bluuebunny/crossref_metadata_2025_split huggingface dataset:
New functional polyamides derived from citric acid and L‐lysine: Synthesis and characterization
Authors: Boustta Mahfoud , Huguet Jovanka , Vert Michel 
Published: March 2011

AbstractNew functional aliphatic polyamides bearing pendant carboxylic acid and tertiary alcohol groups have been synthesized by step‐growth polymerization of protected citric acid in the diacyl chloride activated form and protected L‐lysine using the interfacial method. It has been found that a secondary reaction occurs during polymerization and leads to the formation of intramolecular imide cycles. Cleavage of protecting groups and partial or total hydrolysis of imide functions were carried out stepwisely. Resulting structural changes are discussed on the basis of IR and 13C NMR data.
Reactivity of aryl chlorides with sodium sulfide in the synthesis of aromatic polyamidethioethers
Authors: Nykolyszak Tania , Fradet Alain , Maréchal Ernest 
Published: March 2011

AbstractThe synthesis of aromatic copolyamidethioethers by reaction of dichlorobenzanilides with Na2S has been studied. The reactivity of chlorine atoms is strongly dependent on the nature of the substituent in para position. It is related to the 13C NMR shifts of the relative carbons‐the more deshielded, the more reactive‐and hence to charge densities, agreing with aromatic nucleophilic substitution mechanisms. The results are discussed in relation to the various mechanisms which have been put forward for the reaction of Na2S with 1, 4‐dichlorobenzene (PPS synthesis).
Polymerizability of linear or cyclic monomers under hydrostatic high pressure
Authors: Cansell F. , Fabre D. , Petitet J. P. 
Published: March 2011

AbstractThe behaviour of various monomers (linear, cyclic and heterocyclic) compressed in a diamond anvil cell up to 30 GPa and heated between 20 and 100°C was investigated by Raman spectroscopy. We have showed that the σ liaisons between C‐C, C‐Si, C‐H and Si‐O were stable up to 30 GPa under hydrostatic pressure conditions. On the contrary, C=C or aromatic rings can induce the formation of macromolecular compounds with original properties.
Structure‐property relations and processing of rod‐like aromatic polyamides
Authors: Hatke Wilfried , Schmidt Hans‐Werner 
Published: March 2011

AbstractHomopolyamides and copolyamides with structural characteristics such as bulky lateral substituents, non‐coplanar, 2, 2′‐dimethylbiphenylene units and comonomers of different length were prepared and their structure‐property relations investigated. Polyamides with high solubilities and very low or no degree of crystallinity are obtainable by a combination of monomers with bulky lateral substituents and non‐coplanar biphenylene units. These polyamides form tough, transparent films with good mechanical and thermal properties. Lyotropic liquid crystalline behavior was found in some cases for polyamides with non‐coplanar biphenylene units. The incorporation of monomers with bulky substituents on the terephthalic acid unit lowers the chain stiffness and significantly influences the formation of lyotropic solutions.
The biopolymer bacteriorhodopsin in optical data processing
Authors: Bräuchle Ch. , Hampp N. 
Published: March 2011

AbstractBacteriorhodopsin (BR) from Halobacterium halobium [1] is embedded as a twodimensional crystalline lattice of BR‐trimers in the lipid bilayer of the cell membrane [2]. BR consists of a single polypeptide chain of 248 amino acids which is arranged in seven transmembrane α‐helices. A retinal molecule bound via a Schiff base to lysine‐216 forms the chromophoric group [3]. Under illumination BR creates a proton gradient across the cell membrane which is used by a membrane‐bound ATP‐ase for ATP synthesis [4].
Interphase compatibilization of composites with immiscible blends as matrix: Glass beads filled nylon 6 / polypropylene blend‐composite
Authors: Ishida Hatsuo , Scherbakoff Natalia 
Published: March 2011

AbstractThe effect of a filler on the compatibility of an immiscible Nylon 6/polypropylene blend is studied. A compatibilized system with maleic anhydride grafted polypropylene is used as a reference. Dynamic mechanical analysis, differential scanning calorimetry and scanning electron microscopy measurements are performed for these two distinct systems containing treated and non‐treated glass spheres. An improvement of the properties towards surface‐induced compatibilization is observed when the filler surface is treated with a suitable silane coupling agent. Changes in the viscosity and main relaxations of the studied system are correlated with the presence of the filler and with its surface treatment. The crystallinity, adhesion and morphology behavior supports the rheological results. In this system, the filler takes not only the usual role of reinforcing material but also a new role as modifier of the interphase structure.
Crystal‐amorphous interphases in binary semicrystalline/amorphous polymer blends
Authors: Yoon D. Y. , Ando Y. , Rojstaczer S. , Kumar S. K. , Alfonso G. C. 
Published: March 2011

AbstractCrystal‐amorphous interphases in binary polymer blends that are miscible in the melts but phase separate due to crystallization of one polymer have been investigated theoretically by employing lattice models and experimentally by dielectric spectroscopy measurements. Theory predicts the extent of tight adjacent re‐entry to depend strongly on the energy Eq disfavoring the tight‐fold conformations and to increase slightly with favorable interaction energy ‐ χAB in the blends. The interfacial region of varying composition is predicted to depend strongly on χAB, with the interfacial thickness varying with the reciprocal of |χAB|1/2. Therefore, in the limit χAB → 0 the amorphous polymer, which is miscible in the melt, is predicted to be completely excluded from the interlamellar region, in agreement with experimental results. Dielectric relaxation experiments on semicrystalline blends of poly(vinylidene fluoride) (PVDF) with poly(methyl methacrylate) (PMMA) or poly(vinyl pyrrolidone) (PVP) show the existence of nearly pure PVDF interphase which is not penetrated by PMMA or PVP, despite their strongly favorable interactions with PVDF. These experimental results are discussed and compared with theoretical predictions.
“Synthetic metals”: A novel role for organic polymers
Authors: MacDiarmid Alan G. , Epstein Arthur J. 
Published: March 2011

AbstractThe synthesis and p‐ and n‐doping of polyacetylene, (CH)x, the prototype conducting polymer or “synthetic metal” is described together with a qualitative description of its band structure and changes in band structure on doping to yield positive and negative solitons. Other conducting polymers are briefly discussed. The polyanilines, a large class of versatile conducting polymers involving a novel non‐redox doping process, considered as being of significant commercial technological importance are discussed in particular with reference to their ease of processing. Present and future technological uses of conducting polymers are noted.
Poly(phenylene ether ketones) prepared by electrophilic polycondensation methods
Authors: Jansons Viktors , Dahl Klaus 
Published: March 2011

AbstractPoly(phenylene ether ketones) were prepared by polyacylation reactions in hydrogen fluoride‐boron trifluoride and by aluminum trichloride promoted Friedel‐Crafts reactions modified by Lewis bases. Structural and engineering properties of these polymers are presented.
Development of thermotropic liquid crystalline polymers
Authors: Calundann G. W. , Charbonneau L. F. , Shepherd J. P. 
Published: March 2011

AbstractWholly aromatic, thermotropic liquid crystalline (LC) terpolyesters made from 6‐hydroxy‐2‐naphthoic acid (HNA) and 4,4′‐biphenol (BP) as key components have been prepared and evaluated for utility as high performance fiber precursors. The processability and fiber properties of a specific composition (1) made from both HNA and BP were compared with those of a more well‐known LC terpolyester made from p‐hydroxybenzoic acid, tere‐ and isophthalic acids and BP (Ekonol® type). The advantages of polymer 1 and its high‐modulus fiber are described.
Conducting polymers in redox devices and intelligent materials systems
Authors: Baughman R. H. 
Published: March 2011

AbstractApplications opportunities are described for conducting polymer devices, including (1) batteries and redox capacitors, (2) electromechanical actuators, (3) electrochromic windows and displays, (4) chemical separation and chemical delivery systems, and (5) indicators and sensors. Each of these potential application areas depends upon the dramatic property changes which occur during chemical or electrochemical doping. Since the properties profiles of conducting polymers can be reversibly changed either chemically or electrochemically, these polymers also provide exciting candidates for intelligent materials systems ‐ where sensor, logic element, and actuator functions can be either partially or fully integrated. Results of device and properties investigations are used to evaluate future possibilities for conducting polymers in intelligent material systems.
Novel concepts in electronic polymers: Polyaniline and its derivatives
Authors: Epstein Arthur J. , MacDiarmid Alan G. 
Published: March 2011

AbstractPolyanilines have been known for over one hundred years. Recent studies of this chemically flexible polymer have demonstrated unusual chemical, electrical, and optical phenomena, both in insulating forms and conducting forms. The polyanilines differ substantially from earlier studied polyacetylene, polythiophene, polypyrrole, polydiacetylene, and other polymers in that their electronic structure is based on the overlap of alternating nitrogen atoms and C6 rings. Two classes of the emeraldine form of polyaniline are distinguished by preparation route and crystal structure. For both classes, the Pauli susceptibility indicative of metallic state is correlated with the formation of a three‐dimensionally crystalline region. Charge conduction studies of oriented films and fibers demonstrate that three‐dimensional order between chains is critical for high conductivities. Within the crystalline regions the conduction electrons are substantially delocalized in three‐dimensions while the dc transport is dominated by quasi‐one‐dimensional variable range hopping in the disordered regions. This delocalized charge leads to high absorbance (loss) at microwave frequencies, important for a broad range of applications. The ability to derivatize polyaniline at ring and nitrogen positions allows one to test concepts for the control of conductivity as well as improved processing. The monomethyl derivative, poly(orthotoluidine), has nearly identical electronic structure and crystal structure, yet its conductivity is three orders of magnitude lower than that of emeraldine hydrochloride. This is attributed to increased interchain separation and decreased interchain correlation causing 1‐D localization. Similar 1‐D localization is observed in the self‐doped sulfonated polyaniline system. Extensive photoinduced optical studies of the insulating base forms of polyaniline show the importance of ring rotation in stabilizing photoexcited positive polarons. Long‐lived photoinduced absorptions are observed which are suggested to be a possible basis for erasable optical information storage technology.
Linear infrared dichroism by a double modulation technique
Authors: Abetz Volker , Fuller Gerald G. , Stadler Reimund 
Published: March 2011

AbstractIn the first part of this paper an experimental setup using Fourier‐transform infrared spectroscopy (FTIR) in combination with a photoelastic modulator (PEM) for linear dichroism measurements is described. The second part shows the influence of PEM‐amplitude and scan‐velocity on the sensitivity of the instrument. The third part deals with the fringe‐problem in the baselines of absorbance spectra and its influence on the determination of the linear dichroic ratio.
Infrared spectroscopy on new multiphase thermoplastic elastomers based on hydrogen bond complexes ‐ temperature dependence and orientation behaviour
Authors: Abetz Volker , Hilger Christopher , Stadler Reimund 
Published: March 2011

AbstractThe structure and deformation behaviour of a new class of thermoplastic elastomers is studied by temperature dependent infrared (IR) spectroscopy and by IR ‐ dichroism spectroscopy. The thermoplastic elastomer is based on polybutadiene with statistically distributed side groups which form an anisotropic supramolecular structure via hydrogen bonds. Changes in the IR spectra at elevated temperatures are related to the melting of the ordered structure. The uniaxial deformation behaviour is studied by linear dichroism Fourier‐transform (FT)‐IR spectroscopy. A deformation model is developed which accounts for the major experimental results: while the polybutadiene segments behave as flexible chains with characteristic rubberlike elasticity the polar units within the supramolecular structure show an orientation behaviour characteristic for rodlike molecules.
HPLC‐FTIR identification of reactive diluents in epoxy resins
Authors: Meyer Ulrich , Salzer Reiner , Raddatz Joachim 
Published: March 2011

AbstractThis report compares two types of interfaces for HPLC–FTIR, an on–line and an off–line system. The on–line system consists of a flow cell and an IR beam condenser. In the off–line system, the diffuse reflectance of the solute is measured after evaporation of the solvent. Both systems have been compared with regard to detection and identification limits of the solute.Normal phase HPLC provided the best conditions to identify less concentrated components by FTIR detection.Reactive diluents of aromatic or aliphatic structure have been identified in epoxy resins of low and medium molecular weight.The identification limit for off–line detection is at least one order of magnitude below the limit for on‐line detection.
Ion conduction in polymer electrolytes comprising crown ether and AZA‐crown structures
Authors: Cowie J.M.G. 
Published: March 2011

AbstractIon conduction, in solid solutions of salts mixed with comb‐branch polymers with oligo(ethylene oxide) side chains, has been shown to reach levels that can be of practical use in dry battery applications. Further improvements in conductivity levels may require the discovery of polymer electrolytes capable of inducing greater degrees of ionization of the salt. New systems containing crown ether and aza‐crown units have been synthesised and a preliminary assessment of some of these has been carried out. The results are compared with those obtained with the linear side chain analogues, and are sufficiently encouraging to merit further study.
The characterization of polymer deformation by rheo‐optical fourier‐transform infrared spectroscopy
Authors: Siesler H. W. 
Published: March 2011

AbstractThe mechanical properties of polymeric materials are of considerable importance to their engineering applications. Apart from the chemical structure and the thermal history, molecular orientation has a major influence on the mechanical properties of a polymer. The increased need for more detailed data and a better understanding of the mechanisms involved in polymer deformation has led to the search for new experimental techniques to characterize transient structural changes during mechanical processes. With the advent of rapid‐scanning Fourier ‐ transform infrared (FTIR) spectroscopy, simultaneous vibrational spectroscopic and mechanical (so‐called rheo‐optical) measurements during the deformation of polymers have emerged as a very informative probe for the study of deformation and relaxation phenomena in polymer films in the late seventies and have since then been applied to obtain data on strain‐induced crystallization and orientational and conformational changes during mechanical treatment of a wide variety of polymers.
Free radical entry in emulsion polymerizations
Authors: Maxwell Ian A. , Morrison Bradley R , Gilbert Robert G , Sangster David F , Napper Donald H 
Published: March 2011

AbstractMeasurements of the rate coefficients characterising the entry of free radicals into seed particles in styrene emulsion polymerizations has allowed the rate determining step for entry to be identified. This was found to be the rate of production of oligomeric species in the aqueous phase by monomer addition to the primary free radicals. Once formed the subsequent diffusion of these species to the latex particles (and their incorporation within these particles) is relatively fast, contrary to the assumptions of the previous diffusion controlled theories. The experimental results imply that the entering free radicals contain only two or three monomer units. Thermodynamic considerations show that such species should be both water soluble and surface active. Similar conclusions have been reached for other sparingly water soluble monomers, such as butyl acrylate and butyl methacrylate.
Molecular architecture control in acrylic polymers by group transfer polymerization
Authors: Webster Owen W. 
Published: March 2011

AbstractThe living polymerization of methacrylates by a repeated silyl Michael addition reaction (GTP)a operates at room temperature and permits a high degree of molecular architecture control. Chelic, telechelic, block, comb, star, loop, and ladder polymers have been synthesized. For nucleophilic catalysts other than bifluoride, a dissociative mechanism is now proposed.
Photophysics of vinyl aromatic polymers
Authors: Ghiggino Kenneth P. 
Published: March 2011

AbstractThe experimental approaches required to characterize energy migration and excimer formation in vinyl aromatic polymers are considered. As an example the photophysical processes occurring in poly(acenaphthylene) (PACE) and water soluble acenaphthylene copolymers have been investigated using steady state and time resolved fluorescence spectroscopy. Excimer formation in these polymers is determined by both structural and dynamic factors. The difficulties in the application of fluorescence decay analyses to examine energy migration in polymers are discussed. For PACE with a 9‐methylanthryl (9MA) end‐group and the copolymers containing solubilized 9MA, energy migration and transfer can be demonstrated.
Viscoelastic properties of polymers: From molecular models to non‐linear behavior
Authors: Marin G. , Benallal A. 
Published: March 2011

AbstractThe molecular models of polymer physics (reptation, tube renewal) give a reasonable picture of the diffusion and relaxation of long and flexible chains: the concept of “tube renewal” (constraint release) added to the reptation idea explains the polydispersity effects for multimodal blends as well as for commercial linear polymers. The real issue now is to introduce these concepts in the formalism of non‐linear viscoelasticity in order to explain the experimental data, as a first step in the range of moderate rates of deformation, then at very high strains.
Transient rheological behaviour of melts of liquid‐crystalline polymers compared with that of flexible polymer melts
Authors: Booij H. C. , Palmen J.H.M. 
Published: March 2011

AbstractTransient rheological behaviour of melts of flexible polymers can be described qualitatively by factorable constitutive equations, the functions of which can be obtained by oscillatory and step strain experiments. In start‐up experiments thermotropic LCP melts can exhibit very large overshoots of the stresses, followed by minima, after which steady states are reached through damped oscillations of the signals. It is also possible that the normal stress remains periodic for long times, with large amplitudes, as is shown for a nematic copolyester melt that has been squeezed during the gap setting process. These periodicities scale with the number of revolutions of the rotating plate. After cessation of flow the stresses relax quickly to values that may be unequal to zero and dependent on the position in the period of the stresses where flow is stopped. Dynamic experiments reveal that the melts are very elastic in that state.
Chain conformation in polymer melts during flow as measured by small angle neutron scattering
Authors: Muller R. , Picot C. 
Published: March 2011

AbstractThe anisotropic form factor of polystyrene (PS) chains during tensile and simple shear flows in the melt has been measured by small angle neutron scattering (SANS) on quenched samples containing deuterium labeled chains. For all tensile experiments, carried out in a wide range of strain rates, including linear viscoelastic behaviour, the chain conformation is well predicted by a temporary network model involving the recoverable strain. For binary blends of two PS with different molecular weight, the technique allows to characterize the chain conformation of either species. The scattering patterns of sheared samples show that the principal directions of molecular orientation depend on the magnitude of the scattering vector q: At high q (local level on the chain) the orientation is close to 45° with respect to the shear axis, whereas at low q the chains appear to be almost aligned with the stream lines.
Shear flow characterization of blends containing liquid crystal polymers
Authors: La Mantia Francesco Paolo , Valenza Antonino 
Published: March 2011

AbstractA simple phenomenological approach is proposed in order to predict the presence of minima in the viscosity‐composition curves of blends of thermoplastic with liquid crystal polymer (LCP). When the viscosity of the liquid crystal polymer is larger than that of the thermoplastic matrix, a minimum is observed. A possible explanation of the presence of yield stress in the flow curves of these blends is also given.
Possibilities and limits of pyrolysis
Authors: Kaminsky W. 
Published: March 2011

AbstractIn the public and administration the acceptance for landfilling or incineration of plastic wastes is decreasing. By pyrolysis it is possible to recover hydrocarbons from polymers. Rotary kilns and fluidized bed processes are investigated as processes. As yet, no process has come to an industrial stage. The fact that more plastic wastes will be collected in the future gives a chance for building plants with higher capacity which will be working more economically. Mechanical problems with feed and output could be solved.
Chemical changes in engineering thermoplastics
Authors: Bolon Donald A. , Irwin Patricia C. 
Published: March 2011

AbstractParts molded from reground BPA polycarbonate (PC) resin recovered from used objects do not always give the desired physical properties as parts molded from virgin resin. This loss of properties appears due to a surface hydrolysis of the PC which results in a reduction in molecular weight and formation of bis‐phenol‐A (BPA). The hydrolysis appears to be aided by exposure to uv‐light and humidity. If the surface of the PC is washed with caustic solution, BPA and low MW oligomers are removed and many of the physical properties of the PC are restored.
Recycling of PVC floor coverings; first results after one year of practice
Authors: Bonau Hugo 
Published: March 2011

AbstractSince the end of 1990, the “Arbeitsqemeinschaft PVC Bodenbelags Recycling (Society for the recycling of PVC floorings, AgPR)” collects and recycles PVC floor coverings in Germany. AgPR is an activity as well of PVC producers as of PVC floor covering manufacturers. 19 European companies participate in this venture. AgPR collects used floorings in several areas of Germany. It also pays 150 DM/t of PVC flooring delivered to its recycling plant in Großefehn. This plant has a capacity for recycling 5000 t/a. The used floor coverings are comminuted, ground to powder size and after that reused to manufacture new floor coverings.