine moieties onto each side 2,2′:6′,2″‐terpyridine unit of the main polymeric backbone. Thus, the grafting approach was successfully combined with the metal–ligand coordination chemistry for the preparation of highly soluble polymeric complexes. The resulting complexes were fully characterized by means of 1H NMR, gel permeation chromatography, and ultraviolet–visible spectroscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4838–4848, 2005
Preparation of polyurethane dispersions by miniemulsion polymerization
Authors: Li Chien‐Yu , Chiu Wen‐Yen , Don Trong‐Ming 
Published: September 2005

AbstractWith a two‐step miniemulsion polymerization, hydrophobic polyurethane (PU) dispersions were prepared with a cosurfactant, the costabilizer hexadecane (HD) in the oil phase, and sodium dodecyl sulfate (SDS) in the water phase. The first step involved the formation of NCO‐terminated prepolymers between isophorone diisocyanate and poly(propylene glycol) oligomer in toluene. Next, PU dispersions were produced by a miniemulsion method in which an oil phase containing NCO‐terminated prepolymers, HD, the chain extender 1,4‐butanediol (BD), the crosslinking agent trimethylol propane (TMP), and the catalyst dibutyltin dilaurate was dispersed in the water phase containing SDS. The influence of experimental parameters, such as the ultrasonication time, concentrations of SDS and HD, and TMP/BD and NCO/OH equivalent ratios, on the sizes of the miniemulsion droplets and polymer particles, as well as the molecular weights and thermal properties of the PU polymer, was examined. The chemical structure of the produced PU polymer was identified with a Fourier transform infrared spectrometer. The molecular weight distribution and average particle size were measured through gel permeation chromatography and dynamic light scattering, respectively. The thermal stability of the PU polymer was characterized with thermogravimetric analysis. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4870–4881, 2005
Preparation by controlled radical polymerization and self‐assembly via base‐recognition of synthetic polymers bearing complementary nucleobases
Authors: Lutz Jean‐François , Thünemann Andreas F. , Nehring Rainer 
Published: September 2005

AbstractThe radical polymerization of three monomers bearing nucleobases 1‐(4‐vinylbenzyl)thymine (VBT), 1‐(4‐vinylbenzyl)uracil (VBU) and 9‐(4‐vinylbenzyl)adenine (VBA) was investigated. The corresponding homopolymers could be prepared in high yields via conventional radical polymerization. However, the resulting polymers were found to be only soluble in a few polar solvents. On the other hand, copolymers of dodecyl methacrylate (DMA) with either VBT or VBA could be prepared via both free radical polymerization and atom transfer radical polymerization and could be dissolved in a large variety of organic solvents. Moreover, the formed complementary copolymers P(VBT‐co‐DMA) and P(VBA‐co‐DMA) were found to self‐assemble in dilute solutions in dioxane or chloroform via base recognition, as evidenced by a significant hypochromicity effect in UV spectroscopy. Nevertheless, at higher concentrations in chloroform, both dynamic light scattering and optical microscopy indicate that P(VBT‐co‐DMA), P(VBA‐co‐DMA), or P(VBT‐co‐DMA)/P(VBA‐co‐DMA) mixtures spontaneously self‐assemble into micron size spherical aggregates. 1H NMR and FTIR studies confirmed that the self‐assembly process is driven in all cases via H‐bond formation. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4805–4818, 2005
Increased thermal conductivity of free‐standing low‐dislocation‐density GaN films
Authors: Liu Weili , Balandin Alexander A. , Lee Changho , Lee Hae‐Yong 
Published: September 2005

AbstractProposed high‐power electronic and optoelectronic applications of GaN materials rely heavily on the effectiveness of heat removal from the devices. Here we report the results of our measurements of thermal conductivity in the thick free‐standing GaN films prepared by hydride vapor phase epitaxy. The fabrication method allows one to grow the low‐dislocation density films without the use of non‐native substrates. Our experimental data show that the room tempera‐ ture thermal conductivity in free‐standing GaN films can be as high at 225 W/mK, which is a factor of 1.8 increase compared to a reference GaN film grown on sapphire substrate. The modeling, performed for the given sample parameters, indicates that the low‐temperature thermal conductivity can reach a record value of 7460 W/mK. The presented results are important for the thermal management optimization of GaN‐based devices. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
‘Inclusive’ design for containers: improving openability
Authors: Langley J. , Janson R. , Wearn J. , Yoxall A. 
Published: September 2005

AbstractFor many years the standard engineering design approach has been to design for the most common size or ability and hence ensuring that your product is applicable to the broadest proportion of society. Recently, however, this approach has been seen to be flawed, particularly with regards to consumer packaging (although there many examples in other industries, such as transport). This paper outlines a new approach to packaging design that has been termed ‘inclusive’ design. Copyright © 2005 John Wiley & Sons, Ltd.
Geometry of 1,3‐dihalocyclobutanes by dipole moment analysis
Authors: Lampman Gary M. , Aumiller James C. 
Published: September 2005

AbstractThe dipole moments of cis and trans‐1,3‐dichloro‐, 1,3‐dibromo‐, and 1,3‐diiodocyclobutanes were obtained. The deviation from planarity (angle of puckering) was calculated from the dipole moments. In all cases, the compounds were found to be non‐planar (puckered). Although the angle strain increases slightly for a non‐planar ring, the decrease in torsional strain becomes more important. For the cis‐series, it was found that the angle of puckering was largest for the 1,3‐diiodocyclobutane. For the trans‐series the angle of puckering was the least for the 1,3‐diiodocyclobutane. trans‐1,3‐Dibromo‐1,3‐dimethylcyclobutane has the least amount of puckering of all the compounds studied. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
A new interface to couple thin‐layer chromatography with laser desorption/atmospheric pressure chemical ionization mass spectrometry for plate scanning
Authors: Peng Song , Edler Michael , Ahlmann Norman , Hoffmann Thorsten , Franzke Joachim 
Published: September 2005

AbstractAn interface to allow on‐line qualitative and quantitative full‐plate detection and analysis of compounds separated by thin‐layer chromatography (TLC) is presented. A continuous wave diode laser is employed as a desorption source. Atmospheric pressure chemical ionization mass spectrometry ionizes and subsequently identifies the desorbed sample molecules. Besides direct laser desorption on untreated TLC plates, graphite particles were used as a matrix to couple in the laser power and improve the efficiency of desorption. Copyright © 2005 John Wiley & Sons, Ltd.