bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Agarose 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

Suitable 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

The 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

When 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

Dynamic 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.
Introduction into the study of translational diffusion by laser techniques
Authors: Sillescu Hans
Published: March 2011

We give a short description of the holographic grating technique for determining small tracer diffusion coefficients of photo labeled polymers and the quasielastic light scattering technique for studying polymer polymer interdiffusion. For applications in polymer systems we refer to the recent literature.
Entanglement in polystyrene detected by translational diffusion of photo‐labeled molecules
Authors: Antonietti M. , Fölsch J. K. , Sillescu H.
Published: March 2011

The 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

Polyphosphazenes 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

Alloying 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

In 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

Linear 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

Dynamic 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

The 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:

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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

Various 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

Distribution 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

A 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

The 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

Monometallic 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

AC 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

Polymers 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).
Photosensitive organosilicon polymers for microlithographic application
Authors: Inoue Takashi , Sugiyama Hisashi , Nate Kazuo , Mizushima Akiko
Published: March 2011

Two new families of photosensitive organo‐silicon polymers are described. One is based on the Si‐Si σ‐bond photochemistry and another is based on the combinations of new alkaline‐soluble organosilicon polymers with diazoquinone photosensitizers. Both of these photoactive materials not only give positive photoresist formulations but can act as oxygen reactive ion etch masks in the double‐layer resist scheme to finally offer steep submicrometer organic patterns with high aspect ratio.
The application of holographic techniques to kinetic studies of photopolymerization reactions
Authors: Lougnot Daniel , Carré Christiane , Fouassier Jean‐Pierre
Published: March 2011

The holographic techniques are applied to the kinetic study of a photopolymerization reaction under steady state illumination. A theoretical approach of this problem is introduced which allows the intrinsic initiating activity of several amine‐derived radicals to be determined.
Network formation by chain crosslinking photopolymerization and some applications in electronics
Authors: Kloosterboer J. G. , Lijten G. F. C. M. , Boots H. M. J.
Published: March 2011

Two applications of photopolymerization are described, viz. the replication of optical discs and the manufacturing of aspherical lenses, used for the read‐out of these discs. The development of these and similar processes has required a thorough understanding of the formation of densely crosslinked networks. Results on the evolution of crosslink density with conversion, the delay of shrinkage with respect to conversion and the occurrence and modelling of inhomogeneous network formation are presented.
Fabrication of microstructures with extreme structural heights by reaction injection molding
Authors: Hagmann P. , Ehrfeld W. , Vollmer H.
Published: March 2011

For fabrication of microstructures with extreme structural heights a reaction injection micromolding process has been developed. It uses mold inserts produced by deep‐etch X‐ray lithography and electroforming which have superior surface quality with a surface roughness Rmax of less than 0.02 μm. For methyl methacrylate base casting resins in combination with an internal mold release agent the molding conditions have been optimized on a laboratory‐scale reaction injection molding machine and correlated with thermomechanical measurements. It has been demonstrated by many experiments that in spite of minimum lateral dimensions of only some micrometers and structural heights of some hundred micrometers a yield of approximately 100 % can be obtained in the micromolding process. This new process may be applied for producing innovative microstructure products, e.g. in the fields of sensors, packaging and interconnection in microelectronics, filtration, microoptics and synthetic fibers.
Functional liquid‐crystalline polyesters based on twin nonamethylene spaced p‐oxybenzoate dyads and dithiols
Authors: Angeloni A. S. , Chiellini E. , Galli G. , Laus M. , Torquati G.
Published: March 2011

A new series of thermotropic liquid‐crystalline poly‐(ester‐β‐sulphide)s 9Sn was prepared by reacting the mesogenic nona‐methylene bis[4‐(4‐acryloyloxybenzoyloxy)benzoate] 1 with α,ω‐alka‐nedithiols of varying length. The polymers exhibit nematic and smectic mesophases, which are enantiotropic or monotropic in character, depending on the number n of methylene units in the dithiol precursor (n = 2–10). The phase transition parameters were determined and compared with those of closely related poly(ester‐β‐sulphide)s 6Sn. It is suggested that these systems may be suitable model polymers to test current theory of the existence of highly anisotropic or weakly anisotropic mesophases in polymers.
Electrical studies of heat resistant polymers
Authors: Oraison J. M. , Boiteux G. , Seytre G. , Rabilloud M. , Senneron M. , Sillion B.
Published: March 2011

The present necessity to use heat resistant materials in electronics justify the scientific interest in different heterocyclic polymers. This paper is especially concerned with their applications as dielectric films. The processing to obtain thin films of a polyphenylquinoxaline, a polyhydantoïne and a poly(hydantoïne ‐ imide) was examined and the resulting polymers were characterized thermally and electrically for large ranges of temperature and frequency.
Submillimeter infrared spectroscopy of fluorinated polymers ‐ phase transition study
Authors: Latour M. , Faria R. M. , Moreira R. L.
Published: March 2011

Submillimeter infrared technique is used to study the phase transitions in poly(vinylidene fluoride) homopolymer and copolymers with trifluorethylene. During the phase transition form II to form I, induced by copolymerization, electrical or mechanical stresses, the spectra show an important increasing of the submillimeter absorption. This behavior is explained by changes of the polarizability at phase transition.
Thermal and chemorheological modelling of the processing of advanced epoxy based composites
Authors: Kenny J. M. , Apicella A. , Nicolals L.
Published: March 2011

A general model for the prediction of the rheological behavior of epoxy resins during the processing of epoxy based laminates is presented. The model is able to predict the temperature and the extent of reaction across the laminate thickness during processing. The model leads the computation of the viscosity inside the composite where experimental measurements are not possible. Thermal characterization of the reacting systems gives the input data necessary for the mathematical modelling. The numerical simulation has confirmed the necessity of a controlled temperature ramp in order to obtain a more homogeneous laminated structure. Moreover, the numerical results indicated that the process variables may present anomalous behavior which may affect the physical properties and durability of the final product.
Modeling of interphase in composite materials: Characterization of epoxy resin/aminosilane system
Authors: Sérier A. , Pascault J. P. , My Lam Thanh
Published: March 2011

The system studied here principally is γ‐APS + BADGE (γ‐aminopropyltriethoxysilane + diglycidyl ether of bisphenol A).

The reaction takes place even at −20°C. It is first the epoxy‐amine autocatalytic second‐order reaction, but we also have a cross‐linking reaction which needs more time and higher temperature. The behaviour of this system is the same as γ‐APS‐PGE (phenylglycidyl ether) system: we can obtain the complete disappearance of OH groups.

The thermomechanical properties of the reaction product considerably change with the temperature, moisture and curing time.
Synthesis and properties of segmented poly(hydroxyether‐siloxane)
Authors: Hedrick J. L. , Haidar B. , Russell T. P. , Hofer D. C.
Published: March 2011

Segmented or block poly(hydroxyether‐siloxane) copolymers were synthesized by both a monomer‐oligomer or an oligomer‐oligomer synthetic approach. Perfectly alternating sequence distributions were obtained from the monomer or oligomer(s) bearing mutually reactive end groups, and the hydroxyether linkages are formed simultaneously with the growth of the second block. Differential scanning calorimetry (DSC), Dynamic Mechanical Thermal Analyzer (DMTA), and small angle X‐ray scattering (SAXS) results indicated that microphase separated morphologies were achieved for each of the copolymers, even those structures synthesized by the monomer‐oligomer route. The mechanical properties of the networks ranged from a rubber toughened thermoplastic to a thermoplastic elastomer and depended on which phase was predominantly continuous.
Chemical modification on PVC during the melt: Some fundamental features
Authors: Mijangos C. , Gómez‐Elvira J. M. , Martínez G. , Millán J.
Published: March 2011

Substitution on a commercial sample of PVC with sodium benzenethiolate has been performed in the melt state. The mixing conditions (shear stress, temperature, plasticizer, etc.) have been found to affect both the kinetics and the shape of the rheogram but they scarcely influence the final conversion. The reaction efficiency has been proved to depend linearly on the total amount of nucleophile. The evolution of tactic triads content with degree of substitution has been measured by 13C NMR spectroscopy. To a first approximation, the results agree with those obtained previously in solution which accounts for a mechanism based on the reactivity of some definite conformations.
Fluorination of polyethylene films
Authors: Volkmann Thekla , Widdecke Hartmut
Published: March 2011

Fluorination of HDPE films (100 and 1800 μm thick) and LDPE films (100 μm thick) with elemental fluorine is described. The films were fluorinated at temperatures between 40°C and 100°C. The degree of fluorination was increased by increasing the concentration of fluorine in the F2/N2 gas mixture. A diffusion‐controlled process was indicated by plotting the measured depth of fluorination against the square root of fluorination time. The chemistry of the process was studied by ESCA measurements or by energy dispersive analyses in the scanning electron microscope.
Photolysis and photo‐oxidation of unsaturated polyesters
Authors: Michaille Sylvie , Khalil Zahi , Lemaire Jacques , Arlaud Patrick
Published: March 2011

The photolytic and photo‐oxidative evolution of unsaturated polyesters, crosslinked or not, exposed to polychromatic light is studied using IR, FTIR, UV spectrometries. The influence of each elaboration parameter (nature and concentration of diacids like maleic anhydride, fumaric acid or phthalic acids, nature of glycols, nature and concentrations of crosslinking agents, mode of crosslinking) is determined. The mechanism involving primary excitation of the maleate‐fumarate or of phthalate units and radical reactions accounts for the appearance of hydroxylated and carbonylated groups. Photoyellowing of unsaturated polyesters is related either to the styrene oligomers or to the phthalate units. Through parallel studies of photochemistries in polystyrene (PS) and poly(butylene terephthalate) (PBT) at long wavelengths, the different sources of photo‐yellowing are precised.
Investigations of the phase behavior of rod‐like polyesters and polyamides substituted by flexible side chains
Authors: Ballauff M.
Published: March 2011

The phase behavior of a number of rigid‐chain polyesters and polyamides is reviewed and compared to the result obtained from low‐molecular‐weight model systems. The dilution of the steric forces by flexible side chains appended to the rigid main chains is discussed. It is shown that even stiff‐chain polyamides may be transformed to a thermotropic mesophase and an isotropic melt if the number and length of side chains per repeating unit is high enough.
Polycondensation of low‐active monomers in mesomorphic‐like reaction mixtures and in presence of polymeric matrix
Authors: Zhubanov Bulat A. , Solomin Victor A. , Lyakh Elena N. , Lyapunov Vladimir V. , Dubitsky Yuri A.
Published: March 2011

The study results of the synthesis of polyheterocycles based on dianhydrides, obtained by photochemical reaction of aromatic compounds with maleic anhydride, have been presented. In comparison with aromatic analogues the low reactivity of anhydride cycles is characteristic for tricyclodecenetetracarboxylic dianhydrides. This fact made unsuitable the traditional two‐stage method to synthesize high‐molecular polyheterocycles on the basis of these monomers. There has been estimated a possibility of chain growth of oligomeric polyamic acids (PAMA) in mesomorphic‐like state of its solutions in mixed solvents. In this conditions the PAMA polymerization degree changed from 7 up to 60. These peculiarities have given the opportunity to synthesize polyheterocycles in mild conditions. The features of polycondensation of tricyclodecenetetracarboxylic dianhydrides with bis(4‐aminophenyl) ether in the presence of poly‐4‐vinylpyridine, polyacrylic and polymethacrylic acids have been studied. There have been synthesized high‐molecular‐weight polyimides and polyamidoimides, possessing good physicomechanical and thermal properties.
Laser‐induced polymerization of functional derivatives of acetylene
Authors: Karpacheva Galina , Khoroshilova Valentina , Davydov Boris
Published: March 2011

Photochemical and photophysical processes leading to the formation of polymers with a conjugated double bond system under He‐Cd laser irradiation have been considered. Phenyl‐ and diphenylpropargylamines are utilized as monomers. The polymerization of these monomers is carried out only in the presence of an electron acceptor such as tetrabromomethane. The polymer formation process is directed to obtaining an intermediate compound followed by its polymerization. The polymerization of intermediate compound is carried out by cationic reaction of triple bond in the presence of electron acceptor. The polymer structure and properties have been investigated. The parameters of lightsensitive layers based on diphenylpropargylamine have been determined.
Two‐dimensional NMR methods for studying solid polymers
Authors: Spiess H. W.
Published: March 2011

A survey is given about two‐dimensional (2D) NMR experiments on solid polymers involving 2H‐ and 13C‐NMR. 2D exchange NMR spectra of static samples directly reflect the distribution of rotational angles resulting from ultraslow molecular motions. Typical examples are the chain motion above the glass transition or rotations around a helix axis in semi‐crystalline polymers. 2D‐Magic angle spinning not only allows the detection of molecular order and motion. By combining rotor synchronized MAS with rotations in spin space the correlation of order and mobility can be studied.
The interaction between artificial antigenes based on synthetic polyelectrolytes with immune system cell: Physico‐chemical aspects
Authors: Yaroslavov A. A. , Polinsky A. S. , Sukhishvili S. A. , Kabanov V. A.
Published: March 2011

The model study on physico‐chemical basis of the tentative mechanism of artificial immunogene action was undertaken. Monodisperse carboxylated polystyrene latex was used as model to investigate the following problems: reversibility of polycation adsorption on the negatively charged surface, migration of macromolecules between particles, adsorption of polycation in the presence of abundant proteins. Polycation was proven to adsorb reversibly and, despite its high affinity to the negatively charged surface, to pass from one disperse phase particle to another. Neither positively nor negatively charged proteins prove to hinder polycation adsorption on the surface.
Physico‐chemical properties of polyampholytes in solutions
Authors: Bekturov Esen A. , Kudaibergenov Sarkyt E.
Published: March 2011

The results of studying the hydrodynamic properties, complexation ability and catalytic activity of some synthetic polyampholytes are presented. Much attention has been paid to studying the hydrodynamic and conformational characteristics of amphoteric polyelectrolytes at their isoelectric point (i.e.p.). Specific binding of low molecular weight ions by polyampholytes and complexation of polyampholytes with protein, anionic and cationic polyelectrolytes, surfactants, dyes and metal ions are discussed.
Soluble polyelectrolytes based on some heterocyclic compounds
Authors: Shaikhutdinov Erengaip M. , Kurmanaliev Oraz S.H. , Ermaganbetov Mubarak E.
Published: March 2011

With the purpose of synthesizing the new types of soluble polyelectrolytes for special purposes radical polymerization and copolymerization of a number of heterocyclic compounds in solvents of different types with wide interval of pH medium was investigated. Interrelationships between reaction ability of the studied monomers and dielectric polarization of the media was established. An essential influence of water and pH medium on the polymerization rate and molecular weight of the synthesized polymers is found. The obtained effects are described on the basis of ionized monomers. The possibility to synthesize stereoisomeric polymers based on individual 3‐buten‐1‐ynylpiperidinol isomers was shown. Some perspective ways of their practical application are given.
The influence of the molecular structure of polymers on their reactivity in polycondensation
Authors: Ignatov Vladimir N. , Vasnev Valeri A.
Published: March 2011

The influence of the conditions of synthesis, the chain length and the chemical structure of macromolecules on their reactivity is examined. The main emphasis is placed on the connection between polymer molecular structure and macromolecular effects in polycondensation. The far order effect is presented as the principal chemical factor determining the reactivity of macromolecules in solution polycondensation reactions.
Chemical and spectroscopic methods for investigating polymer degradation and stabilization: Oxidative degradation of a hydrogenated nitrile rubber
Authors: Carlsson D. J. , Chmela S. , Wiles D. M.
Published: March 2011

The oxidation of a hydrogenated butadiene‐acrylonitrile (2:1 mole ratio) rubber has been examined by infrared (IR) spectroscopy and the use of γ‐initiation to give a controlled initiation step. The resolution and sensitivity of the IR technique was enhanced by the use of chemical derivatization in which carboxylic acids were measured as acid fluorides, hydroperoxides as nitrates and alcohols as nitrites. In all of these compounds, their spectra are sensitive to the precise substituents (primary, secondary or tertiary). Oxidation produced hydroperoxides from both tert. H‐C‐C=N and sec. H‐C‐H groups (≈︁1:1.1 mole ratio) as well as chain‐end carboxylic acids [‐CH2‐C(=O)OH]. From a comparison with measurements of peroxyl radicals produced at low temperature, average kinetic chain lengths for the various oxidation products were estimated and compared with these from other ethylene copolymers.
Organoboron antioxidants, 2 boric acid derivatives as secondary antioxidants
Authors: König T. , Männel D. , Schwetlick K.
Published: March 2011

Boric acid esters and arylboronic esters and amides are known to be good primary antioxidants, but they are also capable of destroying hydroperoxides effectively. We have found three principal ways of hydroperoxide decomposition. At first, simple alkyl, but also other esters catalytically destroy hydroperoxides, e. g. cumyl and tert‐butyl hydroperoxide, after an induction period. In a second route, reduction of the hydroperoxides takes place under transformation of oxidizable parts of the organoboron compound. Boric acid catechol esters, for example, reduce tert‐butyl hydroperoxide giving a black precipitate, a reaction product of the instable o‐benzoquinone. Catechol and hydroperoxide in the absence of boron compound do not react. Finally, p‐phenylboronic acid esters reduce hydroperoxides to give alcohol and the corresponding boric acid ester. Many boron derivatives can react in two or all three ways, e. g. 2‐phenyl‐1, 3, 2‐benzodioxaborole. 1 mol of this compound destroys 2 mol of cumyl hydroperoxide giving cumyl alcohol, and more than 10 mol to give acetone and phenol. In side reactions, cumyl hydroperoxide is converted into dicumyl peroxide and acetophenone. The last compound indicates a reaction passing via radicals; but in all cases, this reaction is not important.
Effect of radiolysis on the glass transition temperature of poly (methyl methacrylate)
Authors: Thominette F. , Pabiot J. , Verdu J.
Published: March 2011

A bulk PMMA sample was irradiated by gamma rays (0.69 Gy. s−1), and its structural changes were monitored by steric exclusion chromatography, differential scanning calorimetry, dynamic mechanical spectroscopy and dilatometry. The glass transition temperature Tg decreases more than predicted from the molecular weight data, but the corresponding excess of change is not thermoreversible and can be suppressed by annealing. Strong not thermoreversible changes are also observed around the first secondary transition temperature (≈︁ 60°C) as well as in mechanical spectra and in dilatometric curves. Various hypothetical explanations are examined.
Effect of previous thermal history on physical aging of amorphous poly (ethylene terephthalate)
Authors: Cortés P. , Montserrat S.
Published: March 2011

Physical aging of amorphous PET, at aging temperatures (Ta) of 40 and 60°C and different aging times (ta), has been studied by DSC using two kinds of samples with different thermal history: Liquid‐Nitrogen‐Quenched samples (LNQ) and DSC cooled samples at a controlled cooling rate of 60 K/min (CC). At Ta = 40°C, a sub‐Tg peak appears in LNQ samples but is not clearly observed in the CC samples. At Tg = 60°C, a superposed peak to Tg is observed in both kinds of samples. This different behaviour can be explained considering the distribution of relaxation times in the polymer.
Synthesis and applications of olefin‐contaning polymers
Authors: Amerik Yuri B.
Published: March 2011

The problems of ionic coordination polymerization of higher α‐olefins are summarized briefly. During the polymerization such monomers as 3‐methyl‐butene‐1, vinylcyclohexane and others isomerize into unreactive isomers, and the rate of polymerization and final yield of polymer are sharply decreased as compared with the polymerization of lower olefins. The modification of polypropylene by ionic coordination copolymerization of propylene with higher α‐olefins and polar monomers is considered. Significant modification of carbochain polymers may be obtained by the insertion of heteroatoms in the backbone. New possibilities for chemical “modification” of olefins by direct interaction with sulphur and the unusual aspects of the polymerization of olefin sulfides are also considered. The subsequent transformation of polyolefin sulfide gives polymers which have properties drastically differing from those of polyolefins. In conclusion, some new application areas are described.
Stabilization mechanisms of hindered amines
Authors: Klemchuk Peter P. , Gande Matthew E.
Published: March 2011

As a result of studying the interaction of hindered amine stabilizers (2, 2, 6, 6‐tetramethylpiperidines) with simple hydroperoxides, peroxy radicals, and acylperoxy radicals, the last two in AIBN‐initiated oxidation experiments in chlorobenzene, the following conclusions have been reached:

Hindered amines have multiple mechanisms of functioning as photostabilizers of polymers.

Reactions between tetramethylpiperidines and simple hydroperoxides are too slow at moderate temperatures to make a significant contribution to polymer stabilization.

Reactions between tetramethylpiperidines and alkylperoxy radicals at moderate temperatures occur at varying rates with varying effectiveness for stabilization. With favorable alignment among reaction rates for oxidation propagation and termination, reactions between tetramethylpiperidines and alkylperoxy radicals can play a significant role in oxidation inhibition.

Hydrocarbon polymer photooxidation proceeds by two major paths ‐ the usually accepted alkyl radical/alkylperoxy radical/hydroperoxide route and the usually neglected aldehyde/acyl radical/acylperoxy radical/peracid route.

Hindered amine stabilizers are able to participate in inhibiting both photooxidation reactions ‐ they trap acylperoxy radicals, converting them to carboxylic acids and are converted to nitroxyl radicals in the process; the nitroxyl radicals trap alkyl radicals and the hindered amines trap alkylperoxy radicals to inhibit the other oxidation pathway.

Nitroxyls are regenerated from N‐alkyloxy hindered amines in a fast, efficient reactions with acylperoxy radicals and in slow reactions with alkylperoxy radicals. We postulate neither reaction yields peroxides: carboxylic acids and oxidized alkyloxy substituents are obtained from the first reaction; alcohols and oxidized alkyloxy substituents are obtained from the second reaction.
Crosslinking of ethylene‐vinyl alcohol copolymers via polymeranalogous reactions
Authors: Fedtke Manfred , Henning Kerstin
Published: March 2011

A practical model for polymeranalogous reactions is ethylene‐vinyl alcohol copolymer with a controllable amount of hydroxylic groups. The reaction of the hydroxyl groups with various compounds leads to further functionalized polymers. The functional groups introduced are useful for modification or crosslinking reactions. The modification of ethylene‐vinyl alcohol copolymers with carboxylic anhydrides and hydroxy carboxylic acids is the main subject of this investigation. The crosslinking reaction of these products with bifunctional epoxies was followed by means of viscosimetric measurements. The dependence of the reaction behaviour on the structure of the functionalized polymers used is discussed.
New additives in glass reinforced polyolefins
Authors: Severini Febo , Pegoraro Mario , Ricca Giuliana , Di Landro Luca
Published: March 2011

Poly(butyl acrylate)‐g‐poly(4‐vinylpyridine) graft copolymer and polypropylene modified with maleic anhydride or poly(maleic anhydride) have been prepared and characterised. These products have been tested as coupling agents in glass reinforced polyolefins. The adhesion of glass fiber or glass filler to polyolefin has been evaluated by “Single fiber composite” method or studying the volume variation under tensile strength. The results indicate that all the prepared additives improve the adhesion between olefin matrix and glass filler or fiber.
The influence of oxygen on radiation crosslinking and degradation of polymers at low irradiation doses
Authors: Babić Dragan
Published: March 2011

The influence of oxygen on radiation cross‐linking and scission at low doses has been followed in order to explain anomalous drop of molecular weight found in polyethylene at low irradiation doses. The G ‐ values and yields of crosslinking and scission estimated on the basis of molecular weight measurements (by GPC) are much higher than those obtained through gel content determinations at higher doses. The possible explanations of such a peculiar behavior are suggested and discussed. The influence of oxygen, even when present in the form of air absorbed in the sample, was found to be an important factor of scission process in irradiated polymer.
Structure and rheological properties of PVC melts
Authors: Lyngaae‐Jørgensen J.
Published: March 2011

The Theological properties of PVC compounds reflect the state of the flow units. The steady state structure which may be found in PVC melts is predicted to depend on the interaction of stresses in simple flow and temperatures for transition from rubberlike solid to liquid state and transition from a liquid state containing crystallite aggregates to a liquid state without crystallite aggregates, called the gel destruction temperature Td and the dynamic melting temperature Tdynm, respectively. The model predictions for Td and Tdynm are compared with experimental data.
13C and 1H NMR analysis of structural defects in PVC: Application to the production of defects at various polymerization stages
Authors: Llauro‐Darricades Marie‐France , Bensemra Naima , Guyot Alain , Petiaud Roger
Published: March 2011

High resolution 1H and 13C NMR data were obtained on PVC and PVC reduced with Bu3SnH. The reduction is never complete and CH2Cl groups preferentially remain. It causes almost complete formation of cyclopentane structures from both internal and chain end unsaturation. 1H NMR gives total unsaturation as well as chain end unsaturation except if there are interferences with initiator residues; in that case, its combination with 13 C NMR of reduced PVC gives the chain end unsaturation. By the last method short branches and long ends are determined. Residual primary chlorine in all kinds of branches (methyl, ethyl, butyl, long ends) is taken into account. Long end contents are to be corrected (factor around 1.5), due to incomplete relaxation in standard analysis conditions. 1H NMR of reduced PVC can be used to get the total non‐reduced structures, both ‐CH2Cl and ‐CHCl‐. PVC was prepared by suspension or solution (trichlorobenzene) polymerization at 55° C, using dicetyl peroxydicarbonate as an initiator. The initiator residue content is higher in suspension PVC at very low conversion, and then levels off at a low value; in solution polymerization, it chiefly depends on the monomer/initiator ratio. At low conversion, more chain end and less short branches are present in suspension polymerization. Otherwise, only the butyl branch content shows a definite trend to increase with conversion. In solution polymerization, the number of defects is chiefly dependent on the initial monomer concentration; it is generally much higher than in suspension, except for the chloromethyl branches where both processes give about the same results.