bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of the particle size of the solid protective agent tricalcium phosphate and its in‐situ formation on the particle size of suspension polystyrene
Authors: Bilgiç Tülin , Karali Metin , Savaşçi Ö. Tunç 
Published: April 2003

AbstractIn this study, the effect of the particle size of solid protective agent, commercially obtained and in‐situ formed tricalcium phosphate (TCP), on the particle size of suspension polymerized polystyrene (PS) is investigated. It is concluded that when a solid protective agent like TCP is used, its particle size and distribution plays an important role in both suspension stability and particle size of the PS obtained. As the particle size of the TCP becomes smaller, the particle size of the PS obtained is reduced in line with it. In situ precipitation of TCP reduces its particle size considerably. Therefore, to produce PS with the same particle size, lesser amount of in‐situ precipitated TCP is required which gives way to production recipe savings and cleaner PS products.
The free‐radical polymerization of acrylamide initiated with ceric sulfate in the presence of amino acids
Authors: Erbil Candan , Soydan A. Bahattin , Aroǧuz A. Zehra , Saraç A. Sezai 
Published: April 2003

AbstractPolymerization of acrylamide initiated with ceric (IV) ion in the presence of methionine, phenylalanine, serine and aspartic acid was investigated in sulfuric acid solution. Maximum yield was obtained at 70°C and sulfuric acid concentration of 0.16 mol/1. Both conductometric titration and FT‐IR results showed that the resulting polymers contained carboxy end groups. According to these findings and previous studies in this field, a suitable polymerization mechanism was proposed.
Indium ion removal and recovery by means of water‐insoluble amphoteric starches
Authors: Chan Wu‐Chung 
Published: April 2003

AbstractThe removal and recovery of indium ion (In3+) from solutions with water‐insoluble amphoteric starches containing the phosphate anionic group and the quaternary ammonium or tertiary amine cationic group was investigated. The adsorption capacity of tertiary amine phosphate starch (TAP) and quaternary ammonium phosphate starch (QAP) is 0.54 meq/g and 0.48 meq/g, respectively. The adsorption process has been found to be concentration‐dependent and exothermic, and follows the Langmuir isothermal adsorption. The heat of adsorption (ΔH) is equal to −5.86 kJ/mol for QAP, and equal to −90.44 kJ/mol for TAP. The amount of adsorbed In3+ ion on the adsorbents decreases when inorganic acids (HCl or H2SO4) or sodium salts (NaCl or Na2SO4) are added to the solution. The adsorbed In3+ ion can be desorbed by treating with a HCl solution (1 and 3 M); the maximum percentage of desorption reaches about 80% when 1 N HCl solution is used.
Toughening of highly crosslinked thermosetting resins by blending with thermoplastic polyether imide
Authors: Di Liello V. , Martuscelli E. , Musto P. , Ragosta G. , Scarinzi G. 
Published: April 2003

AbstractA tetrafunctional epoxy resin and a thermosetting bismaleimide resin were modified by adding a thermoplastic polyether imide, commercially available as Ultem 1000. Dynamic‐mechanical data and electron microscopy analyses demonstrated that a two‐phase system was obtained in both the cases after the curing and postcuring processes. A marked increase of the toughness parameters Kc and Gc was found for both the epoxy and BMI‐based blend systems. The toughening effect has been interpreted in the light of the fractografic analyses performed by scanning electron microscopy.
MgCl2·6H2O‐based titanium catalysts for propylene polymerization. Chemical composition and productivity
Authors: Gupta Virendra Kumar , Satish Sheo , Bhardwaj Ishwar Singh 
Published: April 2003

AbstractMgCl2·6H2O was reacted with dichlorodiphenylsilane to obtain anhydrous magnesium dichloride. MgCl2 thus obtained was solubilized in 2‐ethyl‐1‐hexanol to prepare titanium catalysts for propylene polymerization through regeneration of magnesium dichloride by reaction with titanium tetrachloride. The nature of internal lewis base dialkyl phthalate [Ph(COOR)2, where R = Me, Et, and n‐Bu] and reactants concentration (alcohol and dialkyl phthalate) influence the chemical composition and specific surface area of catalysts. The activity of the catalysts changes in the order ßmethyl < ethyl < butyl. The polymerization parameters such as Al/Ti mole ratios, aging time of catalysts and cocatalysts (triethylaluminium) also control the activity. The concentration of the external Lewis base (dimethoxydiphenylsilane) improves the stereospecifity of the catalyst system.
Dopant‐induced laser ablation of PMMA at 308 nm: Influence of the molecular weight of PMMA and of the photochemical activity of added chromophores
Authors: Lippert Th. , Wokaun A. , Stebani J. , Nuyken O. , Ihlemann J. 
Published: April 2003

AbstractPolymers which are not absorbing at the wavelength of irradiation may be sensitized by doping with low concentrations of suitable compounds for laser‐induced surface modification and ablation. In the present study this approach is applied to the ablation of PMMA by 308 nm irradiation (XeCl* excimer laser). Substituted phenyltriazene and diphenyltriazene compounds, two pentazadienes and a hexazadiene are tested as ablation promoters in concentrations of 1, 2, and 5 wt.‐%, respectively. From all of these compounds, nitrogen is released upon photochemical decomposition.A significant influence of the PMMA molecular weight on the ablation characteristics is found: higher molecular weights result in lower ablated depths per pulse. The etch rates achieved for the various dopants are correlated with the photophysical and photochemical parameters (i. e., absorption cross section and photolysis quantum yield) in solution. Above a characteristic minimum concentration of the additive, the ablated depth is approximately inversely proportional to the dopant concentration. In the regime of low laser fluence, the ablated depth per pulse scales with the logarithm of fluence, and is proportional to the quantum yield of photolysis in solution. For the limiting etch rate at high fluence, no correlation with the solution absorption cross section was found.
Polymerisation von butadien mit der in‐situ‐form des katalysatorsystems nickeloctoat/bortrifluoridetherat/aluminiumtriethyl
Authors: Gehrke Klaus , Schröder Karsten 
Published: April 2003

AbstractFür die Butadienpolymerisation ist das Katalysatorsystem Nickeloctoat/Bortrifluoridetherat/Aluminiumtriethyl modifiziert worden. Diesbezüglich wird die Reaktion des Bortrifluoridetherats mit Aluminiumtriethyl vorab durchgeführt (Vorreaktion) und deren Reaktionsprodukt ohne Isolierung mit Nickeloctoat/Aluminiumtriethyl umgesetzt (Alterung), genannt in‐situ‐Katalysator. Anschließend erfolgt damit die Polymerisation des Butadiens.Vorrreaktion und Alterung sind bezüglich Molverhältnissen, Zeit und Temperatur variiert und deren Auswirkungen auf Umsatz und viskositätsmittlere Molmasse bei der Butadienpolymerisation ermittelt worden. Eine Zeit‐Umsatz‐Kurve, erhalten mit dem optimalen Katalysator, wird angegeben.Eine 2‐Stufenpolymerisation ergab keine Desaktivierung bei der Polymerisation.
Study of the condensation products of abietic acid with formaldehyde
Authors: Bicu Ioan , Mustatǎ Fǎnicǎ 
Published: April 2003

AbstractAbietic acid and paraformaldehyde, taken in various molar ratios, were condensed in acid catalysis (p‐toluenesulfonic acid). Toluene was used both as reaction medium and carrier for aqueous condensate. The obtained polymeric products (resins) were characterized by determination of acid number, melting point, molecular weight and viscosity. Spectral methods, e.g. I. R. and 1H‐NMR, were also used in the same scope. The experimental data evidence the fact that abietic acid is a substance with a functionality of minimum 3 as against formaldehyde. There have been obtained some condensation products with three‐dimensional structure and low molecular weight. The polymerization average degree of the resins was found to be 3, although some fractions with polymerization average degree of 6 have been observed. The chemical bonds established between the structural units can be of both methylenic and dimethylene ether type, depending on the molar ratio of reacting substances.
The effects of the proportion of biphenyl‐AlCl3‐CuCl2 polymerization system on structure and electrical conductivity of insoluble polyphenylenes
Authors: Simitzis J. , Zoumboulakis L. , Stamboulis A. , Hinrichsen G. 
Published: April 2003

AbstractPolyphenylenes insoluble in chlorobenzene were prepared by cationic oxidative polymerization of biphenyl with aluminum trichloride as catalyst and cupric chloride as oxidizer. The fraction insoluble in chlorobenzene was doped in a solution of FeCl3 in acetonitrile. The alternating electrical conductivity, the X‐ray diffractograms and the FTIR‐spectra of undoped and doped polyphenylenes were measured. The undoped material was observed to be an insulator. Only one sample exhibited different behavior which was similar to the doped material, that was found to be semiconducting. Both undoped and doped polyphenylenes were found to have a monoclinic crystallographic unit cell. For the preparation of polyphenylenes with maximum electrical conductivity after doping, the stoichiometric proportion of biphenyl/CuCl2 = 1/2 has to be chosen. Similarly, the catalyst proportion biphenyl/AlCl3 has to be either 1/0.75 or 1/1.5. Under these conditions the undoped polyphenylenes had a ratio of para/meta substitution of about 1, the degree of crystallinity was below 60% and the unit cell volume was quite low. The results were discussed according to the reactions taken place during polymerization.
New polymer additives, 3. Telechelic additives for polyolefins
Authors: Wanicek Helmut , Gruber Heinrich , Greber Gerd 
Published: April 2003

AbstractA series of telechelic additives with molecular weights of 500–1500 for polyolefins was prepared by reaction of telechelic polyolefins with amino‐, carboxy‐and aldehyde end groups were obtained by hydrogenation of the corresponding telechelic polybutadienes which were prepared by radical polymerization of butadiene with appropriate functional initiators as well as by anionic polymerization of butadiene and termination with carbon dioxide, ethylene oxide and chloroacetaldehyde dimethyl acetal. Oligomeric polyolefins with stabilizer end groups attached by non‐hydrolyzable CC‐bonds were obtained by end‐capping of living polybutadiene with appropriate functional additive components and subsequent hydrogenation. Preliminary tests of some of the telechelic additives demonstrated excellent compatibility with polypropylene and efficiencies similar to low‐molecular standard additives.
Electroluminescence of poly(phthalidylidene arylene)s
Authors: Lachinov Alexey N. , Zolotukhin Mikhail G. , Antipin Vyacheslav A. , Valeeva Irina L. 
Published: April 2003

AbstractElectroluminescence of thin films of poly(3,3‐phthalidylidene‐4,4′‐biphenylylene) (PPB) and poly(3,3‐phthalidylidene‐2,7‐fluorenylylene) (PPF) was studied. In both cases, electroluminescene was found to be of a threshold origin. Emission maxima and quantum efficiencies for PPB and PPF are 490 and 525 nm, 0.01 and 0.1%, respectively. The electroluminescent characteristics were found to be strongly dependent on the polymer used.
Block/graft copolymer synthesis via ceric salt
Authors: Galioǧlu O. , Soydan A. B. , Akar A. , Saraç A. S. 
Published: April 2003

AbstractAcrylamide and acrylonitrile were polymerized with water‐soluble organic reducing compounds containing hydroxy groups such as methyl cellulose (MC), methyl hydroxy‐propyl cellulose (MHPC) and poly(ethylene glycol)s (PEG) in the presence of Ce(IV) in order to produce graft/block copolymers. The effect of cerium(IV) concentration, temperature, time and monomer concentration on the yield was studied. Copolymers of cellulose derivatives and polyacrylonitrile showed solubility properties similar to polyacrylonitrile. Both cellulose derivative‐polyacrylamide and poly(ethylene glycol)‐polyacrylamide copolymers were soluble in water.
Interpenetrating polymer networks of polyurethane and furfuryl alcohol. I. Morphology and mechanical properties
Authors: Ma C.‐C. M. , Goang D. Y. , Han J. L. , Hsieh K. H. 
Published: April 2003

AbstractPolyurethane/furfuryl alcohol (PU/FA) interpenetrating polymer networks (IPNs) were synthesized from furfuryl alcohol using p‐toluene sulfonic acid as a catalyst and blocked NCO‐terminated PU prepolymer with m‐xylylenediamine (MXDA) as a chain extender. From IR spectrum analysis it was found that the major reactions in the PU/MXDA/FA system are the polymerization of PU/MXDA and the self‐polymerization of FA. The tensile strengths of PU/FA IPNs that contain 5 p.h.r. PU are greater than those of the pure components. The flexural strength, flexural modulus, Shore D hardness and HDT decrease and the notched Izod impact strength increases with the polyurethane content. The compatibility of the compounds in these PU/FA IPNs was investigated by dynamic mechanical analysis and scanning electron microscopy. It was found that glass transition temperatures are shifted inwardly which indicated that the PU/FA IPNs were semicompatible. It was confirmed from scanning electron micrography that the system was heterogeneous.
Image formation of alkyl‐pendent aromatic polyimide by photocoupling with aromatic ketones
Authors: Chiang Wen‐Yen , Mei Wang‐Ping 
Published: April 2003

AbstractPositive and negative photostructures are formed after the polyimide (PI) of 4,4′‐biphthalic anhydride (BPA) and 4,4′‐diamino‐3,3′‐dimethyldiphenylmethane (DADMDPM), PI(BPA/DADMDPM) is doped with Michler′s ketone (MK) and benzophenone (BP), respectively, and is subjected to UV light (400 ± 50 nm) irradiation and solvent development. The principle of positive feature formation is based on the photocoupling of MK with PI, which increases PI solubility and thus enables a positive pattern to be developed. The phenomenon of negative photopatterning results from intermacromolecular H‐bonding between the carbonyl group of the imide ring and the hydroxy group which is formed in the photoinduced coupling reaction between BP and PI. Lithographic evaluation shows that the MK‐doped positive‐acting PI film cannot form useful patterns because UV wavelengths are strongly absorbed by MK, which limits the depth of photocoupling in the film. On the other hand, 2‐μm‐wide lines can be resolved in the BP‐doped negative‐acting 0.6‐μm‐thick PI film.
Sulfobetaine polyurethane ionomers, 4. Study of interactions between polymers and methyl orange
Authors: Buruianǎ T. , Airinei A. , Buruianǎ E. C. , Robilǎ G. 
Published: April 2003

AbstractThe photochemical behaviour of some polyurethane zwitterionomers containing azoaromatic structures of dye type was studied both in solution and polymer film. The interaction between methyl orange and the sulfobetaine structures of the polyurethane chain was followed by electronic absorption spectra.
Mechanical properties of talc‐filled polypropylene. Influence of filler content, filler particle size and quality of dispersion
Authors: Švehlová Vítězslava , Polouček Eduard 
Published: April 2003

AbstractMechanical properties of polypropylene‐talc composites are measured as a function of talc concentration up to 40 wt.‐%, Young's modulus of filled polypropylene shows linear increase with talc concentration up to double the value of unfilled polymer. Yield stress and Charpy notch toughness decrease with increasing talc content below matrix level at the highest filler content. Composite ultimate tensile elongation and tensile impact strength decrease sharply beginning at the lowest filler concentration. The influence of the talc particle size on the mechanical properties, especially composite toughness, mentioned above, is investigated. Four type of talc were used. Notch toughness decreases according to a linear dependence with mean size of talc particles. Evaluating impact strength possible content of agglomerates of filler and other additions is necessary to be included: tensile impact strength gives slow linear dependence with increasing content of filler particles and/or agglomerates above about 10 μm. The influence of talc particle size on the toughness of filled polypropylene becomes strong if the rubber particles are present.
Blends of polyamide 6 and poly(etheraroylhydrazide)s prepared concurrently with polyhydrazide polymerization
Authors: Aslan S. , Lanzetta N. , Laurienzo P. , Malinconico M. , Martuscelli E. , Volpe M. G. 
Published: April 2003

AbstractPoly(etheraroylhydrazide) is synthesized in the presence of PA6 by means of low‐temperature condensation polymerization of 4,4′‐dichloroformyl‐α,ω‐diphenoxydodecane with terephthaloyl dihydrazide (TDH) in order to prepare polyhydrazide/poly‐amide 6 (PEHZ12/PA6) blends. The thermal analysis of the blends by DSC seems to indicate that the two polymers are not interacting. Nevertheless, when the blends are subjected to an extraction process with formic acid in order to remove the PA6, the characterization of the residual PEHZ12 reveales that some interactions do occur between the constituent polymers, at least for selected compositions. Model experiments permit to hypothesize that the polymerization of PEHZ12 proceeds with a chemical interaction between amino end groups of PA6 and growing PEHZ12 chains.
On the synthesis of acrylamide oligomers
Authors: Bortel Edgar , Kochanowski Andrzej , Kowalski Antoni 
Published: April 2003

AbstractThe synthesis of low‐molecular‐weight poly(acrylamide)s (M̄n = 500 – 1 000) is described. Metal‐activated and non‐activated polymerization in aqueous solution was investigated employing hydrogen peroxide as initiator. Among four transition metal salts considered, Cu2+ cations proved to be the most efficient in decomposing H2O2 molecules and were used as activator. The experiments were run at three reaction temperatures (60, 80 and 95°C), at three H2O2 levels (4, 5 and 6 wt.‐% on monomer), and at four Cu2+ levels (900, 600, 300 and 0 ppm by weight of metal on monomer). Thus, ist was possible to prepare acrylamide oligomers with monomer conversions exceeding 95%, and with Mn values covering the narrow range indicated above. Within these low limits a molecular weight control is impossible, even with inclusion of the differentiated levels of Cu2+cations. Intrinsic viscosities are very low, too ([η]) = 20 – 50 cm3/g, without any relations of the individual values to variations of the given process parameters. The work provides an industrial route to very‐low‐molecular‐weight acrylamide oligomers.
Preparation and investigation of silicon rubber containing imide‐siloxane copolymers
Authors: Ghadir M. , Zimonyi E. , Nagy J. 
Published: April 2003

AbstractA study has been carried out on the preparation of some modified imide‐siloxane copolymers. This has been accomplished by means of addition of α,ω‐dihydropoly(di‐methylsiloxane)s to N,N'‐diallyldiimides by hydrosilylation reaction. The copolymers were characterized by IR and NMR spectroscopy methods. Molar mass, molar mass distribution, thermal and mechanical properties of copolymers were determined. These copolymers are used as additives, mixing them in different ratios with a silicone polymer and filler to obtain imide‐silicone rubbers of high temperature vulcanizing (HTV) type. Mechanical properties of the vulcanized rubbers were evaluated.
Polymerization and application of 2‐methacryloyloxyethyl phenyl phosphate in coatings
Authors: Liaw Der‐Jang , Shen Wen‐Chang 
Published: April 2003

Abstract2‐Methacryloyloxyethyl phenyl phosphate (MEPP) was synthesized by reacting 2‐hydroxyethyl methacrylate (2‐HEMA) with phenyl dichlorophosphate (PDCP) followed by hydrolysis. This acrylic monomer containing the phosphate group was introduced into a typical UV‐curable acrylated epoxy system as an adhesion promoter. Good adhesion properties and solvent resistance of the films after UV curing were obtained in the presence of MEPP, although there was a decrease in the curing rate. When MEPP was introduced into acrylated epoxy resin, the contact angle remarkably decreased indicating that the wetting ability was improved. When MEPP was applied to the synthesis of the water‐soluble acrylic resins cured with various water‐soluble epoxy resins at 25°C, the adhesion and corrosion resistance of coating films was improved.
Photoreactions in halogen‐containing negative‐tone novolac resists
Authors: von Lampe Irene , Reinhardt Michael , Lorkowski Hans‐Joachim , Schnabel Wolfram 
Published: April 2003

AbstractThe photolysis of halogenophenol novolacs is determined by the substitution of halogens by hydrogen and the formation of quinoid groups and intermolecular crosslinks. This is concluded from elemental analysis, NMR, IR and optical absorption measurements. The rate of halogen release depends on the chemical nature of the halogen. It increases in the order F < Cl < Br < I. Chlorine elimination from 4‐position is favored over that from 2‐ and 3‐position. Moreover, dimers release chlorine from 4‐position much more readily than trimers and tetramers. ESR measurements at 77 K and flash photolysis studies at 296 K yielded evidence for the intermediate existence of phenoxyl and aryl radicals. Lithographic tests demonstrated the high UV‐sensitivity of resist formulations based on halogen‐containing novolacs. The increase in sensitivity relative to that of formulations based on nonhalogenated novolacs is 6 to 10fold system: 4‐chlorophenol novolac/4,4′‐bisazidobiphenyl (5%) and ca. 25fold system: 4‐chlorophenol/m‐cresol novolac/hexamethoxymethylmelamine (5%). A postulated reactions mechanism concerning the sensitivity increase takes into account that halogen elimination results in the formation of additional radicals that accelerate the rate of crosslinking. Moreover, hydrogen halide generated by hydrogen abstraction of halogen radicals (Hal˙ + RH → H‐Hal + R˙) provides for the acid required to catalyze the reaction of the melamine compound with the novolac matrix.
Silica gel supported zirconocene dichloride/methylalumoxane catalysts for ethylene polymerization: Effects of heterogenation on activity, polymer microstructure and product morphology
Authors: Janiak Christoph , Rieger Bernhard 
Published: April 2003

AbstractThe system zirconocene dichloride/methylalumoxane was supported on silica in order to provide ethylene polymerization catalysts for suspension or gas phase processes. Highest activity was found for a sandwich‐like, three layer anchoring of the zirconium centers on the support surface. The new catalyst systems show a decrease of activity compared to polymerization experiments in homogeneous phase. However, the molecular weights are increased and the weight distributions remain narrow by immobilization of the active catalyst sites. Those supported metallocene catalysts could find application for the synthesis of polyethylene materials with controlled rheology.
Effect of the chemical structure of some hydrogels on their characteristic properties. I. Effect of comonomer composition
Authors: Koßmehl G. A. , Abdel‐Bary E. M. , Sarhan A. A. , Abdelaal M. Y. 
Published: April 2003

AbstractSome hydrogels of different chemical composition were synthesized using 2‐hydroxyethyl methacrylate, methacrylic acid, acrylic acid, and acrylamide in different ratios and crosslinked by ethylene dimethacrylate. Effects of the copolymer composition as well as the type of monomers on some hydrogel characteristics were evaluated. Some characteristic properties, namely soluble fraction percentage, swelling degree, solution uptake, and salt uptake were found to be markedly affected by the hydrogel composition.