bluuebunny/crossref_metadata_2025_split huggingface dataset:
Well‐Defined Aminophenolate Zinc and Magnesium Complexes as Excellent Inhitiators for the ROP of Lactides
Authors: Ejfler Jolanta , Szafert Sławomir , Sobota Piotr 
Published: November 2010

AbstractA series of molecular homo and heteroleptic zinc and magnesium compounds with aminophenolate ligands [(µ,η2‐L2)ZnEt]2 (1), [(η2‐L2)Zn(µ‐BnO)]2 (2), [Zn(η2‐L2)2] (3), [Zn(η2‐L3)2] (4), [Mg(η2‐L3)2] (5) (L2‐H = N‐[methylene(2‐hydroxy‐3,5‐di‐tert‐butylphenyl)]‐N‐methyl‐N‐cyclohexylamine, L3‐H = N‐[methylene(2‐hydroxy‐3,5‐di‐tert‐butylphenyl)]‐N‐methyl‐N‐methyl‐1,3‐dioxolaneamine) have been prepared and characterized. The homoleptic complexes 3–5 are most probably a mixture of diastereoisomers that in solution show an interesting dynamics which plays an important role in their catalytic behavior. The complexes 2–5 are efficient initiators in ring‐opening polymerization (ROP) of lactides to produce polymers with desired molecular weight and narrow polydispersity.
Photopolymerizable Elastomers for Vascular Tissue Regeneration
Authors: Baudis Stefan , Steyrer Bernhard , Pulka Thomas , Wilhelm Harald , Weigel Guenter , Bergmeister Helga , Stampfl Juergen , Liska Robert 
Published: November 2010

AbstractThe aim of this study was to design new resin formulations for blood vessel substitutes with small inner diameter that can be 3D‐printed by Additive Manufacturing (AM). Commercially available urethane oligomer acrylates as crosslinking agents (CAs) with different reactive diluents (RDs) and/or thiol chain transfer agents (CTAs) were examined. It could be shown that the properties of photopolymers of carefully selected CA/RD/CTA combinations can be varied in a wide range, also to fit with those of natural blood vessels. Moreover, these materials showed good biocompatibility in in‐vitro cell culture tests with endothelial cells. A new method to assess the tear resistance of the new materials in comparison with natural blood vessels was designed and established. The tear resistance of the developed photopolymers already approaches those of natural material, although there is still need of improvement. The 3D‐structuring of optimized resin system succeeded. Hence AM has proven to be an ideal tool to manufacture parts with the complex structure of natural blood vessels.
Prediction of Rheological and Chemical Properties of Different Starches Used in the Paper Industry by Near Infrared Spectroscopy (NIRS)
Authors: Schrampf Eva , Leitner Erich 
Published: November 2010

AbstractStarch is one of the most abundant biopolymers, consisting of the polysaccharides amylose and amylopectin and other minor but characteristic constituents depending on the origin. Potatoes, maize, wheat, rice and tapioca are the sources of commercial interest with a large variety of applications both in food and non food areas. The measurements of over hundred starch samples were accomplished over a range of 4000–10000 cm−1 in diffuse reflectance and transmission mode. Quantitative prediction models, based on a partial least squares (PLS) algorithm for the determination of fat content, the main fatty acids, water content, tendency to retrogradation and viscosity were developed. All models are characterized by high correlation coefficients (R2 > 0,98). Principal components analysis (PCA) was applied successfully to distinguish starches regarding their source, provenience and their degree of modification. Both quantitative and qualitative models are cross validated.
Thermoresponsive Hydrogels from Physical Mixtures of Self‐Assembling Peptide and its Conjugate with PNIPAAm
Authors: Maslovskis A. , Saiani A. , Miller A.F. 
Published: November 2010

AbstractThe phase behavior and rheology of a range of physical mixtures of self‐assembling octapeptide FEFEFKFK and its conjugate with the thermoresponsive polymer poly(N‐isopropylacrylamide) (PNIPAAM) have been studied. These systems typically combined the thermo‐responsive character of PNIPAAM and the gelling property of octapeptides where both the elastic behavior and macroscopic melting of the system could be controlled by varying the ratio of pure peptide to peptide‐polymer conjugate.
New Route to Polymeric Nanoparticles by Click Chemistry Using Bifunctional Cross‐Linkers
Authors: de Luzuriaga Alaitz Ruiz , Perez‐Baena Irma , Montes Sarah , Loinaz Iraida , Odriozola Ibon , García Ignacio , Pomposo José A. 
Published: November 2010

AbstractA new route to functional polymeric nanoparticles (PNPs) of different chemical nature in the 3 to 20 nm size range is reported by combining both radical addition fragmentation chain transfer (RAFT) polymerization and “click” chemistry (CC) techniques. RAFT polymerization was employed for the synthesis of well‐defined statistical copolymers with pending –Cl groups along the macromolecular chain. After transformation of the –Cl groups to –N3 groups by treatment with sodium azide, an appropriate bifunctional cross‐linker is employed to obtain PNPs under CC conditions promoting intramolecular cycloaddition (cross‐linking). Following this new route, polystyrene, poly(alkyl (meth)acrylate), polymethacrylic acid, poly(sodium styrenesulfonate) and poly(N‐isopropyl) NPs have been synthesized and in‐deep characterized.
Control of Nano‐Scale Structuring and Reinforcement in Rotational Molding of Polyethylene
Authors: Kulikov Oleg , Hornung Klaus , Wagner Manfred 
Published: November 2010

AbstractPolyethylene (PE) resins used for Rotational Molding have usually particle sizes less than 0.8 mm and used as powders or micro‐pellets. During heating in a rotating mould, these particles get fused and merge into one piece. A disadvantage of the rotomolding process is long cycle times that affect the production rate and increase thermal degradation of the polymer. One of the problems in rotomolding is bubbles of gasses trapped during sintering of the PE powders which reduce mechanical strength of the article produced. We propose to use reacting mixtures of PEG with citric acid as Processing Additive (PA) to rotomolding grades of PE. Silica fume and vinyl‐silanes can be other ingredients of the additive package. The PA accelerates sintering of the PE particulates and greatly reduces number of bubbles in the melt but at high concentrations it impedes flow of the particles. Powders are characterized by low flowability while micro‐pellets have too high flowability for rotomolding. To improve the rotomolding process we propose to fabricate micro‐pellets by extrusion of PE resins comprising the PA at reduced temperatures and pelletizing in open air. The same PA reduces extrusion pressure and suppresses flow instabilities during pelletizing as well as adjusts flowability of micro‐pellets to optimum, accelerates sintering of the PE particulates and removes bubbles from the PE melt. Mechanisms of the observed improvements are discussed.
About Durability of Biodegradable Polymers: Structure/Degradability Relationships
Authors: Commereuc S. , Askanian H. , Verney V. , Celli A. , Marchese P. 
Published: November 2010

AbstractUp to now materials were chosen to satisfy specific property(ies) in relation with the required application. Nowadays, a specific attention has to be devoted to the durability of this property regarding to the lifetime duration. It is the reason why, we paid attention about degradability. Thus, a screening of bio‐ and photodegradability of various selected (co)polyesters has been achieved in order to get better insights about structure / durability relationships. We developed tools allowing the prediction of the behavior of materials upon ageing and the evolution of their properties, regarding to their initial chemical structures. Hence, we could be able to design (co)polyesters characterized by well‐adapted physical, thermal and mechanical properties, but also, with high photostability and/or high biodegradability.
Water‐Soluble Polyelectrolytes with Ability to Remove Arsenic
Authors: Rivas Bernabé L. , Sánchez Julio , Pooley S. Amalia , Basaez Luis , Pereira Eduardo , Bucher Christophe , Royal Guy , Aman Eric Saint , Moutet Jean‐Claude 
Published: November 2010

AbstractArsenic species can be removed from aqueous solutions using the liquid‐phase polymer‐based retention, LPR, technique. The LPR technique removes ionic species by functional groups of water‐soluble polyelectrolytes (WSP) and then using a ultrafiltration membrane that does not let them pass through the membrane, thus separating them from the solution. The ability of WSP with groups (R)4N+X− to remove arsenate ions using LPR was studied. The interaction and arsenate anion retention capacity depended on: pH, the quaternary ammonium group's counter ion, and the ratio polymer: As(V), using different concentrations of As(V). Water‐soluble polychelates were also used for one‐step retention of As(III) in solution. The complex of poly(acrylic acid)‐Sn, 10 and 20 wt‐% of metal gave a high retention of As(III) species at pH 8, although the molar ratio polychelate: As(III) was 400:1. The enrichment method was used to determine the maximum retention capacity (C) for arsenate anions in aqueous solutions at pH 8. In similar conditions, the values of C were 142 mg g−1 for P(ClAETA) and 75 mg g−1 for P(SAETA). The combined treatment of arsenic aqueous solutions by electrocatalytic oxidation (EO) to convert the species of As(III) to As(V) with the LPR technique quantitatively removed arsenic.
Preparation, Characterization and Controlled Release Investigation of Biocompatible pH‐Sensitive PVA/PAA Hydrogels
Authors: Manavi‐Tehrani Iman , Rabiee Mohammad , Parviz Maryam , Tahriri Mohammad Reza , Fahimi Zahra 
Published: November 2010

AbstractIn the present research hydrogel films based on polyvinyl alcohol (PVA) and polyacrylic acid (PAA) blend, with various crosslink densities, have been prepared through different thermal treatment. The results of FTIR and DSC confirmed quality and quantity of conclusion on miscibility of PVA/PAA blends, respectively. Besides, biocompatibility of the samples has been proved in cytotoxicity tests using L929 cells, according to ISO10993–5. Water uptake of the hydrogel blends is measured. pH sensitivity properties of blends are studied with and without boiling in NaOH solutions where the effect of swelling in water before boiling has also been investigated. Preswellings in water and NaOH concentration have been found to be mainly effective on pH sensitivity of PVA/PAA blends. Biocompatibility and pH sensitivity behavior make these hydrogels appropriate candidates to orally deliver drugs such as insulin and peptides that can be released in basic pH of intestine. The stability of these films in acidic solutions and its expansion and also the consequent release of drugs in basic solutions have been studied by using Teofilin as a model drug by UV‐spectrophotometeric measurements.
SAXS Studies of Heating/Cooling Cycle Behavior of Biodegradable BTA/PLA‐b Blends
Authors: Kwiatkowski Ryszard , Dacko Piotr 
Published: November 2010

AbstractSummary: The blends of BTA copolyester (i.e. the Ecoflex® copolyester) and PLA‐b amorphous polylactide with following weight ratios: 90/10, 70/30 and 50/50 have been prepared and their phase structure have determined by using X‐ray methods and DSC method. The thermal behavior of the blends was tested by time resolved SAXS measurements performed during heating/cooling thermal cycle treatment (20÷135÷20 °C). As a result of analysis of desmeared Lorentz corrected SAXS curves using the Hosemann scattering function the changes of characteristics of lamellar structure of BT‐BA stacks within the blends have been determined and linked with changes of lamellar superstructure of the BTA reference sample. Among other thinks, it was found that the rate of the heating induced growth of the BA amorphous layers thickness and consequently of long period of BT‐BA stacks structure increases with the increase of PLA‐b amount, and that BT‐BA stacks are formed significantly later (ca. 5 min.) during the cooling of the melted blends than during the cooling of the melted BTA copolyester.
Well‐Defined Oxide Core‐Poly(vinyl pyrrolidone) Shell Nanoparticles: Interactions and Multi‐Modal Glass Transition Dynamics at Interfaces
Authors: Bershtein Vladimir , Gun'ko Vladimir , Egorova Larisa , Guzenko Natalia , Pakhlov Eugene , Ryzhov Valery , Zarko Vladimir 
Published: November 2010

AbstractInterfacial interactions and dynamics were studied in silica and alumina core‐poly(vinyl pyrrolidone) (PVP) shell nanoparticles with different shell thicknesses starting from 1‐2 nm (monolayer); their geometry and structural organization were comprehensively characterized by several techniques. Far‐ and mid‐IR spectroscopy, combined with DSC activation analysis of the glass transition, allowed to register hydrogen bonding and Lewis/Brønsted interactions, and the multi‐modal glass transition dynamics in PVP nanoshells, as well as their interrelationship. For PVP monolayer, only a few “abnormal” modes constituted glass transition which covered the temperature range from 80 to 230 °C, with varying the activation energy by an order of magnitude.
Modification of Silica by Liquid Polybutadienes Containing Alkoxysilane Groups
Authors: Colucci Giovanna , Di Gianni Anna , Bongiovanni Roberta , Priola Aldo , Torello Francesca , Bracco Silvia , Sozzani Piero 
Published: November 2010

AbstractSummary: The present work describes a method to modify the surface of silica, reducing its polar character and making it compatible and dispersible into hydrocarbon based elastomers. A liquid low molar mass polybutadiene (PB) was grafted with mercaptopropyltrimethoxysilane (MPTS) via radical addition of the thiol group to the double bonds. The silanized PB was reacted with silica via thermal condensation with its silanol groups. 29Si NMR spectra showed that the condensation reaction of the trifunctional silane involved one or two alkoxy groups, while the third alkoxy group remained unreacted, probably for steric reasons. The characterization of the functionalized silica particles was performed by contact angle measurements and TGA analysis.
Experimental Studies for Modelling the Phase Behaviour of Monomer/Polymer/Disc Composites
Authors: Torrens Francisco , Castellano Gloria 
Published: November 2010

AbstractNanoparticles do not stabilize the mixtures of epoxy monomer (prepolymer)/thermoplastic modifier (PS) and the ones of thermoplastic modifier dispersed within cured epoxy matrix. A small amount of thermoplastic co‐polymer poly(styrene‐b‐methyl methacrylate) [P(S‐b‐MMA)] of MMA 4–22 wt.%, mixed with PS, makes compatible the mixtures with monomer epoxy precursor and cured epoxy matrix. The mixtures of cured epoxy matrix with thermoplastic consisting of PS and P(S‐b‐MMA), with nanofil 1%, are stable: the instability produced by the nanofil is overcome by the stability provided by the co‐polymer. A model by Balazs' group to explain the phase behaviour of polymer/clay composites is extended.
Reactive EB Processing of Polymer Compounds
Authors: Gohs Uwe , Leuteritz Andreas , Naskar Kinsuk , Volke Sebastian , Wiessner Sven , Heinrich Gert 
Published: November 2010

AbstractPolymer modification with high energy electrons is well‐established in polymer industry and used for degradation, cross‐linking, grafting, curing, and polymerization. These applications use local and temporal precise input of energy in order to generate excited atoms or molecules as well as ions for subsequent molecule changes via radical induced chemical reactions. Reactive electron beam (EB) processing combines melt mixing process and chemical reaction simultaneously. For this purpose, a 1.5 MeV electron accelerator was directly coupled to an internal mixer in order to induce chemical reactions by energy input via high energy electrons under dynamic conditions of melt mixing of different polymer compounds. In the present study, reactive EB processing was used for the development of a flame retardant polyethylene composite as well as Thermoplastic Vulcanizate. The influence of absorbed dose as well as electron energy and electron treatment time was studied. Increased values of both tensile strength and elongation at break of polymer compounds indicated in‐situ compatibilization upon reactive EB processing.
Prediction of Tensile Curves of Rubber Materials by Different Network Models
Authors: Zidek Jan , Nezbedova Eva , Jancar Josef 
Published: November 2010

AbstractThe paper presents application of rubber elasticity theory to the predictive model of tensile mechanical properties. Poly(methyl methacrylate) was chosen as a model polymer. The input dates were crosslink density and type of chain. The crosslink density was taken from swelling experiment. Two types of chain were analyzed, namely worm like and chain with the realistic function of dihedral potential. Dihedral potential function was derived from molecular model of chain segment. Predictive tensile curve was compared with experimental one. The similarity of potential functions of selective polymers (polypropylene, poly‐vinylchloride, poly‐vinylalcohol, poly‐vinylfluoride, polystyrene) enables to generalize this procedure.
A 1H NMR and theoretical investigation of the conformations of some monosubstituted cyclobutanes
Authors: Abraham Raymond J. , Leonard Paul , Tormena Cláudio F. 
Published: November 2010

AbstractThe complete analysis of the complex 1H NMR spectra of some monosubstituted cyclobutanes was achieved to give all the 1H chemical shifts and nJHH (n = 2, 3 and 4) coupling constants in these molecules. The substituent chemical shifts of the substituents in the cyclobutane ring differ significantly from those in acyclic systems. For example, the OH and the NH2 groups in cyclobutanol and cyclobutylamine produce a large shielding of the hydrogens of the opposite CH2 group of the ring compared with little effect on the comparable methylene protons of butane. These effects and the other 1H shifts in the cyclobutanes were modelled successfully in the CHARGE program. The RMS error (calculated vs observed shifts) for the 34 1H shifts recorded was 0.053 ppm. The conformational equilibrium in these compounds between the axial and the equatorial conformers was obtained by comparing the observed and the calculated 4JHH couplings. These couplings in cyclobutanes, in contrast to the corresponding 3JHH couplings, show a pronounced orientation dependence; 4Jeq–eq is ca 5 Hz and 4Jax–ax ca 0 Hz. The couplings in the individual conformers were calculated at the B3LYP/EPR‐III level. The conformer energy differences ΔGax–eq vary from 1.1 kcal mol−1 for OH to 0.2 kcal mol−1 for the CH2OH substituent. The values of the conformer energy differences are compared with the previous IR data and the corresponding theoretical values from molecular mechanics (MM) and DFT theory. Generally, good agreement is observed although both the MM and the DFT calculations deviate significantly from the observed values for some substituents. Copyright © 2010 John Wiley & Sons, Ltd.
Development and psychometric testing of the register – connectedness scale for older adults
Authors: Register M. Elizabeth , Herman JoAnne , Tavakoli Abbas S. 
Published: November 2010

AbstractConnectedness, maintaining active engagement with life, is crucial to successful aging. Yet, no instruments were found to measure connectedness. The purpose of this study was to develop and test a connectedness scale for older adults. A 72‐item instrument was administered to 428 community‐dwelling older adults. The sample was largely female, White widows/widowers, with a mean age of 76 (SD 6.95) years. The instrument was reduced to 45 items representing five factors with loadings ranging from .40 to .86. The factor labels and their reliability estimates were: (a) self‐regulating (.86), (b) facing aging (.85), (c) being part of a family (.87), (d) having friends (.87), and (e) being spiritual (.88). This promising instrument may advance the science of successful aging. © 2010 Wiley Periodicals, Inc. Res Nurs Health 34:60–72, 2011
Thermal stresses and birefringence in quenched tubes and rods: Simulation and experiment
Authors: Carrillo Antonio J. , Isayev A.I. 
Published: November 2010

AbstractMeasurements and simulations of the radial distribution of the thermal birefringence components, Δn and nθθ − nrr, and the average birefringence, <nzz − nθθ>, in free quenched tubes and rods of polystyrene (PS) and polycarbonate (PC) at different initial temperatures were carried out. The thermal stress and birefringence components were simulated using the linear viscoelastic and photoviscoelastic constitutive equations combined with the first‐order rate equation for volume relaxation and the master curves for the Young's relaxation modulus and strain‐optical coefficient functions of polymers. The numerical procedures used to discretize the governing equations using finite difference method were described. The obtained numerical results provided the evolution of stress and birefringence components with time during and after quenching and an explanation of the measured residual birefringence distribution in quenched tubes and rods. It was also found that the thickness of the slices removed from the samples to measure the thermal birefringence components, Δn and nθθ − nrr, was critical, in particular, when the initial temperatures were close to the glass transition temperature of polymers. With an increase of the initial temperature during quenching, a better agreement between the simulated and measured birefringence components was obtained. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers
Preparation and properties of PBS/sisal‐fiber composites
Authors: Feng Yanhong , Shen Hanzhi , Qu Jinping , Liu Bin , He Hezhi , Han Liyan 
Published: November 2010

AbstractWe report the preparation of polybutylene succinate (PBS)/sisal‐fiber (SF) composites. The effects of mixing temperature and of steam‐explosion pretreatment of SFs on the mechanical properties of the composites were investigated, and the mechanism of action was studied by infrared spectroscopy, scanning electron microscopy, and x‐ray photoelectron spectroscopy. The results indicate that as the mixing temperature increases, PBS flows better and can graft onto steam‐exploded sisal fiber (SESF), the interfacial bond property between SESF and PBS improves, and the mechanical properties of the composites improve. The mechanical properties of the composites are maximal for a mixing temperature of 200°C. The results also demonstrate that the cellulose content and the specific fiber surface area can be increased by steam‐explosion pretreatment, so that the mechanical properties of the composites can be improved. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers
Automated batch emulsion copolymerization of styrene and butyl acrylate
Authors: Mballa Mballa Monique A. , Schubert Ulrich S. , Heuts Johan P. A. , van Herk Alex M. 
Published: November 2010

AbstractThis article describes a method for carrying out emulsion copolymerization using an automated synthesizer. For this purpose, batch emulsion copolymerizations of styrene and butyl acrylate were investigated. The optimization of the polymerization system required tuning the liquid transfer method, sufficient oxygen removal from the reaction medium and setting a proper sampling procedure. The monomer conversion‐time plots obtained with gas chromatography revealed a good reproducibility of the automated reaction kinetics. Furthermore, the particle size distributions and the properties of the final products were found to be highly reproducible. The performance of the automated reactions was subsequently compared with the conventional ones: similar reproducibility of either synthetic method was observed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011