bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface modification of synthetic fibers by excimer laser irradiation
Authors: Watanabe Hirosuke , Takata Tadahiko
Published: April 2003

It was attempted to improve the fiber/rubber adhesion by surface modification of fibers by excimer laser irradiation. The fibers were first treated with a glycidyl ether acrylate compound which is sensitive to UV rays, then cured with a KrF laser and treated with an ordinary RFL (resorcinol formalin rubber latex), and then cured in heat. For poly(ethylene terephthalate) (PET) and poly(p‐phenylene‐3,4′‐oxydiphenylene terephthalamide) (PPODPTA) fibers, the adhesion performances were improved, whereas for poly(p‐phenylene terephthalamide) (PPTA) fibers they were not. In PET fibers, the surface layer was converted into the amorphous state, and therefore the affinities for the treating agents were enhanced. As for the aramid fibers, the copolymer components of the PPODPTA fibers contain crystalline domains, independently, which are oriented sufficiently, leaving almost no amorphous state in which molecules remain relaxed, and are difficult to be fibrillated. On the other hand, the PPTA fibers comprise a skin layer and a core layer composed of fibrils stacked into blocks. Between the blocks, amorphous phases containing a relatively large number of molecular chain ends are present, facilitating the fibrillation. Probably, the molecules in the non‐crystalline state of both of the fibers were relaxed differently, causing different susceptibilities to ablation. This might result in different affinities to the acrylate compound, or different adhesion performances, respectively.
The influence of ageing and polymerization conditions on the polymerization of butadiene using a neodymium catalyst system
Authors: Oehme Annekatrin , Gebauer Ulrich , Gehrke Klaus , Lechner M. Dieter
Published: April 2003

The homopolymerization of butadiene in the presence of a rare earth‐containing catalyst system was examined at 60°C. The catalyst system consists of neodymium octanoate, diethylaluminium sesquichloride and triisobutyl aluminium in n‐heptane. This catalyst shows high activity also at low polymerization temperature and yields polymers with a cis‐1,4 content of nearly 99%. The catalyst ageing and the polymerization conditions were varied and the behaviour of molar mass distribution, conversion and microstructure of polymers is illustrated. Attention is focussed on molar mass distribution of cis‐1,4‐polybutadiene samples which can be unimodal or bimodal in dependence on the preparation conditions.
Niederdruckumkehrosmose mit modifizierten polyacrylnitril‐ultrafiltrationsmembranen
Authors: Becker Margot , Hicke Hans‐Georg , Eisold Christiane , Buschatz Heinz , Paul Dieter
Published: April 2003

Die chemische Modifizierung von Polyacrylnitril‐Ultrafiltrations(PAN‐UF)‐Membranen mit Hydroxylamin führt zu Niederdruckumkehrosmose‐Membranen, die neben verbleibenden Nitrilguppen sowohl Amidoxim‐ als auch Hydroxamsäuregruppen enthalten und bei einem pH von 4,0 bis 6,5 positiv geladen sind.

Die Wasserdurchlässigkeit der Membranen sinkt durch diese Modifizierung von 400 L h−1 m−2 auf 15 L h−1 m−2 (p = 0,3 MPa). Eine umfassende Charakterisierung erfolgte anhand von Trennkurven, IR‐ und NMR‐Spektren, der Hg‐Porosimetrie, der Membranpotentialmessung und der Trennleistung für verschiedene Metallsalze. Infolge des Donnan‐Ausschlusses haben diese Membranen für zweiwertige Metallionen, wie die Härtebildner des Wassers Ca2+ und Mg2+, eine Rückhaltung von 88% bei einem Filtratfluß von 8 L h−1 m−2 (p = 0.3 MPa). Für Schwermetallionen wie Cu2+ und In3+ sind bei annähernd gleicher Rükhaltung wesentlich höhere Durchflußraten von 90 bis 100 L h−1 m−2 (p = 0,3 MPa) möglich.

Im wäßrigen, schwermetallionenfreien Medium unterliegen die Amidoxim‐ und Hydroxamsäuregruppen der Hydrolyse, und es entstehen an der Membranoberfläche Carboxylgruppen, durch die mehrwertige Anionen zurückgehalten werden. Ihr Vermögen zur Wasserenthärtung bleibt erhalten.
Zum thermodynamischen verhalten von polystyrol (PS)/poly(vinylmethylether) (PVME)‐blends
Authors: Radusch Hans‐Joachim , Tung Ngo Trinh , Wohlfarth Christian
Published: April 2003

Das Blendsystem PS/PVME weist ein Phasenverhalten mit einer unteren kritischen Entmischungstemperatur (LCST‐Verhalten) auf, das mit dem Modell von Dee und Walsh sowie mit der kontinuierlichen Thermodynamik modelliert und diskutiert wurde. Die Berechnungsergebnisse zeigen, daß die Prigogine‐Zustandsgleichung in der Lage ist, das reale PVT‐Verhalten der Polymerschmelze recht gut anzupassen. Die mit dem Modell von Dee und Walsh erhaltene Spinodalkurve liefert eine sehr gute Übereinstimmung mit den Ergebnissen der Trübungsmessungen. Die Modellrechnungen zeigen eine Verbesserung der Verträglichkeit dieses Polymersystems bei hohem Druck. Mit der kontinuierlichen Thermodynamik konnte der Einfluß der Polydispersität auf das Phasenverhalten des Blendsystems deutlich gemacht werden. Eine merkliche Verschiebung des kritischen Punktes aus dem Minimum infolge der breiten Molmassenverteilung von PVME wird deutlich.
Synthesis of ketonic resins from self‐polymerization of acetone, 2. Action of bases on acetone and the synthesis of halogenated and diels‐alder adducts
Authors: Cataldo Franco
Published: April 2003

Acetone was polymerized under the action of NaOH, NaOEt or KOH in ethanolic or methanolic solutions at a molar ratio acetone/base ranging from 1.5 : 1 to 12:1 to give a liquid resin. The liquid resin was obtained with a maximum yield of 60% over initial acetone and was always accompanied by variable quantities of isophorone. The polyenic nature of the ketonic resin obtained was shown by infrared and electronic spectroscopy, as well as by using an isophorone resin as model compound. It is proposed that the structure of the acetone resin should be a condensation product of acetone/ isophorone and isophorone/isophorone. Acetone resins (PCA) obtained both with Brönsted acids (PCA‐B), Lewis acids (PCA‐L) and alkaline catalysts (PCA‐A) can be easily halogenated up to certain degrees of saturation. All PCA resins form Diels‐Alder adducts with maleic anhydride, p‐benzoquinone and fumaric acid. The adducts can contain from 1 to 2 dienophile molecules per molecule of resin.
Polymerization of butyl acrylate in microemulsion. Locus of initiation
Authors: Potisk P. , Vašková V. , Capek I. , Klimová M.
Published: April 2003

The locus of initiation in the microemulsion polymerization of butyl acrylate initiated by water‐soluble ammonium peroxodisulfate, partially water‐soluble azoisobutyronitrile and oil‐soluble dibenzoyl peroxide is determined almost exclusively by the initiator solubility in respective phases of the reaction system, regardless of the overall character of the system. This conclusion was drawn taking into account the results of the microemulsion study in comparison with those from inverse microemulsion polymerizations. The polymerization experiments were carried out in the presence of stable nitroxyl radicals acting as polymerization inhibitors of different solubility in water. The consumption of the inhibitor radicals by the combination with radicals from initiator decomposition was followed by electron spin resonance spectrometer.
Effect of structure on the thermal behaviour of ethynyl‐terminated imide resins
Authors: Alam Sarfaraz , Varma Indra K.
Published: April 2003

A series of ethynyl‐terminated aromatic imide monomers containing phosphine oxide in the backbone were synthesized by the reaction of tris(3‐aminophenyl) phosphine oxide (TAP) or bis(3‐aminophenyl)methyl phosphine oxide (BAP) with pyromellitic dianhydride (PMDA) or 3, 3′,4, 4′‐benzophenone tetracarboxylic acid dianhydride (BTDA) or 4, 4′‐perfluoroisopropylidenebis(phthalic anhydride), and 3‐ethynyl aniline. Structural characterization was done by infrared, nuclear magnetic resonance spectroscopy and elemental analysis. Thermal characterization was done by differential scanning calorimetry and thermogravimetric analysis. The decomposition temperatures of cured resins were above 500°C in nitrogen atmosphere. Char yield at 800°C ranged from 52–63.5%.
Modification of transport properties of ion exchange membranes, XIII. Surface‐modified cation exchange membranes prepared from polyamines and a copolymer membrane containing p‐stryenesulfonyl chloride
Authors: Takata Kuniaki , Ihara Hirofumi , Sata Tosikatu
Published: April 2003

A membrane precursor was prepared by the copolymerization of p‐styrenesulfonyl chloride and divinylbenzene in the presence of a poly(vinyl chloride) supported cloth. The surface of the membrane was treated with various amines, and then the sulfonyl chloride groups in the internal part of the membrane were hydrolyzed with an aqueous sodium hydroxide solution in organic methanol or acetone solvent. Hydrolysis conditions were examined for the introduction of the sulfonic acid groups. The membrane modified by ethylenediamine exhibited slightly bipolar properties during the electrodialysis of seawater. Surface‐modified membranes using tetraethylenepentamine exhibited excellent monovalent cation permselectivity, low membrane electric resistance, and long performance durability during the electrodialysis of seawater.
Water‐soluble polymers by interaction of sulfonic polyelectrolytes with dipolar aprotic solvents
Authors: Drǎgan Demetra
Published: April 2003

The solution of the strongly acidic polyelectrolyte poly(2‐acrylamido‐2‐methylpropanesulfonic acid) in N,N‐dimethylformamide or N,N‐dimethylacetamide is accompanied by a simultaneous reaction of amidation of the sulfonic acid to the corresponding sulfonamide groups. Various compositions of binary copolymers poly[(2‐acrylamido‐2‐methylpropanesulfonic acid)‐co‐(2‐acrylamido‐2‐methylpropane‐N,N‐dimethylsulfonamide)] up to high amidation conversions of 98–99% were synthesized and characterized. The amidation of the sulfonic acid groups appears to be a common reaction for different copolymers having 2‐acrylamido‐2‐methylpropanesulfonic acid moieties but fails with the free monomer.
Conductive composites prepared via a propagating polymerization front
Authors: Szalay Judit , Nagy István P. , Barkai István , Zsuga Miklós
Published: April 2003

A novel material, a conducting composite with variable temperature coefficient of electrical conductivity, was prepared in a propagating front of an addition polymerization. Graphite and zinc particles were incorporated into an acrylamide‐triethylene glycol dimethacrylate copolymer. Specific electric resistance values of the materials yielded were measured at room temperature and also conductivity measurements were performed in the range of 20–220°C. The basic recipe was modified by doping the conductive composite materials with microscopic‐scale‐size particles of several inorganic and organic compounds, resulting in significantly different conductivity features of the composite. Scanning electron microscopy was performed to study the morphology of materials yielded. No percolative patterns containing zinc particles were found to support the conductive behavior of the composite. In accordance with to the modifying effect of doping materials we suspect that the acrylamide‐triethylene glycol dimethacrylate copolymer plays a specific role in the electric conductivity behavior of the composite material.
Fundamental properties of fluoropolyether‐based resins and related coatings
Authors: Simeone Giovanni , Turri Stefano , Scicchitano Massimo , Tonelli Claudio
Published: April 2003

New fluoropolyether polyolic resins are presented suitable to be cured with conventional hardeners as polyisocyanates or melamines. These resins are prepared by addition of fluoropolyether macrodiols (Fomblin® ZDOLTX) of various molecular weights to isophorone diisocyanate (IPDI) to give oligomeric NCO‐terminated prepolymers. The final hydroxy functionality is obtained by the reaction of those prepolymers with trimethylolpropane (TMP). The viscosity of the resins is measured at various concentrations (weight fraction 0.8 – 0.4) and temperatures (T = 25–65°C). The results are discussed in terms of the Erickson equation (η vs. concentration) and using the WLF and Arrhenius models (η vs. T). The thermal behavior is studied by DSC for both the resins and cured films indicating the presence of two Tgs, corresponding to the segregated fluorinated and hydrogenated phases, the former particularly evident with the highest molecular weights of the fluorinated macromer. Tensile curves of selfsupported films are then analyzed showing an evident tough‐plastic behavior especially for the isocyanate‐cured films. The application of such materials as high‐durability clear coats is finally proposed.
Modification of melamine‐formaldehyde moulding compounds with epoxy resins
Authors: Braun Dietrich , Unvericht Reinhard
Published: April 2003

In order to improve dimension stability and toughness of melamine formaldehyde moulding materials (MF), compatible bisphenol A epoxy resins (EP) with additional methylol groups were synthesized and characterized. Crosslinking of those epoxyresol resins with 2‐ethyl‐4‐methylimidazole in the presence of MF resin was investigated. Transfer‐moulded specimens revealed a two‐phase morphology in which the EP phase is used as a host for modification with carboxylic functionalized oligomeric NBR rubber (CTBNX), which is not effective in MF moulding materials alone. The addition of 0.5 – 4 wt.‐% CTBNX to the MF moulding materials at an epoxy content of maximum 20 wt.‐% results in 50–100 % increase of elasticity and toughness without serious decrease in stiffness and heat deflection temperature, provided that covalent interfacial bonds exist. In addition, the post‐shrinkage of MF parts decreases if a moderate EP/CTBNX content is introduced.
New polymer multilayer pervaporation membrane
Authors: Kononova Svetlana V. , Kuznetsov Yuri P. , Apostel Regine , Paul Dieter , Schwarz Hans‐Hartmut
Published: April 2003

The formation, morphology and transport properties of a new multilayer pervaporation membrane have been studied.

This membrane consists of a microporous support based on a poly(amideimide), an intermediate poly[2‐(N,N‐dimethylamino)ethyl methacrylate] layer, and a top diffusion layer of ladder polysiloxane. The membrane has low permeability for weakly polar liquids (e.g. cyclohexane); it exhibits dehydrating properties for waterisopropanol mixtures and has high productivity (up to 14.5 kg h‐1 m‐2) and high separation factor (up to 27430) when methanol is isolated from mixtures with cyclohexane. The transport properties of the membrane are discussed with respect to the Henis‐Tripodi resistance model, taking into account the hydrophobic‐hydrophilic nature of the polymers used.
Stat‐poly(Ethylene oxide‐co‐propylene oxide). Synthesis, NMR characterization and crystallinity studies. Correlation with monte carlo simulation
Authors: Hamaide Thierry , Goux Alain , Llauro Marie‐France , Spitz Roger , Guyot Alain
Published: April 2003

Low‐molecular‐weight stat‐poly(ethylene oxide‐co‐propylene oxide) polymers have been prepared anionically using a new heterogeneous catalytic process previously reported. They were fully characterized by 1H and 13C NMR spectroscopy in order to determine the distribution of the ethylene oxide (EO)‐centered triads, as well as the average lengths of poly(ethylene oxide) (PEO) sequences. Low degrees of crystallization were determined by DSC. These copolymers have been successfully used for applications in the solid polymer electrolytes field and high levels of conductivity at room temperature have been measured. The results are in good agreement with those obtained from a Monte Carlo simulation method using the copolymerization terminal model developed for radical polymerization.
Aging of elastomers in nuclear power plants. Effect of temperature and irradiation
Authors: Dole P. , Chauchard J.
Published: April 2003

The thermo and radiooxidation of a poly(ethylene‐co‐methyl acrylate)‐based industrial elastomer has been studied by various techniques. As already shown in the case of thermooxidation, these elastomers lead to crosslinking reactions when submitted to γ irradiation in air. Considering that the thermooxidation rate follows an Arrhenius law, and that the radiooxidation rate is directly proportional to the dose rate, the predominant mechanism (thermooxidation or radiooxidation) can be defined, as a function of aging conditions. This method was successful for two different aging conditions.
Selective adsorption of bilirubin by macroporous poly(glycidyl methacrylate‐co‐divinylbenzene) beads
Authors: Kuroda H. , Tanaka T. , Osawa Z.
Published: April 2003

Macroporous glycidyl methacrylate (GMA)‐divinylbenzene (DVB) copolymer beads have been synthesized and the adsorption of bilirubin, albumin and other serum components were studied. The beads composed of DVB/GMA in the weight ratio of 75/25 provide an excellent bilirubin adsorption ability. When the surface of the beads was previously coated with albumin, discriminating adsorption of the bilirubin in the serum was attained and the adsorption of albumin was depressed. In addition, when the coated albumin was crosslinked with glutaraldehyde, the excellent bilirubin adsorption ability was maintained, however, an adsorption of albumin from the serum occurred.
Synthesis and properties of transition metal complexes with branched poly(ethyleneimine)
Authors: Rivas B. L. , Seguel G. V. , Geckeler Kurt E.
Published: April 2003

Polychelates were obtained by addition of an aqueous solution of the branched poly(ethyleneimine) (BPEI) to the aqueous solutions of Cu(II), Co(II), and Ni(II). All the polychelates were characterized by elemental analysis, FT‐IR, 1H NMR spectroscopy, thermogravimetry, and scanning electron microscopy. Conductivity and magnetic moment measurements were also carried out. The three polychelates showed a change of the chemical shift in 1H NMR spectra due to the metal ion complexing with the polyligand. Accordingly to the spectral study, the polychelates showed different geometric arrangements: Cu‐BPEI square planar, Ni‐BPEI tetrahedral, and Co‐BPEI octahedral.
New poly(vinyl chloride) blends, III. Physico‐mechanical properties
Authors: Rusu Mihai , Bucevschi Mircea‐Dan , Rusu Daniela‐Lorena
Published: April 2003

The concurrent influence of the processing aid (Paraloid K 120N) and the carbon black ratio, as well as the nature and the ratio of the impact modifier (CPE 3615 and Kane Ace B56 A) on the main physico‐mechanical characteristics of the poly(vinyl chloride)‐based unplasticized mixtures have been studied. The results obtained, processed mathematically and plotted graphically in the form of response surfaces, evidenced that the improvement of certain physico‐mechanical properties becomes possible by the introduction of 2.5 parts and 5.0 parts carbon black into these compounds. This is due to the introduction of impact modifiers and processing aids into the mixtures.
Microstructure and electrical conductivity of complex cathodes based on new vanadium oxides and polyether blends
Authors: Morales Enrique , Acosta Jose Luis
Published: April 2003

This paper studies the effect produced by different vanadium oxides on the microstructure of PEO and PEO/PPO blends by means of the analysis of the crystallization kinetics under isothermal and nonisothermal conditions. The electrical properties of the samples were characterized by complex impedance analysis. Results suggest that the additives employed (considering both carbon black and vanadium oxides) promote changes in the microstructure of PEO/PPO polymer blends because of polymer‐additive interactions. All samples tested show good conductivity properties.
Conductivities and some other properties of oxymethylene‐linked 2‐vinylpyridine‐oxyethylene multiblock copolymers
Authors: Xie Hong‐Quan , Cui Min‐Hui , Guo Jun‐Shi
Published: April 2003

Oxymethylene‐linked 2‐vinylpyridine‐oxyethylene (2VP‐EO) mulitblock copolymers doped with LiClO4 or/and tetracyanoquinodimethane (TCNQ) showed ionic electronic and mixed (ionic‐electronic) conductivity. Effects of the poly(oxyethylene) content and of the molar ratios of EO/Li and TCNQ/2VP on the conductivities of the complexes were studied. The optimum molar ratios of EO/Li and TCNQ/2VP were 10 and 1.0, respectively. The copolymers emulsified benzene/water systems and exhibited good phase‐transfer catalysis properties in the Williamson reaction of solid potassium phenolate with n‐butyl bromide. After neutralization with HCI solution, the copolymers showed polyelectrolyte solution properties.
New polyhydrazides and poly(1,3,4‐oxadiazole)s containing pendent phenoxy groups
Authors: Hamciuc Corneliu , Schulz Burkhard , Bruma Maria
Published: April 2003

A series of new polyhydrazides containing pendent phenoxy groups has been synthesized by low‐temperature solution polycondensation of equimolar amounts of diacid dichlorides and 2‐phenoxyterephthalic dihydrazide in N‐methyl‐2‐pyrrolidi‐none (NMP). The thermal cyclization of the polyhydrazides gave the corresponding poly(1,3,4‐oxadiazole)s containing pendent phenoxy groups. The polymers were characterized by viscometry, solubility measurements, IR spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis.
In‐line‐rheometrie durch direkte wandschubspannungsermittlung
Authors: Braun Peter , Mennig Günter
Published: April 2003

Ausgehend von den Grundlagen zur Kapillarrheometrie mit den bekannten Korrekturverfahren nach Rabinowitsch und Bagley wird das traditionelle Verfahren zur Ermittlung des Düseneinlaufdrucks sowie des Wandschubspannungswerts dargestellt. Dieses Verfahren kann bei manchen Materialien zur fehlerhaften Bewertung des Fließverhaltens führen, da ein linearer Druckabfall in den Meßdüsen unterstellt wird. Daher wird eine neue Methode zur direkten Schubspannungsermittlung vorgestellt sowie die dazu notwendige Meßeinrichtung beschrieben. Es handelt sich dabei um eine in‐line integrierbare Düse, die auf der Basis eines auf Piezokraftaufnehmern gelagerten Düsenabschnitts die Reaktionskraft der strömenden Schmelze auf die Düsenwandung ermittelt.

Die Meßergebnisse zeigen, daß bei der Ermittlung der Fließeigenschaften von Materialien, die ein Potential zur Strukturbildung während des Fließvorganges aufweisen, wie z. B. flüssigkristalline Polyester (LCP), mit der In‐line‐Düse korrekte Wandschubspannungen erhalten werden. Mit der klassischen Methode der Kapillarrheometrie hingegen können bei solchen Materialien nur dann vergleichbare Ergebnisse gewonnen werden, wenn zusätzliche Annahmen über den Druckverlauf in der Meßdüse gemacht werden.
Effect of electron beam radiation on mechanical and electrical properties of poly(ethylene‐co‐vinyl acetate)
Authors: Datta Sujit K. , Chaki T. K. , Khastgir D.
Published: April 2003

Ethylene‐vinyl acetate (EVA) copolymer (12% vinyl acetate content) is subjected to electron beam irradiation using trimethylolpropane trimethacrylate (TMPTMA) as a radiation sensitizer. Mechanical and electrical studies of these irradiated samples show that the strength properties (tensile strength, elongation at break) are increased with radiation dosage up to an optimum radiation dose and sensitizer level above which the properties begin to deteriorate. Crosslinking of the polymer takes place on irradiation which is attributed to an increased gel content with increasing radiation dose. Compared to the original samples both dielectric constant and dielectric loss factor decrease for samples subjected to irradiation.
The effects of a slushing oil on the curing and degradation behavior of an oil‐accommodating epoxy adhesive
Authors: Hong S. G. , Shu H. X. , Lin J. J. , Young J. D.
Published: April 2003

The effect of aliphatic slushing oil on the curing and degradation behavior of an oil‐accommodating epoxy adhesive is studied by using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The results of FTIR and DSC indicate that the curing rate of the tested epoxy system is little affected in the presence of the oil. However, the decrease of the curing exotherm accompanied with a broadening of the glass transition confirms that the oil can affect the curing mechanisms and may change the structure of the cured resin. Additionally, it is evident from the TGA results that the thermal resistance of the resin deteriorates in the presence of the oil, which is attributed to the changes in the structure and the degradation mechanism of the epoxy system.
Homogeneous synthesis of cellulose p‐toluenesulfonates in N,N‐dimethylacetamide/LiCl solvent system
Authors: Rahn Kerstin , Diamantoglou Michael , Klemm Dieter , Berghmans Hugo , Heinze Thomas
Published: April 2003

Pure cellulose p‐toluenesulfonates (tosylates) with an insignificant formation of chlorodeoxy groups were prepared by reacting cellulose dissolved in a solution of N,N‐dimethylacetamide and LiCI with tosylchloride (Tos‐CI) in the presence of triethylamine within 24 h at 8°C. Various cellulosic starting materials with a degree of polymerization from 280 to 5 100 were used. The samples obtained were characterized by means of elemental analysis, FTIR and 13C NMR spectroscopy, and their intrinsic viscosities. The rise of the molar ratio of Tos‐CI/anhydroglucose unit (AGU) from 0.6 to 9.0 leads to an increase in the degree of substitution (DS) from 0.4 up to a maximum value of 2.3. The cellulose tosylates are readily soluble in common organic solvents like dimethyl sulfoxide (within the whole DS range) and in N,N‐dimethylacetamide, N,N‐dimethylformamide, acetone, tetrahydrofuran and trichloromethane depending on DS. As revealed by 13C NMR spectroscopy a faster tosylation takes place at the O‐6 atom of AGU compared with the O‐2/3 atoms. This was additionally confirmed by analysis of the corresponding iododeoxy celluloses synthesized with NaI in acetylacetone. Furthermore, some important properties as stability against alkaline and heat were studied as well.
Synthesis, properties and crystallization behavior of poly(ether ether ketone)/poly(phenolphthalein ether sulfone) block copolymers
Authors: Cao Junkui , Su Wencheng , Chen Yan , Wu Zhongwen , Shibata Mitsuhiro , Yosomiya Ryutoku
Published: April 2003

Poly(ether ether ketone) (PEEK)/poly(phenolphthalein ether sulfone) (PPES) block copolymers were synthesized by a condensation reaction of fluorine‐terminated PEEK oligomers and hydroxy‐terminated PPES oligomers. The content of PPES in the copolymers was varied from 12 to 44 wt.‐%, and the effect of the compositional variation on the properties was investigated. Microphase separation was not observed and the copolymers formed a homogeneous system having good compatibility. The crystal structure of the copolymers is rhombic, equal to PEEK. The degree of crystallinity of the copolymers was low and decreased rapidly with the increase of PPES content. Concerning the cell parameters of the crystalline unit, a‐ and b‐axes are apparently longer and V is, thus, also larger compared with PEEK. Analyses of the isothermal crystallization kinetics of the copolymers provided an Avrami exponent (n) of 2.0. The glass transition temperature (Tg) of the copolymers greatly rose but the thermal stability became much poorer with the increase of PPES content. PEEK/PPES block copolymers possess good mechanical properties such as high strength and modulus.
Adhesive properties of some pressure‐sensitive adhesive agents containing oligomer additives
Authors: Florián Štefan , Novák Igor
Published: April 2003

This paper deals with the influence of oligomers, namely propylene oil and butylene oil, of different molecular weight on the adhesive properties of atactic polypropylene (aPP) and its mixtures with styrene‐2‐ethylhexyl acrylate (S‐EHA) copolymer. The mechanical work of adhesion Am of the mixture containing atactic polypropylene and oligomer increases with the molecular weight of the oligomer, which was more significant in the case of propylene oil. For ternary mixtures aPP‐S‐EHA copolymer/oligomer a maximum of adhesion can be observed if the content of the S‐EHA copolymer in the mixture reaches about 30 mass‐%. In the absence of oligomers in the mixture a minimum of adhesion can be observed for this composition, which can be attributed to the incompatibility of the remaining components.
Structural changes in poly(methyl methacrylate) during deep‐etch X‐ray synchrotron radiation lithography. Part I: Degradation of the molar mass
Authors: Schmalz Olaf , Hess Michael , Kosfeld Robert
Published: April 2003

Poly(methyl methacrylate) is a preferred material used in X‐ray lithography. One effect observed after irradiation is a change of its chemical structure, combined with a decrease of the molar mass. This was analysed quantitatively using size exclusion chromatography combined with multi‐angle laser‐light scattering. Based on a kinetic model, an equation was derived which gives a satisfactory description of the dependence of the molar mass on the radiation dose.
Structural changes in poly(methyl methacrylate) during deep‐etch X‐ray synchrotron radiation lithography. Part II: Radiation effects on PMMA
Authors: Schmalz Olaf , Hess Michael , Kosfeld Robert
Published: April 2003

The irradiation of poly(methyl methacrylate) changes the chemical constitution of the polymer. In addition to a decrease in molar mass further radiation‐induced radical reactions cause changes in the chemical constitution of the polymer. Analysis of the reaction products shows that formation of long‐chain branching can be excluded. Along with degradation of the chain lengths, ester groups in the side chains are attacked. The result is a modified polymer with a physical and chemical behaviour different from that of the starting polymer.
Preparation and uranyl ion adsorptivity of macroreticular chelating resins containing a pair of neighboring amidoxime groups in a monomeric styrene unit
Authors: Park In‐Hwan , Suh Jung‐Mok
Published: April 2003

A cyanomethylated styrene‐divinylbenzene copolymer was prepared by the reaction of a chloromethylated styrene‐divinylbenzene copolymer with sodium cyanide. A polystyrene‐based macroreticular resin containing a pair of neighboring nitrile groups in each monomeric styrene unit was obtained from the reaction of the cyanomethylated copolymer with 3‐chloropropionitrile under phase transfer conditions. The resin was reacted with hydroxylamine to afford a chelating resin containing a pair of neighboring amidoxime groups in each monomeric styrene unit. The chelating resin showed high adsorption capacity for uranyl ions. It was found that the resin was an effective adsorbent for other heavy metal ions such as Hg2+ and Pb2+.
Le rôle des systèmes photoamorceurs dans l'efficacité de photoréticulation de l'homopolymère dicyclopentadiène acrylate (DCPA) et acrylate d'éthyle (AE) et des dérivés copolymères DCPA/AE
Authors: Eisele Giles , Fouassier Jean‐Pierre , Reeb Roland
Published: April 2003

L'efficacité de photoréticulation de toute une série de photoamorceurs commerciaux et de systèmes photosensibles multicomposants a été évaluée sur des matrices acryliques non réticulées. Les polymères utilisés pour cette étude sont des homopolymères et des copolymères d'acrylate de dicyclopentadiène/acrylate d'éthyle de composition variable (100/0, 40/60, 20/80, 0/100) synthétisés en solution par voie radicalaire. Les irradiations ont été effectuées à des grandes longueurs d'ondes (λ ≥ 310 nm). Les systèmes benzophénone/peroxyde de benzoyle ont permis d'obtenir des cinétiques de réticulation très rapides pour des temps d'irradation de 10 min.
Phosphorus‐containing polyurethanes based on bisphenol A via N‐alkylation
Authors: Liaw Der‐Jang , Lin Shiuh‐Ping
Published: April 2003

Phosporus‐containing polyurethanes (PU‐P) based on bisphenol A were prepared by N‐alkylation. The structures of N‐alkylated polyurethanes were characterized by IR and 1H NMR spectra. Physical and thermal properties of the phosphorus‐containing polyurethanes were investigated with differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X‐ray diffraction, tests of solubility, limiting oxygen index (LOI) and reduced viscosity. Tg of the N‐alkylated polymers decreased from 120°C for the starting polymer to 29°C of the 2.0 wt.‐% phosphorus‐containing polyurethanes. The viscosity of N‐alkylated polyurethanes also decreased from 0.36 dL g−1 to 0.24 dL g−1. The thermal stability of polyurethanes decreased on the introduction of phosphorus groups. The LOI values of polyurethanes showed that fire resistance of phosphorus‐containing polyurethanes was enhanced. X‐ray diffraction measurements showed that the increased phosphorus content was accompanied by decreased crystallinity of the polyurethanes. The solubility of PU‐P was improved.
Zur härtung von diandiglycidylether mit anhydridmodifizierten phenolischen härtern und zu vergleichbaren in situ‐reaktionen
Authors: Böschel Dorit , Fedtke Manfred
Published: April 2003

Die Härtung von Diandiglycidylether (DDGE) mit hexahydrophthalsäureanhydridmodifiziertem 2,6‐Dimethylol‐p‐kresol (HHPSA‐DMPK) wurde untersucht und mit der in situ durchgeführten Vernetzung von DDGE mit Hexahydrophthalsäureanhydrid (HHPSA) und 2,6‐Dimethylol‐p‐kresol (DMPK) verglichen. Die chemischen Reaktionen wurden durch Titration der Epoxidgruppen und mit verschiedenen spektroskopischen und chromatographischen Methoden untersucht. Es wurde geprüft, ob die weniger aufwendige und daher preiswertere in situ‐Härtung zu Produkten mit gleichen oder besseren Endeigenschaften führt. Weiterhin wurde die Übertragbarkeit der Ergebnisse auf den Einsatz technischer Phenolharzhärter getestet.
Are cured thermoset resins inhomogeneous?
Authors: Dušek Karel
Published: April 2003

This question was addressed using various methods to monitor the process of curing and state of the final network. Attention was particularly focused on the possible inhomogeneous network formation as a consequence of the crosslinking process. An analysis of experimental data has revealed that some cured resins can be considered as homogeneous as the corresponding uncrosslinked materials. Resins cured by simple stepwise alternating chemistries, with good compatibility of components, usually fulfill the criterion of homogeneity. A family of epoxy resins cured with polyamines belongs to this category. Nodular structures seen by electron microscopy are a result of interaction of the electron beam or etching. Such structures are also observed for uncrosslinked polymers investigated under the same conditions. Formation of inhomogeneities in a number of thermoset systems is due to (a) chainwise mechanism of network formation with fast propagation inducing cyclization and steric volume exclusion and (b) poor compatibility of components of the system made stronger by increasing molecular weights and crosslinking during curing. Networks formed by freeradical polymerization and copolymerization of polyvinyl monomers can serve as an example of crosslinking‐driven formation of inhomogeneities.
Effect of aramid‐CTBN block copolymer on phase structure and toughness of cured epoxy resins modified with carboxy‐terminated butadiene acrylonitrile copolymer (CTBN)
Authors: Ochi Mitsukazu , Mimura Kenji , Kiyohara Osamu , Tagami Toshio
Published: April 2003

An Aramid‐CTBN block copolymer was added to a Bisphenol‐A type epoxy resins modified with CTBN. With the addition of the copolymer, the impact strength of the CTBN‐modified systems was about twelve times higher than that of the unmodified system. Transmission electron micrographs of the block copolymer‐epoxy system showed that the diameter of CTBN‐dispersed phase decreased and a number of fine CTBN phases were dispersed in the matrix. The deformability of matrix in these systems increased with a dispersion of the fine CTBN phase. It is concluded that the improvement of toughness of the cured resins is due to the increases in the ductility of epoxy matrix by the incorporating of the dispersion of the fine CTBN phase in the matrix.
The curing of dicyanate ester liquid crystalline thermosets
Authors: Ober Christopher K. , Körner Hilmar , Shiota Atsushi , Laus Michele
Published: April 2003

The attractive physical properties of cyanate ester resins make these materials an important class of high‐performance polymer thermosets for applications such as electro‐optic coatings and thin film dielectrics. Triazine networks have been used as insulating materials for over 25 years; however, in order to meet future requirements such materials must exhibit appropriate glass transition temperatures, high thermal stability, high moduli, good adhesion at elevated temperatures, low dielectric losses, and a low coefficient of thermal expansion (CTE). With our approach to thermoset design and processing we are able to directly control their mechanical and physical properties by curing new liquid crystalline cyanate ester resins in electric fields. Combining new LC materials with non‐LC cyanate monomers leads to a variety of novel ordered network structures and is a convenient method for modifying and controlling their chemical and physical properties. Studies of the new LC thermosets and their mixtures with non‐LC materials will be described.
Design of network polymers by photopolymerization
Authors: Crivello James V.
Published: April 2003

The base and transition metal catalyzed isomerization of allyl and crotyl ethers affords a facile, high yield route to the preparation of a variety of mono‐, di‐, and multifunctional 1‐propenyl and 1‐butenyl ethers. Employing this novel method, monomers containing epoxide, ester, ether carbonate and urethane groups can be prepared from their readily available allyl and crotyl precursors. In general, these monomers display very high reactivity in cationic polymerizations. In our work, we have focused on photoinduced cationic polymerizations of these monomers using diaryliodonium and triarylsulfonium salt photoinitiators. To study these very fast photopolymerizations, extensive use of real‐time infrared spectroscopy was made. Employing this technique, the effects of monomer and photoinitiator structure on the rates of polymerization were studied.
Synthesis and properties of acrylic/silicone polymer networks by hydrosilylation reaction
Authors: Tanabe Hisaki , Ohsugi Hiroharu , Takarada Mitsuhiro
Published: April 2003

The present investigation concerns acrylic/silicone polymer networks formed by the hydrosilylation reaction. Acrylic polymers containing alkenyl groups have been obtained by radical polymerization of a monomer having an alkenyl group and other vinyl monomers. Also a silicone polymer containing SiH groups has been prepared by the equilibrium reaction in presence of sulfuric acid. They are compatible with each other and can be crosslinked by the hydrosilylation reaction. The cured films are approximately of uniform structure and their acid resistance is excellent.
Microgels 4: The preparation of novel microgels and their applications
Authors: Graham Neil B , Mao Jianwen , Urquhart Alison
Published: April 2003

This paper describes studies on the formation of microgels from high functionality mixtures of monomers which are able to polymerise by a step‐growth process to polyurethanes in the specially selected solvent butan‐2‐one. Using the reactants poly(ethylene glycol) 6000, 1,2,6‐hexanetriol and biscyclohexylmethane‐4,4′‐diisocyanate in formulations made to comprise exactly one isocyanate group per hydroxyl, it was found that microgels of number average molecular weight, as determined by Gel Permeation Chromatography, of less than 20,000 were obtained up to the Critical Gelation Concentration which ranged from w/w reactant to solvent concentrations of from ∼ 0.24 to 0.74 at PEG/HT ratios of 1:4 to 4:4 respectively. These polymerisations surprisingly, went to complete conversion without gelation and produced 95 – 99% yields of microgel product after precipitation into a non‐solvent. Intrinsic viscosity determinations on the microgels dissolved in chloroform were determined and used to obtain estimates of the swollen coil densities at infinite dilution from which the critical packing concentration of these swollen coils in the solvent used for the solvent could be estimated. The critical packing concentration was in all cases well below the Critical Gelation Concentration. It was thus clearly demonstrated that the formation of “soluble” microgels is progressing in spite of the system being critically packed. This is a surprising observation and especially so when it is combined with the very low measured weight average molecular weights and high conversions of the products in the critically packed region. The GPC molecular weights decreased at the higher concentrations which is contrary to expectations. The ability to form microgels above critical packing confirms the results obtained and reported previously by us, that a similar phenomenom occurs in the case of the polymerisation of polyfunctional free‐radically polymerised monomer systems. These observations will need to be taken into account when formulating mathematical analyses of the gelation process. This class of products are able to be crystallised from organic solvents and are soluble in water. They are potentially useful as components of pharmaceutical formulations for the controlled release of drugs, high molecular weight active materials and living microorganisms.
Volume phase transition of spherical microgel particles
Authors: Wu Chi , Zhou Shuiqin , Au‐yeung Steve C. F. , Jiang Suhong
Published: April 2003

The volume phase transition of poly(N‐isopropylacrylamide) (PNIPAM) spherical microgel particles was studied by static and dynamic laser light scattering (LLS). The results were compared with the coil‐to‐globule transition of individual long linear PNIPAM chains. The microgel particles have a higher transition temperature, but a less sharp phase transition, in comparison with that of long linear chains. This difference has been attributed to both the short length and the broad length distribution of the subchains inside the microgels. A combination of static and dynamic LLS results revealed that even in a highly collapsed state the microgel particles retained ∼70% of water and the density of the microgel networks increased from 0.021 g/cm3 to ∼0.30 g/cm3 during the phase transition. The temperature‐dependence of the NMR spin‐lattice relaxation times T1 of PNIPAM indicate an association between water and the CH proton on the N‐isopropyl group. Our results also showed that the transition was strongly influenced by the presence of surfactant. Addition of anionic surfactant, such as sodium dodecyl sulfate (SDS), promotes the swelling of the particles and shifts the transition to a higher temperature, while the addition of a cationic surfactant, such as dodecyl pyridine bromide (DPB), has less effects on the swelling and phase transition, which has been attributed to the electron‐rich amide group in PNIPAM. Moreover, a two‐step phase transition was observed for the first time in the presence of SDS. The dynamic LLS results demonstrates that SDS is expelled gradually from the microgel in the first‐step volume phase transition.
Unsaturated polyester diol‐polyurethane composite networks
Authors: Xu M. X. , Liu W. G. , Yao K. D.
Published: April 2003

This article introduced the formation of an unsaturated polyester/diol‐polyurethane hybrid polymer networks(UP/PU HPNs). The phase behavior was examined by the dynamic mechanical properties and the morphology was investigated by transmission microscope(TEM) and atomic force microscopy(AFM). The effect of phase separation on mechanical properties is briefly described as well.
Molecular design of novel network polymers
Authors: Endo Takeshi , Sanda Fumio
Published: April 2003

Cationic, anionic, and radical ring‐opening polymerization of spiro and bicyclic monomers, and their application to network polymers have been developed. Bicyclo orthoesters (BOEs), spiro orthoesters (SOEs), and spiro orthocarbonates (SOCs) were polymerized by cationic double ring‐opening. Bicyclobis(γ‐butyrolactone)s and spirobis(γ‐butyrolactone)s were copolymerized with epoxides by anionic alternating ring‐opening. Polymers from SOCs bearing exomethylene groups consisted of ring‐opened and vinyl polymerized units. The degree of ring‐opening of SOCs depended upon the number of rings and steric hindrance. The radical polymerization of vinylcyclopropanone cyclic acetals depended on the ring‐size. With the monomers bearing 5‐ and 6‐membered acetal rings, single ring‐opened polymers were obtained. With the monomer bearing 7‐membered acetal ring, the polymer mainly consisted of double ring‐opened unit. These monomers could be crosslinked by bifunctionalization. Poly(cyclic orthoester)s linked by covalent bonds with dithiols to bifunctional SOEs were crosslinked by acid catalysts, and the reversible crosslinking‐depolymerization system could be controlled by temperature.
Computational study of network formation of phenolic resins
Authors: Yamagishi Tada‐Aki , Nakatogawa Takuji , Ikuji Masaki , Nakamoto Yoshiaki , Ishida Shin‐ichiro
Published: April 2003

The network formation of phenol‐formaldehyde resin was investigated by the Monte Carlo (MC) simulation technique. The observed value of the gel point, pc, was exactly determined as a critical extent of reaction, where the Mw/Mn in soluble parts is maximum. The MC simulation with the cubic percolation theory was applied to the gelation of phenolic resins and gave an exact gel point, which was in excellent agreement with the observed value of pc. The simulation showed that the intramolecular reaction occurred frequently with increasing the gel fraction beyond the gel point. The structural analysis of the maximum cluster with the computer strongly supported the contribution of the intramolecular reaction to the network formation of the gel.
Characterization of polyurethane network elastomers
Authors: Furukawa Mutsuhisa , Komiya Masaru , Yokoyama Tetsuo
Published: April 2003

Polyester urethane network elastomers with incorporated hard segment oligomers have been prepared by poly(ethylene adipate)glycol (PEA), 2,4‐tolylene diisocyanate (TDI), and 1,4‐butanediol (BD). These hard segment oligomers were hydroxy‐terminated oligomers ([BD‐TDI]n‐BD; n=1,3), obtained by reacting BD with TDI. Concentrations of allophanate as a cross‐linking site were determined by the amine degradation method. Hard segment moieties were obtained by a novel selective hydrolysis of soft segments in the elastomers. Molecular weight distributions of hard segment were measured by means of GPC. Mechanical and thermal properties were measured. Dependence of rubber elasticity on physical cross‐linking between normal elastomers and the elastomers with incorporated hard segment oligomers were discussed.