bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study on the curing between shellac and melamine resin by dielectric measurements
Authors: Goswami D. N. , Kumar S. 
Published: April 2003

AbstractThe curing between shellac and melamine resin was investigated in the solution stage by the measurement of dissipation factor (tan δ) at 100 kHz. It was found that the measurement of dissipation factor with time can be conveniently used for the determination of cure‐time of shellac‐melamine resin blends.
A new class of photopolymers with pendent dimethylmaleimide groups. II. Photocrosslinking of homo‐ and copolymers of N‐(5‐methyl‐3‐oxa‐4‐oxohexen‐5‐yl)‐dimethylmaleimide
Authors: Finter Juergen , Widmer Eduard , Zweifel Hans 
Published: April 2003

AbstractThe polymerization of N‐(5‐methyl‐3‐oxa‐4‐oxo‐hexen‐5‐yl)‐dimethylmaleimide (DMI‐MA) yields poly(methacrylates) with pendent light sensitive dimethylmaleimide (DMI) groups. A series of DMI‐MA homopolymers with different molecular weights (60.000–520.000) and a series of copolymers of DMI‐MA with methylmethacrylate (MMA) with varying DMI content (6–78 mol‐%) were prepared. DMI‐containing polymers show high photosensitivity (6 mJ cm−2 at 365 nm). Exposure energies to insolubilize thin solid photopolymer coatings sensitized with thioxanthone were determined with monochromatic radiation at 365 nm by two different methods: by the photographic step tablet method for coatings on copper substrates and by establishing the gel point exposure for coatings on transparent quartz supports. Minimum exposure energies are linear functions of the molecular weight and of the DMI molar fraction of the polymers. Sensitivity as a function of the sensitizer concentration shows a maximum. The results agree well with theories of photocrosslinking.
Einfluß von inhibitoren auf die lagerfähigkeit von ungesättigten polyesterharzen
Authors: Novák Jiří , Mleziva Josef , Eichler Josef 
Published: April 2003

AbstractIn der vorliegenden Arbeit werden mit Hilfe eines beschleunigten Lagerzeittests die Einflüsse von sieben verschiedenen Inhibitoren auf die Lagerungsfähigkeit von ungesättigten Polyesterharzen verglichen. Es wurde die Lagerzeit von Harzen mit unterschiedlichen Inhibitorgehalten bei verschiedenen Temperaturen verfolgt. Es wurde festgestellt, daß die Reaktionen im untersuchten Temperaturbereich (23 – 120°C) nach dem gleichen Mechanismus, aber für manche Inhibitoren mit unterschiedlicher Aktivierungsenergie verlaufen. Aus den Meßergebnissen wurden mathematische Gleichungen hergeleitet, welche die Abhängigkeit der Lagerzeit von Temperatur und Inhibitorkonzentration ausdrücken. Aus der vorgelegten Arbeit geht hervor, daß beim Vergleich der Wirksamkeit von Inhibitoren außer der Temperatur auch die Inhibitorkonzentration in Betracht gezogen werden muß
Acetylation behaviour of cotton and bagasse celluloses. I. Effect of cold alkali refining
Authors: Abou‐State M. Amine , Fahmy Adel M. , El‐Din Nabil M. Safy 
Published: April 2003

AbstractSecondary cellulose acetates from untreated cotton linters, bagasse dissolving pulp and bagasse kraft pulp as well as the acetates from the same pulps after treatment with sodium hydroxide solutions of different concentrations at room temperature were prepared. The acetates obtained were chemically and physically evaluated. The acetate from the untreated linters showed the best chemical and physical properties. It was followed by the acetylated dissolving pulp and finally the acetylated kraft pulp. The cold alkali treatment of the three pulps increased the accessibility of the cellulose hydroxy groups to reactant molecules and improved the filtrability of the acetates obtained. The higher content of hemicellulose and low molecular weight carbohydrates in the pulp, the lower was the thermal stability of the acetate. Cellulose acetates from alkali treated linters, dissolving pulp and kraft pulp were of lower thermal stability than the acetates obtained from the untreated pulps. However, treatment of the dissolving pulp with 15% sodium hydroxide before acetylation dissolved the degradation products of the carbohydrates which were responsible for the decrease in heat stability.
Grafting of ethyl acrylate onto gelatin in water‐isopropanol medium
Authors: George Anne , Radhakrishnan Ganga , Joseph K. Thomas 
Published: April 2003

AbstractGraft copolymers were synthesized by grafting ethyl acrylate onto gelatin. The reaction was carried out in water‐isopropanol medium (1:1 v/v). Reactions take place within 90 min. The resulting product is insoluble in solvents for the respective homopolymers. Presence of vinyl polymer was confirmed by IR spectra.
Einfluß von Struktur und Konzentration der Comonomeren auf die Eigenschaften von Copoly(butylenterephthalat)
Authors: Dröscher Michael , Horlbeck Gernot 
Published: April 2003

AbstractCopolyester auf Basis Poly(butylenterephtha1at) (PBTP), die bis zu 20 mol‐% Al‐kandicarbonsäure oder Alkandiole mit 4 bis 12 C‐Atomen enthalten, werden hergestellt und charakterisiert. Das Schmelzverhalten wird hauptsächlich, unabhängig von der Struktur, durch den molaren Anteil der Cokomponente bestimmt, während die Glastemperatur der Copolyester durch die Dicarbonsäuren stärker gesenkt wird als durch die Diole. Beide Cokomponenten verbessern die Kerbschlagzähigkeit von PBTP. Die Dicarbonsäuren setzen den E‐Modul stärker herab als die Diole. Copolyester mit Dicarbonsäuren sind hydrolyseanfälliger als PBTP.
Multiblock copolymers by polymeric initiators via free radical mechanism
Authors: Hazer Baki 
Published: April 2003

AbstractPolymeric peroxycarbamate initiators containing polyazoester or polyethylene adipate blocks were synthesized. They can be used to prepare multiblock copolymers by radical polymerization in a procedure involving several steps. Bulk and solution polymerizations are suitable techniques in these steps.The polymerization of styrene with these initiators was investigated over a wide range of conversion. Longer polymerization times led to an expected decrease in peroxygen contents of the active polystyrenes.Styrene/methyl methacrylate/n‐butyl methacrylate, polyethylene adipate/styrene/methyl methacrylate, polyethylene adipate/styrene/methyl methacrylate/n‐butyl methacrylate and polyethylene adipate/styrene/methyl methacrylate/acrylonitrile multiblock copolymers were obtained in this way.
Application of di‐functional organic peroxides in the polymerization of ethylene under high pressures
Authors: Luft Gerhard , Seidl Hans 
Published: April 2003

AbstractThe suitability of difunctional organic peroxides for the synthesis of low density polyethylene (LDPE) was examined with a view to improve the results. Polymerization tests were carried out in a stirrer autoclave pilot plant using three different difunctional compounds with different levels of thermal stability at a pressure of 1700 bar and temperatures of between 180 and 290°C. The conversion and the specific peroxide consumption were measured and the average molar masses of the polymers obtained were determined. The solubility of the peroxides in isododecane was also examined.
The polymerization of hexachloro cyclotriphosphazene by molybdenum silicate and tungsten silicate
Authors: Kajiwara M. 
Published: April 2003

AbstractSolution and bulk polymerizations of hexachloro cyclotriphosphazene (NPCl2)3 were carried out using molybdenum silicate and tungsten silicate as catalysts. The polymer did not form by the solution polymerization, but was obtained by the bulk polymerization. When tungsten silicate was used, a linear polymer was predominantly formed.
Etude des propriétés des films préparés par evaporation des solutions d'un polymére dans différents solvants
Authors: Grognet Annick , Papantoniou Christos 
Published: April 2003

AbstractFilms of a plasticized random terpolymer were prepared by evaporation of solutions in several solvents. The glass transition temperatures of the films were determined and were found to follow the Fox's equation. Their tensile modulus, measured just below the glass transition temperature, was found to depend on the residual solvent content of the films.
Preparation and optical properties of polymer films having lamellar structure and cylindrical air bubbles
Authors: Cha Younsik , Tsunooka Masahiro , Tanaka Makoto 
Published: April 2003

AbstractPolymer films displaying lustrous, iridescent colors were obtained by irradiation of poly(methyl methacrylate) films containing 1,4‐benzoquinone with a medium pressure mercury lamp followed by solvent treatment. The colors were not produced by visible light‐absorbing species in the polymer films because the color seen in reflection was complementary to that seen in transmission.It was found from optical and scanning electron microscopic studies of the polymer films that they have two characteristic optical structures; a great number of microcylindrical air bubbles oriented perpendicularly to the film surface and periodic lamellas with planes parallel to the film surface. The colors of the polymer films were thought to be produced by this periodic lamellar structure which would act as a three dimensional optical reflection grating. Continuous color change on tilting the sample could also be explained by the Bragg equation.
Grafting of acrylonitrile onto different cellulose forms by the xanthate method
Authors: Shukry Nadia , El‐Ashmawy Ahmed E. , El‐Saied Houssni 
Published: April 2003

AbstractWood pulp and regenerated cellulose (viscose fibres) were grafted by the xanthate method. In some cases, the regenerated cellulose was more accessible towards grafting than wood pulp. Grafting of incompletely regenerated viscose fibres which were obtained by changing the spinning conditions in order to spare the step of partial xanthation caused more orientation of the filaments. The mechanical properties of these filaments were in general poor.
Diffusion de l'eau dans le polyuréthanne par spectrometrie micro‐ondes
Authors: Henry François , Berteaud André‐Jean 
Published: April 2003

AbstractParmi les nombreuses méthodes permettant de suivre la circulation de l'eau libre dans un matériau, les méthodes diélectriques (région des micro‐ondes) semblent à la fois particulièrement sensibles et appropriées.A 9 GHz nous avons pu étudier et déterminer, au moyen d'une technique de perturbation d'une cavité résonnante, les coefficients de diffusion de films de polyuréthanne. Des mesures simultanées de perméabilité à la vapeur d'eau ont aussi été entreprises.Les résultats mettent en évidence d'une part un faible comportement Fickien et d'autre part une augmentation du coefficient de diffusion et de perméabilité avec l'épaisseur. Le caractère hydrophile des constituants du film et le manque d'aération de la surface sont pris en compte comme élément d'interprétation.
Study of crosslinking of unsaturated polyester resins by relaxation methods
Authors: Jelcic Zelimir , Hedvig Péter , Ranogajec Franjo , Dvornik Igor 
Published: April 2003

AbstractRadiation and thermal curing of unsaturated polyester resins with styrene were investigated by combining differential thermal analysis with electric and mechanical relaxation techniques. A microprocessor controlled combined relaxation equipment of special construction was used. By radiation initiated curing the reaction was interrupted at different stages and the products were analyzed. Relaxation and simultaneous differential thermal measurements were also made during the course of gamma radiation and peroxide initiated thermal curing. By this way the shift of the characteristic transitions of the resin as a function of conversion could be studied. Also the change of the phase‐structure of the resin caused by the reaction was monitored. By deconvolution of the dielectric spectrum band the physical structure was found to become heterogeneous by crosslinking.Besides the shift of the transition temperatures the oscillator strength of the dielectric transition was found to decrease with conversion. Electrical polarization and depolarization studies were also performed. A special intermittent load thermomechanical technique was used for separating elastic from viscous response of the sample subjected to external mechanical force. The transitions exhibited by the thermomechanical curves were found to shift to higher temperatures by crosslinking and the compliance plateaus decreased.
Charakterisierung von styrol‐acrylnitril‐copolymeren durch ausschlußchromatographie und turbidimetrische titration der dabei erhaltenen fraktionen. II. Untersuchung einer probe mit breiter chemischer verteilung
Authors: Glöckner Gottfried , Albrecht Victoria , Francuskiewicz Frieder , Ilchmann Dieter 
Published: April 2003

AbstractEine Probe eines Styrol‐Acrylnitril‐Copolymeren mit etwa 40 mol‐% Acrylnitril wurde mit Hilfe der Trübungstitration (TT), der Ausschlußchromatographie (SEC), der TT von SEC‐Fraktionen und der Hochdruck‐Fällungschromatographie (HPPLC) der SEC‐Fraktionen untersucht. Während die TT und die SEC für das unfraktionierte Copolymere zwar breite, aber scheinbar homogene Verteilungen nach der Molmasse und der Zusammensetzung lieferten, offenbarten Kreuzuntersuchungen (TT von SEC‐Fraktionen/HPPLC) das Vorliegen von drei ziemlich unterschiedlichen Komponenten. Dieses Ergebnis wurde zuerst durch die TT der SEC‐Fraktionen mit n‐Hexan als Fällungsmittel gefunden. Nachfolgend wurde es mit der HPPLC unter Verwendung eines Elutionsgradienten mit n‐Hexan und Tetrahydrofuran als Komponenten bestätigt. In einem topographischen Bild wurde die Zusammensetzung der untersuchten Copolymerprobe dargestellt.
Stability constants and thermodynamic parameters of some intermacromolecular complexes of acrylic copolymers and poly(vinyl pyrrolidone)
Authors: Chatterjee S. K. , Yadav J. B. , Sethi K. R. 
Published: April 2003

AbstractStability constants and thermodynamic parameters (e.g. ΔH0 and Δ0) have been determined for intermacromolecular complexes of methacrylic acid‐methacrylamide and acrylic acid‐acrylamide copolymers with poly(vinyl pyrrolidone) (PVP). The presence of nonionic units in the copolymers greatly enhances the stability of the complexes with PVP. The enthalpy and entropy changes of the systems with temperature have been interpreted in terms of various modes of interaction between the components.
Effect of thermal treatment on the electrothermographic and electrical properties of poly(acrylonitrile butadiene styrene)
Authors: Pillai P. K. C. , Gupta A. K. , Sharma S. K. 
Published: April 2003

AbstractStudies on the electrothermographic and conductivity behaviour of poly(acrylonitrile butadiene styrene) (ABS) films of different thermal pretreatments were carried out. The resistivity in ABS layers stored at 50°C was found to be low (∼ 1015 Ω · cm). The charge acceptance and its retention also is poor. The reason for that is the adsorption of water molecules. The layers, when thermally treated at 100°C or more for 5 h, show an enhanced resistivity (∼ 1017 Ω · cm at 50°C) and hence an improvement in charge acceptance as well as in charge retention. Environmental and storage conditions as well as thermal treatment during layer preparations have no effect on the temperature dependence of the resistivity beyond 110°C.
Studies on structural aspects of cellulose acetate
Authors: Suthar J. N. , Patel M. J. , Patel K. C. , Patel R. D. 
Published: April 2003

AbstractIn the present investigation an attempt has been made to throw light on the structure of stiff chain amorphous polymers. For this purpose cellulose acetates (CA) having different degrees of substitution (DS) were prepared. The samples were characterised by IR‐spectroscopy, Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). Scanning electron micrographs of the cryogenically fractured surfaces of these polymers showed that along with lamellar structures, nodular structures were also observable.
Radiation induced copolymerization of hydroxyalkyl methacrylate — vinyl acetate networks. Physico‐mechanical properties
Authors: Ramakrishna M. S. , Deshpande D. D. , Babu G. N. 
Published: April 2003

AbstractRadiation induced copolymerization of hydrogel networks based on hydroxyalkyl methacrylates, vinyl acetate, and dimethacrylates was reported. The equilibrium water content of copolymers was compared for the uncrosslinked, and crosslinked materials. The effect of composition of comonomer, nature, and concentration of crosslinker on the mechanical properties of HEMA‐co‐VAc and HPMA‐co‐VAc was discussed.
Beiträge zur galvanisierung von polymeren, 11. Metallisierung von mischungen aus epoxidharzen und acrylnitril‐butadien‐copolymeren
Authors: Springer Jürgen , Förster Frank , Hadiwinoto Siauw Ling 
Published: April 2003

AbstractDie Metallisierung von Mischungen aus Epoxidharzen und Acrylnitril‐Butadien‐Copolymeren hängt von der Wahl des geeigneten Mischungsverhältnisses sowie von dem Härter ab, mit dem das Epoxidharzvorprodukt in Gegenwart des Copolymeren zur Reaktion gebracht wird. Bei der Verwendung von Triethylentetramin als Härter werden die höchsten Werte für die Abzugsfestigkeit erzielt, die durch kurzzeitige Ozonbehandlung auf bis zu 150 N/25 mm gesteigert werden können. Längere Ozonisierungszeiten führen zu geringeren Haftfestigkeiten und zur Schädigung des Materials.Kavernen treten nur bei epoxidharzreichen Mischungen auf und vergrößern sich mit zunehmender Ozonisierungszeit. Diese Proben besitzen relative geringe Abzugsfestigkeiten.
Polystyrene‐supported aluminium silver chloride as selective ethylene adsorbent
Authors: Hirai Hidefumi , Hara Susumu , Komiyama Makoto 
Published: April 2003

AbstractPolystyrene‐supported aluminium silver chloride was prepared as a solid and selective adsorbent for ethylene by refluxing silver chloride, aluminium chloride, and macroreticular‐type polystyrene resin in carbon disulfide, followed by removal of the solvent in vacuo. The adsorbent rapidly adsorbed ethylene about equimolar to aluminium silver chloride under 1 atm at 20°C. Almost all the ethylene adsorbed was released by subjecting the adsorbent to a reduced pressure 8 mm Hg at 20°C for 10 min. The adsorbent, however, showed no adsorption of carbon monoxide under 1 atm at 20°C.
Chemistry and application of organic isocynates, VII. Conversion of hexamethylene diisocyanate into biuret and urea derivatives by means of hexamethylenediamine
Authors: Balewski Andrzej , Lesiak Tadeusz , Ciemniak Grażyna 
Published: April 2003

AbstractAttempts of the conversion of hexamethylene diisocyanate (HDI) into biuret and urea derivatives by treatment with hexamethylene diamine (HDA) at 140°C, 155°C, and 170°C at different molar ratios of the reactants have been described. By means of gel permeation chromatographic analyses, the approximate contents of the mainly formed prepolymers were estimated. Also a scheme of the formation of all obtained oligomers has been proposed. On the basis of the results of physico‐chemical measurements, the influences of temperature and molar ratios of the reagents on the properties of the resulting products have been interpreted. It has been shown, that about 30 prepolymers of molecular weights (MW) up to 1300 having a biuret or a urea structure, are formed.
Improving the dyeing properties of textiles via utilization of redox systems. I. Dyeing of wool and wool/polyacrylic blend fabrics with acid dye
Authors: Ibrahim N. A. , Haggag K. , Hebeish H. 
Published: April 2003

AbstractDyeing of wool and wool/polyacrylic fabrics with an acid dye, namely, Kiton Scarlet 4 R, was carried out in absence or presence of different redox systems. The latter were based on sodium, potassium, or ammonium peroxodisulphate or potassium periodate as oxidant and glucose, sodium thiosulphate, potassium pyrosulphite or thiourea as reductant. Regardless of the redox system used, the colour strength was far greater in presence than in absence of the redox system. Except in case of potassium periodate/glucose redox system, increasing the oxidant concentration up to 0.03 mol/l caused significant enhancement in colour strength. The same was observed upon increasing the temperature from 30 to 60°C as well as the time from 10 to 40 minutes. It is postulated that presence of the redox system alters the mode of dye attachment to the substrate. Association of the dye with the substrate, wool in particular, seems to involve covalent bonding beside the usual salt‐linkage. Hence the approach presented is advantageous in producing dyeings with much higher colour strength and dye fixation at relatively low temperature.
Liquid crystal polymers. 20. Poly(1,4‐cycloalkylhydroquinone terephthalates) with flexible hexamethylene spacers in the main chain
Authors: Dicke Hans‐Rudolf , Lenz Robert W. 
Published: April 2003

AbstractA series of cycloalkylhydroquinone terephthalate copolyesters containing varying amounts of 1,6‐hexanediol flexible spacers were prepared by a two‐step reaction procedure and characterized for their liquid crystalline properties. Included in the series were hydroquinone monomers containing norbornyl, cyclohexyl, cycloheptyl, and cyclooctyl substituents. The norbornylhydroquinone series formed nematic melts at 1,6‐hexanediol contents of 30 mol‐% or less, but not at 40 mol‐%. The glass temperatures and melting points were higher than expected in the norbornylhydroquinone series, but analysis of dyad contents by 13C‐NMR indicated that the comonomers were randomly distributed.
A DSC study of the polymerization of 2‐Vinylpyridine in dimethylformamide
Authors: Alberda van Ekenstein Gert O. R. , Held Bert‐Jan , Tan Yong Y. 
Published: April 2003

AbstractThe polymerization of 2‐vinylpyridine (2VP) in dimethylformamide (DMF) with azobisisobutyronitrile (AIBN) as initiator was studied with a differential scanning calorimeter. By taking an appropriate amount of AIBN and after correction for its decomposition, the following values could be obtained:Heat of polymerization ΔHp,o = −68 ± 4 kJ/mol; overall Arrhenius activation parameters Ea = 90.0 ± 4 kJ/mol and ln A = 24 ± 1.0 (A = 2.6 × 1010 dm3/2/mol1/2. s).
Humidity dependence of the electric characteristics of quaternized poly(vinylpyridine)‐perchlorate complexes
Authors: Hirata Mitsutoshi , Inoue Shozo , Yosomiya Ryutoku 
Published: April 2003

AbstractThe dependence of electrical characteristics of polymer complexes on ambient humidity was studied for complexes of quaternized poly(2‐vinylpyridine) and of quaternized poly(4‐vinylpyridine) with perchlorates (HClO4, LiClO4, KClO4). The electric resistance decreased linearly with the increase in ambient humidity for both types of complexes. The complex containing the perchlorate with the larger ionic radius showed a lower electric resistance. No change was observed in the humidityresistance relationship for more than ten months.
8‐Hydroxy quinoline‐furfural polymers
Authors: Patel A. U. , Patel H. S. , Patel M. N. 
Published: April 2003

AbstractPoly(8‐hydroxyquinoline‐furfural) (8HQ‐Fu) was prepared by condensing 8‐hydroxyquinoline with furfural in the presence of aqueous K2CO3 and NaOH as catalysts using equimolar proportions of the two reactants. The polymer samples were characterized by elemental analysis, IR spectra, and thermogravimetric analysis. The number average molecular weight (Mn) was determined both by vapour pressure osmometry and by non‐aqueous titration. Intrinsic viscosities of all the polymer samples were measured in DMF.Polymeric metal chelates of Cu2+, Fe3+, Co2+, Zn2+, Mn2+, Ni2+ with the 8HQ‐Fu polymer were prepared and characterized.