bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic mechanical spectrometry for the study of multiphase polymer materials
Authors: Cavaille J. Y. , Jourdan C. , Perez J. 
Published: March 2011

AbstractThe dynamic mechanical behaviour of multiphase polymer materials depends on two factors: (i) properties of each phase and (ii) geometric arrangement of these phases (so‐called morphology). Analysis of experimental results has been performed in order to separate these two factors; it leads to informations about morphology, presence of interphase between main phases, chemical composition of different domains and possible changes in physical properties of one phase, induced by its neighbours. The interest in such an analysis based on mechanical spectrometry appears important because of difficulties in direct investigations (low contrast in Electron Microscopy, poor information provided by X‐ray measurements on amorphous polymers … )
Monosized magnetic particles and their use in selective cell separation
Authors: Ugelstad J. , Berge A. , Ellingsen T. , Aune O. , Kilaas L. , Nilsen T.N. , Schmid R. , Stenstad P. , Funderud S. , Kvalheim G. , Nustad K. , Lea T. , Vartdal F. , Danielsen H. 
Published: March 2011

AbstractThe principle of activated swelling has made available polymer particles in the range of 1–100 μm, highly uniform in size, and with great variations in morphology and chemical composition. A short description of the method is given.On the basis of monosized porous macroreticular particles, monosized magnetic polymer particles (MMP) are prepared which are uniform in size as well as in content of magnetic oxides. These particles have found applications in a number of selective cell separation procedures. Special types of MMP have been developed for isolation of organelles and viruses. The use of MMP as contrast agent in magnetic resonance imaging is shortly described.
Chemically and physically crosslinked porous gels
Authors: Flodin Per 
Published: March 2011

AbstractChemically crosslinked gels made by polymerization and copolymerization of trimethylolpropane trimethacrylate have been characterized. Bimodal pore size distributions were obtained. The radii of the large pores (100 Å to 1 μm) varied with concentration while the small ones (20 to 30 Å) were largely independent of the concentration of TRIM. A mechanism of formation of the pores is outlined.Physically crosslinked gels of polyacrylonitrile with highly porous structures were made by cooling polymer solutions in DMF containing varying amounts of water. By controlling the thermal treatment the pore sizes could be varied from 0.1 to 1 μm.Finally the surface modification of cellulose fibers with derivatives of dichlorotriazine is described. It is shown that derivatives containing double bonds in the side chain can form covalent bonds across the interface between cellulose and an unsaturated polyester.
Mechanism of activation of hydroxyl‐containing polymers with N‐hydroxysuccinimide and carbodiimides: Reason for leakage
Authors: Wilchek Meir , Miron Talia 
Published: March 2011

AbstractThe carbodiimide‐mediated reaction of N‐hydroxysuccinimide with carboxyl groups immobilized to hydroxyl‐containing polymers (such as Sepharose or Trisacryl) leads to N‐hydroxysuccinimide ester and N‐hydroxysuccinimide derivatives of β‐alanine which react subsequently with the hydroxyl group of the polymer via ester and carbamate bonds. These derivatives are formed upon interaction of dicyclohexyl carbodiimide with three equivalents of N‐hydroxysuccinimide followed by a Lossen rearrangement. The amount of β‐alanine thus coupled is very high compared to the number of carboxyl groups present on the resin. The β‐alanine bound through the ester bond comprises about 90% of the β‐alanine bound. Alkaline treatment of the ester bonded β‐alanine containing polymers (prior to coupling of amino‐containing ligands) causes a rearrangement yielding β‐alanine with a free carboxyl group coupled through a stable carbamate linkage. After coupling of amino‐containing ligands, the above‐described rearrangement cannot occur, and the β‐alanine‐linked ligand leaks from the polymer via hydrolysis of the ester bond. The newly formed carboxyl groups (derived from the rearrangement) can be used to prepare active esters (e.g. nitrophenyl). Upon coupling with amino‐containing ligands, these esters yield resins bearing chemically stable bonds.
The design of agarose beds for high‐performance hydrophobic‐interaction chromatography and ion‐exchange chromatography which show increasing resolution with increasing flow rate
Authors: Hjertén Stellan , Kunquan Yao , Liao Jia‐li 
Published: March 2011

AbstractAgarose beads (agarose concentration: 15%; diameter: 15–70 μm) were shrunk, crosslinked and derivatized in organic solvents. As crosslinker and coupling agent γ‐glycidoxypropyl tri‐methoxysilane was used. Columns packed with nonporous beads of pentyl agarose and octyl agarose, prepared by this technique, were used for hydrophobic‐interaction chromatography. Characteristic of these columns was that the resolution increased with an increase in flow rate (except for very low flow rates). This very attractive behavior, which violates the generally accepted theory of chromatography, was also exhibited by an ion‐exchanger based on non‐porous agarose beads.
Light in immunoassays: Application of bio‐, chemi‐ and thermochemiluminescence techniques
Authors: Gribnau T.C.J. 
Published: March 2011

AbstractSuitable organic compounds can be forced to emit radiation: by prior irradiation (photoluminescence), by direct chemical reaction (chemiluminescence), by cofactor dependent enzymatic conversion (bioluminescence) or by thermal excitation (thermochemiluminescence). During the 1970's bio‐ and chemiluminescence were started to be explored in labeled immunoassays, exemplified, respectively, by the systems: Firefly luciferin‐luciferase/ATP/O2 and acridinium ester/NaOH/H2O2 or (iso)luminol/H2O2/(micro)peroxidase. Chemiluminescence enzyme immunoassays, using a peroxidase label and luminogen/H2O2 have also been described. More recently thermochemiluminescent labels (e.g. dioxetane derivatives) have been introduced.The luminescent signal must be generated by an additional step before its measurement, and shows “kinetic” behaviour instead of being constant in time. The detection equipment has its special demands, and also the measurement parameter should be properly selected. The final signal can be stabilized over a 10–20 min period by addition of appropriate “enhancers”. The thermochemiluminescent labels have the inherent advantage of high chemical stability during assay performance, and are activated finally without the addition of reagents. The main advantages of luminescence immunoassays are: improvement of the detection limits and, perhaps still more important, a wider dynamic range than for the currently used enzyme immunoassays with fixed endpoint. Examples of the present state of the art, and some organic chemical background will be given.
Plasma protein adsorption: In vitro and ex vivo observations
Authors: Pitt W. G. , Young B. R. , Park K. , Cooper S. L. 
Published: March 2011

AbstractThe in vitro and ex vivo adsorption of blood proteins is studied in order to elucidate the protein‐surface interactions which determine the thrombogenicity and thus the applicability of various polymers in blood contacting devices. The in vitro adsorption of albumin and fibrinogen to four polymers shows that at low solution concentrations, more fibrinogen is adsorbed than albumin. At higher solution concentrations, albumin adsorbs in multilayers while fibrinogen adsorbs, and then partially desorbs spontaneously from the surface. Sequential adsorption studies show that fibrinogen and albumin can partially replace each other. Fibrinogen is preferentially adsorbed over albumin in competitive adsorption studies. In ex vivo experiments, more albumin than fibrinogen is adsorbed from blood during the first 120 minutes of whole blood contact. When exposed to flowing whole blood, pre‐adsorbed fibrinogen desorbs more rapidly than albumin.
Optimisation & scale‐up of affinity chromatography
Authors: Chase Howard Allaker 
Published: March 2011

AbstractWhen affinity chromatography is used on the large scale, economics dictate that the process must be optimised to ensure high throughputs and high adsorbent utilisation. The optimisation of an affinity chromatography process starts with the selection of both the ligand and matrix components of the affinity adsorbent. The relative merits of using highly selective ligands and small particle matrices in the development of high performance chromatography systems is discussed. Once the adsorbent has been chosen the parameters that characterise its interaction with the adsorbate must be characterised from small scale experiments. The method is illustrated in a series of experiments that show the influence of a number of factors involved in the preparation of immobilised monoclonal antibodies on the subsequent performance of the immunosorbents. These parameters together with computer simulations of the chromatography process can be used to design and optimise the operation of large scale systems. Attention has to be given to the optimisation of the adsorption, washing and elution phases of the process. Apart from initial process design, it is also necessary to optimise the chromatographic separation during the run. This involves the need to be able to measure the chromatographic performance in an on‐line manner and a number of approaches to achieve this are described.
Polymer characterization: Quasi‐elastic and elastic light scattering
Authors: Burchard W. 
Published: March 2011

AbstractDynamic or quasi‐elastic light scattering (LS) from polymers in solution arises from concentration fluctuations. With the aid of modern photomultipliers these can be followed as a function of time. A proper evaluation allows to study the center of mass motion and the dynamics of individual chains. The relevance of simultaneous recording of static and dynamic LS is emphazised. Various aspects are discussed in three main sections.In the first part basic relationships are reviewed. The particle scattering factor P(8), structure factor S(q,c) and osmotic compressibility RT(∂c/∂T) occuring in static LS are defined. The time correlation functions (TCF) in dynamic LS are described. The TCF of the scattered electric field contains the time dependent structure factor S(q,t) and the static structure factor S(q). The initial part of the TCF (short delay times) can be approximated by a cumulant expansion; the first cumulant is related to the translational diffusion coefficient D. The concentration dependence of D contains a thermodynamic and a hydrodynamic contribution where the thermodynamic part is identical with the osmotic compressibility in static LS.The second part deals with the behaviour of various polymeric architectures in dilute solutions. Two new structure sensitive parameters, C and = Rg/Rh, are introduced. Chain stiffness and branching are extensively discussed.In the third part properties of different macromolecular architectures in semi‐dilute solution are considered. The inverse osmotic compressibility = osmotic modulus and the concentration dependence of the translational diffusion coefficient are discussed in the light of re‐normalization group and scaling theories.
Entanglement in polystyrene detected by translational diffusion of photo‐labeled molecules
Authors: Antonietti M. , Fölsch J. K. , Sillescu H. 
Published: March 2011

AbstractThe contribution of polymer diffusion studies to clarifying the entanglement problem in polymer chain liquids is reviewed. In particular, we present a phenomenological equation for a critical molecular weight MC as a function of the diffusant and matrix molecular weights, respectively, and compare it with recent theories.
Development of implantable antitumor devices based on polyphosphazenes
Authors: Goedemoed J. H. , De Groot K. 
Published: March 2011

AbstractPolyphosphazenes containing amino acid ester substituents are of considerable interest as bioerodible matrix systems for controlled release of drugs. In order to develop locally acting antitumor devices, a model anticancer agent, melphalan, was physically incorporated in three different polyphosphazene polymers. For studying the release rate of melphalan from the three polymers and the extent of degradation of melphalan during this sustained release process, a flow through‐system was used. This system is characterized by low flow rates, in order to approximate the in vivo implantation situation. Eluents were used, with pH 7.0 and 5.0, showing a melphalan degradation half time (respectively 2.0 and 1.9 hours) comparable with those observed in vitro in human plasma. Polymer 1 (poly[bis(glycine ethyl ester)phosphazene]) released after one week 35% and 42% unhydrolyzed melphalan, at pH 7.0 and pH 5.0 respectively, in a gradual manner. Considerable lower release rates were observed using polymers 2 and 3. Polymer 2 (50% substituted with glutamic acid diethyl ester, 50% with glycine ethyl ester) showed release percentages of 10 and 14%, polymer 3 (50% substituted with phenylalanine ethyl ester, 50% with glycine ethyl ester) 12 and 14% after one week at pH 7.0 and 5.0, respectively. Melphalan concentrations were measured by applying a High Pressure Liquid Chromatography method with fluorescence detection. By this method also the two degradation products mono‐ and dihydroxy‐melphalan could be measured.Considering the release profiles of these degradation products, the conclusion may be drawn that either melphalan is stabilized in the three polymers, or that melphalan is less exposed to the aqueous environment than is the case when used as a solution. These results justify expectations that it should be possible to develop locally acting tumor devices, being able to release an unstable anticancer agent in a gradual manner for several weeks or months and resulting in locally effective drug concentrations during this period.
Polymer alloys: Influence of processing on structure and characteristics
Authors: Menges Georg 
Published: March 2011

AbstractAlloying of polymers, now a standard technique for improving characteristics, is applied both to engineering and many mass plastics. Blending can be used to improve not only toughness, but optical properties or electrical conductivity. Mechanisms underlying the improved toughness of polymer alloys are discussed and the results of investigations reported. Future trends and implications for industry are considered.
Influence of molecular weight and spinning conditions on the crystalline morphology of polypropylene fibres
Authors: Prost C. , Nemoz G. , Hagege R. , Souffache E. , Michel A. 
Published: March 2011

AbstractIn the spinning of polypropylene the “smectic” phase generally appears in the as spun fibres obtained from high fluidity polypropylene (for example M̄w = 118000) at 200°C and more. The amount of the “smectic” form decreases as the draw down ratio increases. At 200°C and for a draw ratio of 40 the “smectic” form is about 70% of the crystalline phase. At 200°C and for a draw ratio of to 130 or higher, only the monoclinic form is observed. At 180°C, and whatever is the draw ratio, only the monoclinic form is observed.For high‐molecular ‐ weight polypropylene (for example M̄w = 320000) the “smectic” form has never been observed whatever is the spinning temperature within the range 220–260°C. The fibres with high amount of smectic phase show low orientation factors, whereas the fibres having only monoclinic form show the highest orientation factors. These results, compared with elongational behaviour of the polypropylene, suggest that the smectic form appears in the fibres as the elongation rate on the spinning line is lower than the relaxation rate of polypropylene chains.
Induced orientation of free chains in a strained rubber: A deuterium magnetic resonance study
Authors: Sotta P. , Deloche B. 
Published: March 2011

AbstractLinear free polydimethylsiloxane (PDMS) chains are dissolved in a PDMS model network. When the system is uniaxially stretched, the free chains, as well as the network chains themselves, acquire a uniaxial orientational order, which is monitored by 2H NMR. The induced orders measured on both kinds of chains are comparable. The order is then investigated as functions of the free chain length and concentration.
Mechanical relaxation processes in polyether block amide copolymers (PEBA)
Authors: Alberola Nicole , Vassel Alain , Christophe Helluin J. 
Published: March 2011

AbstractDynamic mechanical experiments were carried out on a series of polyether block amide copolymers based on poly(tetramethylene oxide) and polyamide 12 with varying PE/PA weight ratio. Internal friction spectra exhibited three main peaks related to the subglass transition of the soft segments, the glass transition of the soft segments and the glass transition of the hard segments, respectively. Moreover, the effect of thermal history on dynamic mechanical behaviour of a particular PEBA sample (70% PA wt) is investigated.
Effects of molecular weight, rubber toughening, and environment on fatigue crack propagation behavior of block amide copolymers
Authors: Giraud Yves , Goletto Jean 
Published: March 2011

AbstractThe Fatigue Crack Propagation (FCP) behavior of block amide copolymers is investigated as a function of molecular weight, rubber toughening as well as environmental conditions. The enhancement of FCP resistance with increasing average molecular weight is shown and correlated to features observed on the fracture surface. Particular attention is paid to hysteretic heating, measured with an infrared camera, in the crack tip zone of different average molecular weight copolymers and rubber‐toughened copolymer. A FCP approach of stress‐cracking in an aqueous solution of zinc chloride is proposed here. An improvement in FCP resistance as the average molecular weight increases, similar to that exhibited in normal environment, appears. The shift in da/dN values over the tested range of magnified image can be approximated by an exponential function:magnified image
The influence of polymer structure on the electrical and mechanical properties of some synthetic films
Authors: Latour‐Slowikowska H. , Las T. , Kowalik T. , Daniewska I. , Wasiak A. 
Published: March 2011

AbstractVarious physico‐chemical properties of films prepared from PP/PE blends are investigated and compared with those of homopolymers. Crystallographic structure and morphology of films are correlated with the properties studied. Special emphasis is made toward investigation of dependences between the structure and the properties: electrical, mechanical as well as water sorption.
Characterization of silicas by adsorption
Authors: Vidal A. , Papirer E. , Zaborski M. , Morawski J. C. 
Published: March 2011

AbstractDistribution of silica surface active sites and examination of their surface heterogeneity have been assessed by study of their reactivity towards alcohols, water and polyamines, and by characterization of the initial and modified samples. The results obtained provided valuable informations as for the surface structural characteristics of the solids and their dependence on mode of preparation.
Dual curing systems based on UV curing and alkoxysilane group condensation
Authors: Gozzelino G. , Ferrero F. , Priola A. 
Published: March 2011

AbstractA study was performed on dual curing systems based on UV curing of reactive unsaturations (acrylic double bonds) and successive alkoxysilane group condensation. The systems were obtained by mixing a typical epoxy acrylic resin with different amounts of monomers containing alkoxysilane groups (3‐methacryloyloxypropyltrimethoxysilane, MEPTS, and 3‐mercaptopropyltrimethoxysilane, MPTS) in the presence of a photoinitiator and a condensation catalyst. After UV curing, the kinetics of the alkoxysilane group condensation was followed by Fourier Transform Infrared Spectroscopy (FTIR) analysis at different temperatures and water vapour pressures. Higher condensation rates were obtained in the systems containing MPTS with respect to the MEPTS system. Also the adhesion on glass sheets was better in the presence of MPTS with respect to MEPTS. These results were attributed to the different structures and to the different crosslinking density obtained in the presence of the two monomers. Wetting tension, Attenuated Total Reflectance (ATR‐FTIR) and X‐Ray Photoelectron Spectroscopy (XPS) measurements are in agreement with these conclusions.
Microwave spectrometry study of first stages of latex coalescence
Authors: Cansell F. , Henry F. 
Published: March 2011

AbstractThe measurement of the complex dielectric constant (ϵmagnified image = ϵ′‐ j ϵ″) in the dipolar absorption domain of the “free” water molecule (microwave region) makes it possible to follow quasi specifically and precisely the water circulation and its interactions with any latex. Weight and dielectric constants variations were simultaneously recorded during water evaporation, which, occurring in a latex, led to particle coalescence and film formation. The influence of the glass transition temperature of polymers, the particle size distribution, the medium ionic strength and emulsifier in a latex were studied.
Cationic ≠3‐allylmetal complexes, 13a) electrical properties of new poly(phenylacetylene) obtained from nickel catalysts
Authors: De Souza R. , Neibecker D. , Tkatchenko I. , Boiteux G. , Revillon A. 
Published: March 2011

AbstractMonometallic complexes of Nickel have been successfully, tested in reaction with olefinic and acetylenic compounds. This paper is devoted to one of the resulting products, a polyphenylacetylene which presents interesting properties. It is readily obtained avoiding the step of a polymer precursor; it is soluble in several solvents, stable in air up to 200° C and may possess a rather high conductivity, depending on polymerization conditions. This is a noticeable difference versus previously reported polyphenylacetylenes which were insulating materials.
AC ‐ conductivity of polymers doped by different crystalline CT complexes
Authors: Boiteux G. , Seytre G. , Vallet G. , Jeszka J. K. , Kryszewski M. , Tracz A. , Ulanski J. 
Published: March 2011

AbstractAC conductivity for polymers reticulate doped with crystalline CT complexes was studied. The lack of the conductivity dependence on frequency was found for systems composed of different inert amorphous and semicrystalline polymers and different CT complexes, both for bulk‐and surface‐conducting films. This result reflect very high continuity of the network in these systems.
Development of ion‐conducting polymer electrolytes for use in high‐energy lithium rechargeable batteries
Authors: Duval M. , Gauthier M. , BΈLANGER A. , Harvey P. E. , Kapfer B. , Vassort G. 
Published: March 2011

AbstractPolymers based on poly(thylene oxide) (PEO) are a very promising new type of stable electrolytes for lithium rechargeable batteries. Their relatively low ionic conductivities can be more than compensated by the very small electrolyte thicknesses that can be used. Specific energies of 100 Wh/kg at sustained specific powers of 70 W/kg, have been obtained at Hydro‐Québec with 100 μm of PEO electrolyte at 100°C. In an electric vehicle, this would give a driving range of over 300 km at 80 km/h, more than three times as much as lead‐acid batteries. PEO‐related polymers have been developed for lower temperature applications such as computers or portable appliances. Advantages over competitive Ni‐Cd batteries are higher energy densities and absence of self‐discharge, with expected shell lifes of 10 years. Laboratory prototypes (3600 cm2, 10 Wh) demonstrate the absence of scale‐up effects and excellent cycling capability (over 300 charge‐discharge cycles).