bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of some phosphorous compounds on the thermo‐oxidative stability of poly(ethylene terephthalate)
Authors: Karayannidis George , Sideridou Irini , Zamboulis Demetris , Stalidis George , Bikiaris Demetris , Wilmes Aloyse
Published: April 2003

A series of poly(ethylene terephthalate) (PET) samples was prepared from dimethyl terephthalate and ethylene glycol. In each sample a phosphorous compound was added as heat stabilizer after the transesterification and before the polycondensation. These compounds were: phosphoric acid, tributyl phosphate, triphenyl phosphate, phenyl‐phosphonic acid, phenylphosphinic acid, and sodium phenylphosphinate. Firstly, their interference with the transesterification catalyst was examined. Their stabilization effect was estimated by DSC analysis in nitrogen and air. Various thermal criteria have been used, such as stabilization coefficient and induction period of oxidation. Under the conditions used for polymerization, the more efficient stabilizers were tributyl phosphate, phenylphosphonic and phenylphosphinic acid.
Composites from furfuryl alcohol and inorganic solids by cationic initiation, 3. Scanning electron microscopic investigations of solid poly(furfuryl alcohol)‐silica composites
Authors: Spange Stefan , Winkelmann Heinz , Martinez Ricardo
Published: April 2003

Composites of poly(furfuryl alcohol) grafted onto silica, with different percentage of grafting, have been investigated by scanning electron microscopy, elemental analysis and UV/Vis‐reflectance spectroscopy. The size of the silica particles used for the coating procedure is not changed till a percentage of grafting to around 30%. A content of polymer higher than 35 wt.‐% enhances the bonding between the particles due to the crosslinking of poly(furfuryl alcohol) on the surface with those in solution leading to the agglomeration of the particles. A general model of cross‐linked poly(furfuryl alcohol)‐silica composites is suggested.
Electrical conductivity changes of polymers with conjugated double bonds induced by exposure to vapors and gases
Authors: Bischoff Gerlinde , Schmidt Werner F.
Published: April 2003

Exposure of polyacetylene, polypyrrole, poly(phenylacetylene), and poly‐p‐phenylene to oxidizing or reducing gases and vapors leads to changes of their electrical conductivity which can be explained by a three step model involving as a first step adsorption at the surface, as a second step diffusion into the bulk of the material and as a third step irreversible chemical changes due to reaction between the dopant and the polymer chain. These three regimes are sometimes well separated in time. During the adsorption regime, the conductivity change is reversible with respect to removal of the vapor atmosphere by evacuation.
Permeation‐fließanalyse an polymernetzwerken
Authors: Häusler Karl‐Georg , Kretzschmar Timo
Published: April 2003

Es wurde eine Permeationsmeßzelle zur fließanalytischen Detektion des Permeationsstromes durch gequollene Polymernetzwerke entwickelt. Diese Apparatur ermöglicht es, den Permeationskoeffizienten P und den Diffusionskoeffizienten D an gequollenen Polymernetzwerken zu messen.

Die eingesetzten Proben, 1,4‐cis‐Polybutadien (Buna cis 132) und Polysiloxan (Wacker SilGel 600), wurden β‐strahlenchemisch bzw. thermisch vernetzt und mittels Quellungsmessungen, Sol‐Gel‐Analyse sowie Messung des uniaxialen Kompressions‐modules Gccharakterisiert. Die Molmassen der unvernetzten Ausgangsprodukte wurden mit der Gelpermeationschromatographie (GPC) ermittelt.

Die aus dem stationären Permeationsverlauf berechneten Permeationskoeffizienten und Diffusionskoeffizienten korrelieren linear bzw. exponentiell mit der Vernetzungs‐dichte bzw. dem Volumenquellungsgrad der Proben im Quellungsgleichgewicht.
Influence of crosslinking density of poly(butylacrylate) backbone on processibility of poly(vinylchloride) grafted onto poly(butylacrylate)
Authors: Zhang Xiaochun , Wang Luoli , Qian Baogong
Published: April 2003

Graft copolymers of vinyl chloride onto poly(butylacrylate) with alternating amount of diallylphthalate crosslinker (PBA‐g‐VC) have been synthesized by suspension polymerization. Taking into account different crosslinking density of PBA, the processing behaviour of PBA‐g‐VC was studied with a Brabender Plasticorder and a viscoelastometer. The experimental results showed that, with increasing crosslinking density of PBA, the processing behaviour of PBA‐g‐VC improved initially, then reached an optimum and finally declined with further increase in crosslinking density of the backbone. Based on the results of viscoelastometer measurement, the mechanism of change of processibility of graft copolymer is discussed.
Vinyl ester resins, 3. Effect of ethyl methacrylate on thermal and mechanical properties
Authors: Choudhary Manjeet S. , Varma Indra K.
Published: April 2003

This paper describes the effect of ethyl methacrylate (EMA) on the thermal and mechanical properties of glass fibre‐reinforced laminates of vinyl ester resins derived from diglycidyl ether of bisphenol‐A and methacrylic acid. The thermal stability and the curing characteristic of the resins were investigated by thermogravimetric analysis and differential scanning calorimetry. The glass transition temperature of the laminates decreased with increase in EMA content. Dilution of vinyl ester resin with EMA resulted in a decrease in flexural strength and flexural modulus of the laminates.
α,ω‐Bis(2,3‐epoxypropyl)oligooxyethylene‐based crosslinked resins as solid‐liquid phase‐transfer catalysts
Authors: Dimonie Mihai , Teodorescu Mircea
Published: April 2003

α,ω‐Diglycidyl‐oligoethylenoxides were prepared by reacting α,ω‐dihydroxy‐oligoethylenoxides with epichlorohydrin. They were then crosslinked with triethylenetetramine to form catalyst beads which were tested for their liquid‐solid phase‐transfer catalyst activity in the reaction of 1‐bromobutane with potassium phenoxide. Regardless of the oxyethylene chain length, the catalyst beads showed significant activity, which was relatively high for oligomers with a great number of oxyethylene repeating units.
The effects of radiation‐modified silica and monomeric diluents on the properties of dental composite resins
Authors: Hsiue G. H. , Chang H. L.
Published: April 2003

2,2‐Bis[4‐(2‐hydroxy‐3‐methacryloyloxy‐propoxy)phenyl]propane (Bis‐GMA) was used as the main ingredient for a dental composite. The dental composite was prepared by mixing high viscosity Bis‐GMA with a low‐viscosity diluent monomer. Three monomers were used: triethylene glycol dimethacrylate (TEGDMA), trimethylol propane trimethacrylate (TMPTMA), and trimethylol propane triacrylate (TMPTA). The mixed components were allowed to polymerize under visible light. The degree of conversion was higher for the sample with lower viscosity. The silica which was used as filler in the dental composite was modified by using the radiation‐induced polymerization method in which methyl methacrylate (MMA) was grafted onto the silica gel. The higher the content of PMMA in the modified filler, the lower the hardness of the composite. Most properties of the samples are the same as those of a commercial product. The compressive strength is higher due to the strong filler‐matrix interface which is provided by 60Co γ‐ray radiation.
GPC investigation of polyimide‐siloxane copolymers. Calibration procedure
Authors: Szesztay M. , Ghadir M.
Published: April 2003

Gel permeation chromatography calibration of ultra‐styragel columns for additive polyimide‐siloxane copolymers was developed using peak assignments. The results show that polystyrene (PS) calibration can be used with good approximation for the samples of molar masses higher than 1000 g mol−1.
Miscible blends of polycarbonate with polyurethane elastomers
Authors: Fambri Luca , Penati Amabile , Kolarik Jan
Published: April 2003

Polyurethane elastomers based on aliphatic polycarbonate diols and/or polypropylene glycols form miscible blends with polycarbonate, thus potentially improving its resistance to microcrack initiation and growth. Up to 20 wt.‐% of synthesized polyurethane elastomers were dissolved in polycarbonate via solution casting or melt mixing. Some phase separation was detected in films cast from solutions with 10 to 20 wt.‐% of polyurethane elastomers; such blends usually turned into single‐phase systems by subsequent thermal annealing. Among the tested polyurethane elastomers, the products based on toulene diisocyanate and mixtures of polycarbonate diols with polypropylene glycols were found to be effective modifiers for polycarbonate; therefore, they were also used in the blends prepared by melt mixing and processed by injection moulding.
Modifizierung der oberfläche von polyamid‐6‐monofilamenten
Authors: Groten Robert , Höcker Hartwig
Published: April 2003

Polyamid‐6‐Monofilamente wurden in festem Zustand mit Toluylen‐2,4‐diisocyanat (TDI) in Toluol in Gegenwart von Bis(2‐ethyl‐hexanoyloxy)‐zinn (SnOct2) behandelt und dadurch in der Oberfläche vernetzt. Gegenüber unmodifizierten Polyamid‐Monofilamenten konnten Verbesserungen der Temperaturbeständigkeit, der Höchstzugkraft, der Dehnbarkeit, der Lösungsmittel‐ und der UV‐Stabilität erreicht werden. Die Unlöslichkeit der diisocyanatmodifizierten Filament‐“Hullen” in Ameisensäure wies auf eine Vernetzung in den äußeren Bereichen der verstreckten PA‐6‐Filamente hin. Zur Charakterisierung der Vernetzungspunkte wurde aus ϵ‐Caprolactam (ϵ‐CL) und TDI die Modellsubstanz Toluylen‐2,4‐bis‐carbamoyl‐bis‐ϵ‐caprolactam (TCC) synthetisiert.
Covalent binding of an azo dye to films of vinyl chloride copolymers containing functional groups
Authors: Hensema Edwin René , Berger Joseph
Published: April 2003

Coupling of a dye to a polymer matrix allows the preparation of intrinsically coloured products and prevents the migration of the dye out of the polymer matrix. The binding reaction of a functionalized dye to, and the simultaneous crosslinking of poly(vinylchloride) (PVC) containing hydroxy groups (PVCOH) using a triisocyanate was investigated.

The binding efficiency of the azo dye 2′‐chloro‐4‐(N‐ethyl‐N‐hydroxyethylamino)‐2‐methyl‐4′‐nitroazobenzene (CHMP) to two poly(vinylchloride‐co‐vinylacetate‐co‐vinylalcohol) samples containing different concentrations of hydroxy groups using 1,1,1 ‐tris[N‐(3‐isocyanato‐4‐methylphenyl) carbamoyl‐oxymethyl]propane (TIC) was studied under various reaction conditions. The binding efficiency of the dye to the polymer matrix was investigated using Soxhlet extraction whereas the reaction between isocyanate and hydroxy groups was studied using IR. It was shown that an increasing amount of TIC results in a more efficient binding of the dye to the polymer matrix and in a higher crosslinking density of the polymer matrix. A good correlation was also found between the swelling degree of crosslinked PVCOH films and the crosslinking density due to TIC reacting with PVCOH.
Synthesis and polymerization of chiral monomers containing dimethylaminobornane moieties
Authors: Liu Jui‐Hsiang , Lin Ming‐Ter
Published: April 2003

Chiral monomers (cis, endo‐3‐dimethylamino‐2‐bornyl methacrylate (DABM) and N, N‐dimethyl[cis,endo‐2‐(2‐vinyloxyethoxy)‐3‐bornyl]amine (DVEBA)) were synthesized from (+)‐camphor. The free radical homopolymerization of both DABM and DVEBA, and the copolymerization of both chiral monomers with achiral methyl methacrylate and styrene, resp., were carried out in various organic solvents. Effects of temperature, solvents, and reaction time on the polymerizations were studied. Dependences of the specific rotation of the chiral copolymers on the feed concentration and reaction conditions were investigated. Application of the chiral polymers on the asymmetric induction were also investigated.
Lichtinduzierte polymerisation, 2. Polymerisation von methylmethacrylat mit 9,9‐disubstituierten acridanen
Authors: Braun Dietrich , Hettig‐Rupaner Claudia
Published: April 2003

Am Beispiel von 9‐Benzyl‐9‐phenylacridan und von 9‐Benzyl‐10‐methyl‐9‐phenylacridan wird gezeigt, daß 9,9‐disubstituierte Acridane bei der Bestrahlung mit UV‐Licht auch ohne Gegenwart von Wasserstoffdonatoren unter Radikalbildung zerfallen und die Polymerisation von Methylmethacrylat ausldösen können.
Composites of surface‐treated wood fiber and recycled polypropylene
Authors: Sain M. M. , Imbert C. , Kokta B. V.
Published: April 2003

The effect of surface treatment of saw dust on the physico‐mechanical properties of saw dust‐filled polypropylene composites was studied. Whereas the elastomer‐pretreated saw dust decreases the strength of composites, in‐situ addition of interface modifiers, such as maleated polypropylene, m‐phenylene bismaleimide

Systematic name: N‐(3‐maleimidophenyl)maleimide.

‐modified polypropylene, during kneading of polypropylene with untreated or elastomer‐pretreated saw dust improved the mechanical properties with a marginal sacrifice of impact strength. The chemical nature of interphase modifiers played an important role on the mechanical properties of the composites, e.g., maleated polypropylene was most effective among the modifiers used in this study. Halogenated elastomers and phenolic modified polypropylene improved the flame resistant properties of the composites. More over, properties varied with the particle size of wood fiber. The morphological study of the fracture surfaces of composites revealed that interfacial adhesion is improved by adding maleated polypropylene.
Photomodifizierung von Ultrafiltrationsmembranen, 2. Ultrafiltrationseigenschaften von mit Arylaziden photochemisch modifizierten Polyacrylnitril‐membranen
Authors: Ulbricht Mathias , Hicke Hans‐Georg
Published: April 2003

Nach einem neuartigen Verfahren mit Hilfe von neun, mit verschieden hydrophilen bzw. hydrophoben Substituenten synthetisierten aromatischen Aziden unterschiedlich photochemisch modifizierten Polyacrylnitril‐Ultrafiltrations‐Membranen wurden in UF‐Versuchen charakterisiert. Dabei sollte der Einfluß der so erzielten Oberflächenfunktionalisierungen (Hydrophilierung, Einführung von Ladungen oder Hydrophobierung) auf das Trennverhalten (Wasserdurchläassigkeit und Selektivitäat für Dextrane, Permeabilität während und nach der UF bzw. nach einfachem Kontakt mit Ovalbuminund mit Lysozym‐Lösungen) studiert werden. Die Modifizierung mit den Arylaziden, die hydrophile Gruppen enthalten (4‐Azidobenzoäure, Ib, (4‐Azidophenyl)‐tri‐methylammoniumiodid, If, Natrium‐4‐azidobenzolsuflfonat, Id), führt zu einer erhöhten Durchlässigkeit der Membranen für Wasser und Dextrane. Alle anderen Azide, darunter besonders stark die deutlich hydrophoben 2‐Naphthoylazid, Ih, und 2‐Naphthoylazid, IX, verringern die Wasserpermeabilität, erhöhen das Rückhaltevermögen für Dextrane und verstärken die Effekte der Wechselwirkungen mit Ovalbumin (pH = 5,0). Das wird in Flußreduzierungen verglichen mit der unmodifizierten PAN‐UF‐Membran sichtbar. Ein positiver Effekt der Photomodifizierung wird besonders deutlich bei der UF von Lyasozym (0,05%, pH = 10,5) mit der mit Id modifizierten Membran (Jv = 48,1 l/m2h) im Vergleich zur Ausgangs‐Membran (Jv = 13,1 1/m2h). Die Perspektiven und die Grenzen des Modifizierungsverfahrens werden abschließend diskutiert.
Radiation‐induced grafting of styrene onto FEP. films: Structure and thermal behaviour of copolymers
Authors: Gupta B. , Scherer G. G.
Published: April 2003

Thermal characteristics of radiation‐grafted FEP‐g‐polystyrene copolymer films were evaluated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The grafting of polystyrene onto FEP film introduced a two‐step degradation pattern where polystyrene degradation occurred in the range of 400–460°C beyond which the loss in the FEP component was observed. DSC studies showed that the heat of fusion was reduced in the grafted FEP samples. This was attributed to the dilution of inherent crystalline zones by the incorporation of amorphous polystyrene grafts into the amorphous region of the FEP matrix. The melting temperature, on the other hand, remained constant for the entire range of graft levels (0–40%). All the copolymer films exhibited two glass transition temperatures (Tg) each corresponding to the FEP and polystyrene moieties. However, the Tg in grafted films were found to be higher as compared to that in ungrafted FEP and homopolystyrene films. These results have been explained in terms of the decrease in the segmental mobility of macromolecular chains in the grafted films.
Membranen aus poly(p‐phenylen‐1,3,4‐oxadiazol)
Authors: Leibnitz E. , Eisold C. , Paul D.
Published: April 2003

Poly(p‐phenylen‐1,3,4‐oxadiazol) (POD) ist aufgrund seiner thermischen Stabilität, pH‐ und Lösungsmittelbeständigkeit ein interessanter Werkstoff zur Herstellung von Membranen. Die Herstellung von POD‐Membranen und deren Trenneigenschaften im Prozeß der Ultrafiltration werden untersucht.
Agitation scale‐up model for the suspension polymerization of vinyl chloride
Authors: Özkaya Nesrin , Erbay Erol , Bilgiç Tülin , Savaşçi Ö. Tunç
Published: April 2003

Studies were carried out to develop a mathematical model based on experimental results to correlate agitation and other polymerization parameters with the particle size of PVC and to specify the limits of agitation speed within the defined agitation system. Computer regression analysis of about 30 vinyl chloride polymerizations in reactors with 10 L to 27 m3 tank volume are carried out. The particle size of PVC (d50) is correlated to various polymerization parameters such as impeller diameter (D), impeller speed (N), reactor tank diameter (T), liquid height (H1) and tank volume (V) (NWe = Weber number):

d50 = 4346.8 (N)−0.905 (D)−0.901 (T)−0.514 (H1)−0.131

d50/D = 273292.1 NWe−0.51

Nmin = 3049.1 D−1.1 (T/D)−0.113

In these equations only the values 3049.1, −0.113, 4346.8 and 273 292.1 depend on the recipe. When the recipe is changed these variables must be determined by one or two bench‐scale polymerizations to adjust the correlations to the new recipe conditions so that they can be also used for scale‐up purposes with the new recipe.
Modelluntersuchungen zur topologie der härtung geordneter epoxidnetzwerke
Authors: Kirchmeyer Stephan , Müller Hanns‐Peter , Dhein Rolf , Meier Helmut‐Martin
Published: April 2003

Die Härtung von 4‐Phenyl‐4‐(2,3‐epoxypropoxy)benzoat (I) mit den isomeren Aminophenylaminobenzoaten II bis V führt zu unterschiedlich geordneten Epoxidnetzwerken. Die Bildung verschiedener Intemediate während der Härtungsreaktion wurde anhand von Modellverbindungen studiert. Aus der Reaktion der monoamino‐substituierten Phenylbenzoate VI bis IX mit Epoxid wurden die Reaktionskostanten für die Addition an das primäre und das sekundäre Wasserstoffatom der Aminogruppen bestimmt. Die kinetischen Daten lassen sich für eine schrittweise Simulation des Härtungsverlaufs verwenden. Es wurden Argumente dafür gefunden, daß sich bei Verwendung der Amine mit 4‐Aminobenzoat‐Strukturen gut geordnete, schnell vernetzende Intermediate bilden.
Branched poly(ethylene imine) support for resins with retention properties for heavy metal ions
Authors: Rivas Bernabé L. , Maturana Hernán A. , Perić Iván M.
Published: April 2003

A crosslinked poly(ethylene imine), using epichlorohydrin as crosslinker, was prepared and subsequently modified in order to obtain the corresponding N‐methylated, N‐carboxymethylated and N‐phosphonomethylated derivatives. The sorption characteristics of these functionalized resins were studied by a batch equilibration technique, for uptake of Cu(II), Fe(II), Fe(III) and uranyl ions from aqueous solution. Resins with tertiary amine or ammonium groups show negligible sorption for Fe(II), Fe(III) and Cu(II) at pH 1, in contrast with high sorption for U(VI), which is readily eluted with sodium carbonate.
Immobilisierbare stabilisatoren für EPDM‐kautschuk
Authors: Braun Dietrich , Rettig Rainer , Rogler Wolfgang
Published: April 2003

Als immobilisierbare Antioxidantien für Ethylen‐Propylen‐Dien‐Terpolymere (EPDM) wuren 4‐(Mercaptoacetamido)‐diphenylamin

Systematischer Name: 2‐Mercapto‐N‐[4‐phenylamino phenyl]‐acetamid.

(MADA) und Dithiodiglycolsäure‐bis‐[N‐(4‐anilinophenyl‐amid]

Systematischer Name: 2,2′‐Dithiobis[N‐(4‐phenylamino)phenyl]‐acetamid.

(DAPA) hergestellt und charakterisert. Zur Simulation der Reaktionen bei der Umsetzung dieser Antioxidantien mit EPDM‐Kautschuken wurden Modellreaktionen mit trans‐4‐Decen, 2‐Ethylidennorbornan und 2,3‐Dihydrodicyclopentadien

Systematischer Name: Tricyclo[5.2.1.02,6]‐3‐decen.

durchgeführt. Die Reaktionsprodukte wurden chromatorgraphisch aufgetrennt und durch IR‐Spektroskopie charakterisiert. Dabei wurde auch der Einfluß von Azoinitiatoren auf die Additionsreaktion untersucht.

Die Umsetzung von EPDM mit den genannten Stabilisatoren wurde im BrabenderPlastographen bei 140 bis 180°C Massetemperatur untesucht. Der Gehalt an immobilisiertem Stabilisator wurde mit Hilfe der Thermoanalyse und UV‐spektroskopisch bestimmt. Die höchsten Gehalte an immobilisiertem Stabilisator (73%) wurden mit MADA bei 180°C Massetemperatur erzielt. DAPA ist ebenfalls bis maximal 69%immobilisierbar. Die praktische Baruchbarkeit der Immobilisierung von Mercaptostabilisatoren an EPDM‐Kautschuk wurde am Beispiel von strahlenvernetzten Kabelisoliermassen bestätigt.
Kinetic investigation of the polymerization of an epoxy resin by DSC and temperature profile determination during cure
Authors: Sbirrazzuoli Nicolas , Girault Yvonne , Elegant Lucien
Published: April 2003

Kinetic parameters of the polymerization of an epoxy resin, characterized by a high enthalpy and a low heat conductivity, are determined by DSC analysis. The mean value obtained from the peak maximum evolution methods (Kissinger, Ozawa and Lam) for the activation energy Ea was 62.71 kJ · mol−1; the Achar‐Brindley‐Sharp method, using the homogeneous law and the sample temperature, led to 68 kJ · mol−1. A comparison between theoretical computations (obtained from a modeling of the temperature profile in the DSC crucible during cure) and measurements is given. The increase of the apparent kinetic parameters with the heating rate V (expressed with a parameter e = ΔEa/ΔV) essentially results from the overestimation of the temperature, induced by the exothermicity of the phenomenon. A decrease of e from 1.725 to 0.613 is observed, with the measured temperature instead of the set calorimeter temperature.
Determination of avrami‐exponents of isotactic polypropylene by means of X‐ray methods
Authors: Wenig W. , Lemke B.
Published: April 2003

Avrami‐exponents of polypropylene have been measured using two methods: observing the spherulitic growth in the polarization microscope, and measuring the crystallinity as a function of crystallization time using X‐ray wide angle scattering. Both methods yield the same values, showing that the determination of the Avrami‐exponent with optical microscopy is of sufficient accuracy despite the limitations of this method imposed by the restricted crystallization volume between the glass slides. Using the X‐ray method, the Avrami‐exponent of the secondary crystallization volume between the glass slides. Using the X‐ray method, the Avrami‐exponent of the secondary crystallization occurring at longer crystallization times can be measured. It is shown that this type of crystallization takes place within the already existing spherulites, whose size distribution is not changed.
Poly(phthalidylidene arylene)s: Synthesis of poly(3,3‐phthalidylidene‐4,4′‐biphenylylene) by precipitative homopolycondensation of 3‐(4‐biphenylyl)‐3‐chlorophthalide
Authors: Zolotukhin Mikhail G. , Kozlov Valerii G. , Sorokina Yulia L. , Sedova Elvira A. , Nefedjev Konstantin V. , Gileva N. G.
Published: April 2003

The synthesis of poly(3,3‐phthalidylidene‐4,4′ ‐biphenylylene) (PPB) by precipitative Friedel‐Crafts homopolycondensation of 3‐(4‐biphenylyl)‐3‐chlorophthalide was studied. The polymer‐catalyst complex precipitated from the initially homogeneous reaction mixture was shown to be active and providing the growth of macromolecular chains. The polymer obtained in the form of smooth, transparent glass‐like particles, depending on the reaction parameters, may have either uni‐ or bimodal molecular weight distribution. Molecular characteristics were not found to depend on the size of the polymer particles. “Precipitative” PPB shows improved properties and higher crystallinity in comparison with “solution” PPB.
The electrical conductivity of cellulose HYPHAN® and its complexes
Authors: Hanna A. A. , Kenawy I. M. M. , Mohamed A. K. , El‐Said Kh. S.
Published: April 2003

The electrical conductivity, σ, of cellulose HYPHAN® and its complexes with Cr3+, Mn2+, Mo5+ or Hg2+ was measured from room temperature to 510°C. The activation energy, ΔE, of the samples was calculated from log σ against 1/T curves. The results show that the electrical conductivity increases by temperature with two maximum peaks. The first peak is attributed to the moisture content, while the second one is attributed to the thermal degradation of the cellulose chain. The values of the activation energy indicate that the samples change from low semiconductor to high semiconductor property with heating.
Characterization of thermoplastic poly(ethyleneterephthalate)‐glass fibre composites, 1. Crystallization study
Authors: Gauthier Catherine , Chauchard Jacques , Chabert Bernard , Saktoun Mostafa , Boudet Alain
Published: April 2003

This paper presents the influence of glass fibres on crystallization kinetics and on matrix morphology for poly(ethylene terephthalate) (PET)/glass fibre composites. The following parameters are also considered: fusion‐crystallization conditions, thermal stability and the addition of nucleating agents in the matrix (talc or sodium benzoate). It clearly appears that the influence of those additives on the crystallization of PET is predominant compared to the effect of stiffening fibres. Moreover, the application of shear stresses at the PET/glass fibre interface promotes the growth of a different crystalline superstructure.
The oxidative degradation of stabilized LLDPE under accelerated and natural conditions
Authors: Tidjani Adams , Fanton Elisabeth , Arnaud René
Published: April 2003

Photodegradation and loss of UV stabilizer resulting from natural and accelerated exposure in stabilized linear low density polyethylene (LLDPE) are investigated by spectroscopic techniques. It is found that the processes governing the loss of UV stabilizer are quite different under the two modes of UV exposure. This result clearly demonstrates that predictions concerning polymer lifetime based on the disappearance of additives must be avoided. For a large number of stabilized samples, acceleration factors according to different criteria have been estimated. Examination of the natural photodegradation process of stabilized LLDPE through mechanical property changes establishes that stabilized LLDPE undergoes catastrophic breakdown of the elongation at break the instant the carbonyl IR band begins to develop.
Study on compatibilization‐crosslinking synergism in PVC/LDPE blends
Authors: Xu Chengwei , Fang Zhengping , Zhong Jianhua
Published: April 2003

Influences of nitrile rubber (NBR, acrylonitrile content 33.5 – 36.5 wt.‐%) on the structure and mechanical properties of poly(vinyl chloride) (PVC)/low density polyethylene (LDPE) blends and its synergism with crosslinking agent have been studied. The addition of NBR to the blend is accompanied by a decrease in domain size and improvements in mechanical properties of the blend. When dicumyl peroxide (DCP) is added to the blend together with NBR, good synergism is caused and mechanical properties will improve dramatically. It is concluded that NBR can promote the phase dispersion of PVC and LDPE and their interfacial adhesion. Then, the probability of DCP existing at the interface will increase and more co‐crosslinked products will form. Therefore, compatibilization and crosslinking are both exerted sufficiently.
Effect of α‐methyl styrene on curing behaviour and interfacial properties of glass fibre‐reinforced vinyl ester resins
Authors: Padma G. , Varma I. K. , Sinha T. J. M. , Patel G. H.
Published: April 2003

The curing behaviour of bismethacryloyl derivative of diglycidyl ether of bisphenol A (vinyl ester VE resin) containing styrene and α‐methyl styrene (MS) as reactive diluents was studied. Delayed curing was observed in samples containing increasing proportions of MS. Interfacial shear stress of untreated as well as γ‐methacryloyloxy‐propyl trimethoxy silane (MTS) treated, glass fibre‐reinforced VE resin composites were measured by single fibre technique. In comparison to untreated glass fibres, a 30 – 50% increase in interfacial shear stress was observed in composites based on MTS treated glass fibres. Addition of up to 5 wt.‐% MS to VE resin did not affect the interfacial shear strength (ILSS). This behaviour was observed by using ILSS measurement of both glass fabric‐reinforced composites as well as single fibre specimens. Further increase in MS to 15 wt.‐% resulted in an increase in ILSS and bending stiffness as well as flexural strength.
Substantial modifications of ethylene/vinyl acetate copolymers: Saponification and graft copolymerization
Authors: Liaw Der‐Jang , Su Bing‐Yaun
Published: April 2003

Modifications of ethylene/vinyl acetate copolymers (EVA) by saponification and graft polymerization with various acids were studied. The greater the degree of saponification, the higher is the melting temperature, the crystallinity and the melt viscosity of poly(ethylene‐co‐vinyl alcohol‐co‐vinylacetate). Tensile tests display that the flexibility of EVA decreases gradually as the degree of saponification increases. This effect may be caused by the interaction of hydrogen bridges after saponification. Graft copolymers of EVA with various acids were studied. The greater the portion of vinyl acetate of EVA, the greater is the graft ratio with various acids decreases in the order acrylic acid > fumaric acid > itaconic acid > maleic anhydride; this order may reflect a steric effect.

Relationships between peel strength and the degree of saponification of EVA show that the adhesive strength increases initially and reaches a maximum value at a degree of saponification in the range of 20 ∼ 30%. The adhesive strength of EVA grafted with acid increases remarkably at low acid contents (less than 0.5 wt.‐%) and then remains constant even at greater acid content in the graft copolymer.
Oberflächenstrukturierung polymerer Fasern durch UV‐Laserbestrahlung. 14. Neue Modellvorstellungen und Simulation durch zelluläre Automaten
Authors: Kesting Wolfgang , Bahners Thomas , Knittel Dierk , Schollmeyer Eckhard
Published: April 2003

Bei der Bestrahlung von Polymeren mit gepulstem UV‐Excimer‐Laserlicht werden unter geeigneten Bedingungen regelmäßig orientierte Berg‐ und Talstrukturierungen auf der Polymeroberfläche ausgeprägt. Im Rahmen dieser Arbeit werden in geeigneten Modellvorstellungen mögliche Mechanismen einer UV‐laserinduzierten Strukturbildung vorgestellt und beschrieben. Es wird davon ausgegangen, daß der Lichtenergieeintrag in die Polymeroberfläche in hohen Aufheizraten zur Erwärmung und Aufschmelzung führt. Unter dem Einfluß eingefrorener Eigenspannungen setzen in einer dünnen, aufgeschmolzenen Schicht der Polymeroberfläche lokal begrenzte Schrumpfbzw. Fließvorgänge ein, indem sich einzelne Teilsysteme (Schmelzvolumenelemente, Makromoleküle) in einem geordneten Verhalten umlagern. Dieses irreversible Phänomen einer Selbstorganisation verläuft hierbei unter ständigem Verbrauch von Energie, welche durch den Lichtenergieeintrag und durch die im Material gespeicherte elastische Energie zur Verfügung gestellt wird. Mit einem Computermodell eines zellulären Automaten werden die wesentlichen Merkmale dieser thermomechanisch induzierten Strukturbildung veranschaulicht.
Magnetic bead cellulose
Authors: Lenfeld Jiří
Published: April 2003

Mangetic bead cellulose was prepared from viscose and ferrite powder by employing the suspension procedure using the thermal sol‐gel transition. The particles thus obtained can be stirred if acted upon by an external rotary magnetic field of a common permanent magnet. Isolation of the particles from reaction suspensions should proceed in a thin layer using a strong magnetic field. Magnetic bead cellulose prepared from supermagnetic powder of the SmCoFe alloy shows a better behaviour in the magnetic field than ferrite materials.
High pressure polymerization of ethylene with a homogeneous metallocene catalyst
Authors: Luft Gerhard , Batarseh Brigitte , Cropp Richard
Published: April 2003

Soluble metallocene catalysts can be easily metered into high pressure polymerization reactors. The performance of a homogeneous zirconocene catalyst for the polymerization of ethylene under high pressures was tested at 1500 bar and temperatures between 80 and 260°C in the presence of methyl aluminoxane as cocatalyst. Besides the productivity of the catalyst and the overall rate of polymerization, the most important properties of the prepared polymers were determined. The results were compared with those found earlier with a heterogeneous titanium catalyst supported on magnesium dichloride.
Ionic strength dependence of the stability of polyelectrolyte complexes. Its importance for the isolation of multiply charged polymers
Authors: Trinh Cam Khon , Schnabel Wolfram
Published: April 2003

Complexes of polyanions and polycations that precipitate at low ionic strength, [I], from aqueous solutions become soluble when [I] is increased. The critical ionic strength for resolubilization [I]crit has been determined for various combinations of polyanions and polycations. [I]crit depends on the chemical nature of the polyelectrolytes. Provided the difference in [I]crit is sufficiently large, different polyelectrolytes of the same charge state can be separated via selective precipitation with the aid of an appropriate polyelectrolyte of opposite charge state. The method has been exemplified by separating albumin from polyphosphate via precipitation as polyelectrolyte complex with poly(N‐ethyl‐4‐vinylpyridinium bromide). The process was performed at pH 8, where albumin acts as polyanion.
Lichtinduzierte polymerisation, 3. Polymerisation von methylmethacrylat mit 2,3‐dimethyl‐4,6‐diphenylchinolin/bis(2‐ethoxyethyl)ether
Authors: Braun Dietrich , Hettig‐Rupaner Claudia
Published: April 2003

2,3‐Dimethyl‐4,6‐diphenylchinolin ist ein initiierendes Chinolinderivat, dessen Lichtabsorption weiter oberhalb 300 nm liegt als die von 2,3‐Dimethyl‐4‐phenylchinolin. Daher werden mit diesem Initiator bei der lichtinduzierten Polymerisation von Methylmethycrylat in Gegenwart des Wasserstoffdonators Bis(2‐ethoxyethy1)ether (Diethylenglycoldiethylether, DEGDEE) bei sonst gleicher Polymerisationskinetik höhere Bruttopolymerisationsgeschwindigkeiten erreicht.
Analysis of epoxy resins by matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Pasch Harald , Unvericht Reinhard , Resch Martin
Published: April 2003

Bisphenol A‐based epoxy resins were analysed by matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS). The samples were separated into their oligomers according to the degree of polymerization and the type of functional groups. Nine different functional species were found to be present in bisphenol A‐epichlorohydrin resins. In the case of resol epoxy resins, in addition to the oligomer distribution, the distribution of the methylol groups was determined. The quantitative treatment of the spectra and the determination of the average functionality and the molar mass of the samples is discussed.
Copolyimides: Thermal and mechanical properties
Authors: Gupta Ashok K. , Choudhary Manjeet S. , Varma Indra K.
Published: April 2003

Polyamic acids with different proportions of benzidine (Bz) and 4,4′‐diamino‐diphenylmethane (DADPM) were prepared by polycondensating different molar ratios of Bz and DADPM with pyromellitic dianhydride (PMDA) in dimethyl formamide. Chemical cyclodehydration of copolyamic acids by acetic anhydride/pyridine resulted in corresponding copolyimides. Polymers were characterized by determination of intrinsic viscosity and nitrogen content. Thermal stability was investigated by thermogravimetric analysis. Some of the copolyamic acids were wet spun into fibres and subsequently converted to polyimides. Copolyimide fibres containing benzidine moiety had better mechanical properties than those containing DADPM.
Studies on miscibility of blends of thermoplastic polyurethane and poly(ethylene‐co‐methyl acrylate)
Authors: Santra Robin N. , Chaki Tapan K. , Roy Sanjay , Nando Golok B.
Published: April 2003

Blends of polyether‐based thermoplastic polyurethane (TPU) and poly(ethylene‐co‐methyl acrylate) (EMA, 21 wt.‐% MA) were prepared by melt mixing and subsequent compression moulding. Infrared spectroscopy studies and dynamic mechanical analysis reveal that the polymers are miscible in the entire composition range.
Synthesis and characterization of functionalized phenyl acrylate polymer supports
Authors: Narasimhaswamy T. , Murthy N. T. , Sumathi S. C. , Reddy B. S. R.
Published: April 2003

Various substituted phenyl acrylates (4‐nitro (NPA), 4‐benzoyl (BPA), 2‐carbomethoxy (CPA), 2‐formyl (FPA) and 2,4,6‐trichloro (TCPA) phenyl acrylate) were copolymerized with 4 mol‐% DVB in aqueous suspension at 80°C. The resulting copolymers were characterized by means of FT‐IR and high resolution solid state 13C NMR spectroscopy. The particle size distribution and average particle size of the typical systems were determined. Scanning electron microscopy provided information about size, shape and morphological features of the resins. The thermal stabilities of the resins were determined by thermogravimetric analysis.
Graft polymerization of acrylamide onto maize starch using potassium persulfate as initiator
Authors: Khalil M. I. , Mostafa Kh. M. , Hebeish A.
Published: April 2003

Graft polymerization of acrylamide (Aam) onto maize starch using potassium persulfate as initiator was investigated under different conditions including concentration of initiator and monomer, polymerization time and temperature and liquor ratio. Based on the results obtained, appropriate conditions for grafting acrylamide onto starch were established. These conditions were also used for grafting other monomers onto maize starch. Results obtained indicate that acrylamide acquires the highest graft ability while acrylic acid acquires the least, while acrylonitrile and methacrylic acid in between. The water solubility of both nitrogen‐ and carboxy‐containing copolymers increases by increasing the monomer content up to a certain value, then it decreases.
The copolymerization of styrene with the cyclic carbonate of glycidyl methacrylate
Authors: Wendler K. , Fedtke M. , Pabst S.
Published: April 2003

The free‐radical copolymerization of styrene with (2‐oxo‐1,3‐dioxolan‐4‐yl)methyl methacrylate (cyclic carbonate of glycidyl methacrylat; GMACC) was carried out in N,N‐dimethylformamide and toluene solution under batch conditions. In toluene, a precipitate was formed during polymerization. The composition of the copolymers was determined by 1H‐NMR, IR spectroscopy and elemental analysis. The monomer reactivity ratios were calculated by different methods from the copolymer composition data. The values obtained for the different techniques were compared and showed a good agreement.
Sulfobetaine polyurethane ionomers. 3. Dielectric and mechanical properties of polyester polyurethane ionomer films and related compounds with Pb2+ and Co2+
Authors: Diaconu I. , Coman P. , Buruianǎ T. , Buruianǎ E. C.
Published: April 2003

Tensile and dielectric relaxation properties of sulfobetaine polyurethane ionomers based on polyesters were studied comparatively to the non‐ionic polyurethane and derived compounds with Pb2+ and Co2+, using stress‐strain and thermally stimulated depolarization currents (TSDC) methods. Introduction of ionic centers into polyurethane chain improves the tensile properties and modifies the TSDC spectra. These effects are assigned to an enhancement of the microphase segregation. Complexation with Pb2+ and Co2+ diminishes the tensile properties, suggesting that an increase of phase mixing occurs determined by a partial neutralization of ionic centers. Treatment with H2S slightly increases tensile properties and changes TSDC spectra owing to the presence of the semiconducting microphases formed by clustering of the metal sulfides PbS and CoS, respectively.
Preparation of block copolymers with macro‐azonitriles as the initiator
Authors: Yürük H. , Ulupìnar S.
Published: April 2003

Block copolymers containing poly(ethylene oxide) or poly(propylene oxide) prepolymer segments and methyl methacrylate were prepared. A stepwise procedure was first employed to prepare macro‐azocarbamates by capping hydroxy‐terminated poly(ethylene oxide) or poly(propylene oxide) with 3‐isocyanatomethyl‐3,5,5‐trimethylcyclohexyl isocyanate and subsequently reacting this intermediate with 4,4′‐azobis(4‐cyano‐n‐pentanol)

Systematic name: 2, 2′‐azobis(5‐hydroxy‐2‐methylpentanenitrile).

. The resulting polymeric azocarbamates were used as free‐radical initiators for the polymerization of methyl methacrylate. Various modes of preparation and the properties of the copolymers are described. Formation of block copolymers is illustrated by several analyses and measurements of elastic modulus versus temperature.
Photo‐oxidative degradation of PPO/PET blends
Authors: Chandra R. , Mishra S. , Kumar P. , Rajabi L.
Published: April 2003

Photo‐oxidative degradation of blends of poly(ethylene terephthalate) (PET) and poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) was studied considering the mutual influence of both components. The photo‐oxidation of these systems was investigated in the temperature range 30–100°C to study the effects of segmental motion of polymer chains. For short time of UV‐illumination at 365 nm the process is diffusion controlled and can be explained with the help of Waite's theory. The segmental interactions of polymer segments in the blends also affect the diffusion coefficients and the activation energy values. Higher values of the activation energy of PET in the blends cause a decrease of chain breaking.
Poly(benzoxazinone‐imide)s and poly(benzoxazinone‐phenylquinoxaline‐imide‐amide)s containing hexafluoroisopropylidene units
Authors: Hamciuc C. , Bruma M. , Mercer F. , Belomoina N. M. , Popescu F.
Published: April 2003

Fluorine‐containing poly(benzoxazinone‐imide)s and poly(benzoxazinone‐phenyl‐quinoxaline‐imide‐amide)s have been synthesized by solution polycondensation of di‐acid dichlorides containing imide and hexafluoroisopropylidene groups with 4,4′‐di‐aminodiphenylmethane‐3,3′‐dicarboxylic acid or with mixtures of the latter with a di‐amino phenylquinoxaline. These polymers show high thermal stability, the decomposition temperatures being in the range of 450–470°C.

Transparent flexible films were cast from the solutions of the corresponding polyamidic acid intermediates that after thermal cyclization showed low dielectric constant which recommends them for future applications in microelectronics.
Ceric‐induced grafting of ethyl‐acrylate onto sodium alginate
Authors: Shah Samir B. , Patel Chandrakant P. , Trivedi Harikrishna C.
Published: April 2003

Sodium alginate was graft‐copolymerized with ethyl acrylate using ceric ammonium nitrate as an initiator. In order to optimize the conditions for grafting, the concentrations of nitric acid, initiator and monomer together with temperature, time and amount of substrate were varied. The kinetic scheme of free radical graft copolymerization has been proposed and the equations relating the values of rate of polymerization, rate of graft copolymerization and rate of homopolymerization are also suggested. The experimental results agree very well with the proposed kinetic scheme.
Water‐soluble polyamides as potential drug carriers, VII. Synthesis of polymers containing intrachain‐ or extrachain‐type amine ligands by interfacial polymerization
Authors: Chiba Urvashi , Neuse Eberhard W. , Swarts Jannie C. , Lamprecht Gert J.
Published: April 2003

Aliphatic polyamides comprising poly(ethylene oxide) chain segments of various lengths, designed for use as drug carriers, are synthesized by interfacial polymerization of succinyl chloride with the two Jeffamine types ED‐900 and ED‐2001, formally described by the supplier as O,O'‐bis(2‐aminopropyl)poly(ethylene glycol) 800 and O,O'‐bis(2‐aminopropyl)poly(ethylene glycol) 1900. Copolyamides comprising both short‐chain diamine and Jeffamine segments are similarly prepared, as are polyamides made up of cystine and diamine segments. The polymerizations are performed in a two‐phase methylene chloride‐water system at temperatures near or below 0°C. The product polymers, crudely fractionated by staged aqueous‐phase dialysis at an ultimate molecular‐mass cut‐off of 25000, are collected after freeze‐drying as water‐soluble resins or solids and are characterized microanalytically and by 1H NMR spectroscopy. Inherent viscosities are in the range of 10–20 ml g−1. The drug‐binding potential of a representative target polymer is probed by the covalent anchoring of a ferrocene compound used as a drug model, giving a water‐soluble polymer‐ferrocene conjugate.
Study on poly(2,6‐dimethyl‐1,4‐phenylene oxide)/SBS triblock copolymer blends
Authors: Chiu Hsien‐Tang , Hwung Dao‐Shinn
Published: April 2003

The relationship between the miscibility and the physical properties of polymer blends of poly(2,6‐dimethyl‐1,4‐phenylene oxide) and polystyrene (PS), high‐impact polystyrene (IPS) and poly(styrene‐block‐butadiene‐block‐styrene) (SBS), which are blended in different compositions by a twin‐screw extruder is discussed. The three types of SBS that were used are SBS1, SBS2 and SBS3 having different styrene/butadiene ratios. Dynamic mechanical analysis and differential scanning calorimetry were used to study the miscibility. The morphology was examined by SEM. The miscibility of the blends decreases with decreasing PS content. The notch sensitivity is improved by blending. Finally, the micelle model was used to explain the testing phenomena.
Die kristallisation von polybutylenterephthalat (PBT) und polycarbonat (PC) im polymerblend PBT/PC
Authors: Radusch H.‐J. , Androsch R.
Published: April 2003

Das Kristallisationsverhalten sowohl von PBT als auch von PC ist im definiert verarbeiteten Blend infolge intermolekularer Wechselwirkungen zwischen den unterschiedlichen Molekülen in der Schmelze verändert.

Die über die Glasübergangstemperaturen gemessene teilweise Mischbarkeit der amorphen Phasen führt bei PBT zu einer Erniedrigung des Kristallinitätsgrades, wenn die kinetischen Bedingungen des Kristallisationsprozesses keine kristallisationsbedingte Entmischung zulassen. Der auf den PBT‐Anteil normierte Kristallinitätsgrad ist bei kleinen Abkühlgeschwindigkeiten vom PC‐Anteil unabhängüg.

In der Mischung PBT/PC 40/60 Gew.‐% kommt es bei hohen Kühlraten zu einer fraktionierten Kristallisation. Die Kristallisationstemperatur bei anisothermer Kristallisation ist bei geringen PC‐Gehalten durch Änderung des Keimbildungsmechanismus erhöht. Bei isothermer Kristallisation steigt mit zunehmendem PC‐Anteil die Kristallisationshalbwertszeit des PBT an.

Das normalerweise amorphe PC kann in Gegenwart von PBT in den PC‐reichen Mischungen besonders schnell kristallisieren, wobei der Kristallisations‐ bzw. Ordnungsprozeß des PC in situ mittels der Röntgenbeugung gemessen wurde. Kalorimetrische Untersuchungen bestätigen dieses Ergebnis und erlauben eine quantitative Abschätzung des PC‐Kristallinitätsgrades zu ca. 20% im Blend PBT/PC 5/95 Gew.‐%.
Studies on vinyl ester resin and its urethane derivative as coating materials
Authors: Pachha R. R. , Thakkar J. R. , Patel R. D. , Patel R. G. , Patel V. S.
Published: April 2003

The present paper is concerned with the coating applications of a vinyl ester resin derived from diglycidyl ether of bisphenol‐A and its urethane derivative. The mild steel panels coated with the synthesized resins were evaluated for their gloss on the surface, scratch hardness and chemical resistance. The incorporation of styrene in the resin systems improves the properties of coatings remarkably.