bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Molecular Weight on Physical and Mechanical Properties of Linear Symmetric S‐(S/B)‐S Triblock Copolymers
Authors: Thunga Mahendra , Staudinger Ulrike , Ganß Martin , Weidisch Roland , Knoll Konrad 
Published: December 2008

AbstractSymmetric linear S‐(S/B)‐S triblock copolymers with 80 wt.‐% of PS having a block composition of 20‐60‐20 and a S/B ratio of 70:30 in the middle block are studied with varying molecular weights ($\overline M _{\rm w}$). Increase in the$\overline M _{\rm w}$leads to a change in the morphology from disordered to ordered microphase separated structure, as characterised by TEM and SAXS. Two distinct glass transitions for PS‐ and PB‐rich phases are observed from DMA measurements, which are due to phase separation at high$\overline M _{\rm w}$. Rheological studies (master curves) reveal an extended rubbery plateau and a delay in the terminal response with an increase in$\overline M _{\rm w}$, whereas a terminal flow behaviour is observed for materials having a disordered nature at low$\overline M _{\rm w}$. A brittle‐to‐tough transition is observed from tensile tests with the increase in$\overline M _{\rm w}$.magnified image
New Block Copolymers with Poly(N,N‐dimethylaminoethyl methacrylate) as a Double Stimuli‐Responsive Block
Authors: Schacher Felix , Müllner Markus , Schmalz Holger , Müller Axel H. E. 
Published: December 2008

AbstractThe synthesis of several diblock copolymers with DMAEMA via anionic polymerization is presented; PS‐b‐PDMAEMA, PB‐b‐PDMAEMA, poly(p‐tert‐butoxystyrene)‐b‐PDMAEMA, and PEO‐b‐PDMAEMA. The latter was synthesized using sec‐butyllithium as initiator in presence of the phosphazene base t‐BuP4, enabling a facile changeover from an oxyanion to a carbanion. All reactions resulted in narrowly distributed block copolymers (PDI < 1.1). For PEO‐b‐PDMAEMA, diblock copolymers with a high blocking efficiency and a near‐narrow molecular weight distribution (PDI < 1.40) could be prepared. The advantage of the presented one‐pot synthesis is a significant higher blocking efficiency compared to commercially available PEO macroinitiators under similar conditions.magnified image
Preparation of Monodisperse Polylactide Microspheres by Dispersion Polymerization Using a Polymeric Stabilizer with Hydroxy Groups
Authors: Muranaka Makoto , Ono Tsutomu 
Published: December 2008

AbstractMonodisperse poly(D,L‐lactide) (PDLLA) microspheres have been prepared by dispersion polymerization of D,L‐lactide with a synthetic polymeric stabilizer. The polymerization is carried out in xylene/heptane (1:2, v/v) at 368 K for 3 h with poly[(dodecyl methacrylate)‐co‐(2‐hydroxyethyl methacrylate)] (P(DMA‐co‐HEMA)). P(DMA‐co‐HEMA) has hydroxy groups as an initiation group for pseudoanionic dispersion polymerization. The particle diameter and the coefficient of variation concerning the diameter distribution of the obtained PDLLA microspheres are 3.9 µm and 4.3%, respectively. In addition, from the results of dynamic light scattering measurements, it is found that P(DMA‐co‐HEMA) and the PDLLA‐grafted copolymer form a micellar structure in solution.magnified image
Structural characterization of flavonoid glycosides by multi‐stage mass spectrometry
Authors: Vukics Viktoria , Guttman András 
Published: December 2008

AbstractFlavonoids are secondary plant metabolites of great structural variety and high medicinal significance. The search for new chemical entities and the quality control of flavonoid containing natural products require easy‐to‐use but reliable and robust analytical methodologies. For structural elucidation of flavonoids and their glycosides, nuclear magnetic resonance (NMR) and mass spectroscopy (MS) are the generally used techniques. In phytochemical analyses, however, high amounts of flavonoids are difficult to isolate for NMR, thus low sample volume requiring MS based methods are emerging. This review summarizes and compares currently available methods for structural elucidation of flavonoids by LC–MS and LC–MSn, and focuses on the identification options of unknown flavonoid glycosides in complex samples (e.g., plant extracts) with the emphasis on the differentiation of isomeric compounds. © 2008 Wiley Periodicals, Inc., Mass Spec Rev 29:1–16, 2010
Investigation of Barrier Properties of Poly(ethylene vinyl acetate)/Organoclay Nanocomposite Films Prepared by Phase Inversion Method
Authors: Shafiee M. , Ramazani S.A. A. 
Published: December 2008

AbstractSummary: In this research work, to reduce permeability of poly(ethylene vinyl acetate) packaging films, organoclay nanocomposites of these thermoplastics were prepared by solution method. Organoclay are mixed with polyethylene vinyl acetate (EVA) with 18 and 28% of vinyl acetate (VA) content in solution phase. Solutions of 3, 5 and 7% of organoclay are prepared under reflux condition and then nanocomposite films are prepared by thermal phase inversion method. Morphological and gas barrier properties of different prepared samples have been investigated. Morphology of prepared nanocomposite films and order of exfoliation of clay were investigated using X‐ray diffraction (XRD) and transmission electron microscopy (TEM) instruments. XRD and TEM indicated that the prepared nanocomposites had predominantly intercalated morphologies. Gas permeability measurements showed that the presence of organoclay significantly increases the barrier properties of EVA/nanocomposite films even at the low concentration of clay.
Modeling of Viscoelastic Fluid Flow Behavior in the Circular Die Using the Leonov‐Like Conformational Rheological Constitutive Equations
Authors: Ramazani S.A A. , Kanvisi M. 
Published: December 2008

AbstractSummary: In this paper, the flow behavior of Leonov‐Like conformational rheological model, which has root in the generalized Poisson bracket formalism based on the conformation tensor, have been studied in the circular die flow. Prediction of the normal stress differences during the flow of these fluids lets us to follow and calculate relaxation dependent phenomena such as die swell. The model predictions have been compared for the four families of mobility expressions. The Study of the model prediction sensitivity to its mobility term shows that model predictions can cover a wide range of rheological behaviors generally observed for polymer melts and solutions in the circular die flow.
Metal Ions Uptake by Chelating Resin Derived from o‐Substituted Benzoic Acid and its Synthesis, Characterization and Properties
Authors: Shah Pathik M. , Shah Ajay V. , Shah Bhavna A. 
Published: December 2008

AbstractSummary: Chelating resin [AFM] was synthesized by condensation of Anthranilic acid, Formaldehyde with m‐Cresol. The chelating resin was characterized by FTIR Spectra, Elemental Analysis and SEM Photographs. The thermal behavior of the resin was characterized by TGA. The thermodynamic parameters such as Activation Energy (Ea), Order of decomposition (n), Entropy of decomposition (S*), Enthalpy (H*) and Free energy (G*) were calculated by Coats and Redfern method using TGA graph. The chelating behaviour of the prepared resin was studied out with using some metal ions [Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II)]. The sorption capacities of metal ions is found in the following order, Pb(II) < Zn(II) < Cd(II) < Cu(II) < Ni(II). The rate of half exchange was rapid t1/2 < 20 min for lead ion. The separation of binary mixtures [Cu(II) and Zn(II) in brass and Pb(II) and Cd(II)] was successfully carried out using Kd value.
Adsorption Behavior of Metal Ions by Amidoxime Chelating Resins
Authors: Nilchi A. , Rafiee R. , Babalou A. A. 
Published: December 2008

AbstractIn this work, the acrylonitrile (AN) – divinylbenzene (DVB) –methylacrylate (MA) resin was synthesized via suspension polymerization in the presence of toluene as diluent, and benzoylperoxide (BPO) as initiator. The effect of MA, toluene and alkaline treatment on the exchange capacity of the resin were investigated. The results showed that the anion exchange capacity decreased with an increase in the amount of MA, while alkaline treatment had no significant effect. Also, the cation exchange capacity increased with an increase in the amount of hydrophilic agent and reached a maximum point. The sorption equilibrium was achieved relatively fast within 40 mins, and the resin exhibited affinity towards lead (II), copper (II) and in particular uranium (VI). The adsorption of uranium was directly depended up on the pH value. Furthermore, the macroreticular chelating resin, containing amidoxime group had higher adsorption of uranium (VI) in comparison to other metal ions studied. Finally, the alkaline treatment enhanced the potential for much faster adsorption characteristics and the highly porous chelating resin provided a more favorable pore structure for the rapid rate of diffusion of metal ions.
Thermodynamic Analysis of Phase Separation of a Thermoplastic in the Precursors of Different Epoxy‐Amine Systems
Authors: López Joaquín , Rico Maite , Pena Carlos , Montero Belen 
Published: December 2008

AbstractThe miscibility of a thermoplastic, polystyrene (PS), with the precursors of several epoxy‐amine systems has been studied thermodynamically and experimentally. The epoxy‐amine systems were different only in the origin of amino groups, which were provided by a monoamine (MA) and a diamine (DA) in different proportions. Cloud‐point curves (CPC) at conversion zero were reported for five modified systems with different MA‐DA proportion. All CPCs showed an UCST behaviour. CPC shifted to lower temperatures when the ratio of MA/DA in the system increased, meaning that the MA produces an increase in the miscibility of the system. A model based on the Flory‐Huggins theory was used for the thermodynamic analysis, in which the dependence of interaction parameter on temperature and composition, χ(T,ϕ), and the polydispersity of components were considered. A general equation for χ(T,ϕ) also depending on the MA‐DA proportion was reached and used to obtain the phase diagram of the different systems. A high level of agreement between theoretical and experimental CPCs was obtained.
Synthesis and Properties of Highly Swelling PAAm/Chitosan Semi‐IPN Hydrogels
Authors: Mahdavinia Gholam Reza , Pourjavadi Ali , Zohuriaan‐Mehr Mohammad Jalal 
Published: December 2008

AbstractA semi‐interpenetrating polymer network (semi‐IPN) hydrogel composed of crosslinked chitosan and polyacrylamide (PAAm) was prepared in the presence of formaldehyde as a crosslinker. The swelling capacity of hydrogel was shown to be affected by the crosslinker and the PAAm/chitosan ratio. The PAAm/chitosan semi‐IPN hydrogels are swelled at low pHs that attributed to both osmotic pressure and repulsion of NH groups on chitosan backbones. The swelling of hydrogel in acidic pHs showed that with increasing of chitosan content in the hydrogel, the swelling capacity was increased. But the swelling capacity of hydrogel in neutral pH is reversed, i.e. the higher the PAAm/chitosan ratio, the higher the swelling capacity. The results also indicated that the semi‐IPN hydrogel had different swelling capacity in various pHs. It showed a reversible pH‐responsive behavior at pH 2 and 10.
Phenolic Antioxidant for Polyolefins from Grafted Phenol on Polyethylene Wax
Authors: Khalaf Moayad N. , Shnawa Hussein A. , Goda Mostafa K. , Lazem Mohamed A. , Abd‐Alemam Dia'a A. 
Published: December 2008

AbstractSummery: This study consists of the preparation of a new polymeric antioxidant from the grafting of phenol on the backbone of chlorinated polyethylene wax by alkylation's reaction in the presence of AlCl3 as catalyst. The chemical structure of the prepared phenolic polyethylene wax(ph ‐ wax) was characterized by FTIR. The thermal oxidation of HDPE was examined by monitoring the amount of O2 uptake by samples of HDPE with the (ph‐wax) volumetrically at 230 °C, also the thermal oxidation degradation of HDPE with the (ph‐wax) derivative was studied by monitoring the weight loss of the samples during heating at 250 °C and under normal air as atmosphere. The results of this study show a decrease in the rate of HDPE oxidation in the presence of ph‐wax at four percent (0.2, 0.4, 0.6 and 0.8) %wt/wt of polymer, while the oxidation time of HDPE increased from (5) min. for pure HDPE to reach (41) min. for (0.8) % sample. The thermograms and thermal data of this study indicate that the stability of HDPE increases with the percent of the (ph‐wax) (0.6 and 0.8) wt/wt%. Generally, these results show that phenolic wax has excellent performance as an antioxidant for polyethylene.
Holistic investment assessment: optimization, risk appraisal and decision making
Authors: Tziralis Georgios , Kirytopoulos Konstantinos , Rentizelas Athanasios , Tatsiopoulos Ilias 
Published: December 2008

AbstractOn deciding for the most appropriate investment when capital restrictions exist, investors define their alternatives and analyze each one of them. Traditionally, the definition, appraisal and analysis stages are treated separately. Herein, an innovative holistic method is proposed for bridging these stages. Within this method, investment attributes definition occurs by genetic algorithm optimization, while the analysis of the investment is realized through simulation. The method also proposes theNPV Expected Shortfalland theNPV Risk Preference Indexas investment evaluation criteria. An illustrative case study of two mutually exclusive renewable energy investment scenarios is also used for demonstration purposes. Copyright © 2008 John Wiley & Sons, Ltd.
A class of implicit variational inequalities and applications to frictional contact
Authors: Capatina Anca , Cocou Marius , Raous Michel 
Published: January 2009

AbstractThis paper deals with the mathematical and numerical analysis of a class of abstract implicit evolution variational inequalities. The results obtained here can be applied to a large variety of quasistatic contact problems in linear elasticity, including unilateral contact or normal compliance conditions with friction. In particular, a quasistatic unilateral contact problem with nonlocal friction is considered. An algorithm is derived and some numerical examples are presented. Copyright © 2009 John Wiley & Sons, Ltd.
Some results concerning the state of bending for transversely isotropic plates
Authors: Passarella Francesca , Zampoli Vittorio 
Published: January 2009

AbstractIn this paper, we present a series of basic theorems for transversely isotropic plates characterized by a state of bending. More precisely, we show a reciprocal theorem and a uniqueness result without positive definiteness assumptions on the elastic coefficients. Moreover, we establish some variational and minimum principles. Finally, we give a Galerkin representation of the solution. Copyright © 2009 John Wiley & Sons, Ltd.
Residual rickets or osteomalacia: a case dating from the 16–18th centuries from Krosno Odrzańskie, Poland
Authors: Haduch E. , Szczepanek A. , Skrzat J. , Środek R. , Brzegowy P. 
Published: December 2008

AbstractA skeleton from a 16–18th century burial site in Krosno Odrzańskie, Poland, was examined using classical morphological, metric and macroscopic palaeopathological observations, as well as radiography and tomography of the skull and long bones. A wide variety of the observed bone deformations probably occurred as a consequence of past rickets and/or osteomalacia, whose primary cause may also have been chronic renal failure. Preservation of the bones enables a discussion of the cause of such pathological changes. The subject under study appears to be a very interesting example of an individual whose skeleton shows advanced pathological alterations associated with the subject's vitamin D deficiency, overall health conditions and relatively long lifespan. Copyright © 2008 John Wiley & Sons, Ltd.
Taphonomy, life history, and human exploitation of Rhinoceros sinensis at the Middle Pleistocene site of Panxian Dadong, Guizhou, China
Authors: Schepartz L. A. , Miller‐Antonio S. 
Published: December 2008

AbstractRhinoceros remains are commonly found in Chinese Pleistocene archaeological localities. This study examines the characteristics of the Rhinoceros sinensis sample from Panxian Dadong, a karst cave in the mountains of western Guizhou province, with a mammalian fauna in association with stone artefacts and human remains from the late Middle Pleistocene (MIS 6‐8). The distribution of skeletal elements shows a predominance of foot (metapodial and phalanges) and lower limb (carpals and tarsals) bones, while the dental age‐at‐death profile, constructed using dental eruption and tooth wear data, is characterised by a high frequency of prime age adult teeth. There is little taphonomic evidence for the involvement of non‐human carnivores or natural agencies in the formation of the faunal assemblage. Instead, it appears that human activities were responsible for the unexpected prevalence of prime age adults. Copyright © 2008 John Wiley & Sons, Ltd.
Synthesis and characterization of thermotropic liquid crystalline polyurethanes from 4,4′‐bis(6‐hydroxyhexoxy) biphenyl and aliphatic diols
Authors: Wei Chun , Gong Yongyang , Yang Xianglian , Wang Min 
Published: December 2008

AbstractA series of thermotropic liquid crystalline polyurethanes (LCPUs) were synthesized by the polyaddition reactions of 2,4‐toluene diisocyanate (2,4‐TDI) with 4,4′‐bis(6‐hydroxyhexoxy)biphenyl (BHHBP) and aliphatic diol. The intrinsic viscosities of the polymers were measured by Ubbelohde viscometer, and the chemical structure was confirmed by Fourier transform infrared spectroscopy (FT‐IR). The LCPUs were examined by differential scanning calorimetry (DSC), polarized optical microscopy (POM), wide angle X‐ray diffraction (WAXD), and thermogravimetric analysis (TGA). The intrinsic viscosities were 0.56–0.83 dl/g. According to the melting point (Tm) and the isotropic temperature (Ti) of the LCPUs, the temperature range of the liquid crystalline phase became wider with increased number of methylene spacers in the polyurethane. The LCPUs exhibited a nematic phase with a threaded texture and had a wide mesophase temperature range. The decomposition temperature of the LCPUs was  >300°C. On WAXD, the LCPUs give a dispersing peak at 2θ ≈ 20°, and a strong diffraction peak at 2θ ≈ 25°. Copyright © 2008 John Wiley & Sons, Ltd.
Synthesis and properties of poly(acrylamide‐co‐acrylic acid)/polyacrylamide superporous IPN hydrogels
Authors: Ao Haiyong , Huang Miaoliang , Wu Jihuai , Lin Jianming , Tang Qunwei , Sun Hui 
Published: December 2008

AbstractPoly(acrylamide‐co‐acrylic acid)/polyacrylamide [P(AM‐co‐AA)/PAM] hydrogel with superporous and interpenetrating network (IPN) structure was prepared by a prepolymerization reaction and a synchronous polymerization reaction and frothing process. Scanning electron microscope (SEM) images show that the resultant hydrogel possesses abundant interconnected pores. DSC indicates that the porous structure enhances the swelling ratio and reduces the interaction between water and the hydrogel. In contrast, the IPN by PAM decreases water absorbency and enhances water retentivity. It is found that a superporous stucture in the hydrogel increases the equilibrium swelling ratio and decreases the compressive strength of the hydrogel. On the other hand, the increase in AM oligomer (oligo‐AM) amount decreases the equilibrium swelling ratio and improves the compressive strength of the hydrogel. Therefore, the two‐steps synthesis method can be used to construct a hydrogel with superporous and IPN structure. The swelling and mechanical properties of the hydrogel can be improved effectively. Copyright © 2008 John Wiley & Sons, Ltd.
Biocomposites based on Alfa fibers and starch‐based biopolymer
Authors: Belhassen R. , Boufi S. , Vilaseca F. , López J. P. , Méndez J. A. , Franco E. , Pèlach M. A. , Mutjé P. 
Published: December 2008

AbstractBiocomposite materials based on Alfa cellulose fibers (esparto grass plant) as reinforcing element and starch‐based biopolymer matrix were prepared and characterized in terms of mechanical performance, thermal properties, and water absorbance behavior. The fibers and the matrix were first mixed in the melted state under mechanical shearing using a plastograph and the obtained composites were molded by injection process. The tensile mechanical analysis showed a linear increase of the composite flexural and tensile modulus upon increasing the fiber content, together with a sharp decrease of the elongation at break. The fibers′ incorporation into the biopolymer matrix brings about an enhancement in the mechanical strength and the impact strength of the composite. Dynamic mechanical thermal analysis (DMTA) investigation showed two relaxations occurring at about −30 and 35°C. The addition of Alfa fibers enhanced the storage modulus E′ before and after Tα, which is consistent with the reinforcing effect of Alfa cellulose fibers. Copyright © 2008 John Wiley & Sons, Ltd.
Estrogens and the risk of complex regional pain syndrome (CRPS)
Authors: de Mos M. , Huygen F. J. P. M. , Stricker B. H. Ch. , Dieleman J. P. , Sturkenboom M.C. J. M. 
Published: December 2008

AbstractObjectiveSince complex regional pain syndrome (CRPS) shows a clear female predominance, we investigated the association between the cumulative as well as current exposure to estrogens, and CRPS.MethodsA population‐based case–control study was conducted in the Integrated Primary Care Information (IPCI) project in the Netherlands. Cases were identified from electronic records (1996–2005) and included if they were confirmed during a visit (using International Association for the Study of Pain Criteria), or had been diagnosed by a specialist. Controls were matched to cases on gender, age, calendar time, and injury. Measures of cumulative endogenous estrogen exposure were obtained by questionnaire and included age of menarche and menopause, menstrual life, and cumulative months of pregnancy and breast‐feeding. Current estrogen exposure at CRPS onset was retrieved from the electronic medical records and determined by current pregnancy or by the use of oral contraceptive (OC) drugs or hormonal replacement therapy (HRT).ResultsHundred and forty‐three female cases (1493 controls) were included in analyses on drug use and pregnancies, while cumulative endogenous estrogen exposure was studied in 53 cases (58 controls) for whom questionnaire data were available. There was no association between CRPS and either cumulative endogenous estrogen exposure, OC, or HRT use. CRPS onset was increased during the first 6 months after pregnancy (OR: 5.6, 95%CI: 1.0–32.4), although based on small numbers.DiscussionWe did not find an association between CRPS onset and cumulative endogenous estrogen exposure or current OC or HRT use, but more powered studies are needed to exclude potential minor associations. Copyright © 2008 John Wiley & Sons, Ltd.