bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antioxidants and stabilizers, 109. The reaction between antioxidant N,N′‐diphenyl 1,4‐phenylene diamine and 1‐cyano‐1‐methylethyl
Authors: Taimr Luděk , Prusíková Miluše , Pospíšil Jan 
Published: April 2003

AbstractThe mechanism of action of an antioxidant, N,N′‐diphenyl‐1,4‐phenylene diamine (I, DPPD)Decoding of abbreviations see p. 48.
, was investigated under model conditions. After oxidation to a semiquinone radical, phenyl (4‐phenylamino phenyl)aminyl (VIII), or to Wurster's cation phenyl (4‐phenylamino phenyl)ammoniumyl (IX), I reacts with 1‐cyano‐1‐methylethyl (model alkyl) by two routes, both of which are accelerated by weak acids. One of these routes results in alkyl being bound to nitrogen with formation of N,N′‐diphenyl N‐(1‐cyano‐1‐methylethyl)1,4‐phenylene diamine (III). The latter compound is labile, and particularly in the presence of acids readily splits off olefin with regeneration of DPPD. This behaviour is a model of the regeneration mechanism of the stabilizing effect of DPPD, which alternately with its oxidation product (VIII or IX) deactivates the alkylperoxyl and alkyl radicals during the ageing of hydrocarbon substrates under conditions of the relative deficiency of oxygen. The other route leads to binding of the alkyl in the benzene ring with formation of N,N′‐diphenyl 2‐(1‐cyano‐1‐methylethyl) 1,4‐phenylene diamine (IV) and N,N′‐diphenyl 2‐(1‐cyano‐1‐methylethyl) 1,4‐benzoquinone diimine (V), thus modelling the binding of DPPD in the polymer chain, and even the crosslinking of the chain during the ageing of a polymer inhibited with DPPD. Due to the presence of the nitrile group, IV undergoes some further changes, which give rise to the formation of 3,3‐dimethyl 2‐imino‐1‐phenyl 5‐phenylamino indoline (VI) and 2‐acetylimino 3,3‐dimethyl‐1‐phenyl 5‐phenylamino indoline (VII).
Organotin polymers XIV. Synthesis and copolymerization reactions of p‐acryloyloxy‐tri‐n‐butyltin benzoate with some vinyl monomers
Authors: Shaaban Abd‐El‐Fattah Fadel , Azab Mohamed Morsy , Messiha Nagi Naguib 
Published: April 2003

Abstractp‐Acryloyloxy‐tri‐n‐butyltin benzoate (ABTB) was prepared by the reaction of p‐hydroxy‐tri‐n‐butyltin benzoate and acrylic acid in the presence of dicyclohexylcarbodiimide. The monomer reactivity ratios for the copolymerizations of ABTB (M1) with methyl acrylate (M2), ethyl acrylate (M2), n‐butyl acrylate (M2), methyl methacrylate (M2), styrene (M2) and acrylonitrile (M2) have been found to be r1 = 0.080, r2 = 1.046; r1 = 0.039, r2 = 1.585; r1 = 0.019, r2 = 2.076; r1 = 0.150, r2 = 1.710; r1 = 0.113, r2 = 1.339 and r1 = 0.007, r2 = 2.853, respectively. The Q and e values for the prepared organotin monomer were calculated. Copolymerization reactions were carried out in solution at 70°C using 1 mol‐% azobisisobutyronitrile. The structure of the ABTB monomer and the prepared copolymers was investigated by IR and 1H‐NMR spectroscopy.
Coordination polymers, 2. Effect of iodine doping on electrical properties of coordination polymers derived from terephthalaldehyde bis(S‐benzyldithiocarbazate)
Authors: Paliwal L. J. , Kharat R. B. 
Published: April 2003

AbstractThe electrical properties of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) chelate polymers of terephthalaldehyde bis(S‐benzyldithiocarbazate) (TBDTC) have been studied. Similarly, different concentrations of iodine were doped to these chelate polymers to increase their conductivity for producing a new class of electrical conductive material. The current interest in doping of iodine in chelate polymers is to a great extent due to their possible application in power sources and electrochemical devices. Electrical conductivity of chelate polymers and iodine doped chelate polymers have been studied over a wide range of temperature (∼ 300−450 K). From the electrical conductivity of these polymers activation energies of electrical conduction have been evaluated. A comparison of electrical conductivity and activation energy of electrical conduction of simple and iodine doped polymers has been made and conclusions about the role of iodine in chelate polymers regarding the electrical conductivity have been drawn.
Modification of polybutadienes by catalytic and photochemical decomposition of dimethyldiazomalonate
Authors: Yaǧi Yusuf , Anaç Olcay , Mazlumoǧlu Tülay 
Published: April 2003

AbstractModifications of polybutadienes via catalytic and photolytic decomposition of dimethyldiazomalonate (dmdm) are described. This method pertains to the generation of highly reactive carbenes which give rise to the formation of addition and insertion products. Chemical structures of the modified polymers were confirmed by NMR spectroscopy. It was found that carbene dimers were also formed in a significant extent depending on the molecular weight and microstructure of the initial polymers.
Grafting of N‐methylolacrylamide onto flax/polyester fabric using ferrous cellulose thiocarbonate/H2O2 redox system
Authors: Higazy A. , Bayazeed A. , Hebeish A. 
Published: April 2003

AbstractGraft copolymerization of N‐methylolacrylamide onto flax/polyester blend fabric using ferrous cellulose thiocarbonate/H2O2 redox system was investigated under different conditions including hydrogen peroxide concentration (1−60 mmol/l), ferrous ammonium sulphate concentration (1−50 mmol/l), N‐methylolacrylamide concentration (5−200%, based on weight of sample), polymerization time (10−90 min), temperature (20−50°C), and pH of the medium (1.1−11). The nitrogen content and/or the methylol content were used for calculation of graft yields. Results obtained indicated that graft yields, derived from nitrogen analysis, are higher the greater the H2O2 concentration increases till 40 mmol/l, then level off. On the other hand, graft yields derived from methylol content exhibit maximum value at 10 mmol/l H2O2. The results indicate also that grafting was highly favoured when it was carried out using 1 mmol/l ferrous ammonium sulphate and pH 4.4 at 30°C for 60 min. The apparent activation energy of the copolymerization reaction amounts to 9.74 kJ/mol. Furthermore, the graft yield increases by increasing N‐methylolacrylamide concentration within the range studied. The work was further extended to include a comparison between the polymerization efficiencies of the ferrous cellulose thiocarbonate/H2O2 redox system and the ferrous/H2O2 redox system in inducing grafting of N‐methylolacrylamide onto flax/polyester blend fabric. For this reason, the two systems were studied with respect to graft yield, homopolymer proportion, total conversion, graft efficiency, and homopolymer efficiency.
Structural studies on chars from fire retardant intumescent systems
Authors: Bertelli G. , Camino G. , Marchetti E. , Costa L. , Locatelli R. 
Published: April 2003

AbstractThe protection provided by intumescent chars against the action of the flame is generally attributed to their physical insulating properties. These in turn depend on the physical chemical structure of swollen char, which however has been scarcely studied. It is shown that scanning electron microscopy and microanalysis by energy dispersive system supply detailed information on the morphology and the chemical composition of intumescent systems. The data obtained contribute to the understanding of the fire retardance mechanism.
Comportement électrique des interfaces polyéthylène‐métal en liaison avec l'adhésion
Authors: Lavielle Lisette , Prévot Jean‐Louis , Schultz Jacques 
Published: April 2003

AbstractL'adhésion entre aluminium et polyoléfines est obtenue par fusion sous pression de la polyoléfine au contact du métal. Seules les polyoléfines modifiées adhèrent au métal, par suite de la formation de réactions chimiques à l'interface polymère‐métal.L'équivalent électrique de l'interface a été étudié en établissant les caractéristiques intensité‐potentiel en courant continu pour des tensions appliquées allant jusqu'à 1500 V. Une bonne corrélation apparaît entre propriétés électriques pour les différents assemblages polyéthylènes ou polypropylènes greffés et aluminium. Un modèle de l'interface polymère‐métal, associant une barrière de Schottky et une charge d'espace, modulée en fonction des propriétés adhésives est proposé.Ainsi l'adhésion peut être reliée à une répartition différente des charges à l'interface polymère‐métal.
Vernetzung von carboxymethylcellulose über enzymatisch spaltbare ester
Authors: Klemm Dieter , Geschwend Günter 
Published: April 2003

AbstractVernetzte, in Wasser quellbare und durch Esterasen spaltbare Alkoxycarbonylethoxymethylester der Carboxymethylcellulose entstehen durch heterogene und homogene O‐Alkylierung von Natriumcarboxymethylcellulose mit bifunktionellen α‐Brom‐α‐ethoxy‐essigsäureestern. Diese enzymatisch aufhebbare Vernetzung ist sowohl für die gesteuerte Veränderung der Löslichkeit von Carboxymethylcellulose als auch für die schrittweise Freisetzung von inkorporierten biologisch aktiven Verbindungen in Abhängigkeit von der Esteraseaktivität von Bedeutung.
Synthetic resins VIII. Preparation and characterization of p‐aminoacetophenone/substituted benzoic acid/formaldehyde resins
Authors: Panda Jayanti , Lenka Subasini , Nayak Padma L. 
Published: April 2003

AbstractA number of resins has been prepared by condensing p‐amino‐acetophenone (p‐AAph) with substituted benzoic acid such as m‐toluic acid (m‐TA), o‐toluic acid (o‐TA), phthalic acid (PhA), p‐nitrobenzoic acid (p‐NBA), p‐chlorobenzoic acid (p‐CIBA) and formaldehyde (F) in presence of some acids and bases as catalysts. The resins were characterized by infrared spectra of the characteristic groups. The solubility parameters were calculated from Small's group contribution which agreed well with the experimental values. The thermal behaviour and the bacteriological properties of the resins have also been investigated.
Preparation and characterization of dimethylacrylamide based polymer supports
Authors: Arshady Reza 
Published: April 2003

AbstractA systematic study of the preparation of dimethylacrylamide resins carrying amino, carboxyl or activated carboxyl functionality is reported. Details of the syntheses of dimethylacrylamide (1) and a number of acrylamide‐based crosslinking (2) and functional (3–5) monomers are given. The terpolymerization of 1 and 2 with 3 (or with 4 or 5) by a water in oil (w/o or reverse) suspension polymerization procedure is described for the preparation of dimethylacrylamide resins having a wide range of functionality and swelling behaviour. The swellability of several of the resin samples in dichloromethane, dimethylformamide, dimethylsulfoxide, methanol, acetic acid, and water is given. Typical chemical transformations of dimethylacrylamide resins are also described.
Development of materials for the production of plastic fasteners
Authors: Otaigbe Joshua Usifo 
Published: April 2003

AbstractAn investigation into the formation of mushroom shaped ends of polypropylene (PP), polyester, nylon 6, PP/nylon 6, and nylon 6/silica monofilaments when cut with a hot wire was carried out. The ability to form mushroom shaped ends depends on the draw ratio attainable and its resultant ability to shrink. Blending nylon 6 with polypropylene increased the shrinkage and the draw ratio of nylon 6 reaches a maximum of 5.4 at 30/70 wt.‐% polypropylene in nylon 6.
Synthesis and some properties of carbazole modified polyvinylchloride and the cation exchange resin therefrom
Authors: Biswas Mukul , Mitra Pradyot 
Published: April 2003

AbstractThe chlorine displacement reaction between PVC and N‐methylcarbazole‐3,6‐diamine affords a condensate which is insoluble in all possible solvents of PVC. The overall thermal stability of this condensate is appreciably higher than that of PVC. The dielectric behavior is also significantly different from that of unmodified PVC. Sulfonation of the PVC‐carbazole condensate affords a cation‐exchange resin with SO3H and COOH functional moieties.
Polyvinyl acetate as a template for the radical polymerization of methyl methacrylate
Authors: Tewari Neeta , Srivastava A. K. 
Published: April 2003

AbstractThe template polymerization of methyl methacrylate (MMA) along with atactic polyvinyl acetate (at‐PVAC, M̄v = 55880) at 60°C for 120 min in dimethyl formamide (DMF) has been measured dilatometrically to study the effects of the concentrations of template, monomer, and initiator upon the kinetics. The resulting plots of relative polymerization rate (VR) vs. the at‐PVAC‐ and MMA‐concentration showed that in the present system the polymerization is a combination of three different reaction mechanisms, the blank reaction and two template mechanisms (I and II). The order of reaction with respect to template, monomer and initiator is 0.66, 0.75 and 0.40, respectively. Viscometric measurements showed that complexation between at‐PVAC and PMMA was maximum when the template/polymer ratio was 1 : 1 and the time required for complete complexation was 10 min. The overall energy of activation was 33.5 and 25.0 kJ mol−1 in the presence and absence of at‐PVAC, respectively.
Synthese verschiedener Oxincellulosen für spurenanalytische Anreicherungsverfahren
Authors: Csanády Georg , Narayanan Prakash , Müller Kurt , Wegscheider Wolfhard , Knapp Günter 
Published: April 2003

AbstractEs werden mehrere Synthesemöglichkeiten für die Herstellung von an Cellulose immobilisierten 8‐Hydroxychinolin‐ und 8‐Hydroxychinolin‐5‐sulfonsäure‐Derivaten beschrieben, die zu einem Produkt mit einer Kapazität von 500–800 μmol/g, hoher Austauschgeschwindigkeit und guter Stabilität gegenüber dem Eluenten führen. Die scheinbare Komplexbildungskonstante der Oxincellulosen mit Zn2+ ist etwa 2 · 105 mol−1 dm3.
Synthesis and characterization of some 2,4′‐dibenzyldiisocyanate ionic polymers. V. Ionene polymers
Authors: Buruianǎ Tinca , Beştiuc Ioan , Caraculacu Adrian 
Published: April 2003

AbstractCationic polyurethanes containing piperazine rings on the macromolecular chain were synthesized by a Menschutkin reaction. A prepolymer with tertiary dimethylamino end groups and a dihalide were used in the first step, and N,N′‐dimethylpiperazine in the second step. The viscometric behaviour of dilute solutions in solvents with high dielectrical constants was studied.
Oberflächenstrukturierung polymerer Fasern durch UV‐Laserbestrahlung. 4. Der Einfluß äußerer Spannungsfelder
Authors: Bahners Thomas , Bossmann Adelgund , Schollmeyer Eckhard 
Published: April 2003

AbstractDieser Beitrag berichtet über die UV‐Laserbestrahlung von Elastomerfasern unter dem Einfluß verschieden großer äußerer Spannungsfelder und unterschiedlicher Laserbedingungen. Aus der Literatur ist bekannt, daß synergetische Effekte, die als Ursache der Oberflächenstrukturierung angesehen werden, sowohl durch Temperaturwie auch Spannungsfelder getrieben sein können. Daher sollen die beschriebenen Experimente untersuchen, welche der genannten Bedingungen in der Hauptsache zur Instabilität des Systems und damit zur Oberflächenstrukturierung führen.
Isocyanatfreie, zweikomponentige Polyurethansysteme
Authors: Schmitt Felix 
Published: April 2003

AbstractBasis dieser neuen Gruppe von Polyurethanrohstoffen bilden dimerisierte, cycloaliphatische Isocyanate. Die bei der Dimerisierung gebildete Uretdionstruktur zeichnet sich durch deutlich abgestufte Reaktivität gegenüber verschiedenen Aminen aus. Von Reaktionsharzen, die als funktionelle Gruppen Uretdionstrukturen enthalten, werden die Härtungsreaktion und das Härtungsverhalten beschrieben. Neben den Grundlagen zum Verständnis dieser Reaktionsharze wird der Stand der Entwicklung zur technischen Nutzung aufgezeigt. Anwendungsgebiete eröffnen sich auf dem Polyurethan‐Lack‐Sektor und bei der Urethanmodifizierung von Beschichtungen und Lacken auf Epoxidharzbasis.
Gelbfäurbung von weißpigmentiertem PVC bei Dunkellagerung nach Bewitterung
Authors: Hepp Dieter 
Published: April 2003

AbstractBei der künstlichen und natürlichen Bewitterung von weißen Fensterprofilmustern beobachtet man häufig eine Vergilbung, die meßtechnisch verfolgt werden kann durch Erfassung des b‐Wertes. Diese Vergilbung entsteht während der Dunkellagerungsphase und wird mit der Länge der Dunkellagerung verstärkt, bis sie eine gewisse Sättigung erreicht. Bei erneuter Exposition im Freien oder im Bewitterungsgerät ist diese Vergilbung reversibel. Es liegt die Vermutung nahe, daß es sich um ein Gleichgewicht zwischen Vergilbung im Dunkeln und Ausbleichen im Hellen handelt. Hierzu wurde ein Mechanismus vorgeschlagen, der den Zerfall von unter Sonneneinstrahlung gebildeten zyklischen Peroxiden im Dunkeln beinhaltet.Als Konsequenz dieser Arbeit sollte bei der Beurteilung von weißem PVC‐Material für den Außeneinsatz immer sofort nach Ende einer Expositionszeit die Farbveränderung gemessen werden, um Fehlmessungen, die durch längeres Lagern entstehen können, zu vermeiden und wirtschaftlichen Schaden von dem Produzenten abzuwenden.
Mutual miscibility of chlorinated hydrocarbon polymers derived from polyethylene and polyvinylchloride
Authors: Braun D. , Herth J. , Hellmann G. P. 
Published: April 2003

AbstractThe compatibility of chlorinated hydrocarbon polymers of two different comonomer sequence orders was investigated. One series of copolymers (“PVCx”) was prepared via reduction of polyvinylchloride, the other (“PECx”) via chlorination of polyethylene in solution. The blends PECx/PECy, PVCx/PVCy and PVCx/PECy were analyzed with a film casting method at 30°C and 110°C. Miscibility increases in the system PECx/PECy steadily in the direction of increasing chlorine content. Due to the comonomer sequence order in the copolymers PVCx the systems PVCx/PVCy and PVCx/PECy show in the range around x = 1 an extra effect favouring phase separation. In the latter system this effect is so strong that polyvinylchloride (PVCx = 1) is even incompatible with the chlorinated polyethylene PECx=1 although both have the same overall composition.
Toughening of epoxy‐polyamide adhesives with rubbery reactive microgels
Authors: Zhu Zheng , Xue Ruilan , Yu Yunchao 
Published: April 2003

AbstractAn elastomeric microgel with reactive carboxyl groups was prepared by emulsion copolymerization of an unsaturated polyester with 2‐ethylhexyl acrylate. An epoxy resin was grafted onto the microgel particles through the addition of the carboxyl group to the epoxy group. The blend of the microgel and the epoxy resin was very stable, the microgel remained as discrete microsphere in the cured resin. The incorporation of the microgel did not cause a significant effect on the network structure of the matrix resin, while the toughness and the adhesive strength of the epoxy‐polyamide resins were improved tremendously.
Crystallization kinetics of isotactic polypropylene containing organic pigments
Authors: Włochowicz A. , Eder M. 
Published: April 2003

AbstractThe isothermal and non‐isothermal crystallization of isotactic polypropylene coloured with selected organic pigments was examined by differential scanning calorimetry. It was found that the nucleating ability of pigments is connected with their chemical nature and with the reduction of the free energy for critical nucleus formation. The experimental data were analysed in terms of the well known Avrami equation.Blue pigment and Red lake are substances which accelerate the crystallization of isotactic polypropylene, while Orange pigment decreases the crystallization rate slightly.
Molecular weight studies on chlorinated atactic polypropylene
Authors: Mukherjee A. K. , Patri M. 
Published: April 2003

AbstractMolecular weight studies of chlorinated atactic polypropylene (CAPP), prepared by thermal chlorination of atactic polypropylene (APP), have been carried out by viscosity measurements and gel permeation chromatography. In general, the intrinsic viscosity [η], number average molecular weight (Mn) and weight average molecular weight (Mw) are dependent on degree of chlorination as well as synthesis conditions. The phenomena observed are discussed.
Glutarimide copolymer additive for high service temperature PVC
Authors: Patterson John R. , Cinoman Douglas S. , Dunkelberger David L. 
Published: April 2003

AbstractA major disadvantage of PVC is its low glass transition temperature which limits the service temperature of finished articles to about 70°C. An additive has been developed that can be formulated with PVC to form blends with increased service temperature. With proper formulating, higher heat distortion temperatures can be achieved without sacrificing other properties including clarity. This is especially important in clear PVC applications where no increase in haze is noted with the addition of the acrylic/imide copolymer.
Selectivity and cooperativity in interpolymer complexation involving an acrylic copolymer, non‐ionic polymer, and a polyelectrolyte
Authors: Chatterjee S. K. , Yadav D. , Khan A. M. , Sethi K. R. 
Published: April 2003

AbstractSelectivity in interpolymer complex formation involving methacrylic acid‐methacrylamide (MA‐MAm) copolymer, poly(vinyl pyrrolidone) (PVP), and poly(ethylene imine) (PEI), has been studied in aqueous medium by several experimental techniques, e.g., viscometry, potentiometry, conductometry and infra‐red spectroscopy. Complexation ability of PEI has been found to be greater than that of PVP with respect to MA‐MAm copolymer. A “ladder like” structure is predicted for the polyelectrolyte complexes in view of the high charge density of the polyelectrolytes.
Acrylic carriers for the immobilization of enzymes
Authors: Kolarz Bożena N. , Łobarzewski Jerzy , Trochimczuk Andrzej , Wojaczyńska Maria 
Published: April 2003

AbstractThe influence of the supermolecular structure of carriers obtained by aminolysis of nitrile or ester groups of acrylic copolymers crosslinked with divinylbenzene or ethylene dimethacrylate was investigated. The enzymes peroxidase, glucoamylase and urease immobilized on the carriers of a porous structure display a higher activity as compared to carriers with an expanded structure. The number of functional groups in the carrier influences the activity of the immobilized enzyme, but there is no linear relationship.
Beiträge zur konfigurativen Zuordnung von Isophorondiamin und ‐diisocyanat sowie Derivaten
Authors: Born L. , Wendisch D. , Reiff H. , Dieterich D. 
Published: April 2003

AbstractZur Klärung der konfigurativen Zuordnung der Isomerengemische von Isophorondiamin und diisocyanat (IPDA u. IPDI) wurden die isomerenreinen, kristallinen Bis(dimethylamino)harnstoffe3aund3bmittels Röntgenstrukturanalyse untersucht. Die Ergebnisse zeigen für3adiecis‐ und für3bdietrans‐Konfiguration im Einklang mit Hatada et al. und im Gegensatz zu frühern Untersuchungen. Somit sind die jeweiligen Hauptkomponenten von IPDA und IPDI eindeutigcis‐konfiguriert. Die13C‐NMR‐Daten von1bis5gestatten nunmehr die konfigurative Zuordnung beliebiger Derivate von IPDA und IPDI.
Newly proposed relationship between peak dispersion coefficient and width of the experimental chromatogram based on theories of proposed instrumental spreading shape function in size exclusion chromatography
Authors: Omorodion S. N. E. , Hamielec A. E. 
Published: April 2003

AbstractThe newly proposed instrumental spreading shape function (ISF) of Omorodion and Hamielec1, has been evaluated in a more recent publication2. It has now been applied to reveal the peak broadening capabilities of peak dispersion coefficient in aqueous size exclusion chromatography (SEC), as it relates to the width of the experimental chromatogram. These new theoretical developments have been employed on series of dextran standards/CPG‐10 systems.