bluuebunny/crossref_metadata_2025 huggingface dataset:
Peripherally restraining type rubber bearing
Authors: Sasaki Teruo
Published: April 2003

Seismic isolation was reconfirmed to be extremely efficient for the protection of buildings, and hence human life, on the occasion of the Great Hanshin Earthquake. Rubber bearings are placed under the buildings for isolation, and thus the type of rubber bearings is a dominant factor for efficient isolation. In this report, the performance of peripherally restraining type rubber bearing (PRB) was examined where its contracted model was found to simulate the performance of full scale PRB precisely. Damping ratio and vertical spring constant of PRB are as good as the existing ones. PRB showed lower critical shear strain, but it was concluded that no problems were found for the actual use of PRB.
Preparation and structural characteristics of stimuli‐responsive hydrogel microsphere
Authors: Nakazawa Yoshiyuki , Kamijo Yukiko , Fujimoto Keiji , Kawaguchi Haruma , Yuguchi Yoshiaki , Urakawa Hiroshi , Kajiwara Kanji
Published: April 2003

Monodisperse hydrogel microspheres were prepared by precipitation polymerization from acrylamide (AAm), methylenebisacrylamide (MBAAm) and methacrylic acid (MAc) in ethanol, and examined their stimuli response by changing pH or temperature. The microsphere was found to contract continuously by heating. The microsphere with a lower‐content MBAAm exhibit more pronounced heat‐contraction. Also at low pH the microsphere contracted due to the protonation of the carboxyl group in MAc. The internal structure was observed by small angle X‐ray scattering (SAXS) and the stimuli‐response mechanism was discussed from the view of network chain conformation.
Elastic properties of real elastomers at small deformations
Authors: Takigawa Toshikazu , Urayama Kenji , Yamasaki Satoshi , Masuda Toshiro
Published: April 2003

Elastic properties of real elastomers were examined by using partial derivatives of the strain energy density function (W) with respect to the invariant (Ii, i=1,2,3) of deformation tensor. The values of the derivatives at zero strain limit for styrene‐butadiene rubber (SBR), nitrile‐butadiene rubber (NBR) and butadiene rubber (BR) were compared with those derived from the theory shown in the previous paper, where compressibility of the materials was taken into account. The asymptotic behavior of the derivatives for isoprene rubber (IR) and segmented polyurethaneurea (SPU) was also compared with those of the three types of rubbers. It was shown that the theoretical predictions for the limiting value agreed fairly well with the experimental values of the elastomers.
Network formation and swelling behavior of photosensitive poly(vinyl alcohol) gels prepared by photogenerated crosslinking
Authors: Shindo Yoichi , Katagiri Naoya , Ebisuno Toichi , Hasegawa Masatoshi , Mitsuda Miyuki
Published: April 2003

Poly (vinyl alcohol) with pendent styrylpyridinium groups (SbQ) is insolubilized by photoirradiation. An association takes place in SbQ groups. The association of polymer chains becomes marked with increasing the number of SbQ groups. Mainly intermolecular crosslinks were formed. Transparent and homogeneous macrogels consisting of several intermolecular crosslinks are obtained.

The proportion of the free water to the bound water in PVA‐SbQ gels was 3.3−2.9 despite of the large change in conversion of photodimerization of SbQ groups, x=0.27−0.58. The water uptake after swelling of the gels in water increased 6–27 times compared to the original weight at pH=7. The higher the degree of photocrosslinking, the lower was the degree of swelling. The water diffusion coefficients, D, were (2.2−5.8) × 10−5 cm2 S−1 for a 88% saponified PVA with 1 . 3 mol% SbQ groups. The volume of the gel increased discontinuously about 10‐fold for the 99% saponified PVA with 0 . 096 mol% SbQ and 51% water (49% acetone). The acetone concentration at the transition decreased with increasing the degree of saponification of the PVA.
Permeation and separation of organic liquid mixtures through liquid‐crystalline polymer networks
Authors: Inui Kuniaki , Miyata Takashi , Uragami Tadashi
Published: April 2003

A side‐chain liquid‐crystalline polymer (LCP) was synthesized by the addition of the mesogenic monomer to poly(methyl siloxane) in presence of a Pt‐catalyst. When an aqueous solution of 10wt% ethanol was permeated through a LCP membrane by pervaporation at various temperatures, the permeation rate increased with increasing temperature and drastically changed at glass‐nematic (Tg) and nematic‐isotropic (TNI) transition temperatures of the LCP membrane. The LCP membrane exhibited the waterpermselectivity in the glassy and liquid‐crystalline states. The ethanol concentration in the permeate increased with increasing permeation temperature and the LCP membrane changed from the waterpermselectivity to the ethanol‐permselectivity around TNI. These results suggested that the permselectivity was influenced by the change of the LCP membrane structure, that is, its state transformation. It was found that a balance of the orientation of mesogenic groups and flexibility of siloxane chains is very important for the permeability and selectivity.
pH‐controlled uphill transport of ammonium ions through polymer membranes with sulfonic acid groups
Authors: Miyata Takashi , Tsutsui Kiyoko , Uragami Tadashi
Published: April 2003

Uphill transport of ammonium ions through a membrane with sulfonic acid groups were investigated with pH‐controllers which keep the solution at a constant pH. A membrane with sulfonic acid groups was prepared by casting an aqueous solution containing poly(styrenesulfonic acid) and poly(vinyl alcohol) on a glass plate. When a membrane with one side alkaline and the other acidic was fixed as a diaphragm in a cell, ammonium ions were transported from the alkaline side to the acidic side through the membrane against the concentration gradient of the adjacent solutions. Uphill transport of ammonium ions with pH‐controllers was more efficient than without, thus keeping the pH difference between both sides of the membrane constant, which is a driving force for the uphill transport. Furthermore, the effect of pH of the acidic side on the uphill transport was investigated and the mechanism of the pH‐controlled uphill transport is discussed.
Preparation of oxidized 6‐O‐glycolchitosan, pH sensitivity of its aqueous solution and of its cross‐linked hydrogel
Authors: Ohya Yuichi , Okawa Koji , Murata Jun‐ichi , Ouchi Tatsuro
Published: April 2003

Chitosan and 6‐O‐glycolchitosan, a water‐soluble chitosan derivative, were oxidized by periodate. In the case of chitosan, only degradation products were obtained. With 6‐O‐glycolchitosan, however, water‐soluble amphoteric polyelectrolyte derivatives of chitosan having higher molecular weight were obtained. The oxidized 6‐O‐glycolchitosan (OX‐GC) showed a pH sensitive change of viscosity in aqueous solution. Moreover, the OX‐GC hydrogel, cross‐linked with glutaraldehyde, showed a pH sensitive swelling behavior. The OX‐GC showed biodegradation behavior by lysozyme after acetylation.
Ideal crosslinked‐polymers and their characterization in free‐radical monovinyl‐divinyl copolymerizations
Authors: Matsumoto Akira , Okamoto Atsushi , Okuno Seiji , Aota Hiroyuki
Published: April 2003

The critical conditions in which the classical Flory‐Stockmayer gelation theory (F‐S theory) is applicable to monovinyl‐divinyl copolymerizations were pursued in detail. The resulting prepolymers or precursors of ideal crosslinked‐polymers were characterized as standard polymers for the discussion of network formation in free‐radical monovinyl‐divinyl copolymerizations. Methyl methacrylate was copolymerized with a small amount of ethylene dimethacrylate, butylene dimethacrylate or nonapropyleneglycol dimethacrylate in the presence of lauryl mercaptan, a chain transfer agent to reduce the occurrence of a thermodynamic excluded volume effect and intramolecular crosslinking as the primary and secondary factors, respectively, for the greatly delayed gelation in the free‐radical monovinyl‐divinyl copolymerizations and, moreover, to keep the primary chain length constant by inhibiting a gel effect. The ratio of the actual gel point to the theoretical one reached 1.1, supporting the validity of F‐S theory. The resulting prepolymers were subjected to SEC‐MALLS analysis to determine the molecular weights, the molecular‐weight distributions and the radii of gyration; the correlations of molecular weight vs. elution volume and radius of gyration vs. molecular weight were useful for the characterization of the precursors of ideal network‐polymers.
A polymer network of unsaturated polyester and bismaleimide resins: Yielding and fracture behaviour
Authors: Abbate Mario , Martuscelli Ezio , Musto Pellegrino , Ragosta Giuseppe
Published: April 2003

The yielding and the fracture behaviour of an intercrosslinked polymer network obtained by the simultaneous curing of an unsaturated polyester (UP) and a thermosetting bismaleimide resin (BMI) was investigated in a wide range of temperatures and testing rates. The yield stress σy and the Young's modulus E increase by increasing the testing rate and decreasing temperature. Moreover, under the same testing conditions, σy and E increased as the BMI content in the blend was enhanced. On the other hand, it was found that the fracture parameter Kc was not affected by the presence of BMI. The yielding process was analyzed using the theories both of Argon and Bowden and the molecular parameters derived there were related to the molecular structure of the network developed upon curing.
Polycondensation of novolacs containing dominately ortho‐ortho‐methylene linkages
Authors: László‐Hedvig Z. , Szesztay M. , Tüdős F.
Published: April 2003

In an early stage of the polycondensation of phenol/formaldehyde (Ph/F) systems catalyzed by bivalent metal acetates (Me2+(ac)2), 2‐hydroxy‐benzylalcohol (2‐OH‐BA) formation was selective in the weak acidic medium and only in the presence of the catalyst. The concentration change in 2‐OH‐BA and its hemiformal (HF) was followed by GPC as a function of the pH value of the system and the catalyst concentration and was found to be independent of the type of metal used in the catalyst but dependent on the pH value of the medium and on the catalyst concentration. An extremely high catalyst concentration does not cause further increase in the overall rate of 2‐OH‐BA formation. It was proved by 1H NMR that at higher conversion and in the presence of Me2+(ac)2 catalyst, the o‐o′‐ArCH2Ar isomers are dominating over o, p′ and p,p′ ones. Novolacs with overwhelming o‐diphenylmethane structures are thermally stable up to 400°C and can be crosslinked without hexamethylenetetramine (HEXA).
Miscibility of linear low density polyethylene (LLDPE)‐graft‐poly(methyl methacrylate) with poly(vinylidene fluoride) (PVF2) and its application as compatibilizer LLDPE/PVF2 blends
Authors: Li Lin , Tang Tao , Huang Baotong
Published: April 2003

Differential scanning calorimetry (DSC), Fourier‐transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X‐ray photoelectron spectroscopy (XPS) were used to study the miscibility of blends of a graft copolymer of poly(methyl methacrylate) on linear low density polyethylene (LLDPE‐g‐PMMA, G‐3) with poly(vinylidene fluoride)

Systematic name: poly(1,1‐difluoroethylene).

(PVF2) and the compatibilization of blends of LLDPE/PVF2. The specific interaction between PMMA side chains and PVF2 in G‐3/PVF2 binary blends is weaker than that between the homopolymers PMMA and PVF2. There are two states of PVF2 in the melt of a G‐3/PVF2 (60/40, w/w) blend, one as pure PVF2 and the other interacting with PMMA side chains. The miscibility between PMMA side chains and PVF2 affects the crystallization of PVF2. LLDPE‐g‐PMMA was demonstrated to be a good compatibilizer in LLDPE/PVF2 blends, improving the interfacial adhesion and dispersion in the latter. Diffusion of PMMA side chains into PVF2 in the interfacial region reduces the crystallization rate and lowers the melting point (Tm) and the crystallization temperature (Tc) of PVF2 in the blends.
Matrix‐assisted laser desorption/ionization mass spectrometry of synthetic polymers. 3. Analysis of condensation polymers
Authors: Pasch Harald , Rode Karsten , Ghahary Reza , Braun Dietrich
Published: April 2003

Matrix‐assisted laser desorption/ionization mass spectrometry is shown to be a suitable method for the analysis of condensation polymers. Although these products are rather low in molar mass, they exhibit a complex chemical structure. Phenolic novolacs and resols can be analysed with respect to the degree of polymerization and the type and number of functional groups. Modified phenolic resins, such as epoxidized novolacs, can be identified and the degree of epoxidation can be determined. It is shown for polycarbonates and polyesters that depending on the reactant ratio linear oligomers with different endgroups and cyclic oligomers are formed.
Molecular characterization of branched thermoplastic polyurethane in dilute solutions on N‐methyl‐2‐pyrrolidinone
Authors: Lederer Klaus , Macko Tibor , Imrich‐Schwarz Gabriele , Aust Nicolai , Kolmanics Thomas , Schwarz Thomas
Published: April 2003

Seven homologous samples of a thermoplastic polyurethane (TPU) were characterized in dilute solutions of N‐methyl‐2‐pyrrolidinone (NMP) by size exclusion chromatography (SEC) on normal‐phase silica gel, low‐shear viscometry and membrane osmometry. The Staudinger‐Mark‐Houwink (SMH) constants of this homologous series were obtained by a new procedure of calculation on the basis of universal calibration of SEC with narrow polystyrene standards. The calculated SMH constants for these TPU samples in NMP at 298 K (K = 3.94 mL g−1, a = 0.29) prove the branched structure of this TPU samples and were further confirmed by osmometry.
Dielektrische Untersuchung der Härtung eines Epoxidharzes mit anhydridmodifizierten phenolischen Härtern
Authors: Böschel Dorit , Schramm Frank , Fedtke Manfred
Published: April 2003

Die Härtung verschiedener Epoxidharzsysteme wurde mit Hilfe der dielektrischen Analyse verfolgt. Da sie sehr empfindlich ist, erwies sie sich zur Beobachtung der Nachhärtungsperiode besser geeignet als die Differentialkalorimetrie. Am Beispiel der Vernetzung von Diandiglycidylether mit anhydridmodifizierten Phenolnovolaken wird gezeigt, daß mittels dielektrischer Analyse die Bestimmung von Glasumwandlungstemperaturen möglich ist; dagegen ist diese Methode für die Ermittlung von Gelierzeiten nicht geeignet.
Linear polythioesters, XXVI. Products of interfacial polycondenation of bis(4‐mercaptomethylphenyl)methane with some aliphatic and isomeric phthaloyl dichlorides
Authors: Podkościelny Wawrzyniec , Podgórski Mieczysław
Published: April 2003

New polythioesters were synthesized by interfacial polycondensation of bis(4‐mercaptomethylphenyl)methane with selected aliphatic and isomeric phthaloyl dichlorides. To determine optimum polycondensation conditions, the influence of the following factors on reduced viscosity and yield were studied: type of organic phase, concentration of hydrogen chloride acceptor (NaOH), concentration of reagents, aqueous/organic phase ratio, rate of acid chloride addition, reaction time and reaction temperature.

A thorough examination was carried out only for the polycondensation of dithiol with adipoyl and isophthaloyl dichlorides chosen as model systems. The structures of polythioesters were confirmed by elemental analysis, X‐ray analysis and infrared spectroscopy. Some physicochemical, mechanical and electrical properties were determined. The molecular weights were not measured, because of the low solubility of the obtained polythioesters.
Blocked isocyanate. Reaction and thermal behaviour of the toluene 2,4‐diisocyanate dimer
Authors: Querat E. , Tighzert L. , Pascault J. P. , Dušek K.
Published: April 2003

Due to the difference in reactivity between free isocyanates and uretdione rings, diisocyanate dimers can be used as blocked isocyanates. They offer the potential advantage that no volatile by‐products are formed. The toluene 2,4‐diisocyanate dimer contains one uretdione ring, formed by dimerization of two isocyanate groups, and two free isocyanate groups. The latter react rapidly with the hydroxy groups of a polycaprolactone diol at temperatures above 80°C. The pure dimer thermally dissociates above 150°C; dissociation is reversible. In the presence of OH groups, the regenerated isocyanate groups can then react to form urethanes. Our experiments have also revealed the formation of allophanate groups as reaction products of an uretdione ring with a hydroxy group. The influence of initial molar ratio of reactants and of temperature on the mechanisms have been discussed. Allophanates are not stable at high temperature in presence of remaining hydroxy groups, their dissociation leads to urethanes. Application of branching theory has shown that the system can gel due to allophanate formation in a wide range of initial molar ratios of NCO to OH groups.
The effect of alumina particulate morphology on the properties of reinforced poly(propylene) and poly(ethylene‐co‐vinyl acetate) composites
Authors: Prachar Michael Jiri , Hay James , Ponton Clive
Published: April 2003

The effect of alumina particulates on a thermoplastic matrix is investigated, in particular the effect altering the alumina particle size and morphology has on the mechanical properties. Different grades of alumina are used and two thermoplastic matrices; namely poly(propylene) and poly(ethylene‐co‐vinyl acetate). Investigations showed that optimum properties were achieved with the alumina of smallest particle size and lowest aspect ratio. Preliminary work has also been performed on the use of silane coupling agents and they have proved effective in increasing the tensile properties of the composites.
Optimal design of free‐radical batch polymerizations with one charge of monomers and initiator
Authors: Hollbeck Christoph , Bandermann Friedhelm , Günther Claus
Published: April 2003

Based on an earlier paper of Chen and Lee, a procedure is developed to determine optimal reaction times for predetermined monomer conversions and number‐average degrees of polymerization in an azeotropic free‐radical batch copolymerization with one charge of monomers and initiator. The procedure allows for the calculation of the admissible range of monomer concentrations, the determination of an appropriate initiator and its most suited concentration to arrive at the goal in reaction times as short as possible. The validity of the model was tested in the free‐radical copolymerization of acrylonitrile and butadiene in chlorobenzene at 343 K, using 1,1′‐azocyclohexanenitrile (ACN) and 2,2′‐azoisobutyronitrile (AIBN) as initiators. The agreement of theoretical and experimental data was satisfying. It is pointed out that the gel effect can be incorporated into the model, and that the procedure can also be used in the design of free‐radical homopolymerizations.
ÉTude préliminaire des propriétés microlithographiques d'une résine renfermant un polyimide et un bis‐azide sensible aux UV lointains
Authors: Sailhan Valérie , Kasseh Abdeslam , Mertz Christian , Montginoul Claude , Giral Louis , Schué François
Published: April 2003

L'étude préliminaire des propriétés microlithographiques des résines obtenues en mélangeant un polyimide et un bis‐azide a permis de montrer que de telles résines pourraient probablement être utilisées en tant que résines microlithographiques sensibles aux UV lointains. En effet ces résines donnent des couchages homogènes qui ont des épaisseurs convenables. De plus, elles sont très sensibles aux irradiations: elles subissent alors des modifications de structure lorsqu'on les irradie par des radiations de longueur d'onde égale à 254 nm. Les parties ainsi insolées sont insolubles dans les solvants constitués par des mélanges d'eau et de dioxane ou d'eau et de 1‐N‐méthylpyrrolidone alors que ces mêmes solvants solubilisent parties non insolées.
The role of molar volume of the organic solvents in the swelling system EPDM vulcanizate/solvent
Authors: Hrnjak‐Murgić Z. , Jelenĉić J. , Bravar M.
Published: April 2003

Eight samples of poly(ethylene‐co‐propylene‐co‐diene) (EPDM, containing 55 wt.‐% ethylene) were vulcanized with 0.5–8.0 phr dicumyl peroxide. The influence of molar volumes V1 of cyclohexane, hexane, heptane, iso‐octane, tetrachloromethane, carbon disulfide, xylene, benzene, toluene, tetrahydrofuran, trichloromethane and chlorobenzene on the swelling intensity of the EPDM vulcanizates was studied, and it was found that regardless of the solubility parameters, polarity, dielectric constants, acidity or basicity of solvents, a linear relationship exists between V1 and number of moles of solvent in the gels, n1. With increase of V1, n1 decreases.
Zur substituentenverteilung in kationischen xylanderivaten
Authors: Ebringerová Anna , Hromádková Zdena
Published: April 2003

Trimethylammonium‐2‐hydroxypropylxylans with degrees of substitution (DS) ranging from 0.25 to 0.98 were hydrolysed to monomer units, and the 13C NMR spectra of the hydrolysates as well as products separated therefrom were taken and assigned. Monosubstitution of the xylose units was found mainly to occur in the studied DS range. At lower DS, substitution of OH‐2 groups is preferred, whereas at higher DS the regioselectivity is lost.
Urethane‐acrylate compositions cured by UV radiation as intermediate protective covers of optical fibers
Authors: Podkoscielny Wawrzyniec , Tarasiuk Bogdan , Rayss Jan , Podkoscielny Wiesław Marian
Published: April 2003

The present paper deals with studies concerned with an optimization of the synthesis of urethane‐acrylic UV‐cured resins intended for application as protective coatings for optical fibers. Oligoetherdi‐ and triols, toluylene diisocyanate and isophorone diisocyanate, as well as hydroxyethyl methacrylate and hydroxypropyl methacrylate were used for synthesis. Active diluents butyl acrylate, 2‐ethylhexyl acrylate, 1,4‐butanediol diacrylate or their mixtures, and 2,2‐dimethoxy‐2‐phenylacetophenone as a photoinitiator were added to the urethane‐acrylic dimers comprising polymerization‐active double bonds. The compositions were characterized by the determination of density, viscosity, refractive index, gel content, glass transition temperature, Shore hardness, Young's modulus, breaking stress, relative elongation at break, thermal resistance and water vapour diffusion coefficient before and after curing.

The utility of these compositions for protective intermediate coatings of optical fibers was checked and confirmed under manufacturing conditions.
Electric resistivity of hydroscopic copoly(ester‐ether)s containing zwitterionic units and their utilization for antistatic modification of polyester fiber
Authors: Sano Yoshiyuki , Lee Chan Woo , Kimura Yoshiharu , Saegusa Takeo
Published: April 2003

Block copoly(ester‐ether)s containing different ionic units, i.e., sulfobetaine (S‐betaine), carbobetaine (C‐betaine), and ammonium tosylate, were prepared and evaluated as antistatic modifiers of PET fiber. The ionic units were readily derived from N,N‐bis(2‐hydroxyethyl)methylamine and co‐condensed randomly with the polyester and poly(oxyethylene) (PEO) units. For the copolymers containing S‐betaine units, a thick filament was melt‐spun to evaluate their apparent electric resistivity. Depending on the unit compositions (25–75 wt.‐% of PEO and 1–2 mol‐% of S‐betaine), resistivities ranging from 108 to 1010 Ω cm‐1 were obtained. Then, the three copolymer‐type modifiers were blended with poly(ethylene terephthalate) (PET) by the ordinary blend‐spinning technique. The blend PET fibers obtained showed not only good mechanical properties, but also improved antistatic properties. Particularly, the fiber blended with the copolymer containing S‐betaine units had the shortest half‐life time of leakage of static charge, although the surface area resistivity, being in the order of 1013 Ω cm‐2, was similar to that of the fibers blended with the copolymers containing C‐betaine and ammonium tosylate units. These blend PET fibers were found to retain good antistatic properties even after dyeing and repeated washings, because both the hydrophilic and ionic groups are immobilized with the polyester chains.
Untersuchungen zum reaktionsverhalten beim vorliegen von depolymerisationsreaktionen. Untersuchung von copolymerisationen des α‐methylstyrols
Authors: Fleischhauer Jürgen , Schmidt‐Naake Gudrun , Scheller Dieter
Published: April 2003

Für die radikalischen Copolymerisationen von α‐Methylstyrol (MS) mit Methacrylnitril (MAN) sowie MS mit Acrylnitril (AN) wurden Untersuchungen zur Prüfung der in der Literatur postulierten kinetischen Modelle des „sequenzlängenunabhängigen”︁ bzw. „sequenzlängenabhängigen”︁ Terminalmodells mit Depolymerisationsschritten durchgeführt. Sie basieren auf Analysen der Sequenzverteilungen aus 13C‐NMR‐Spektren. Resultate von 13C‐NMR‐Untersuchungen an MS/MAN‐Polymeren variabler Zusammensetzung werden vorgestellt. Reaktionsparameter und Gleichgewichtskonstanten wurden direkt aus den Informationen der 13C‐NMR‐Spektren für das Terminalmodell mit Depolymerisationsschritten in Abhängigkeit von der Reaktionstemperatur der Polymeren bestimmt. Hieraus konnten die Polymerisationsenthalpie ΔH = 26,5 ± 0,5 kJ mol−1, die Polymerisationsentropie ΔS = 95 ± 5 J mol−1 K−1 sowie die Ceilingtemperatur Tceiling = 65 ± 1°C für MS bestimmt werden. Es wurde nachgewiesen, daß im Rahmen der Terminalnäherung auch mit Berücksichtigung von Depolymerisationseinflüssen keine adäquate Beschreibung des Copolymerisationsverhaltens im Falle der untersuchten Systeme möglich ist. Vielmehr konnten als Ergebnis der Untersuchungen sowohl in Copolymeren von MS mit AN als auch mit MAN signifikante Penultimate‐Effekte nachgewiesen werden. Aufbauend auf diesen Ergebnissen wird die Anwendung eines auf einer Penultimate‐Näherung basierenden Modells, welches auch das Gleichgewicht in den Wachstumsreaktionen von MS berücksichtigt, zur theoretischen Vorhersage des Copolymerisationsverhaltens vorgeschlagen.
Instrumented impact testing of phenolphthalein polyether ketone
Authors: Han Yanchun , Li Binyao , Yang Yuming
Published: April 2003

The Charpy impact fracture behaviour of unnotched specimens of phenolphthalein polyether ketone (PEK‐C) was studied over a temperature range from room temperature to 220°C by using an instrumented impact tester. The load‐time and energy‐time curves of PEK‐C at different temperatures were recorded. From these curves, some important parameters, such as the maximum impact load, the maximum stress, the total impact energy, the crack initiation energy, the crack propagation energy etc., were obtained and their temperature dependences of PEK‐C were investigated. The point of 100 percent maximum load on the load‐time trace was shown to be the yield point. Two parameters, the ductile ratio (D.R.) and the ductility index (D.I.) were applied to characterize the ductility of PEK‐C and their relationships to the relaxation processes were discussed.
On the copolymerization of styrene with some UV stabilizers based on triazinylaminobenzotriazole
Authors: Konstantinova T.
Published: April 2003

The copolymerization of styrene with three polymerizable UV stabilizers based on triazinylaminobenzotriazole was investigated. The relationship between the polymerization rate and the character of the UV stabilizer was established. The general conclusion was that the presence of the UV stabilizer retarded the polymerization of styrene, without significant effect on the molecular weight and the thermostability of the copolymers thus obtained.
Cardanol‐phenol‐formaldehyde resins. Thermal analysis and characterization
Authors: Huong Nguyen Le , Nieu Nguyen Huu , Tan Ton That Minh , Griesser Ullrich J.
Published: April 2003

Phenolic resins (resols) based on phenol and cardanol, a natural alkyl phenol from cashew nut shell liquid (Anacardium occidentale L.), were synthesized, and their thermal and chemical resistances as well as their mechanical properties were determined. The results show that the addition of certain amounts of cardanol (less than 15 wt.‐%) to phenol distinctly improves the chemical resistance and some mechanical properties such as tensile, flexural and Izod impact strengths of the resins. At the same time, the high thermal stability of pure phenol‐formaldehyde resins still remains in the temperature range of high relevance.
Effects of surface crystallinity on dynamic mechanical properties of compression‐molded polypropene sheets
Authors: Kawamoto Naoshi , Mori Hideharu , Yui Nobuhiko , Nitta Koh‐hei , Terano Minoru
Published: April 2003

Dynamic mechanical properties are measured for a series of compression‐molded polypropene sheets having the same bulk crystallinity but different surface crystallinity. The temperature of the α‐dispersion was shifted to lower temperatures with lowering the surface crystallinities of the sheets. A shoulder peak, which is ascribed to the surface layer, appeared between the α‐ and β‐dispersion for the sheets. In addition, the application of the Takayanagi model to the experimental results suggests the difference in the continuity of the amorphous phase between the surface layer and the bulk.
Electrically conductive polyaniline/poly(butadiene‐co‐styrene‐co‐2‐vinylpyridine) latex composites
Authors: Xie Hong‐Quan , Liu Hao , Liu Zhi‐Hong , Guo Jun‐Shi
Published: April 2003

A series of conducting polyaniline/poly(butadiene‐co‐styrene‐co‐2‐vinylpyridine) (PBSP) latex composites was prepared by polymerization of aniline in the presence of PBSP latex. The mass loading of polyaniline in the composite latex can be controlled by varying the PBSP latex/aniline charging ratio and oxidant/aniline molar ratio. The composites were characterized by elemental analysis, transmission electron microscopy and thermogravimetric analysis. The effects of the concentration of the reactants on the conductivity at room temperature and the mechanical properties of the composite films formed from the latices were studied.
Synthesis of benzoin terminated poly(tetrahydrofuran)s
Authors: Önen AyşLen , Yagci Yusuf , Schnabel Wolfram
Published: April 2003

Living poly(tetrahydrofuran) (PTHF) was terminated with the sodium salt of benzoin to yield polymers with photoactive end groups. The PTHF macroinitiators obtained were characterized and used as an initiator in the free radical polymerization of methyl methacrylate.
Chain‐cycle equilibrium in the course of the polycondensation of aldehydes with α,ω‐dithiols
Authors: Sensfuß Steffi
Published: April 2003

The course of the proton catalysed solution polycondensation of aromatic aldehydes and α,ω‐dithiols (C6–C8) has been investigated by the use of benzaldehyde/triethylene glycol dithiol or hexamethylene dithiol. Too long reaction periods lead to a polymer degradation under the conditions of synthesis. It is caused by a complex polymerization equilibrium between cyclic, oligomeric and polymeric mercaptals after removal of the reaction water. The chain propagation simultaneously proceeds via open‐chain and cyclic intermediates. The polymers may be transformed into cycles and vice versa. The chain‐cycle equilibrium preferably takes place in solvents like CH2CI2, CHCI3 or benzene, but hardly in dioxane or DMSO.

Polymercaptals derived from aromatic dithiols (4,4′‐thiodibenzenethiol) and benzaldehyde analogously undergo chain scission under weakly acidic conditions (CH2CI2, reflux). However, in this case a mixture of linear and cyclic mercaptal structures is presumably formed.
Polystyrol und styrolcopolymere
Authors: Gausepohl Hermann , Warzelhan Volker
Published: April 2003

Polystyrene is with a present day sales volume of 8,5 million tons a year one of the most important thermoplastics worldwide. Its unique property profile makes polystyrene an ideal material for housings, refrigerator inliners and demanding packaging applications, when transparency and/or surface quality as well as stiffness are important. Its economic success is due to its favourable price/performance ratio and also not least to its excellent processability as an amorphous material.

In this contribution the versatility and potential for innovation of polystyrene and its copolymers are discussed. Using standard and impact modified polystyrene, it is shown how the maturity of the polymerisation process, the broad spectrum of product modifications as well as processing know how of this class of materials have helped to promote the breakthrough of this product to an acknowledged plastic material.

Modern polystyrene variations are increasingly meeting the special property requirements of other materials, like for example high heat resistant PPE/PS‐I blends, weather resistant ASA and AES plastics, tough and crystal clear star polymers or hydrogenated and unhydrogenated elastomers.

A special feature of polystyrene is that it is one of the few monomers which can be polymerised using all the known methods for vinyl monomers to produce high molecular weight products. Thus the newest polymerisation techniques using metallocene catalysed and anionic polymerisation methods lead to products with the property profile of engineering plastics.

Polystyrene will continue to grow in the future and thus increase in importance, especially while it can be easily depolymerised and in the form of styrene monomer recycled.
Polyamide, polyester und polyoxymethylen. Die klassischen technischen kunststoffe und ihre perspektiven
Authors: Heym Manfred
Published: April 2003

Polyamide, polyester and polyoxymethylene having presently a worldwide sales volume of 2,4 million tons a year are important engineering thermoplastics. Based on their special property profiles they are mainly used in the automotive and electronic industry for high performance functional parts. This contribution presents polymerisation processes, properties, and selected new developments for these polymer classes.

Semiaromatic polyamides due to their dimensional stability and thermal resistance lend themselves to applications which were so far reserved for thermosets or metals. Glass fiber reinforce polyamides designed to have the highest possible heat ageing resistance can take important functions under the hood. A polyamide blend used as a material for exterior body parts is key to light weight cars with strongly reduced fuel consumption. Halogene free flame retardant polyamide increases fire safety and environmental safety in flame sensitive applications.

Polybutyleneterephthalate as the technically most important polyester offers new perspectives in blends with amorphous polymers leading to lower distortion and better surface quality in glass fiber reinforced parts. Polybutylenenaphthalate is widening the range of application of polyesters towards higher temperatures. Copolyesters derived from polybutyleneterephthalate are biologically degradable and are therefore promising materials for fermentable foils.

Polyoxymethylene copolymers show an outstanding combination of stiffness, dimensional stability, friction and wear as well as resistance against hot water and fuel.

As a result of their excellent properties and the existing potential for further improvements polyamide, polyester and polyoxymethylene will continue to grow above average in the future.
Sind polyurethanwerkstoffe ein reifes gebiet?
Authors: Müller Peter
Published: April 2003

The world‐wide production of polyurethanes has exceeded 6 mio. metric tons in 1994. Compared with the produced amounts of large‐scale thermoplastics such as PE, PVC, PP and PS, polyurethanes keep the 5th place.

Polyurethanes (PUR) are segmented polymers, which can be synthesized from preformed building blocks in a modular unit construction system. The chemical modules and the various possibilities of combination will be discussed here.

Tailor‐made polyurethane materials can be divided into two main‐fields of application: foams and compact PUR.

The main constituents of polyurethane materials are diisocyanates and polyols. These key‐ chemicals are well characterised with respect to their technological, economical and ecological properties. Taking into account the availability, the masses of production and the experiences that have been collected with the PUR main constituents, these PUR precursors seem to be very mature already.

In contrast to this, the PUR‐materials made from these building blocks still offer numerous novel problem‐solutions, resulting from the variability of the diisocyanate‐poly‐addition reaction: PUR materials are most commonly segmented into several phases. The formation of hard‐ and softsegments can be easily demonstrated by looking at thermoplastic polyurethanes (TPU). A deeper understanding of this phase separation and the molecular organisation within these materials promises to realize prospectic polymeric architectures with new and improved properties. PUR materials will still be able to offer new answers to future requirements in balancing economical and ecological needs. By looking at the life‐cycles of soft and hard‐foams, polyurethane‐coatings and thermoplastic PUR‐elastomers, this contribution will adress the question: “Is PUR‐chemsitry still a challenging field?”
Polymethacrylate‐werk‐ und wirkstoffe mit breiter anwendung
Authors: Wunderlich Winfried
Published: April 2003

The industrial application of polymethacrylates includes plastic materials such as the classical PMMA for transparent sheets and moulded parts as well as functional polymers, which are widely used as processing aids or modifying agents. The adaption of their properties to specific needs of the market can easily be reached because of the broad variability of methacrylic chemistry. Improved and new properties result from tailor made structures on the molecular and supramolecular level. Products like macromonomers, polymeric tensides or thermoplastic elastomers are examples of this.

The discovery of the compatibility of polymethacrylates with other polymers extend their application in blends and coextruded products. This was particularly supported by new developments in processing and extrusion technique. The progress in chemistry, physics and technology promotes a continuous growth of the polymethacrylates and their introduction into new uses. This is proved by examples from various applications.
Fire‐retardant action of potassium nitrate in polyamide 6
Authors: Levchik Sergei V. , Levchik Galina F. , Camino Giovanni , Costa Luigi , Lesnikovich Anatolii I.
Published: April 2003

The addition of 10–20 wt.‐% of potassium nitrate (KNO3) to polyamide 6 (PA 6) improves the fire retardance of the polymer. The thermal decomposition behaviour of the PA 6/KN03‐mixture was studied using thermogravimetry, differential scanning calorimetry and thermal volatilisation analysis. Solid products of the thermal decomposition of the mixture were analysed by infrared spectroscopy, X‐ray diffraction and electron paramagnetic resonance. It was found that KNO, prevents flowing and dripping of the melt and promotes charring on the surface of the polymer which decreases its fire hazard and improves its fire retardance. On the other hand, KNO3 exothermally reacts with PA 6 in the condensed phase and supplies oxygen to the gas phase which increases the combustibility of PA 6. The mechanism of the chemical interaction of KN03 with PA 6 is discussed.
Effect of tricalcium phosphate, hydroxyethyl methacrylate, and ethylene glycol dimethacrylate on the mechanical properties of acrylic bone cement
Authors: Yang Jen‐Ming , Lu Charng‐Shing , Hsu Ying‐Gev
Published: April 2003

The effects of the addition of tricalcium phosphate (TCP), hydroxyethyl methacrylate (HEMA), and ethylene glycol dimethacrylate (EGDMA) on the properties of standard surgical Simplex‐P radiopaque bone cement have been investigated. The fracture surface after tensile test was studied by scanning electron microscopy. The influence of these components on the temperature rise during polymerization was investigated. It was found that the tensile strength, the bending strength, and the compressive strength decreased with increasing TCP content, whereas the inverse was observed for the Young's modulus. The tensile strength slightly increased with increasing HEMA content and then it levelled off when the HEMA content was higher than 15 wt.‐%. It seemed that there were maximum tensile, bending and compressive strengths when 2 wt.‐% EGDMA (in HEMA) was added. Polymerization occurred more rapidly when HEMA and EGDMA were added, whereas the inverse result was found with TCP.
pH‐sensitivity of the swelling of a chitosan‐pectin polyelectrolyte complex
Authors: Yao Kang De , Tu Haili , Cheng Fa , Zhang Jing Wu , Liu Jing
Published: April 2003

This paper deals with a novel polyelectrolyte complex (PEC) of two natural polyelectrolyte ligands, i.e. chitosan (CS) and pectin (PTn). The composition and its effect on the swelling properties of this CS‐PTn PEC were studied. The results reveal that the swelling of the polyelectrolyte complex is connected with its composition and is also affected by the degree of deacetylation of CS and the methoxy degree of PTn.
The relative physical and thermal properties of polyurethane elastomers. Effect of chain extenders derived from dihydroxynaphthalene
Authors: Liaw Der‐Jang
Published: April 2003

Polyurethane elastomers were synthesized based on polyols such as poly(caprolactonediol) and poly(tetramethylene glycol), diisocyanates such as diphenylmethane‐4,4′‐diisocyanate (MDI) and dicyclohexylmethane‐4,4′‐diisocyanate (HMDI), and two dihydroxynaphthalenes (DHNs) and their brominated derivatives used as chain extenders. The effects of the chemical structures of the chain extenders on the physical and thermal properties of the polyurethanes were investigated. Because of the higher degree of phase mixing of the 1,5‐DHN unit, the 1,5‐DHN‐based polyurethanes have higher Tg values and higher dynamic properties than 2,7‐DHN‐based polyurethanes. Introduction of bromine atoms increased the flame retardance. However, the large free volume of bromine atoms restricted the rotation of DHNs, thus, directly decreasing the degree of phase‐mixing and crystallinity of the polyurethanes. Introducing bromine atoms also decreased the mechanical and dynamic properties and increased the solubility of the polyurethanes.
Chemical stability of some poly(amide imide) type polymers
Authors: Hamciuc Elena , Hamciuc Corneliu , Airinei Anton , Bruma Maria
Published: April 2003

The stability of some heterocyclic poly(amide imide)s in acidic and alkaline medium was compared to the structurally related polyimide and poly(amide imide)s without other heterocyclic groups. All the polymers have high stability in acidic medium. The introduction of additional heterocycles such as 1,3,4‐0xadiazole or phenylquinoxaline into the macromolecular chain of a poly(amide imide) increases substantially the resistance to alkaline medium. Polyamides containing imide rings only in the side chain are more stable to hydrolysis than related polyamide having imide units in the main chain.
Analysis of the chemical composition of poly(ε‐caprolactam)‐block‐polybutadiene copolymers by photoacoustic FTIR spectroscopy and by FT Raman spectroscopy
Authors: Schmidt Pavel , Roda Jan , Nováková Václava , Pastor José M.
Published: April 2003

The chemical composition of poly(ε‐caprolactam)‐block‐polybutadiene copolymers (PCL‐PBD) was investigated by FT infrared spectroscopy with photoacoustic detection and by FT Raman spectroscopy. The derived calibrations were used for the estimation of content of butadiene units in the PCL‐PBD fractions soluble and insoluble in 2,2,2‐trifluoroethanol.
Synthesis and modification of a trifunctional epoxy resin with amino‐terminated poly(dimethylsiloxane)s for semiconductor encapsulation
Authors: Shieh Jeng‐Yueh , Ho Tsung‐Han , Wang Chun‐Shan
Published: April 2003

A high‐performance trifunctional epoxy resin based on the triglycidyl ether of tris (4‐hydroxyphenyl)‐methane (TETM) was synthesized by the condensation of 4‐hydroxybenzaldehyde with phenol followed by epoxidation with epichlorohydrin. The structure of TETM was confirmed by mass spectra, infrared and nuclear magnetic resonance spectroscopy. Amino‐terminated poly(dimethylsiloxane)s were used to reduce the stress of the trifunctional epoxy resin cured with phenolic novolac resin for electronic encapsulation application. The dispersed silicone rubbers effectively reduce the stress of cured epoxy resins by reducing the coefficient of thermal expansion and flexural modulus while the glass transition temperature was hardly depressed.
Zur Kinetik der stabilisierten Fällungs‐polymerisation eines Kationischen Monomeren in wäßrigen Natriumchlorid‐Lösungen
Authors: Hildebrandt Volker , Reichert Karl‐Heinz
Published: April 2003

Die Kinetik der stabilisierten Fällungspolymerisation des kationischen Monomeren N‐(2‐Methacryloyloxyethyl)‐N,N‐dimethylbenzylammoniumchlorid (MADAMBQ) in wäßrigen Natriumchlorid‐Lösungen wurde mittels Reaktionskalorimetrie untersucht. Polyethylenoxid höherer Molmasse wurde als Stabilisator eingesetzt. Die Reaktionsgeschwindigkeit ist über einen größeren Umsatzbereich nahezu konstant und fällt anschließend mit dem Umsatz annähernd linear ab. Die Teilchengrößenverteilung der gebildeten Dispersion ist bimodal mit Teilchen von etwa 1 bis 30 μm Durchmesser.

Zur Beschreibung des Geschwindigkeitsverlaufs der Fällungspolymerisation wird ein Modell vorgeschlagen, das die Polymerisation in der Wasser‐ sowie in der Polymerphase berücksichtigt. Die Teilchenbildung soll durch homogene Nukleierung erfolgen. Es wird angenommen, daß die Konzentration des Monomeren in den Phasen durch ein Nernstsches Verteilungsgleichgewicht bestimmt wird. Zu Vergleichszwecken wurde auch die Polymerisation von MADAMBQ in Lösung und als nicht stabilisierte Fällungspolymerisation durchgeführt.
Starpolymers by soft‐hard‐soft block copolymers
Authors: Kéki S. , Bogács C. , Bogács L. , Daróczi L. , Zsuga M.
Published: April 2003

A novel synthesis of starpolymers from a soft‐hard‐soft triblock has been reported. The triblock was obtained by adding isobutene (IB) “in situ” to the living styrene (S) polymerization mixture initiated by the p‐dicumylchloride/TiCl4/pyridine system. Microphase separation was observed by transmission electron microscopy and differential scanning calorimetry. Treatment of the PIB‐PS‐PIB triblock with CCI4 in the presence of AICI3 led to the starpolymer and the number of arms was estimated by size‐exclusion chromatography to be 20.
Specialty polymeric membranes, 7. Pervaporation separation of benzene/cyclohexane mixtures with nylon 6‐graft‐poly(oxyethylene) membranes
Authors: Yoshikawa Masakazu , Takeuchi Susumu , Kitao Toshio
Published: April 2003

Novel membrane materials for pervaporation separation of benzene/cyclohexane mixtures were prepared by the introduction of oligo(oxyethylene)s, such as diethylene glycol, poly(ethylene glycol) 200 (PEG200) and poly(ethylene glycol) 400 (PEG400) onto Nylon 6. The polymeric membranes from modified Nylon 6 thus prepared showed permselectivity toward benzene. Some membranes exclusively permeated benzene from benzene/cyclohexane mixture.
Water‐swellable rubbers containing powdery poly(acrylamide) hydrogel
Authors: Hron Petr , Vymazalova Zdenka , Lopour Petr
Published: April 2003

Hydrophilic composite materials were prepared by combining powdery poly(acrylamide) hydrogel with various technical rubbers (natural rubber, chlorobutyl rubber, EPDM rubber). The dependence of the quality of the dispersions of powdery hydrogel in rubbers on the method of dispersion was studied and properties (swelling capacity in water, mechanical characteristics) of the composites were measured. The natural rubber/hydrogel composites showed the best swellability (>80 vol.‐%). The mechanical properties of the composites are comparable to those of the unmodified rubbers, both in the dry and water‐swollen state.