bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Graft 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

The 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

L'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

Vernetzte, 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

A 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

A 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

An 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

The 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

The 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

Es 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

Cationic 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

Dieser 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

Basis 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

Bei 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

The 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

An 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

The 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

Molecular 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

A 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

Selectivity 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

The 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

Zur 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

The 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.
Relationships between mechanical properties and microhardness of polyethylenes
Authors: Lorenzo Vicente , Pereña José Manuel , Fatou José María G.
Published: April 2003

The values of the elastic modulus (E) and the yield stress (Y) and the shape of the strain‐stress curves of different polyethylenes have been related to the microhardness (MH) of these materials, considering the roles that the crystalline, amorphous, and interfacial regions play in the deformation of semicrystalline polymers. Linear relations between microhardness and degree of crystallinity, (1 – λ)d, and between the logarithms of E and MH have been found. The variations of the parameters 100Y/E and σmin/Y (σmin is the relative minimum value of the nominal stress for elongations above the yield point) as a function of (1–λ)d follow different trends for linear and branched polyethylenes. Moreover, it has been found that the ratio MH/Y is smaller than three for these materials, approaching this theoretical value (Tabor relation) only for the highest crystallinity levels.
Ein modell zur quantitativen beschreibung der morphogenesis von PVC‐S, IV. Berücksichtigung der hüllenbildung und modellanwendung
Authors: Henschel Ines , Platzer Bernd , Weickert Günter
Published: April 2003

Beim PVC, das nach dem Suspensionsverfahren in Rührbehältern hergestellt wird, bildet sich (bedingt durch die Tropfenrotation) eine Hülle aus dicht zusammengelagerten Partikeln um das PVC‐Korn. In der vorliegenden Arbeit wird das in vorherigen Artikeln1–3 vorgestellte Modell der Morphogenesis von PVC‐S um diese Vorgänge erweitert. Die Modellparameter werden abgeleitet, und es wird die Anwendbarkeit des Modells durch Vergleich seiner Ergebnisse mit rasterelektronenmikroskopischen Meßwerten nachgewiesen. Es ist in der Lage, die Veränderungen mehrerer Hierarchieebenen der inneren Morphologie über den gesamten Umsatzbereich nachzubilden.
Gelpermeationschromatographie von anionischen polyurethan‐dispersionen
Authors: Lorenz O. , Brocker J. , Gerhard H. , Haulena F. , Roeder D.
Published: April 2003

Es wird über die Gelpermeationschromatographie (GPC) weitgehend monodisperser PMMA‐Latices sowie anionischer Polyurethan‐Dispersionen mit unterschiedlich breiter Teilchengrößenverteilung (TGV) unter Verwendung eines Copolymeren aus Oligoethylenglycol, Glycidylmethacrylat und Pentaerythroldimethacrylat (Fractogel TSK) als Säulenfüllmaterial berichtet. Das Elutionsvolumen des Peak‐Maximums sowie die Peak‐Breite sind von der Ionenstärke des Elutionsmittels abhängig. Die TGV der Dispersion wurde außerdem durch Ultrazentrifugation bestimmt. Wie bei den PUR‐Dispersionen gezeigt werden konnte, entspricht das Peak‐Maximum des GPC‐Diagramms dem Zahlenmittel des Partikeldurchmessers D̄N bzw. dem D50‐Wert (Durchmesser, bei dem 50% der Masse erfaßt sind). Lösungsmittel und andere Additive, die in den PUR‐Dispersionen enthalten sein können, lassen sich ebenfalls durch GPC identifizieren.
Flüssigkristalline hauptkettenpolyester mit trans‐1,4‐cyclohexyleneinheiten
Authors: Braun Dietrich , Schülke Ulrike
Published: April 2003

Das flüssigkristalline Verhalten von Polyestern aus trans‐1,4‐Cyclohexylen‐bis(4‐hydroxybenzoat) und Alkandicarbonsäuren wird mit Hilfe der Differentialkalorimetrie (DSC), der Mikroskopie und der Röntgenstrukturanalyse untersucht. Ein Vergleich der Daten aus Viskositätsmessungen und der Gelpermeationschromatographie (GPC) gibt Aufschluß über die Molekulargewichte der Polyester.

Die Synthese und Charakterisierung eines neuen, ähnlich aufgebauten Polyesters aus alternierenden Cyclohexylen‐ und Phenylenringen wird beschrieben.
Intumescent fire retardant systems: Effect of fillers on char structure
Authors: Bertelli G. , Marchetti E. , Camino G. , Costa L. , Locatelli R.
Published: April 2003

Scanning electron microscopy and microanalysis by energy dispersive system show that the structure of the foamed char obtained on burning polypropylene fire retarded with an intumescent additive system, can be strongly modified in the presence of typical inorganic fillers. Modifications involving both the physical and chemical characteristics of the char might be related to chemical reactions between fillers and acid phosphorus moieties of the fire retardant. Fillers that modify the structure of the char tend to decrease the efficiency of the fire retardant system.
Heat resistant polyamideimides, 3. Synthesis, characterization, and evaluation of thermal and other properties
Authors: Ghosh Malay
Published: April 2003

Polyamideimides have long been known for their excellent heat resistance properties. This paper will report the synthesis of two new polyamideimides from 4,4′‐bis‐(3‐carboxylphthalimidyl)biphenyl and/or 4,4′‐bis‐(3‐chlorocarbonylphthalimidyl)biphenyl and two aromatic diamines by using solution polycondensation reaction at low temperature in polar organic solvents. The optimum conditions necessary for the polycondensation reaction have been studied. Characterization of polymers is done by elemental analysis, IR data, and viscosity measurements. The prepared polymers are partially soluble in electron donating organic solvents for example dimethyl formamide, dimethyl acetamide, m‐cresol etc. In addition to heat resistance properties of polymers, chemical stability towards acid and base and moisture absorption properties have been evaluated.
The influence of pore dispersion and polymer/surface interaction on peak dispersion phenomenon in size exclusion chromatography
Authors: Omorodion S. N. E. , Hamielec A. E.
Published: April 2003

Based on the newly proposed instrumental spreading shape function (ISF) of Omorodion and Hamielec1 and the new theoretical developments on peak dispersion phenomenon2, the present study reported herein deals with some of the non‐inherent contributing sources to peak dispersion phenomenon in SEC. Despite when the choice of a suitable mobile phase has been accomplished for a particular polymer/packing material system3–5, the need to optimize the system for minimum peak broadening is still very important. The major contributing sources discussed here are the roles of pore dispersion (large pores) and polymer/small pore‐size surface area interactions resulting from the traditional method of column arrangements. The systems employed in the study are dextran/mostly CPG systems. Other packing materials employed included Bio‐glass (BG) and EM‐gel (EM), both of large pore size range.
Crosslinking of polyethylene photoinitiated by benzoquinones and naphthoquinones
Authors: Zamotaev Pavel V. , Luzgarev Sergey V.
Published: April 2003

Crosslinking of polyethylene (PE) photoinitiated by some benzoquinones and naphthoquinones has been studied. The quantum yields (φ) of the initiator reactions in PE under UV irradiation were measured. The φ‐values for benzoquinone, tetrachlorobenzoquinone, tetrabromobenzoquinone, tetrafluorobenzoquinone, naphthoquinone, and 2,3‐dichloronaphthoquinone were equal to 0.23, 0.18, 0.14, 0.26, 0.09, and 0.11, respectively. Naphthoquinones were more effective as initiators in photocrosslinking of polyethylene.
Modification of wood fiber surface by grafting and its effect on mechanical properties of polystyrene filled system
Authors: Raj R. G. , Kokta B. V. , Daneault C.
Published: April 2003

Polystyrene (PS) was reinforced/filled with grafted thermomechanical pulp (TMP) of aspen and birch. The dependence of tensile properties of composites on different loadings of filler, on polymer loading in grafted fiber, on the presence of homopolymer in grafted fiber, and on impregnation of fibers with PS were studied. PS filled with grafted aspen and birch (lower polymer loading) showed a significant increase in tensile strength and modulus. Fracture energy and elongation of the composites decreased with an increase in the concentration of filler.
Composite model calculation for the thermal expansibility of high density polyethylene
Authors: Bandyopadhyay Partha , Biswas Prabir K. , Basu Asok N.
Published: April 2003

The thermal expansibility of high density polyethylene is calculated within the framework of the composite model which has already been found useful in describing its mechanical properties and thermal conductivity. The orientational changes of the units of which the bulk of the polymer is supposed to be composed has been derived from a two parameter empirical relation proposed by the authors. A comparative study of the variation of the orientational parameters with processing conditions has also been included.
Immobilization of 2,4‐ionene on a macroporous poly(styrene‐divinylbenzene) resin and its effect on the rate of the cobaltphthalocyanine‐catalyzed oxidative coupling of mercaptoethanol
Authors: Van Streun Karel H. , Meuldijk Jan , German Anton L.
Published: April 2003

A poly(quaternary ammonium) salt, 2,4‐ionene, has been immobilized on a macroporous chloromethylated poly(styrene‐divinylbenzene) resin (XAD‐2). The ionene content of the resin, determined by CHN elemental analysis, was 50.2 g/kg resin. The most important side effect of the modified resin, catalyst (2,4‐ionene) bleeding, can be detected by a spectrophotometric method capable of determining extremely low concentrations of free ionene in the supernatant of the resin.

The activity of these immobilized 2,4‐ionene/cobalt(II)phthalocyanine‐tetrasodiumsulfonate (CoTSPc) complexes towards the oxidative coupling of thiols is much lower than in the homogeneous case, but still considerably higher than for the polymer free system. The observed decrease in reaction rate does not originate from the considerable mass transfer resistances but predominantly from catalyst properties like a very low local N+/Co ratio. The active sites appear to be present in the outer shell of the resin particles only.
Thermal and UV degradation of impact‐resistant polystyrene
Authors: Mlinac‐Mis̆ak M. , Jelenc̆ić J. , Bravar M.
Published: April 2003

A commercial type of impact‐resistant polystyrene (IPS) was investigated. Two types of antioxidants, Irganox 245 and Irganox PS‐800 were added to IPS in amounts of 0.05 to 0.2%. Films, dumbbells and straight test pieces were subjected to thermal and UV ageing.

Films of 250 μm thickness were thermally treated at 100°C and separately UV irradiated at 360 nm for 24, 72, 120 and 168 h. Dumbbells and straight test pieces were only thermally aged at 100°C for 7, 14, 21, 28 and 35 days.

Carbonyl and hydroxy group content as well as polybutadiene‐(PB)‐unsaturation absorbances of films were measured by IR spectroscopy.

Breaking strength, elongation and izod impact‐strength of test pieces were determined.
Molecular aggregation of PEEK with PES blends and the block copolymers composed of PEEK and PES components
Authors: Wu Zhongwen , Zheng Yubin , Yan Hongmao , Nakamura Tomoki , Nozawa Takafumi , Yosomiya Ryutoku
Published: April 2003

Polymer blends of PEEK with PES were prepared by the solution blending method. Copolymers composed of PEEK and PES components were synthesized from these oligomers. The formation conditions exerted an influence over the molecular aggregation and the crystallization behaviors of the blend films and block copolymers which were examined by X‐ray diffractometry and DSC analysis. As a result, phase‐separation in the blend films was found when the formation temperature was high. The blend films formed at 340°C, quenched and annealed at 180°C, exhibited the same crystallization behavior as those of PEEK. In the case of the blend films formed at 300°C, the annealing of the films at 250°C was required to crystallize the blend films. The Tg of a copolymer with a PEEK component content of more than 50% tends to shift toward a higher temperature than the Tg of PEEK itself, and the Tm of the copolymer toward a lower temperature than that of PEEK ist.
XPS and SSIMS studies on CF4/O2 plasma treated polycarbonate
Authors: Occhiello E. , Morra M. , Garbassi F.
Published: April 2003

XPS, SSIMS and water contact angle measurements have been used to characterize the chemical effect of CF4/O2 discharges on polycarbonate (PC) made from bisphenol A. We found that the surface modification induced by plasma treatment can be clearly explained on the basis of the acitve species present in the plasma, whose concentration has been studied by actinometry.

With very low amounts of O2 in the gas feed (1%) extensive fluorination of the surface occurs, due to grafting of the fluorocarbon radicals. Perfluorinated islands are formed, as shown by the high value of advancing contact angles. In the 20–80% O2 range, fluorine atoms react with the surface, partially inducing etching. Low amounts of fluorine are observed on the sample and no perfluorinated islands. Oxygen participates in etching and oxidizes the PC surface. We observed an increase of the surface concentration of oxygen with increasing the O2 amount in the gas feed and also the formation of strongly oxidized islets on the sample surface, as shown by the dramatic reduction of receding contact angles. A reduction of surface aromaticity, observed by XPS and SSIMS, is the consequence of these reactions.
The photocopolymer rod of ethyleneglycol dimethacrylate with methylmethacrylate
Authors: Liu Jui‐Hsiang , Wang Jenn‐Hwa , Chu Ming‐Huei
Published: April 2003

The photocopolymerization of ethyleneglycol dimethacrylate (EGDMA) with methylmethacrylate (MMA) containing benzoin methyl ether (BME) as initiator was carried out in a glass tube to fabricate a light‐focusing plastic rod (radius Rp) with a parabolic refractive index distribution (distribution constant A) in the region near the center axis (radius Rc). The dependence of A and Rc/Rp on MMA/EGDMA feed ratio, influence of BME concentration on the refractive index distribution, and the reproducibilities of the photopolymerizations were investigated. The Rc/Rp increased with the feed ratio used under BME = 1.0 wt.‐% at velocity of UV lamp V = 0.58 mm/min. On the other hand, Rc/Rp increased with the feed ratio to 0.2 and then decreased remarkably with the feed ratio in the range of 0.2–0.25 with BME = 0.6 wt.‐% at V = 0.735 mm/min. Plastic rods fabricated in the investigation using photopolymerization have lens characteristics and good reproducibilities.
Effects of drawing conditions on the properties of optical fibers made from polystyrene and poly(methyl methacrylate)
Authors: Dvořánek Ladislav , Machová Luďka , Šorm Miloslav , Pelzbauer Zdeněk , Švantner Jiří , Kubánek Vladimír
Published: April 2003

Monofilaments possessing various degrees of birefringence were obtained by changing the drawing rate, the molten polymer temperature, and the molecular weight of polystyrene (PS) and poly(methyl methacrylate) (PMMA). The “brittle‐toductile” transition point of optically pure PS was found in the range of birefringences of −0.6 · 10−3 to −2.6 · 10−3. Both the height and position of this point are influenced by M̄w, molecular weight distribution, and polymer melt temperature. The birefringence of PS is higher by two orders of magnitude than that of PMMA in which this transition point has not been observed. The mechanical and optical properties depend not only on the average amount of orientation characterized by the birefringence but on what portion of the relaxation spectrum of the polymer is preferentially oriented. During the drawing of PS and PMMA monofilaments crazes are formed in the centre of the fibers and do not reach the surface.
Temperaturabhängigkeit der ammoniak‐diffusion in polymerfilmen
Authors: Müller F. W. , Schiller K. , Jänchen U. , Marx J.
Published: April 2003

Die Temperaturabhängigkeit der Ammoniak‐Diffusion in 14 transparenten filmbildenden Polymeren wurde zwischen 15 und 90°C mit Hilfe einer neuen absorptionsspektroskopischen Methode untersucht. Eine lineare Freie‐Energie‐Beziehung zwischen der Aktivierungsenergie der Diffusion (ED) und dem präexponentiellen Faktor der Arrhenius‐Gleichung (DO) entspricht dem Verhalten permanenter Gase im Glaszustand der Polymeren, die NH3‐Diffusionskoeffizienten sind jedoch im Mittel etwa eine Größenordnung kleiner. Wie ein Vergleich der Aktivierungsenergien für die Diffusion von Ammoniak und Sauerstoff in drei Polymeren zeigt, ist dafür nicht ein größerer effektiver Van‐der‐Waals‐Radius des NH3 verantwortlich, sondern die verminderte Aktivierungsentropie der Ammoniak‐Diffusion.
Elution behaviour of diolmodified epoxides in size exclusion chromatography
Authors: Tänzer Wolfram , Szesztay Márta , László‐Hedvig Zsuzsa , Fedtke Manfred , Tüdős Ferenc
Published: April 2003

The reaction of bisphenol A‐diglycidyl ether (BADGE) with butane‐1,4‐diol (BD) in the presence of Mg(ClO4)2 leads to linear and branched oligomers. The formation ratio of these products depends on the reaction temperature. In experiments at 100°C, an epoxide consumption of up to 70% can be observed using HPLC. In this range all products show good solubility in THF, so that it is possible to follow the increasing molar mass by using SEC. A characteristic relation of the molar mass against the conversion rate is derived and SEC data of a branched product are discussed.
Alternating electrical conductivity of polyphenylenes and their pyrolysis residues after doping
Authors: Simitzis J. , Boro I. , Hinrichsen G.
Published: April 2003

o,m,p‐Polyphenylenes were prepared by oxidation‐cationic polymerization of biphenyl and then pyrolyzed up to 800°C. The o,m,p‐polyphenylenes as well as their pyrolysis residues were doped with anhydrous FeCl3 from their solution in acetonitrile. The real part of the alternating electrical conductivity σ′ of the undoped and doped materials was determined at room temperature.

Decreasing σ′‐values of pyrolyzed residues at 600°C without doping were observed because of the large weight losses during the pyrolysis leading to chain scission reactions within the polymer. At higher pyrolysis temperatures (i.e. 700°C, 800°C) the σ′‐values are increased due to the formation of closed aromatic systems in the polymer. The doped materials have higher σ′‐values in relation to the corresponding specimens without doping, with the exception of the pyrolysis residues at 800°C. The dependence of doping effect and time was also determined. The transition of the organic polymer to the pyropolymers can be followed and characterized by the measurement of alternating electrical conductivity.
Ataktisches polypropylen als pfropfgrundlage für die monomeren vinylacetat und vinylchlorid. Herstellung undeigenschaften der pfropfprodukte
Authors: Schellenberg Jürgen , Hamann Bernd
Published: April 2003

Die Möglichkeiten des Einsatzes von ataktischem Polypropylen als Pfropfgrundlage zur Herstellung von Pfropfcopolymerisaten des Vinylacetates und Vinylchlorids bzw. von Polypropylen‐Vinylacetat‐Pfropfprodukten als Pfropfgrundlage zur Herstellung von Pfropfcopolymerisaten des Vinylchlorids werden in Abhängigkeit von der Ausgangsgemischzusammensetzung untersucht.

Nach Abmischung der Pfropfprodukte mit Polyvinylchlorid bzw. ABS/Polyvinylchlorid‐Mischungen werden ausgewählte mechanische Eigenschaften sowohl in Abhängigkeit von der Menge des enthaltenen Pfropfproduktes als auch von der Zusammensetzung der Pfropfpolymerisate dargestellt.
Synthesis of polyethylenes with high polydispersity
Authors: Luft Gerhard , Dorn Max
Published: April 2003

For a number of applications the use of polyethylenes with a high polydispersity is recommended. In order to prepare such grades polymerisation tests were performed in a stirred autoclave in laboratory scale. The autoclave was run continuously at 1800 bar in the range of 210 to 285°C with 60 s residence time. Difunctional peroxides with identical and with different substituents on both OO groups were tested. For comparison, monofunctional compounds from industrial processes were used. The concentration of the peroxides in the feed was varied between 3 and 60 mol ppm.

By GPC, polydispersities of 5 to 9, comparable to those of commercial polyethylenes, were measured on the samples produced with the monofunctional peroxides. Distinctly higher polydispersities of up to 13 were achieved by the use of the difunctional peroxides, especially with the symmetrical compound.
Strukturuntersuchungen an PF/cellulosepapier‐verbunden mittels dynamisch‐mechanischer analyse
Authors: Döhring Dieter , Raubach Heinz , Singer Klaus , Jäkel Evelyn , Goering Harald
Published: April 2003

Es wird versucht, für Verbunde aus mit Holzöl sowie Tricresylphosphat modifizierten Phenol‐Formaldehyd‐Polykondensaten und Cellulosepapier, die als Leiterplattenbasismaterial technisch in großem Umfang genutzt werden, mittels Torsionsschwingungs‐ und dielektrischer Messungen einen Zusammenhang zwischen dem strukturellen Aufbau und den Verbundeigenschaften herzustellen. Die innere Weichmacherwirkung von Holzöl wird diskutiert. Die Holzölmodifizierung bewirkt neben einer Flexibilisierung, daß durch Beseitigung sterischer Behinderungen ein größerer Umsatz der funktionellen Gruppen bei der Resitbildung erreicht und der Vernetzungsgrad im Vergleich zu einem unmodifizierten PF‐Hartpapier erhöht wird. Die Messungen zeigen, daß Tricresylphosphat als äußerer Weichmacher wirkt, der die zwischenmolekularen Wechselwirkungen herabsetzt.
Highly active peroxides in the radical polymerization of ethylene under high pressure — conversion and initiator usage
Authors: Luft Gerhard , Grimm Hubert , Dorn Max
Published: April 2003

By using highly active peroxides, it is possible to reduce the polymerization temperature necessary for the synthesis of low density polyethylene. In order to examine a number of peroxides for their suitability as low temperature initiators, polymerization tests were carried out at 1900 bar, 70–140°C, with an average residence time of 30 s in a continuously operating laboratory facility equipped with a stirred autoclave. Apart from a number of perneodecanoates, two peroxy dicarbonates, a sulphonyl peroxide, and a difunctional peroxide were used.

The initiator consumption was high at polymerization temperatures below 100°C. The results obtained with the different peroxides varied considerably. As the temperature increased, the initiator consumption decreased rapidly to reach almost the same level for all the individual peroxides at above 120°C. The difunctional compound that proved highly suitable for the low polymerization temperatures desired was 1,4‐di‐(2‐neodecanoyl peroxy isopropyl)benzene, the consumption at 100°C of which amounted to 13 g initiator/kg PE. Using a quantity of 40 g initiator/kg PE, a reactor temperature of 82°C could be employed. The peroxy dicarbonates and tertiary butyl perneodecanoate gave less satisfactory results.
Melt flow and mechanical properties of sulfonated butyl rubber ionomers
Authors: Xie Hong‐Quan , Xu Ji‐Geng
Published: April 2003

Study of melt flow properties and mechanical properties of sulfonated butyl rubber ionomers showed that in the case of lithium ionomers addition of zinc stearate lowered obviously the melt viscosity, represented by torque value of a Brabender rheometer, and enhanced tensile strength of the ionomer up to 25% of zinc stearate, while in the case of ethylamine neutralized ionomer addition of zinc stearate lowered the melt viscosity not so obviously as in the case of lithium ionomer and slightly affected the tensile strength. Amine neutralized ionomers exhibited very low permanent sets, while the lithium ionomer showed much higher permanent set, which increased with sulfonate group and amount of zinc stearate added. Increase of neutralization degree below equivalent ratio of 1 significantly raised the melt viscosity and tensile strength.

For monovalent cation ionomer, melt viscosity and tensile strength diminished with decreasing ionic potentials, but for divalent cation ionomers with increasing ionic potentials and with decreasing covalent character tensile strength decreased and melt viscosity increased.

For different amine neutralized ionomers tensile strength decreased in the following orders: ethylamine > triethylamine > diethylamine; isopropylamine > ethylamine > tertiary butylamine > methylamine; ethylamine > hexylamine > dodecylamine > octadecylamine.
Modelling the kinetics of the precipitation polymerization of acrylic acid
Authors: Avela Arno , Poersch Hans‐Günter , Reichert Karl‐Heinz
Published: April 2003

A kinetic model for the free‐radical precipitation polymerization of acrylic acid in toluene was developed and verified experimentally by using an isothermal reaction calorimeter. The model predicts the rate of polymerization accurately up to complete conversion in the temperature range of 40 to 60°C.
SEC on cellulose nitrate: DP‐Ve relationship and evaluation of different methods to determine the calibration parameters
Authors: Soubelet O. , Presta M. A. , Marx‐Figini M.
Published: April 2003

The calibration behaviour of the system cellulose nitrate‐μ‐Styragel‐THF has been studied using about 30 different calibration samples prepared by defined acid catalyzed degradation of cotton cellulose. The samples covered a range of DP between 150 < DP < 8000. It is shown that the DP‐Ve relationship is characterized by the existence of three subsequent stages. Consequently, two sources of errors in the DP‐Ve calibration must be taken into consideration. One refers to the methods as such to elaborate the calibration parameters, and the other one arises by neglecting that the DP‐Ve relationship involves 3 distinct stages. The extent of the two classes of errors in regard to the exactness of the determined molecular weight averages and molecular weight distributions is discussed.
The influence of sepiolite on the compatibility of semicrystalline polymer blends
Authors: Acosta José Luis , Herrero Consuelo R. , Morales Enrique
Published: April 2003

Melting point depression analysis in polymer blends allows the determination of the polymer/polymer interaction parameter X23 of these systems. This work deals with the influence of a filler, like sepiolite, on the compatibility of two systems such as polyvinylidene fluoride/polymethylmethacrylate and polyvinylidene fluoride/polystyrene through the analysis of this parameter X23. The results obtained demonstrate the compatibilizing effect of sepiolite at high filler loadings.
Water‐Soluble polyamides as potential drug carriers. I. Poly(α,β‐D,L‐asparthydrazide‐CO‐D,L‐ornithine)
Authors: Meirim Maria G. , Neuse Eberhard W. , Parisi Frank
Published: April 2003

The polycondensation of d,l‐aspartic acid with Nδ‐phthaloyl‐l‐ornithine in phosphoric acid at 185°C gives rise to the formation, in 60 — 75% yield, of random copolymers of the poly(d,l‐succinimide‐co‐Nδ‐phthaloyl‐D,L‐ornithine) type 6 possessing inherent viscosities (DMF) in the range of 5 — 15 ml g−1. Copolyimides of the same compositions 6 and comparable chain lengths are obtained from aspartic acid and the copper chelate of the phthaloylornithine. Treatment of copolymers 6 with hydrazine hydrate in DMF leads to N‐deprotection and opening of the intrachain succinimide rings with formation of hydrazide side groups. The resultant polyamides are of the poly(α,β‐d,l‐asparthydrazide‐co‐d,l‐ornithine) type 7. Shorter reaction periods give incomplete hydrazinolytic ring opening, and the remaining succinimide units are cleaved hydrolytically during the subsequent aqueous workup, thereby transforming into aspartic acid units. The polyamides so formed possess the general poly(α,β‐d,l‐asparthydrazide‐co‐α,β‐d,l‐aspartic acid‐co‐d,l‐ornithine) structure 8 Both types 7 and 8 are soluble in water and, in this medium, give inherent viscosities of 5 — 14 ml g−1. The potential drug‐anchoring capabilities of these amine‐functionalized polyamides are demonstrated by coupling reactions with model carboxylic acids.
Antioxidants and stabilizers, 111. Regeneration mechanism of the antioxidant action of N‐isopropyl‐N′‐phenyl‐1,4‐phenylenediamine
Authors: Taimr Ludĕk , Prusíková Milus̆e , Pospís̆il Jan
Published: April 2003

In connection with the investigation of the mechanism of antioxidant action of antidegradants in hydrocarbon polymers under the conditions of a relative deficiency of oxygen, scavenging of a model alkyl (1‐cyano‐1‐methylethyl,R°) was studied with Nisopropyl‐N′‐phenyl‐1,4‐phenylenediamine (Ia)

For abbreviations see p. 11.

and its oxidation product, i.e. Nisopropyl‐N′‐phenyl‐1,4‐benzoquinonediimine (IIa). While pure Ia and IIa do not react with the radical R° almost at all, their mixture is able to scavenge R° effectively. The reaction is further accelerated with acids. The alkyl R° combines with the antidegradant molecule in two ways, one of which leads to the substitution at the nitrogen atom between the aromatic rings, giving rise to VIa, while the other consists in the substitution of phenylene, leading to VIIIa. The product VIa is labile, and at vulcanization temperatures it readily splits off olefin in a neutral medium, being regenerated to Ia. In the presence of acids this reaction proceeds even at lower temperatures. In the other product, i.e. in VIIIa, the alkyl R° is bound firmly, but due to the presence of the nitrile group, VIIIa is readily cyclized by the effect of acids, and an indoline derivative X is formed. The formation of VIIIa is a model of the formation of an “unextractable fraction” of antidegradant Ia in the stabilization of hydrocarbon polymers. Investigations based on the isolation of reaction products bear at the same time evidence of the possibility of regeneration of an effective antioxidant in the stabilized substrate.