bluuebunny/crossref_metadata_2025_split huggingface dataset:
Organic Ion Exchangers. Synthesis and Their Behaviour in the Retention of Some Metal Ions
Authors: Neagu Violeta , Bunia I. , Luca Cornelia 
Published: March 2006

AbstractSummary: Three pyridine strong base anion exchangers as beads were obtained by quaternization reactions of a 4‐vinylpyridine : 8% divinylbenzene copolymer of gel type. These resins possess methyl / ethyl / butyl radicals as substituents on N+ atoms and have exchange capacities of 4.80 mEq/g and 2.10 mEq/mL. For pyridine strong base anion exchangers, the behaviours in the retention processes of Cr(VI) as oxyanions and Ga(III) as [GaCl4]− complex anion were evaluated with the bath method. All the resins exhibited retention properties, but the retained amounts of the metal cations are different as a function of the alkyl length as substituent on N+ atoms and the complex anion nature. Thus, Cr(VI) oxyanions are best retained by the resin with CH3 as substituent on N+ atoms while [GaCl4]− complex anion by the resin with C4H9 as substituent on N+ atoms. By aminolysis reaction of an ethylacrylate : acrylonitrile : divinylbenzene copolymer as beads of macroporous type with NH2OH · HCl in the presence of C2H5OH a new chelating ion exchanger was performed which contains both amidoxime and hydroxamic acid functional groups.This ion exchanger has the retention property for different metal cations but its retention capacities values are strongly dependent of the nature of metal cation and the counterion as well as pH of the solution. Thus, in the static conditions Zn(II) cation with NO anion as counterion is retained with the best result at pH = 5. As an example, for the aqueous metal cation solution of 10−2 M concentration for Zn(NO3)2 the resin possess at equilibrium a retention capacity of 6.70 mmol Zn/g dry resin and for Cu(II) from Cu(NO3)2 solution of same concentration, the retention capacity is 0.22 mmol Cu/g dry resin and Fe(III) from Fe(NO3)3 solution is not retained.
Metal Ion Removal from Aqueous Solution by Liquid Phase Polymer‐Based Retention Technique
Authors: Rivas Bernabé L. , Pereira Eduardo D. , Robles Pamela , Cid Rocío 
Published: March 2006

AbstractSummary: Water‐soluble poly[3‐(dimethylamino)propylacrylate] is synthesized by radical polymerization with a yield of 87%. The polymer structure is confirmed by FT‐IR and 1H‐NMR spectroscopies. The polymer lost only 3% of weight up to 100 °C. The narrowest molecular weight distribution is observed with the fraction between 3,000 and 10,000 Da. P(DAPA) presents a high affinity for the metal ions Pb2+ and Cu2+, while the other metal ions are not significantly retained. By increasing the filtration factor, Z, metal ion affinity decreases, indicating a very weak ligand‐metal interaction and the possibility of its destruction when washed with water at the filtration cell's pH. For Z = 10, the retention values of Pb2+ and Cu2+ at pH 5 are 76.5% and 48.5%, respectively, while the values for Cu2+ and Cd2+ at pH 7 are 89.5% and 40.4%, respectively.
Spectrocyclic Voltammetry of Ruthenium Purple Electrodeposited on a WO3/Tris(2,2′‐bipyridine)‐ruthenium(II)/Polymer Hybrid Film
Authors: Sone Koji , Yagi Masayuki 
Published: March 2006

AbstractSummary: Electrochemical reactions of Ruthenium purple, Fe[RuII(CN)6]3 (RP; FeIII‐RuII) were studied using a spectrocyclic voltammetry (SCV) technique. The SCV measurement for an RP film coated on an ITO electrode showed a reversible redox between RP and Ruthenium white (RW; FeII‐RuII) at 0.14 V vs saturated calomel reference electrode (SCE). An RP film was electrodeposited on a hybrid film of tungsten trioxide (WO3)/tris(2,2′‐bipyridine)ruthenium(II) ([Ru(bpy)3]2+; bpy = 2,2′‐bipyridine)/poly(sodium 4‐styrenesulfonate) (PSS) (denoted as WRP film) from a colloidal solution containing 0.5 mM FeCl3, 0.5 mM K4[Ru(CN)6] and 40 mM KCl using a potentiodynamic multi‐sweep technique. In a cyclic voltammogram (CV) of a WRP/RP film, a redox response was observed at 0.61 V in addition to essential redox responses of WRP hybrid film (a [Ru(bpy)3]2+/[Ru(bpy)3]3+ redox at 1.03 V and a HxWO3/WO3 redox below 0.09 V), but a redox response of RW/RP was not observed at 0.14 V. The SCV measurement for the WRP/RP film suggested that the redox response at 0.61 V is attributed to a redox of [Ru(bpy)3]2+/[Ru(bpy)3]3+ interacted electrostatically with RP. It also showed that RW is oxidized to RP via [Ru(bpy)3]2+/[Ru(bpy)3]3+ redox and RP is reversibly reduced to RW via HxWO3/WO3 redox. This unique geared electrochemical reaction for the WRP/RP film leads to a hysteresis property of an RW/RP redox.
Synthesis of Citric Acrylate Oligomer and Its In‐Situ Reaction with Chrome Tanned Collagen (Hide Powder)
Authors: Haroun A. A. , Masoud R. A. , Bronco S. 
Published: March 2006

AbstractSummary: The purpose of this study was to formulate the new combined system of acrylic and citric acids, which was prepared by free radical polymerization and esterification reaction at the same time to form citric‐acrylate CAC oligomer. The presumable chemical structure of this oligomer and the reaction mechanism were investigated by different spectroscopic tools (1H,13C‐NMR and ATR‐IR), GPC and TGA/DTA. The effect as masking agent of the eco‐friendly oligomer (CAC) in the chrome tanning of the collagen and the pickling of the hide was approached by the study of the hydrothermal and mechanical properties of in‐situ treated/grafted chrome tanned collagen (hide powder) and pickled hide, respectively. The use of citric acrylate CAC oligomer instead of the traditional strong acids resulted in significant improvement in chrome exhaustion and physical properties of the leather.
Water Soluble Dextran‐Polyacrylamide Graft Copolymers for Capturing Metal Ions
Authors: Kutsevol N. , Guenet J.‐M. , Melnyk N. , Sarazin D. 
Published: March 2006

AbstractSummary: The graft copolymers of Polyacrylamide (PAA) to Dextran (Mw = 20000 and Mw = 70000) have been synthesised by ceric‐ion‐reduced redox initiation method. Molecular characteristic of graft copolymers were determined from light scattering, SEC, and viscometry data. It was established that the increase of molecular weight of Dextran component up to 3.5 times do not influence essentially organization at molecular level of these copolymers in aqueous solution. Thet D‐g‐PAA copolymers capable of binding the heavy metal ions.
Dissociation Energy Computations for Saline Bonds Implied in Interactions Mediated by Peptidoglicans
Authors: Muntean Simona , Kurunczi Ludovic , Bologa Cristian , Ilia Gheorghe , Simon Zeno 
Published: March 2006

AbstractSummary: Dissociation energy and hydration energy calculations, in water solution, are presented for saline bonds mediated by Ca2+ and Mg2+ ions with Brőnstedt type bases (COO, OSO3, OH). A computationally intensive method, Polarisable Continuum Model (PCM) using 6‐31G* basis set, was applied. Hydration energies were computed by various methods, as well as dissociation energies of some L2M complexes. L2Ca complexes result as more stable against dissociation than L2Mg complexes. Hydration energy calculation results, for some of the methods, here used, seem rather reliable as compared to experimental results.
Colouring Agents for SBR Vulcanizates and Their Effects on Ageing and UV Radiation Resistance
Authors: Botros Samir H. , Eid Mahmoud A. M. , Abd‐El‐Ghaffar Mahmoud A. 
Published: March 2006

AbstractSummary: Metal free and some metal‐perylene polymers as well as some metal phthalocyanine polymers were incorporated into styrene butadiene rubber (SBR) compounds as colouring agents. The ageing and UV resistance of the vulcanizates obtained were studied in terms of their mechanical properties. The results obtained revealed that cobalt perylene and cobalt phthalocyanine polymers showed superior performance in SBR vulcanizates against thermal ageing and UV radiation. The optimum concentration of cobalt phthalocyanine polymer was found to be 1 phr (parts per hundred parts of rubber).
Ansa‐Metallocenes by Intramolecular Ring Closure Reactions – Syntheses and Applications
Authors: Erker Gerhard 
Published: March 2006

AbstractExamples of a functional group chemistry at the Group 4 bent metallocene frameworks are presented and discussed that allow for the preparation of ansa‐metallocenes at the stage of the intact organometallic complexes. These examples include ansa‐metallocene formation by means of intramolecular olefin metathesis reactions, by photochemical [2+2] cycloadditions of pendant olefinic moieties and even of a Mannich‐type carbon carbon coupling reaction of enamino substituents attached at the Cp‐rings. Many of the resulting ansa‐metallocene systems were employed as components of reactive homogeneous Ziegler‐Natta olefin polymerization and copolymerization catalysts. The Mannich coupling reaction was also used in 3ferrocenophane chemistry, eventually leading to novel chelate ligand systems that were employed in catalytic asymmetric polyketone formation.
Living Olefin Polymerisation and Block Copolymer Synthesis in the Presence of a Single‐site Catalyst Containing a Phenoxyimine Ligand
Authors: Weiser Marc‐Stephan , Mülhaupt Rolf 
Published: March 2006

AbstractA new phenoxyimine catalyst (Bis‐(N‐(3′,5′‐diiodo‐salicylidene)‐2,6‐difluoroaniline)‐titanium(IV)‐dichloride) has been synthesised and characterised. After activation with MAO, it was used as highly active catalyst in living olefin polymerisation of ethylene and propylene. Ultra‐high molecular weight polyethylene and atactic polypropylene of low polydispersity were obtained. The living character of the polymerisation was shown by on‐line polymerisation kinetics and linear growth of number‐average molar mass with polymerisation time. A block copolymer of the type PE‐block‐P(E‐co‐P) was prepared and characterised by CRYSTAF analysis and AFM micrographs.
Synthesis of Very Small Polymer Particles by Catalytic Polymerization in Aqueous Systems
Authors: Mecking Stefan , Monteil Vincent , Huber Johannes , Kolb Ludmila , Wehrmann Peter 
Published: March 2006

AbstractThe preparation of aqueous dispersions of very small particles (size < 30 nm) of various polymers (polyethylenes, stereoregular 1,2‐polybutadiene, and polyalkenamers) by catalytic polymerization with a water‐soluble catalyst, or with microemulsions of lipophilic catalysts is reviewed.
Tandem Copolymerization: An Effective Control of the Level of Branching and Molecular Weight Distribution
Authors: Frediani Marco , Piel Christian , Kaminsky Walter , Bianchini Claudio , Rosi Luca 
Published: March 2006

AbstractThe term “tandem catalysis” addresses the action of two or more different catalysts in a single reactor to yield a product that is otherwise inaccessible to the individual catalysts. Its application to the production of branched polyethylene from ethylene feedstock as well as of homopolymers or copolymers with controlled molecular weight distribution is a relatively recent and successful technique. A great variety of combinations of late and early metal precursors, in different experimental conditions, have been successfully employed in tandem processes to prepare polyolefins with improved properties and performance parameters. In this article, we report on two examples of tandem catalysis, where either cooperative or independent actions take place.
Using the Transfer Function of an Isoperibolic Reaction Calorimeter for Thermo‐kinetic Analysis
Authors: Gaulke Arnd‐Lüder , Pauer Werner , Moritz Hans‐Ulrich 
Published: March 2006

AbstractIt is an aim of the present work to determine the chemical heat flow rate of a reaction without explicitly solving the heat balance equations. Therefore, it is necessary to calculate the heat flow rate directly from the temperature course of an experimentally determined reaction. For this transformation the transfer function of the calorimeter is needed1. An isoperibol reaction calorimeter was used for the experiments. With different calibrations and gained transfer functions, it is shown that the chemical heat flow rate can be determined from the temperature course of a reaction. The evaluation is fast and easy to use, which improves automation and prevents possible input errors.
Metallocene Catalysts for Olefin Oligomerization
Authors: Janiak Christoph , Blank Frederik 
Published: March 2006

AbstractMetallocene complexes with a cocatalyst such as methylalumoxane, MAO can be used as catalysts in the dimerization or oligomerization of olefins (alkenes) including the (co‐/hydro‐)oligomerization of ethene, of the α‐olefins propene, 1‐butene, 1‐pentene, 1‐hexene, and higher α‐olefins, branched α‐olefins, cyclic olefins and α,ω‐dienes. Possible applications of α‐olefin oligomers are summarized. Oligo‐olefins can be analyzed by gel permeation chromatography (GPC) or 1H NMR spectroscopy for molecular weight determinations and by 1H and 13C NMR spectroscopy or MALDI‐TOF mass spectrometry for their end group structure.
New Polyolefin Nanocomposites and Catalyst Supports Based on Organophilic Boehmites
Authors: Xalter Rainer , Halbach Tobias S. , Mülhaupt Rolf 
Published: March 2006

AbstractPE‐boehmite nanocomposites were prepared by means of metallocene‐catalyzed in situ polymerization of ethylene in presence of dispersed boehmites which were rendered organophilic by modification with organic acids. Polymerization activity, filler dispersion and mechanical properties of the nanocomposites were investigated as a function of type and concentration of the organophilic boehmites. Sulfonate modified boehmites were used as supports for MAO‐activated single site metallocene catalysts and nanocomposite formation via fragmentation of the self‐assembled nanoparticles and redispersion during polymerization.
Control of Ultrahigh Molecular Weight Polypropene Microstructures via Asymmetric “Dual‐Side” Catalysts
Authors: Cobzaru C. , Rieger B. 
Published: March 2006

AbstractAsymmetric ansa‐metallocene catalysts based on fluorenyl and specifically substituted indenyl ligands allow a continuous change of the properties of isotactic polypropene and thus generate a new portfolio of polypropene materials, ranging from excellent thermoplastic elastic to stiff plastomers. Controlling the length of the crystallizable, isotactic segments by means of isolated stereoerrors introduced into the isotactic enchainment made this possible. The combination of synthetic, structural and polymerization studies of a series of ansa‐asymmetric catalysts has provided much insight into the effectiveness of the substitution patterns on tailoring the polymer microstructures. Ligand substitution, temperature and concentration of the propene monomer in the reaction medium can influence stereoerrors distribution, and therefore the crystallinity of the materials. Ultrahigh molecular weight polypropenes with tacticities varying in a broad range (20% < [mmmm] < 80%) are available via (Ind‐Flu)‐based asymmetric hafnocenes.
Ethylene/1,3‐Cyclohexadiene Copolymerization by Means of Methylaluminoxane Activated Half‐Sandwich Complexes
Authors: Heiser Dirk E. , Pelascini Frederic , Kramer Dominic , Scott Jennifer , Gambarotta Sandro , McCahill Jennifer , Stephan Douglas W. , Okuda Jun , Mülhaupt Rolf 
Published: March 2006

AbstractEthylene copolymerization with 1,3‐cyclohexadiene (CHD) was investigated by using methylaluminoxane (MAO) activated single‐site catalysts including bridged and non‐bridged titanium half‐sandwich and bimetallic cobalt(I) complexes. MAO activated CpTiCl2[NP(tBu)3] (Cp = cyclopentadienyl, tBu = tert‐butyl) gave high molecular weight CHD copolymers without encountering catalyst activity losses. According to the NMR microstructure investigation the resulting copolymers are highly regioregular.
Direct Copolymerization of Propene and Ethene‐based Macromers to Produce Long Chain Branched Syndiotactic Polypropene
Authors: Rulhoff S. , Kaminsky W. 
Published: March 2006

AbstractCopolymers of propene and ethene‐based macromers have been prepared in a direct copolymerization. First macromers in a range of 3000–11600 g/mol were synthesized by varying the polymerization temperature and ethene concentration with the metallocene catalyst [(CH3)2CCp2]ZrCl2/MAO. These vinyl terminated ethene oligomers were copolymerized with propene by Cs symmetric catalyst [Ph2C(Cp)(Flu)]ZrCl2 to a long‐chain branched syndiotactic polypropylene. The LCB‐sPP was separated from the bimodal product by a fractional crystallization with p‐xylene and 2 ‐ ethoxy ethanol at 130 °C. A detailed analysis of the purified copolymer was given by GPC, DSC and 13C NMR spectroscopy.
New Materials Designed by Coordination Polymerization of ω‐undecenyl Macromonomers
Authors: Peruch Frédéric , Catari Edgar , Zahraoui Said , Isel François , Lutz Pierre Joseph 
Published: March 2006

AbstractThe major part of the present paper discusses the ability of well‐defined ω‐undecenyl polystyrene, polyisoprene or poly(styrene‐block‐isoprene) macromonomers to undergo coordination homopolymerization in the presence of selected titanium catalysts. Special emphasis is given to the influence of the nature of the catalyst, the polymerization temperature and the macromonomer molar mass and concentration on homopolymerization yield and average degree of homopolymerization (DPn). Titanium‐based catalytic systems such as CpTiCl3/MAO and Cp*TiCl3/MAO only yielded dimers. The use of the homogeneous metallocene catalyst with constrained ligand geometry (CGC‐Ti/MAO) having an open active site, significantly improved the degree of polymerization. Increasing macromonomer molar mass, causes only a slight decrease of DPn whereas conversion increased moderately. The final section briefly discusses the copolymerization of ω‐undecenyl polystyrene macromonomers with ethylene in the presence of Versipol™ catalysts.
Synthesis of Copolymers with Sterically Hindered and Polar Monomers
Authors: Donner Matthias , Fernandes Mercia , Kaminsky Walter 
Published: March 2006

AbstractDifferent highly substituted C1 symmetric metallocenes have been investigated for the copolymerization of ethene and norbornene. The influence of the feed ratio and the polymerization temperature were varied to characterize the polymer by means of microstructure, thermal properties and catalysts activity. The bulky structured ligands of the catalysts lead to highly stereoregular copolymers with semi‐crystalline phases even at low norbornene incorporation. Two different allyl ethers (allyl ethyl and allyl propyl ether) have been used to copolymerize with ethene using metallocene catalyst system (rac‐[Me2Si(2‐Me‐4‐(1‐Ph)Ind)2]ZrCl2/MAO). In order to investigate the influence to ether incorporation to polymer properties, we have performed experiments varying comonomers concentration in feed, polymerization temperature and ratio Al(MAO)/Zr. The higher comonomer incorporation was followed by loss of cristallinity of the produced polymer. Additionally, the catalytic activity and melting point of the polymers also decrease with increase in comonomer concentration in feed.
Rheological Characterization of Long‐chain Branched Polyethylenes and Comparison with Classical Analytical Methods
Authors: Stadler Florian J. , Piel Christian , Kaminsky Walter , Münstedt Helmut 
Published: March 2006

AbstractLong‐chain branched polyethylenes are still of great interest today. In some cases their characterization is not an easy task with classical analytic methods (GPC‐MALLS and NMR) because of the limited sensitivity at low concentrations of long‐chain branches. Rheological methods make a valuable contribution to the characterization due to their high sensitivity with respect to long‐chain branches. Using rheology it was possible to get an insight into the influence of different comonomers and comonomer concentrations on the long‐chain branch incorporation in LLDPE. A variation of polymerization parameters such as polymerization pressure was found to influence the rheological behavior. From these findings some conclusions with respect to the molecular structure could be drawn.
The Rheology of Linear and Long‐chain Branched Polymer Melts
Authors: Wagner Manfred H. 
Published: March 2006

AbstractBy generalising the Doi‐Edwards tube model to the Molecular Stress Function theory, the non‐linear rheology of polymer melts can be described quantitatively. The strain‐hardening of linear polymer melts in extensional flows can be accounted for by a strain energy function, which reflects the increase of strain energy due to tube squeeze. In comparison to linear polymer melts, long‐chain branched polymer melts show enhanced strain‐hardening. This is due to the fact that while the backbone of the branched macromolecule is stretched by deformation, side chains are compressed. It is demonstrated that the experimentally observed slope of the elongational viscosity after inception of strain‐hardening depends on the ratio β of total molar mass to backbone molar mass as predicted by the model. The steady‐state (plateau) value of the elongational viscosity depends on the maximum relative stretch, $f_{MAX}^2$, which can be supported by chain segments and which represents the maximum elastic energy storable in the polymeric system.
Syndiospecific Polymerization Catalysts for Styrene Based on Rare Earth Metal Half‐Sandwich Complexes
Authors: Hitzbleck Julia , Beckerle Klaus , Okuda Jun , Halbach Tobias , Mülhaupt Rolf 
Published: March 2006

AbstractIn the presence of an trialkyl aluminum cocatalyst the activation of scandium, yttrium and lutetium mono(cyclopentadienyl) complexes with various substituted cyclopentadienyl ligands by [Ph3C][B(C6F5)4] results in highly efficient catalysts for the syndiospecific polymerization of styrene. As active species half‐sandwich alkyl cations is assumed that is isostructural with the mono(cyclopentadienyl) titanium alkyl cation originally proposed by Zambelli.
Sorption Studies of Propylene in Polypropylene Polymerized with Novel Ziegler‐Natta‐Catalysts in Liquid and Gas Phase
Authors: Patzlaff M. , Wittebrock A. , Reichert K.‐H. 
Published: March 2006

AbstractPolypropylene was produced in gas phase and liquid phase using different supported Ziegler‐Natta‐catalysts. Sorption behaviour of propylene in polymer particles was studied gravimetrically. The analyzed polymer fractions have average diameters between 250 and 875 µm. Generally it was found that the effective diffusion coefficient is increasing with increasing size of polymer particles. With electron microscopy a change of polymer particle morphology with particle size and type of catalysts was observed.
The Study of Cavitation in HDPE Using Time Resolved Synchrotron X‐ray Scattering During Tensile Deformation
Authors: Schneider K. , Trabelsi S. , Zafeiropoulos N.E. , Davies R. , Riekel Chr. , Stamm M. 
Published: March 2006

AbstractReal time synchrotron Small‐Angle and Wide‐Angle X‐ray Scattering was performed during the tensile deformation of a high‐density polyethylene copolymer. The changes of the structure in the crystalline and in the amorphous domains were followed during the three characteristic stages of the load‐displacement curves: The elastic stage and the plastic range composed of the stage of the lowering load in the force‐displacement‐curve (yielding) and the strain hardening. Competitive phenomena like crystallite fragmentation and cavitation were found to occur simultaneously in the phase of lowering the load but at different length scale. We prove that the void formation occurs mainly during yielding. During strain hardening there was no further increase of the void volume fraction, only changes in void size.