bluuebunny/crossref_metadata_2025_split huggingface dataset:
A microhardness test for monitoring the thermal stabilization of solid PVC
Authors: Gonzalez Ana , Pastor Jose Maria , de Saja Jose Antonio , Perez Aurelio 
Published: April 2003

AbstractThe Vickers microhardness test has been found to be a new and attractive analytical tool for the study of the thermal degradation of rigid poly(vinyl chloride) sheets stabilized with different ratios of calcium/zinc carboxylates.
Computer‐simulation der polykondensation von phenol mit formaldehyd
Authors: Steffan Roland 
Published: April 2003

AbstractDer zeitliche Verlauf der Polykondensation von Phenol mit Formaldehyd zu Resolen wird anhand eines kinetischen Modells mit einem Mikrocomputer simuliert. Durch Variation der Geschwindigkeitskonstanten und des Ausgangsmolverhältnisses von Phenol und Formaldehyd wird der Einfluß unterschiedlicher Reaktionsbedingungen auf wichtige Harzeigenschaften wie Restmonomergehalt, zahlenmittlerer Polymerisationsgrad, Verzweigungs‐ und Methylolierungsgrad untersucht. Die Eigenschaftsmerkmale der Endprodukte werden insbesondere durch das Ausmaß intramolekularer Vernetzungen, d. h., durch den Mikrogelanteil beeinflußt.
Acetylation behaviour of cotton and bagasse celluloses. II. Effect of hot alkali refining
Authors: Abou‐State M. Amine , Fahmy Abel M. , El‐Din Nabil M. Safy 
Published: April 2003

AbstractThe alkali pretreatments of cotton linters, bagasse dissolving pulp, and bagasse kraft pulp increased the accessibility of the cellulose hydroxy groups to acetylating molecules. The pretreatment with hot alkali resulted in a higher degree of esterification than with cold alkali.The filterabilities of cellulose acetates obtained from alkali pretreated samples of cotton linters, dissolving pulp, and kraft pulp were better than in case of the untreated samples. Hot refining resulted in better filterability than cold refining, but resulted in stronger degradation and lower thermal stability than cold refining.The presence of hemicelluloses in the untreated pulp lowered the reactivity towards acetylation but favoured the reactivity towards xanthation. In case of cotton linters both reactivities were improved by the alkaline pretreatments. The increase in reactivity resulting from the depolymerization of the cellulose overcame the increase in inaccessibility resulting from drying after the alkaline treatment.The removal of hemicelluloses from the dissolving and kraft pulps by alkaline extraction deteriorated the reactivities towards xanthation, but had a favourable effect on the reactivity towards acetylation.
Graft copolymerization of methyl methacrylate with EPR and EPDM rubber. Effect of solvent and initiator
Authors: Severini Febo , Pegoraro Mario , Giudice Monica 
Published: April 2003

AbstractThe homopolymerization and graft copolymerization of methyl methacrylate with EPR and EPDM rubber was studied in a variety of solvents using benzoyl peroxide and azobisisobutyronitrile as initiators. Under the conditions of our experiments the yield of homopolymer and of graft copolymer for the solvents used increased in the ordercyclohexane > decaline > toluene > benzeneThe grafting yield depends particularly on the concentration of the rubber solution. The grafting mechanism is discussed in terms of different initiators (AIBN and Bz2O2).
Migration of a representative additive from standard and from high‐impact polystyrene into test fat HB 307
Authors: Klahn J. , Figge K. , Meier F. 
Published: April 2003

AbstractThe migration of the antioxidant n‐octadecyl‐3‐(3,5‐di‐tert.‐butyl‐4‐hydroxyphenyl)‐propionate from standard polystyrene and selected high‐impact polystyrenes into the test fat HB 307 was investigated by means of radiotracer techniques, especially its dependence on contact time and temperature. Characteristic differences between the migration properties of the additive in standard polystyrene on the one hand and those in the high‐impact types on the other hand were found which obviously are caused by the different physical structures of these plastics. In the high impact types below 70°C the predominant migration process was found to be diffusion from the disperse rubber phase near the contact surface, whereas above this temperature the additive molecules are preferably diffusing through the polystyrene matrix.Simple rules are given by which the procedure for calculating migration values — which we developed earlier for polyolefins — can be used to predict the migration of additives from high‐impact polystyrene into fat.
Compatibility and molecular structure of rubbers
Authors: Braun Hans‐Georg , Rehage Günther 
Published: April 2003

AbstractCompatibility of 17 pairs of rubbers has been investigated by means of phase separation, glass transition measurements and electron microscopy. Influence of structural details like side chains, configuration of monomer units and distance between double bonds in the chain on the compatibility of polymers has been elucidated. Experimental data lead to following results:Side chains have the strongest influence on compatibility; poly(isobutene) and poly(pentenamer), e.g., are highly incompatible. With decreasing influence on compatibility follows the configuration of the double bond in the polymer chain. Polymers with equal configuration are more compatible than polymers with different configuration. The structural detail with the weakest influence on compatibility is the distance between double bonds along the polymer chain. Poly(octenamer) and poly(pentenamer), e.g., with 6 and 3 methylene groups between the double bonds are less compatible than poly(butadiene) and poly(pentenamer) with a distance of 2 and 3 methylene groups.Cis‐poly(pentenamer) and natural rubber were found to be highly compatible although electron micrographs show domains with an average diameter of 50 Å.
Radiation‐Induced graft copolymerization, I. Graft copolymerization of methyl methacrylate onto nylon‐6
Authors: Nayak P. L. , Lenka S. , Das A. P. 
Published: April 2003

AbstractThe radiation‐induced graft copolymerization of methyl methacrylate onto nylon fibers was investigated at room temperature. The homopolymer was separated by soxhlet extraction. The graft yield increases with increase of dose rate from 0.1768 to 0.7072 Mrad. The percentage of grafting increase with increasing monomer concentration. Addition of copper sulphate and a non‐ionic surfactant, sodium lauryl sulphate, supresses the formation of homopolymer. The value of Gb, the number of branches per 100 eV of energy absorbed in the substrate polymer, and the value of α, the fraction of substrate polymer grafted, have been computed. A kinetic scheme has been suggested.
Synthesis and characterization of resins from urea and acrolein
Authors: Šebenik A. , Osredkar U. , Vizovišek I. 
Published: April 2003

AbstractThe reactions of urea with acrolein in neutral and acidic media were studied by means of 1H‐ and 13C‐NMR spectroscopy. The addition of aldehyde groups to urea seems to be the first step of the reaction. In the second step in neutral medium the groups and the double bonds react with the amide groups. In the acidic medium the condensation of as second step was dominant. In the further course of the reaction highly crosslinked resins are formed which are insoluble and unmeltable. Chemical shifts of individual compounds are given. On the basis of these data, it was possible to set up tentative reaction schemes. The determination of the concentrations of reaction products as functions of reaction time allowed to establish the kinetics of individual reactions.
Aromatische polyphosphonate: Thermoplastische polymere von extremer brandwidrigkeit
Authors: Schmidt Manfred , Freitag Dieter , Bottenbruch Ludwig , Reinking Klaus 
Published: April 2003

AbstractDurch alkalikatalysierte Polykondensation aromatischer Dihydroxyverbindungen mit Phosphonsäurediarylestern in Gegenwart geringer Mengen an speziellen verzweigenden Monomeren wurden verzweigte, hochmolekulare, thermoplastisch verarbeitbare Polyphosphonsäureester erhalten, die eine herausragende Flammwidrigkeit zeigen. Die mechanischen, thermischen, elektrischen und chemischen Eigenschaften eines typischen Vertreters dieser Thermoplastklasse — dem Poly[4,4′‐dioxydiphenylmethylphosphonat] — werden erstmals beschrieben. Es zeigt sich, daß das obengenannte Polymethylphosphonat zu den gut thermoplastisch verarbeitbaren, wärmeformbeständigen, äßerst schlag‐ und kerbschlagzähen Kunststoffen gerechnet werden kann, das innerhalb der halogenfreien Thermoplaste die höchste Flammwidrigkeit besitzt und sogar einen Großteil der hochhalogenhaltigen Kunststoffe in der Brandwidrigkeit übertrifft. Über den Verbleib des chemisch gebundenen Phosphors unter Pyrolysebedingungen an Luft wird eine Aussage gegeben: die Pyrolysegase enthalten ca. 2/3 des im Polymeren gebundenen Phosphors in Form von Phosphorsäure und Methylphosphonsäure. Die Anhebung der Wärmeformbeständigkeit der Polyphosphonate gelingt durch Einkondensation von Carbonat‐ und Arylestergruppen unter Bildung von thermoplastischen amorphen Polycarbonatophosphonaten und Polyesterphosphonaten — ebenfalls Kunststoffen mit signifikant verbesserten Brand‐widrigkeitseigenschaften.
Struktur und eigenschaften von mehrphasenkunststoffen. Deformations‐ und bruchverhalten von polycarbonat/ABS‐mischungen
Authors: Morbitzer L. , Kreß H. J. , Lindner C. , Ott K. H. 
Published: April 2003

AbstractPC/ABS‐Mischungen haben als polymere Konstruktionswerkstoffe in den verschiedensten Anwendungsbereichen zunehmend an Bedeutung gewonnen, weil sie aufgrund ihres Legierungsaufbaues günstige Eigenschaftskombinationen besitzen. Obwohl diese Legierungen bereits seit längerem im Einsatz sind, liegen in der Literatur nur vergleichsweise wenige Untersuchungen über die grundlegenden physikalischen Aspekte vor. Mit den hier vorgestellten Untersuchungen wird der Einfluß unterschiedlicher Zusammensetzungen der Mischungen aus den Einzelkomponenten PC, SAN und Pfropfpolymerisat (SAN gepfropft auf Polybutadien) auf das Phasenverhalten sowie auf das Yield‐ und Bruchverhalten betrachtet und mit den Deformationsmechanismen in Verbindung gebracht. Eine nachfolgende Arbeit wird sich mit der Deformationsmorphologie befassen.
Emulsion polymerization of methyl methacrylate in presence of egyptian delta titano magnetite ore using different initiators
Authors: Moustafa Abdalla B. , Badran Ahmed S. , El‐Fettouh Abou , Abd‐El‐Hakim A. , Diab Moustafa A. , Shandy Sami M. M. 
Published: April 2003

AbstractThe emulsion polymerization of methyl methacrylate was carried out either emulsifier free initiated with NaHSO3 or with dodecylbenzene sodium sulphonate or potassium persulphate at different temperatures. The polymerization was carried out in aqueous media in absence and in presence of Egyptian Delta titano magnetite ore (EDTMO) (black sand). When small amounts of the ore were added the initial rate of polymerization was found to increase with the increase of the amount of ore. Larger amounts of the ore resulted in a decrease of the rate. When the reaction was initiated with sodium bisulfite the rate of polymerization was found to increase with the increase of EDTMO. In presence of 0.1 g/50 cm3 (reaction mixture) of the ore, the apparent activation energy Ea was found to decrease from 14.2 without EDTMO to 9.9 kcal/mol when the polymerization was initiated with sodium persulphate, and from 30.2 to 24.4 kcal/mol when initiated with potassium persulphate. The obtained average molecular weights were found to increase with the increase of EDTMO.
A hydroxyketone‐diamine poly schiff base and its polymeric chelates
Authors: Patel M. N. , Jani B. 
Published: April 2003

AbstractThe preparations of a poly(azomethine) (PSB) via condensation of 4,4′‐dihydroxy‐3,3′‐dibenzylbiphenyl with 4,4′‐diaminodiphenylmethane and its polychelates are described. PSB acts as a tetradentate ligand. A structure of the polymers is proposed. All the polychelates except those with Zn(II) as metal are paramagnetic, dark colored powdery solids which are insoluble in common organic solvents.
Synthesis and polymerization of a styryl terminated oligovinylpyrrolidone macromonomer
Authors: Akashi Mitsuru , Kirikihira Isamu , Miyauchi Noriyuki 
Published: April 2003

AbstractThe esterification of a carboxy group terminated vinylpyrrolidone oligomer with chloromethylstyrene under mild conditions resulted in a styryl terminated oligovinylpyrrolidone macromonomer. The purity of the obtained macromonomer was greater than 95%. Copolymerization of the macromonomer with styrene in ethanol using BPO as catalyst yielded a graft copolymer having a hydrophobic backbone and amphiphilic branches, which was found to have a spherical form and was dispersable in water and ethanol.
Blockcopolymere aus poly‐1,4‐benzamid und 6‐66‐copolyamiden. 1. Synthese und charakterisierung
Authors: Martin Roland , Götz Walter , Vollmert Bruno 
Published: April 2003

AbstractDurch irreversible Polykondensation von 4‐Aminobenzoylchlorid‐Hydrochlorid in einer Lösung von Aminoendgruppen besitzenden 6‐66‐Prepolyamiden wurden Segmentcopolyamide aus Poly‐1,4‐benzamid und 6‐66‐Copolyamid (60/40) hergestellt. Die Molekulargewichte der eingesetzten aliphatischen Copolyamide, bestimmt durch photometrische Analyse nach Umsetzung mit 2,4‐Dinitrofluorbenzol, betrugen 5 000, 13 000 und 21 000. Die Molekuargewichte des Aramids wurden nach einer Näherungsmethode durch Viskosimetrie in konzentrierter Schwefelsäure bestimmt.Der Nachweis des Blockcopolyamids gelang qualitativ durch Untersuchungen des Löslichkeitsverhaltens in NMP/LiBr/H2O‐Mischungen sowie quantitativ durch Kombination von Extraktionsversuchen mit Trifluorethanol mit Trübungstitrationen in H2SO4/H2O.
Electronic processes in poly(p‐phenylene) and related compounds I. Paramagnetic and electrical properties of doped poly(p‐phenylene)
Authors: Czerwiński W. , Bala W. , Kreja L. 
Published: April 2003

AbstractPoly(p‐phenylene) (PPP) was prepared by polymerization of benzene and was exactly purified from oligomers and the catalyst. IR spectra of the resulting material indicated only para substitution and a DP about 20. PPP is a polycrystalline substance with a small degree of crystallinity and is thermally resistant up to 798 K. The annealing of pristine polymer produced a material with higher crystallinity and crystallite size. In our investigations we examined the electrical properties of doped (AlCl3) and undoped PPP at different temperatures. The mechanism of conductivity is explained assuming the existence of the Schottky barriers between polycrystalline grains and intergrain regions. The WAXS and ESR data are compared with the electrical results.
A simple method for evaluation of molar volumes Vu and V1 for polymer‐diluent systems
Authors: Patel K. C. , Patel R. D. 
Published: April 2003

AbstractA simple method for the evaluation of the molar volume of the repeating unit Vu of a polymer and that of the diluent used for determining the thermodynamic parameters from the fusion of polymer‐diluent systems has been reported. The thermodynamic parameters calculated using these values are in fairly good agreement with those reported in the literature.
Morphology and mechanical properties of silicate filled polyurethane elastomers based on castor oil and polymeric MDI
Authors: Varma A. J. , Deshpande M. D. , Nadkarni V. M. 
Published: April 2003

AbstractElastomers of castor oil and polymeric 4,4′‐diphenylmethane diisocyanate (PMDI; functionality 2.7) filled with clay, wollastonite, silica, talc, and calcium carbonate were prepared and their properties compared with the unfilled elastomer. It was found that clay and wollastonite fillers can be used for cost reduction without any detrimental effects on the mechanical properties. Scanning electron micrograph studies of freshly cut surfaces of the silicate filled elastomers showed that clay and wollastonite are much more compatible with the elastomer than silica, talc, and calcium carbonate. Results of gel time measurements in the castor oil — PMDI reaction are also presented as a help for the selection of processing parameters in the manufacture of the filled and unfilled elastomer.
Modification of polyethylene with methacrylic acid, IV. Diffusion of methanol vapour through modificate membranes
Authors: Bryjak Marek , Trochimczuk Witold 
Published: April 2003

AbstractThe diffusion of methanol vapour through membranes obtained from polyethylene and from polyethylene grafted with 5 · 10−4 mol/cm3 of poly(methacrylic acid) was studied. Different mechanisms of diffusion have been found in each type of membrane. The comparison of diffusion coefficients, activation energies and time lags suggested that methanol molecules diffuse through the poly(methacrylic acid) domains. A structural model of the modified polyethylene has been proposed.
The influence of sulphur and its mixtures with polyfunctional monomers on the efficiency of crosslinking of polypropylene initiated by dicumyl peroxide
Authors: Čapla Milan , Borsig Eberhard , Lazár Milan 
Published: April 2003

AbstractGel formation in crosslinking of isotactic polypropylene initiated by dicumyl peroxide (DCP) is increased by addition of sulphur at 170°C; the dependence of gel formation on sulphur concentration (cDCP = const.) has a maximum at DCP/S equal to one. The highest gel content at DCP/S = 1 is obtained in the presence of about 0.7% of sulphur. The addition of divinylbenzene influences slightly the gel content, while pentaerythritol tetrallylether decreases it considerably.
Competitive interaction of polyanions and 2‐(4′‐hydroxyphenylazo) benzoic acid with bovine serum albumin
Authors: Kuramoto Noriyuki , Sakamoto Munenori , Komiyama Jiro , Iijima Toshiro 
Published: April 2003

AbstractThe binding of the anionic dye 2‐(4′‐hydroxyphenylazo) benzoic acid (HABA) to bovine serum albumin (BSA) at pH 6.0–7.5 was studied by spectrophotometry. The values of the dissociation constants were obtained by use of a modified Langmuirtype equation for HABA. Competitive binding of the polyanions sodium poly(styrene sulfonate) (PSSNa), potassium poly(vinyl sulfate) (PVSK), poly(acrylic acid) (PAA), and poly(methacrylic acid) (PMAA), with HABA to BSA were evaluated by variations in the difference spectra of BSA‐HABA‐polymer systems.
Sauerstoffbeweglichkeit und photooxidativer zerfall von 1‐(4′‐N,N‐diethylaminophenyl)‐azo‐2‐naphthol in polymerfilmen
Authors: Müller Franz Werner , Schiller Kurt , Marx Jörg 
Published: April 2003

AbstractDer photooxidative Zerfall von 1(4′‐N,N‐Diethylaminophenyl)‐azo‐2‐naphthol, das in 17 verschiedenen organischen polymeren Bindemitteln eingebettet war, wird wesentlich beeinflußt durch die Effizienz der Triplettbildung, die chemische Natur des Polymeren und die Diffusion des Sauerstoffs in diesem.Untersuchungen zur Löschung der verzögerten Fluoreszenz von Pyronin B durch Sauerstoff in den verschiedenen Bindemitteln führen beim Vergleich mit den Ausbleichraten des Azofarbstoffs zu dem Schluß, daß der geschwindigkeitsbestimmende Schritt für den photooxidativen Farbstoffzerfall in den Polymeren die zeitlich und räumlich begrenzte Diffusion des Singulettsauerstoffs vom Ort seiner Entstehung zum Fänger ist.Neben Darstellungen zur Meßmethode wird auf die kinetische Analyse der Fluoreszenzlöschversuche eingegangen.
Copolymerization of 4‐vinylpyridine macromers with butylacrylate
Authors: Severini Febo , Pegoraro Mario , Saija Leo 
Published: April 2003

Abstract4‐Vinylpyridine macromers ending with methacryloyl functions have been prepared. Their reactivity in copolymerization with butylacrylate is considerably lower than that of 4‐vinylpyridine monomer. Graft copolymers with butyl acrylate have been prepared and characterized.
Blockcopolymere aus poly‐1,4‐benzamid und 6‐66‐copolyamid. 2. Haftvermittelnde eigenschaften in KEVLAR‐verbundsystemen
Authors: Martin Roland , Götz Walter , Vollmert Bruno 
Published: April 2003

AbstractKEVLAR‐Filamente wurden mit der Lösung eines Blockcopolymeren aus Poly‐1,4‐benzamidsegmenten (M̄w= 28 600) und 6‐66‐Copolyamid (60/40)‐Segmenten (M̄w= 19 000) in 96proz. H2SO4imprägniert. Danach wurden die Filamente in Thermoplastfolien unterschiedlicher Polarität (Polyamid‐6, eine pfropfcopolymerhaltige Legierung aus Polyethylen und Polyamid‐6, ein Acrylester‐Acrylsäure‐Ethylen‐Terpolymeres (Ionomer) und LD‐Polyethylen) senkrecht zur Folienebene eingelagert. In Faserauszugsversuchen wurden zur Charakterisierung der Haftfestigkeit die Delaminierungsscherspannung, die Delaminierungsarbeit und die Reibungskraft beim Herausziehen der Faser gemessen.Die Imprägnierung von KEVLAR‐Fasern mit Blockcopolyamid erhöhte die Haftfestigkeiten in polaren Matrixmaterialien erheblich. Bei Ionomer‐Folien war die relative Steigerung der Delaminierungsarbeit mit 670% bei weitem am höchsten. Bei Polyamid‐6 und bei der Polyamid‐Polyethylen‐Legierung betrug der Effekt 130%, während bei dem unpolaren Polyethylen praktisch keine Änderung festzustellen war.REM‐Untersuchungen der herausgezogenen Fasern lassen erkennen, daß das Zerrißen der Verbundmaterialien nicht nur entlang der Faser‐Matrix‐Grenzfläche verlief, sondern daß dabei auch grenzflächennahe Bereiche von Faser und Matrix beteiligt waren.
Influence of solvent on the thermodynamic parameters and stability of some complexes of poly(ethylene oxide) and acrylic copolymers
Authors: Chatterjee S. K. , Yadav J. B. , Sethi K. R. 
Published: April 2003

AbstractStability constant and thermodynamic parameters (e.g. ΔH0, ΔS0) have been determined for interpolymer complexes of several acrylic copolymers and poly(ethylene oxide) in aqueous medium and water‐DMF mixtures. It has been observed that stability constant and thermodynamic parameters of the interpolymer complexes change with the composition of the medium. Some of these observations have been attributed to the change in the degree of solvation of component polymers, reduced hydrophobic interaction and dielectric constant of the medium.
Graft copolymerization onto natural rubber, VIII. Graft copolymerization of methyl methacrylate onto rubber using a potassium bromate/thiourea redox system
Authors: Lenka Subasini , Nayak Padma L. , Mohanty Indu B. 
Published: April 2003

AbstractThe graft copolymerization of methyl methacrylate onto natural rubber (NR) was investigated by varying monomer concentration, initiator concentration, temperature, and using different solvents and substrates. When the potassium bromate concentration increases up to 5 X 10‐3 mol/l the extent of grafting increases and decreases again with further increase of the potassium bromate concentration. The extent of grafting increases with increasing monomer concentration up to 0.9388 mol/1. With further increase of monomer concentration it decreases. With increasing temperature up to 50°C, the extent of grafting increases and with further increase of temperature it decreases. The effect of addition of CuSO4 as well as of different solvents and monomers has been investigated. A suitable mechanism has been suggested and the kinetic rate expression has been derived.