bluuebunny/crossref_metadata_2025_split huggingface dataset:
Indirekte klassifikation von sechs oximierenden aldehydgruppen in oxycellulose nach dem polymerisationsgrad
Authors: Blaha Jan , Černý Pavel , Jahn Karel 
Published: April 2003

AbstractDie stufenweise Oximierung bei 20, 23, 25, 28, 30 und 35°C ermöglichte die qualitative und quantitative Trennung von sechs verschiedenen Aldehydgruppen in Oxycellulose. Für die Berechnung des Gehaltes bn der n‐ten Aldehydgruppe bei einer bestimmten Oximierungstemperatur wurde eine modifizierte Berechnungsmethode nach einer verbesserten Gleichung angewandt. Das vorgeschlagene Verfahren ermöglichte die Charakterisierung der chemischen Strukturen von sechs verschiedenen Aldehydgruppen in Oxycellulosemakromolekülen. Es wurden lineare Abhängigkeiten zwischen den Gehalten an diesen Aldehydgruppen sowie den Aldehydsummenwerten und DP‐Werten bei logarithmischer Darstellung gefunden, die eine indirekte und schnelle Aldehydbestimmung in Oxycellulosen über den DP‐Wert ermöglichte. Für die indirekte Bestimmung der Aldehydgruppen über den DP‐Wert wurde ein Computerprogramm ausgearbeitet.
Autoxidation of thiols with cobalt(II)phthalocyanine‐tetra‐sodium sulfonate attached to poly(vinylamine), 6. Immobilized catalysts by crosslinking of poly(vinylamine)
Authors: Brouwer Wilfried M. , Traa Piet A. M. , de Weerd Teun J. W. , Piet Pieter , German Anton L. 
Published: April 2003

AbstractPoly(vinylamine), being both carrier and promotor of the thiol oxidation catalyst cobalt(II)phthalocyanine‐tetra‐sodium sulfonate (CoPc(NaSO3)4), was crosslinked with α,α′‐dichloro‐p‐xylene, thus yielding porous hydrophilic networks. The effects of experimental parameters such as stirring speed, particle size, degree of crosslinking, distribution of catalytic sites (CoPc(NaSO3)4) in the catalyst particles, pH, temperature, and thiol concentration were investigated. Reaction rates observed for the immobilized catalyst system appeared to be 4–30 times lower as compared with the water soluble polymeric catalyst system but still higher than those of the polymer free CoPc(NaSO3)4 catalyst.At a stirring speed around 3 · 103 rpm not the mass transfer from the bulk to the catalyst particles but intra‐particle diffusion limits the reaction rate. Accordingly, an uncrosslinked polymeric catalyst anchored to silica, with catalytic sites situated close to the particle surface, exhibited comparatively high activity, i.e. only four times lower than the soluble polymeric catalyst.In addition, the heterogeneous catalyst systems showed resemblance in kinetic behaviour with the soluble polymeric thiol oxidation catalyst.
The homopolymerization and copolymerization of an azo dye, N‐methyl‐N‐[4‐(2,5‐dichlorophenyl) azophenyl]‐2‐aminoethyl methacrylate
Authors: Lokaj Jan , Morozova Elena Mikhailovna , Eliseeva Valentina Ivanovna , Hrabák František 
Published: April 2003

AbstractThe properties of a polymerizable dye, N‐methyl‐N‐[4‐(2,5‐dichlorophenyl)azophenyl]‐2‐aminoethyl methacrylate (I), its homopolymerization and the properties of the homopolymer were characterized. The copolymerization parameters (r1, r2) ofIwith styrene (St), methyl methacrylate (MMA), N,N‐dimethyl‐2‐aminoethyl methacrylate, 2,2,2‐trichloroethyl methacrylate and methacrylic acid and the rates of copolymerization were determined in benzene solution at 50°C with 0.01 M 2,2′‐azobisisobutyronitrile as initiator. The Alfrey‐Price e and Q constants were calculated forIusing the r1, r2values for the systemI/St. The retardative effect of the azo group in the homopolymerization and copolymerization ofIwas evaluated by determining the ratio of rate constants of addition of polymer radicals to the model azo compound and to the monomer in the homopolymerization of St and MMA. The relative permittivities of monomers and their solutions were measured, and the effect of the molecular interaction of comonomers on the composition of the copolymers was discussed.
Antioxidants and stabilizers, 98. An investigation of the synergism between N‐isopropyl‐N′‐phenyl‐1,4‐phenylenediamine and 2,6‐dialkylphenols
Authors: Taimr L. , Pospíšil J. 
Published: April 2003

AbstractThe rubber antidegradant, N‐isopropyl‐N′‐phenyl‐1,4‐phenylenediamine (I), after being oxidized to N‐isopropyl‐N′‐phenyl‐1,4‐benzoquinonediimine (II) may again be partly regenerated by a reaction with 2,6‐dimethylphenol with the simultaneous formation of a compound containing one fragment derived from 2,6‐dimethylphenol and two fragments derived from I. For this compound we suggest structure IV (a, b, or c). This compound readily decomposes, yielding a further molecule of antidegradant I. The cooperative effect between I and 2,6‐dimethylphenol can also be seen in the autoxidation of squalene. The behaviours of some further simple alkyl derivatives of phenol in a reaction with II are described.
Effect of carbon black and thermal aging on the conduction mechanism of natural and styrene butadiene rubbers
Authors: Ghani A. A. , Eatah A. I. , Hashem A. A. , Hassan H. 
Published: April 2003

AbstractTwo types of carbon black namely fast extrusion furnace black (FEF) and high abrasion furnace black (HAF) were incorporated with a concentration of 50 phr into styrene butadiene rubber (SBR) and natural rubber (NR). The effect of the time of aging and temperature on the electrical conductivity was studied. It was found that a thermal aging at 95°C leads to the appearance of minimum in conductivity (σ) in both FEF/NR and HAF/NR. This was explained by a competition between two factors: degradation and increase of crosslinking density in the rubber matrix. In case of FEF/SBR and HAF/SBR it seems that these factors have comparable effects on the conductivity after 10 days of aging. From the current‐voltage (I‐V) characteristics the carrier concentration, trap density, and the drift mobility were calculated. The minimum found in the temperature dependence of σ for FEF/NR is discussed and found to be controlled by the relative dimension of carbon and rubber aggregates.
Modification of polysaccharides: Degradation and graft copolymerization onto dextran
Authors: Samal R. K. , Sahoo P. K. , Ray S. S. , Nayak S. N. 
Published: April 2003

AbstractA water soluble muco‐polysaccharide, “dextran”, was subjected to selective degradation and graft copolymerized with acrylamide and methylmethacrylate. Using ceric ions as initiator a low molecular weight model dextran and dextran‐g‐poly(acrylamide) as well as dextran‐g‐poly(methylmethacrylate) copolymers were prepared. The selective chain degradation and the graft copolymerizations were carried out at varying concentrations of Ce(IV) and monomer and varying temperatures. The course of degradative chain cleavage has been followed by viscometry. The low molecular weight model dextran and the copolymers were purified by usual methods. Their physical and chemical properties were tested and compared with the base. The energy of activation for the chain degradation and other related thermodynamic parameters have been evaluated.
Vinyl polymerization by carbon black, IV. Some properties of modified carbon black compared with its polymerization initiating activity
Authors: Haque Shah A. , Biswas Mukul 
Published: April 2003

AbstractAll grades of carbon black contain large amounts of unpaired electrons and organic functional groups. Polymerization reaction is possibly initiated by the unpaired electrons on the surface; the functional groups have promotional effect on the initiation process. All the properties like texture, geometry, surface area, pH of the aqueous slurry, ash content, and elemental composition have effects on the polymerization reaction. These pertinent physicochemical and surface properties of unmodified and modified N 220 carbon black have been studied in relation to N‐vinylcarbazole polymerization.
Proton magnetic relaxation times of isotactic polypropylene films treated with tetrachloroethylene
Authors: Tanaka Hiroshi 
Published: April 2003

AbstractProton spin‐lattice (T1) and spin‐spin (T2) relaxation times of isotactic polypropylene films with different thermal histories, treated with tetrachloroethylene, were measured with pulsed NMR. For the melt‐quenched sample T11 (the longer T1) increases and T2a (the longest T2) decreases with increasing treatment temperature. The mass fraction of mobile region (Fa) decreases and the mass fraction of rigid region (Fc) increases with increasing treatment temperature. T11 increases almost linearly with increasing Fc, indicating that the removal of the mobile amorphous region is mainly responsible for the change in T11.For the annealed sample T11 also increases with increasing treatment temperature, although a slight decrease in T11 for the low treatment temperature is observed. There is a large decrease in T2a when the treatment temperature is raised, suggesting that a comparatively selective extraction occurs for the annealed sample.
Physical characterization of isotactic polypropylene/ethylene‐propylene copolymer blends
Authors: Kalfoglou Nikos K. 
Published: April 2003

AbstractThe properties of solution‐mixed blends of isotactic polypropylene (iPP) and an amorphous ethylene‐propylene copolymer (EPM), containing 40 wt.‐% of ethylene, were studied throughout the composition range. The techniques used were differential scanning calorimetry (DSC), dynamic mechanical spectroscopy, and optical microscopy. Morphological examination revealed a heterogeneous structure. The dynamic mechanical technique at isochronous conditions (110 Hz) between ‐120 and 160°C confirmed the heterophase nature of the blends and revealed limited phase mixing of the amorphous components of the two constituents. DSC measurements of specimens quenched at 0°C, indicated that EPM rubber promotes crystallization of the iPP phase.Appropriate mechanics models tested in the complete composition range led to the conclusion that the system is incompatible, with rubber spherical inclusion strongly adhering to the iPP matrix, up to an EPM volume fraction Φ (EPM) ≃ 0.70. At higher EPM compositions, matrix reversal occurs — a fact corroborated by the available mechanical data for this blend.
Segmented copolyetherurethane‐ureas and semicarbazides for blood circulation systems, IV. Mass spectrometric investigations 2, linear‐temperature programmed pyrolysis (LTP‐Py)
Authors: Düssel H.‐J. , Wenzel N. , Hummel D. O. 
Published: April 2003

AbstractCopoly(etherurethane‐urea)s (PEUU) from different polyethers with hydroxyl endgroups, with 4,4′‐diisocyanato‐dicyclohexylmethane and 4,4′‐diamino‐diphenylmethane (as a chain extender) were heated linearly within the ion source of a mass spectrometer. The analysis of the evolved gases allows the identification and detailed characterization of the investigated polymers. The building units of PEUU — polyethers, diisocyanates, and the diamine — can be identified by key fragments. These are formed during pyrolysis and can be identified with field ionization or low‐voltage electron impact ionization.Furthermore, the polyethers with hydroxyl endgroups as well as the PEUU can easily be distinguished by their volatilization rate curves. Fragments resulting from cleavages of the different bond types present, e.g., urea, urethane, ether in this order, are generated during the linear increase of temperature; they are pinpointed by repetitive scanning of the mass spectra.
Organic sulfur compounds, III. Addition products of ethylene oxide to bis(2‐hydroxyethyl)disulfide
Authors: Sokołowski Adam , Burczyk Bogdan 
Published: April 2003

AbstractThe composition of products resulting from the reaction of bis(2‐hydroxyethyl)disulfide with ethylene oxide in the presence of sodium methoxide, dimethyl cyclohexylamine and boron trifluoride etherate as catalysts was determined. The addition reactions were carried out at 80°C, under normal and increased pressure, using the reagents in molar ratios of 1:1. Under these conditions the degree of disulfide conversion varied within the 70–80% range. Oxyethylene derivatives of bis(2‐hydroxyethyl)disulfide were the main products of the investigated reaction. Additionally, slight amounts of ethylene glycols (2–4%) and sulfides (2–4%) were found resulting from a reaction of ethylene oxide with the decomposition products of the starting disulfide.
On the polymerization of acrylamide in methanol in presence of poly(ethylene glycol)
Authors: Pantar A. V. , Atreyi M. , Rao M. V. R. 
Published: April 2003

AbstractAcrylamide was polymerized in presence of poly(ethylene glycol)‐200 (PEG), with persulphate as initiator, in methanol as reaction medium, with varying monomer concentrations. The polymers obtained were finely divided powders and readily soluble in water, unlike pure polyacrylamide. The incorporation of PEG into the polymers was demonstrated by nitrogen determination, IR, and NMR studies. PEG does not covalently link to the polyacrylamide chains, but forms a blend with the polymer.
Single stage process for desizing, scouring, and bleaching of cotton fabric
Authors: Hebeish A. , El‐Bazza S. 
Published: April 2003

AbstractThe efficiency of a treating bath formulation consisting of H2O2, sodium hydroxide, chelating agents, wetting agent, metal ions, and MgSO4 · 7H2O in effecting combined desizing, scouring, and bleaching of cotton fabric using a winch beck system was investigated under different conditions. Presence of MgSO4 · 7H2O at a concentration of up to 3 g/l was essential for stabilization of the strongly alkaline H2O2 solutions (containing 10 g/l NaOH) at 95°C for 90 min to achieve complete starch removal and to bring about fabric with satisfactory whiteness and absorbency without seriously degrading the fibre substance. Chelating agents, namely EDTA and gluconic acid (2 g/l, each) assisted in stabilization of H2O2 even in presence of Fe3+, Cu2+ or both ions and resulted in improved whiteness and lower fibre degradation but had no effect on residual starch or on wettability of the fabric. The wetting agent used had no significant effect on stabilization of H2O2 and fibre degradation, but it helped starch removal and improved the wettability of the fabric. The decomposition of H2O2 increased by increasing its own concentration from 2 to 12 ml/l as well as the concentration of sodium hydroxide from 5 to 17.5 g/l. The same hold true for temperature (60 to 98°C) and duration (30 to 150 minutes). Combined desizing, scouring, and bleaching of loomstate cotton fabric could successfully be effected by using a treating bath consisting of sodium hydroxide (10 g/l), H2O2 (4 ml/l), MgSO4 · 7H2O (3 g/l), EDTA (2 g/l), gluconic acid (2 g/l), anionic/nonionic wetting agent (1.5 g/l) at 95°C for 90 min, and a material : liquor ratio of 1 : 25.
Photooxidation of polystyrene. Effect of stabilizers
Authors: Choudhary V. , Bhaskar V. U. , Varma I. K. 
Published: April 2003

AbstractThe effect of commercially available stabilizers such as Tinuvin‐327, Tinuvin‐770, and Irganox‐1024 on the photooxidation of polystyrene (PS) was investigated by following the changes in molecular weight and molecular weight distribution. Structural changes during degradation were studied by 1H‐NMR‐ and IR‐Spectroscopy and by Electron Spectroscopy for Chemical Analysis (ESCA). Neat PS films became very brittle and yellow on exposure to UV light. Tinuvin‐770 stabilized the PS films towards discolouration and brittleness.The ESCA studies of surface photooxidation of polystyrene indicate the formation of ketonic and methylene ether groups in the initial stages (˜ 100 h). At later stages ester and carbonate groups are formed.
Kinetics of vinyl polymerization initiated by potassium permanganate/β‐hydroxybutyric acid redox system
Authors: Behari K. , Gupta K. C. , Verma Meena 
Published: April 2003

AbstractThe aqueous polymerization of acrylamide initiated by potassium permanganate/β‐hydroxybutyric acid has been studied volumetrically at 35 ± 0.01°C in an inert medium. The rate of polymerization shows nearly square root dependence on β‐hydroxybutyric acid at low concentration (3.12 – 12.5 · 10−3 mol dm−3). The order with respect to potassium permanganate has been found to be 0.6 indicating thereby a bimolecular mode of termination. The polymerization rate has been varied linearly at low monomer concentrations i.e. from 2.5 –7.0 · 10−2 mol dm−3. The dependence of number average degree of polymerization on the initial rate of polymerization and temperature has been determined. The over‐all activation energy has been found to be 51.66 kJ mol−1. A kinetic reaction scheme is proposed on the basis of experimental results.
Reactive polymers, 49. Changes in the porous structure of macroporous copolymers due to successive effects of solvents and temperature
Authors: Hradil J. , Švec F. 
Published: April 2003

AbstractBy drying at 78°C, the macroporous terpolymer 2,3‐dihydroxypropyl methacrylate‐co‐sodium methacrylate‐co‐ethylene dimethacrylate with a water retention of 3.78 g H2O/g loses porosity which is renewed by reswelling. Drying of this terpolymer at 0–25°C by which water or methyl alcohol is removed does not disturb its porosity. Less swelling copolymers such as 2,3‐dihydroxypropyl methacrylate‐co‐ethylene dimethacrylate with a water retention of 1.71 g H2O/g do not lose its permanent porosity when dried. Inversion gas chromatography has made possible the determination of the glass transition temperature of these macroporous terpolymers (Tg = 45°C) by using heptane and methyl alcohol as retention acids. With respect to this, and using scanning electron microscopy the loss of porosity due to drying was interpreted as sintering of macroporous copolymers whose polymer networks swell to a higher degree on heating above Tg.
Herstellung und eigenschaften von pfropfcopolymerisaten des vinylacetats auf ataktischem polypropylen
Authors: Schellenberg Jürgen , Hamann Bernd , Runge Jürgen 
Published: April 2003

AbstractDie Verwendbarkeit von ataktischem Polypropylen als Pfropfgrundlage für die Pfropfcopolymerisation mit Vinylacetat wird untersucht. Die erhaltenen Pfropfprodukte werden hinsichtlich ihres Quellverhaltens und bezüglich ihrer Glasumwandlungstemperaturen und Pfropfparameter bei unterschiedlichen Pfropfproduktzusammensetzungen charakterisiert.Nach Abmischung der Pfropfprodukte mit Polyvinylchlorid werden einige mechanische Eigenschaften sowohl in Abhängigkeit von der Menge des enthaltenen Pfropfproduktes als auch von der Zusammensetzung der Pfropfcopolymerisate dargestellt.
Dependence of soiling and soil release of easy care cotton on factors‐controlling the finishing treatment
Authors: Ibrahim N. A. , Hebeish A. 
Published: April 2003

AbstractThe conventional pad‐dry‐cure method was used for effecting crosslinking of cotton with N‐methylol finishing agents under different conditions. Factors studied include nature and concentration of finishing agent and softener, type and concentration of catalyst, and curing temperatures. Variation of soiling and soil release characteristics of crosslinked cotton with these factors were investigated. The effect of finishing agent on aqueous soiling followed the order:Carbamate reactant‐fabric > Dimethylolethylene urea‐fabric > Dimethyloldihydroxyethylene urea‐fabric > Untreated fabric > Modified triazinone‐fabric ≥ Modified ethylene urea‐fabric. On the other hand, the effect of these finishing agents was to enhance the susceptibility of the fabric to oily soiling. Nevertheless, nature of the finishing agent governed the magnitude of this enhancement. Aqueous and oily soil release depended also upon the nature of finishing agent, soiling increased and soil release decreased by increasing finishing agent concentration. Type of catalyst exerted a considerable influence on aqueous and oily soil release without significantly affecting the degree of soiling. For aqueous soil release, the following order was found:
Al2(SO4)3 · 18H2O > MgCl2 · 6H2O > urea nitrate > ZnCl2 · 6H2O > Zn(NO3)2 · 6H2O > urea phosphate > urea oxalate > NH4 · H2PO4 ≥ NH4Cl.A reverse order held good for oily soil release. Both aqueous and oily soil release were impaired by increasing catalyst concentration. Similarly, nature and concentration of the softener had no striking effect on soiling while they did on soil release. Raising the curing temperature from 80 to 140°C caused substantial reduction in case of soil removal of urea salts catalyzed‐crosslinked cotton samples while having the degree of soiling practically intact.
Graft copolymerization of perfluoroheptyl methacrylate/glycidyl methacrylate mixtures with cotton fabric using Fe2+‐thioureadioxide‐H2O2 redox system
Authors: El‐Alfy E. , Waly A. , Hebeish A. 
Published: April 2003

AbstractThe ability of Fe2+‐thioureadioxide‐H2O2 redox system to induce polymerization of perfluoroheptyl methacrylate (PFHMA) and glycidyl methacrylate (GMA) individually as well as in binary mixtures was investigated under different conditions. Results obtained indicated that (a) PFHMA monomer could substantially be polymerized with cotton cellulose only in presence of GMA, (b) maximum contribution of PFHMA in the polymer add‐on occurred upon using PFHMA mixture at a ratio of 50:50 at 80°C, (c) presence of PFHMA along with GMA offsets the fast termination rate of the latter as temperature increased from 60° to 90°C, (d) GMA activated PFHMA while the latter adversely affected GMA, (e) none of the PFHMA/GMA mixtures at ratios 2:8, 5:5, 8:2 showed synergetic effects, (f) H2O2 concentration of 0.01% and thioureadioxide concentration of 0.04% constituted the optimal concentrations for polymerization of PFHMA/GMA at a ratio of 5:5, and (g) the polymerization reaction proceeded initially very fast, then levelled off. (h) The water/oil repellency of the copolymerized cotton samples relied on the percent of PFHMA in total percent polymer add‐on; these properties attained maximum at 4.25% PFHMA in a total polymer add‐on of 22.5%.
Polychelates of a tetrafunctional bisoxime
Authors: Suthar H. B. , Shah J. R. 
Published: April 2003

AbstractMn(II)‐, Co(II)‐, Ni(II)‐, and Zn(II)‐polychelates of 4,4′‐(4,4′‐Biphenylylenebisazo)‐di(2‐hydroxy acetophenone oxime) have been synthesized and characterized on the basis of their physicochemical properties. An octahedral structure is suggested for all the polychelates. The order of thermal stability for all the polychelates was determined from their thermogravimetric analyses.
Interface distribution functions of isotactic polystyrene — poly(2,6‐dimethylphenylene oxide) blends
Authors: Wenig W. , Schöller T. 
Published: April 2003

AbstractMorphological parameters of isotactic polystyrene (iPS) · poly(2,6‐dimethylphenylene oxide) (PPO) blends have been determined from measurements of the small angle X‐ray scattering by calculating interface distribution functions. Applied to the compatible system iPS/PPO this method yields a number of reliable parameters such as the long period and mean thicknesses of crystal lamellae and interlamellar spacings. A comparison of the results obtained from the calculation of the interface distribution functions with those derived from model calculations show that theoretical calculations using the density model yield essentially the same results.
Effect of styrene on properties of vinyl ester resins, I
Authors: Varma I. K. , Rao B. S. , Choudhary M. S. , Choudhary V. , Varma D. S. 
Published: April 2003

AbstractThe paper describes the effect of styrene on the properties of bis(methacryloxy) derivatives of epoxy resins (vinyl ester resins). The styrene concentration in the resin was systematically varied between 20–60 wt.‐%. The curing characteristics of vinyl ester resins changed only marginally on dilution with styrene. Dilution with styrene resulted in a decrease in tensile modulus and increase in elongation of neat resin castings and glass fibre reinforced laminates. The glass transition temperature of laminates was determined by dynamic mechanical analysis and was found to decrease with increasing styrene content.