bluuebunny/crossref_metadata_2025 huggingface dataset:
Facilitated oxygen transport in (polystyrene‐block‐polyisoprene‐block‐polystyrene)‐graft‐poly(1‐vinylimidazole) containing three cobalt‐containing schiff bases
Authors: Hsiue Ging‐Ho , Hsu Wey‐Leun
Published: April 2003

Membranes of (polystyrene‐block‐polyisoprene‐block‐polystyrene)‐graft‐poly(1‐vinyl‐imidazole) (SIS‐g‐VIm) reacted with three cobalt‐containing Schiff bases (CoS) were prepared and studied. SIS‐g‐VIm was obtained by radiation‐induced graft copolymerization of 1‐vinylimidazole onto poly(styrene‐block‐isoprene‐block‐styrene) triblock copolymer. Membranes of SIS‐g‐VIm reacted with three cobalt‐containing Schiff bases (SIS‐g‐VIm‐CoS) were prepared by the solution casting method. The co‐ordination numbers and formation constants of these reactions were determined. Equilibrium constants and thermodynamic parameters of SIS‐g‐VIm‐CoS membranes for binding and dissociation of oxygen were determined by UV/VIS spectroscopy. The permeability and O2/N2 permselectivity of the SIS‐g‐VIM‐CoS membranes were measured at various upstream gas pressures and temperatures. Oxygen permeation through the SIS‐g‐VIm‐CoS membranes can be explained by dual‐mode‐facilitated transport theory.
Preparation of multiphase block copolymers by redox polymerization process, 2. Polymerization of acrylonitrile by the Mn(III)‐poly(ethylene glycol) redox system
Authors: Cakmak Ismail
Published: April 2003

Redox polymerization of acrylonitrile (AN) with poly(ethylene glycol) using Mn(III) as catalyst was carried out to yield poly(ethylene glycol‐block‐acrylonitrile). The principal parameters (concentration of reactants, temperature) affecting the synthesis were examined. Successful blocking has been confirmed by infrared and 1H nuclear magnetic resonance spectroscopy as well as gel permeation chromatography.
Poly(sulfide sulfone) by activated nucleophilic displacement polymerization
Authors: Dutta Pradip K. , Maiti Sukumar
Published: April 2003

A poly(sulfide sulfone) was synthesized by activated nucleophilic displacement reaction between bis(4‐nitrophenyl)sulfone and anhydrous sodium sulfide at 200°C in N‐methyl‐2‐pyrrolidone (NMP). The polymer is soluble in NMP, dimethylformamide, dimethylsulfoxide and other highly polar solvents. The molecular weight of the polymer (M̄n = 2.500) having an inherent viscosity of 15 mL/g at 30°C in DMF was determined by 1H‐NMR spectroscopy. The polymer has a glass transition at approx. 73°C and char residue of 36% at 600°C in air. The limiting oxygen index of the polymer is ∼37.
Modelling the polymerization of 1,3‐butadiene in solution with a neodymium catalyst
Authors: Proß Alexander , Marquardt Peter , Reichert Karl‐Heinz , Nentwig Wolfgang , Knauf Thomas
Published: April 2003

The batch polymerization of butadiene in hexane with an in‐situ‐activated Ziegler‐Catalyst containing neodymium versatate, ethylaluminium sesquichloride and triisobutylaluminium was studied at 45°C. The rate of polymerization was determined by online density measurements. A mathematical model has been developed which is able to describe the kinetics of polymerization at different catalyst ratios. At molar ratios of aluminium/neodymium above 40 a bimodal molar mass distribution can be observed by gel permeation chromatography which leads to the assumption of more than one active species being present in the polymerization system.
Fluorine‐containing polyimides with phenylquinoxaline units
Authors: Sava Ion , Bruma Maria , Belomoina Nataliya , Mercer Frank W.
Published: April 2003

A series of new polyimides with phenylquinoxaline units have been synthesized by solution polycondensation of 2,2‐bis(1,3‐dioxo‐1H,3H‐isobenzofuran‐5‐yl)hexafluoropropane (hexafloroisopropylidene‐diphthalic anhydride) with aromatic diamines containing preformed phenylquinoxaline units. These polymers are soluble in polar amidic solvents and can be processed into transparent, flexible films, having low dielectric constants and high thermal stability with decomposition temperatures above 400°C.
A route to preparation of bromomethylated poly(2,6‐dimethyl‐1,4‐phenylene oxide)
Authors: Líška Juraj , Borsig Eberhard , Tkáč Ivan
Published: April 2003

Bromination of poly(2,6‐dimethyl‐1,4‐phenylene oxide)

Systematic name: Poly(oxy‐2,6‐dimethyl‐1,4‐phenylene).

(PPO) in halogenated aromatic hydrocarbons has been investigated in order to find optimum conditions for preparation of bromomethylated polymer when using either molecular bromine or N‐bromosuccinimide as brominating agent. It was found that bromination of the methyl group of PPO took place in chlorobenzene with dicumyl peroxide initiator at 132°C and no phenyl‐brominated product was obtained. The parallel bromination of the phenyl group and the methyl group of PPO, however, occurs at temperatures below 130°C with either molecular bromine or N‐bromosuccinimide. At temperatures above 150°C, cross‐linking of PPO accompanying the bromination starts to play the important role in PPO modification.
The free‐radical terpolymerisation of ethylene, methyl acrylate and vinyl acetate at high pressure. Polymerization tests
Authors: Luft Gerhard , Stein Franz , Dorn Maximilian
Published: April 2003

In this study, the terpolymerisation, under high pressure, has been examined for the ethylene‐methyl acrylate‐vinyl acetate system. The polymerisations were carried out in a high pressure polymerisation facility designed for continuous operation. To assess the effect of pressure and temperature on the reaction, polymerisation was carried out at two different pressures of 1 900 and 1 100 bar and at temperatures of 180 and 230°C. By varying the concentration of the ethylene, methyl acrylate and vinyl acetate monomers in the feed, polymers of different composition were obtained. The ratio of the monomer concentrations in the reactor was calculated from the amount of polymer weighed out and its comonomer content as well as the composition of the feed, using the mass balance for the ideal stirred tank reactor. The result was used to determine the reactivity ratios of the three possible binary copolymerisation systems ethylene/methyl acrylate, ethylene/vinyl acetate and methyl acrylate/ vinyl acetate. This made it possible to predetermine, by calculation, the composition of a product obtained by continuous polymerisation in a stirred autoclave.
Preparation of optically active polymer layers by after‐glow plasma polymerization
Authors: Hartwig Andreas , Steinhauser Hermann , Ellinghorst Guido
Published: April 2003

After‐glow plasma polymerization is described as a new method to prepare polymeric layers from unsaturated monomers. An optically active acrylic monomer is used in this investigation. The deposition rates are given as functions of plasma power, pressure, distance between plasma and deposition zone, flux and kind of auxiliary gas (He, Ne, Ar, Kr) and of monomer flux. The polymers prepared are optically active, the IR spectra comply with those of polymers synthesized in bulk. Mostly the polymers prepared by after‐glow plasma polymerization are cross‐linked and therefore insoluble. NMR spectra of soluble samples show that the polymers are atactic. After‐glow plasma polymerization occurs by a radical chain growth mechanism. Membranes made from these polymers are able to separate racemates.
Effect of α‐methyl styrene on properties of epoxy‐novolac based vinyl ester resins
Authors: Padma G. , Varma I. K. , Sinha T. J. M. , Patel D. M.
Published: April 2003

The paper describes the synthesis of vinyl esters using epoxy‐novolac resin. The curing behaviour of the resins containing different portions of styrene and α‐methyl styrene (α‐MS) as reactive diluents was studied by gel time determination. Delayed curing was observed in samples containing increasing proportions of α‐MS. An increase in the α‐MS content resulted in a decrease in the tensile strength and increase in heat deflection temperature of the cured sheets. The flexural strength and flexural modulus of both resin and glass fibre‐reinforced composites (resin content approx. 41 wt.‐%) increased. Treatment with boiling water (12 h) of laminates resulted in a decrease in interlaminar shear strength with an increase in α‐MS content.
Photocrosslinkable polymers based on maleimidemodified acrylates
Authors: Nair C. P. R.
Published: April 2003

Novel photocrosslinkable polymethacrylate systems with enhanced thermal stability and solvent resistance were synthesized. Copolymers of methyl methacrylate (MMA) or butyl acrylate (BuA) with 4‐maleimido benzoic acid (MBA) were synthesized and photocrosslinkable methacrylic functions were incorporated through the pendent COOH groups. Photofunctional groups were introduced by the acid chloride route and by the epoxy‐carboxy reaction. Photocrosslinking was performed using UV radiation of 350 nm in the presence of a photo‐initiator. The kinetics of photocuring was studied with a model multiacrylate. The imide‐modified photocured acrylate polymer exhibited enhanced solvent resistance and thermal stability, compared with the unmodified polymer.
Polybenzpinakole als Initiatoren für die radikalische Polymerisation
Authors: Braun Dietrich , Meid Holger
Published: April 2003

Durch Photopolymerisation von 4,4′‐Dibenzoyldiphenylmethan und 4,4′‐Bis(aαhydroxybenzy1)‐diphenylmethan mit UV‐Licht in benzolischer Löisung lassen sich Polybenzpinakole herstellen. Die Polymeren können durch Fällungsfraktionierung in Fraktionen mit Molekulargewichten bis etwa 20000 aufgetrennt werden. Polybenzpinakole zerfallen ebenso wie Benzpinakol thermisch in Diarylhydroxymethyl‐Radikale. Diese initiieren bei 60 bis 100°C die radikalische Polymerisation von Styrol direkt und teilweise auch durch Wasserstoffübertragung von den Initiatorradikalen auf das Monomere. Mit steigender Temperatur nimmt dabei der Anteil der Wasserstoffübertragung an der Initiierung ab, was aus den Reaktionsordnungen bezüglich der Monomerkonzentration geschlossen werden kann. Soweit die Polymerisation von Styrol mit Oligo‐Benzpinakol direkt durch Diarylhydroxymethyl‐Radikale ausgelöst wird, entstehen Polystyrolketten mit eingebauten Oligo‐Benzpinakol‐Segmenten, die thermisch spaltbar sind, was durch die Abnahme der Molekulargewichte beim Erhitzen in toluolischen Lösungen bestätigt wird.
Methodological investigations on the thermal stability of polypropylene
Authors: Wallius Satu
Published: April 2003

The correlation between different methods of measuring thermo‐oxidative stability of polypropylene has been studied. The oxidation induction times were measured using differential scanning calorimetry (DSC) in the temperature range from 160°C to 240°C up to 10000 min. The same samples were oven‐aged in the temperature range from 130°C to 160°C up to 13000 h.

The dynamic experiments performed by DSC show different results for differently stabilized samples. At slow heating rates the results of the dynamic experiments corresponded best to the results of the isothermal experiments.

The straight‐line Arrhenius plots of the isothermal DSC measurements do not correlate with the straight‐line Arrhenius plots of the oven‐aging tests. The Arrhenius plots obtained by these two methods either intersect close to the melting temperature of polypropylene or show jumps towards longer times when switching from DSC to oven‐aging. It was found that the apparent activation energies obtained from the oven‐aging tests are much lower than these obtained by DSC measurements. Almost the same activation energies were obtained for all the samples in oven‐aging, while for the differently stabilized samples the activation energies from DSC measurements showed different results.

Antistatic additives and colour pigments influence the thermal stability of polypropylene. Especially red pigment acts like a stabilizer for polypropylene, which is noticed at oven‐aging testing, but at higher temperatures it loses this stabilizing effect.
Free‐Radical stabilizers for the thiol/ene‐systems
Authors: Klemm Elisabeth , Sensfuß Steffi , Holfter Uta , Flammersheim Hans Jürgen
Published: April 2003

By means of calorimetric investigations it is shown that dithiol/diene‐mixtures show a more or less distinct spontaneous dark reaction, without light and in the absence of initiators. Pyrogallol, hydroquinone and catechol were tested as stabilizers. The efficacy of the stabilizer to transform the radicals resulting from charge transfer interaction of the thiol with the ene component into an inactive species decreases in the order mentioned above.
The participation of block copolymers in the increase in the number of tie molecules
Authors: Kučera Miloslav
Published: April 2003

Three‐block copolymers polyamide‐block‐polyX‐block‐polyamide (where X is styrene, ethylene‐co‐1‐butene, and others) are able to improve substantially the toughness of poly(ϵ‐caprolactam). Outer blocks of these copolymers are able to take part in folding lamellae of semi‐crystalline polyamide, inner blocks are not. They operate as a spacer, meaning that the end blocks of copolymers capable of folding become parts of different lamellae, or that the unfoldable part of a block copolymer is pushed out of a folding lamella with a certain probability of the remaining outer block taking part in folding another lamella.

This increases the number of tie‐molecules.
Effect of the particle size of the solid protective agent tricalcium phosphate and its in‐situ formation on the particle size of suspension polystyrene
Authors: Bilgiç Tülin , Karali Metin , Savaşçi Ö. Tunç
Published: April 2003

In this study, the effect of the particle size of solid protective agent, commercially obtained and in‐situ formed tricalcium phosphate (TCP), on the particle size of suspension polymerized polystyrene (PS) is investigated. It is concluded that when a solid protective agent like TCP is used, its particle size and distribution plays an important role in both suspension stability and particle size of the PS obtained. As the particle size of the TCP becomes smaller, the particle size of the PS obtained is reduced in line with it. In situ precipitation of TCP reduces its particle size considerably. Therefore, to produce PS with the same particle size, lesser amount of in‐situ precipitated TCP is required which gives way to production recipe savings and cleaner PS products.
The free‐radical polymerization of acrylamide initiated with ceric sulfate in the presence of amino acids
Authors: Erbil Candan , Soydan A. Bahattin , Aroǧuz A. Zehra , Saraç A. Sezai
Published: April 2003

Polymerization of acrylamide initiated with ceric (IV) ion in the presence of methionine, phenylalanine, serine and aspartic acid was investigated in sulfuric acid solution. Maximum yield was obtained at 70°C and sulfuric acid concentration of 0.16 mol/1. Both conductometric titration and FT‐IR results showed that the resulting polymers contained carboxy end groups. According to these findings and previous studies in this field, a suitable polymerization mechanism was proposed.
Indium ion removal and recovery by means of water‐insoluble amphoteric starches
Authors: Chan Wu‐Chung
Published: April 2003

The removal and recovery of indium ion (In3+) from solutions with water‐insoluble amphoteric starches containing the phosphate anionic group and the quaternary ammonium or tertiary amine cationic group was investigated. The adsorption capacity of tertiary amine phosphate starch (TAP) and quaternary ammonium phosphate starch (QAP) is 0.54 meq/g and 0.48 meq/g, respectively. The adsorption process has been found to be concentration‐dependent and exothermic, and follows the Langmuir isothermal adsorption. The heat of adsorption (ΔH) is equal to −5.86 kJ/mol for QAP, and equal to −90.44 kJ/mol for TAP. The amount of adsorbed In3+ ion on the adsorbents decreases when inorganic acids (HCl or H2SO4) or sodium salts (NaCl or Na2SO4) are added to the solution. The adsorbed In3+ ion can be desorbed by treating with a HCl solution (1 and 3 M); the maximum percentage of desorption reaches about 80% when 1 N HCl solution is used.
Toughening of highly crosslinked thermosetting resins by blending with thermoplastic polyether imide
Authors: Di Liello V. , Martuscelli E. , Musto P. , Ragosta G. , Scarinzi G.
Published: April 2003

A tetrafunctional epoxy resin and a thermosetting bismaleimide resin were modified by adding a thermoplastic polyether imide, commercially available as Ultem 1000. Dynamic‐mechanical data and electron microscopy analyses demonstrated that a two‐phase system was obtained in both the cases after the curing and postcuring processes. A marked increase of the toughness parameters Kc and Gc was found for both the epoxy and BMI‐based blend systems. The toughening effect has been interpreted in the light of the fractografic analyses performed by scanning electron microscopy.
MgCl2·6H2O‐based titanium catalysts for propylene polymerization. Chemical composition and productivity
Authors: Gupta Virendra Kumar , Satish Sheo , Bhardwaj Ishwar Singh
Published: April 2003

MgCl2·6H2O was reacted with dichlorodiphenylsilane to obtain anhydrous magnesium dichloride. MgCl2 thus obtained was solubilized in 2‐ethyl‐1‐hexanol to prepare titanium catalysts for propylene polymerization through regeneration of magnesium dichloride by reaction with titanium tetrachloride. The nature of internal lewis base dialkyl phthalate [Ph(COOR)2, where R = Me, Et, and n‐Bu] and reactants concentration (alcohol and dialkyl phthalate) influence the chemical composition and specific surface area of catalysts. The activity of the catalysts changes in the order ßmethyl < ethyl < butyl. The polymerization parameters such as Al/Ti mole ratios, aging time of catalysts and cocatalysts (triethylaluminium) also control the activity. The concentration of the external Lewis base (dimethoxydiphenylsilane) improves the stereospecifity of the catalyst system.
Dopant‐induced laser ablation of PMMA at 308 nm: Influence of the molecular weight of PMMA and of the photochemical activity of added chromophores
Authors: Lippert Th. , Wokaun A. , Stebani J. , Nuyken O. , Ihlemann J.
Published: April 2003

Polymers which are not absorbing at the wavelength of irradiation may be sensitized by doping with low concentrations of suitable compounds for laser‐induced surface modification and ablation. In the present study this approach is applied to the ablation of PMMA by 308 nm irradiation (XeCl* excimer laser). Substituted phenyltriazene and diphenyltriazene compounds, two pentazadienes and a hexazadiene are tested as ablation promoters in concentrations of 1, 2, and 5 wt.‐%, respectively. From all of these compounds, nitrogen is released upon photochemical decomposition.

A significant influence of the PMMA molecular weight on the ablation characteristics is found: higher molecular weights result in lower ablated depths per pulse. The etch rates achieved for the various dopants are correlated with the photophysical and photochemical parameters (i. e., absorption cross section and photolysis quantum yield) in solution. Above a characteristic minimum concentration of the additive, the ablated depth is approximately inversely proportional to the dopant concentration. In the regime of low laser fluence, the ablated depth per pulse scales with the logarithm of fluence, and is proportional to the quantum yield of photolysis in solution. For the limiting etch rate at high fluence, no correlation with the solution absorption cross section was found.
Polymerisation von butadien mit der in‐situ‐form des katalysatorsystems nickeloctoat/bortrifluoridetherat/aluminiumtriethyl
Authors: Gehrke Klaus , Schröder Karsten
Published: April 2003

Für die Butadienpolymerisation ist das Katalysatorsystem Nickeloctoat/Bortrifluoridetherat/Aluminiumtriethyl modifiziert worden. Diesbezüglich wird die Reaktion des Bortrifluoridetherats mit Aluminiumtriethyl vorab durchgeführt (Vorreaktion) und deren Reaktionsprodukt ohne Isolierung mit Nickeloctoat/Aluminiumtriethyl umgesetzt (Alterung), genannt in‐situ‐Katalysator. Anschließend erfolgt damit die Polymerisation des Butadiens.

Vorrreaktion und Alterung sind bezüglich Molverhältnissen, Zeit und Temperatur variiert und deren Auswirkungen auf Umsatz und viskositätsmittlere Molmasse bei der Butadienpolymerisation ermittelt worden. Eine Zeit‐Umsatz‐Kurve, erhalten mit dem optimalen Katalysator, wird angegeben.

Eine 2‐Stufenpolymerisation ergab keine Desaktivierung bei der Polymerisation.
Study of the condensation products of abietic acid with formaldehyde
Authors: Bicu Ioan , Mustatǎ Fǎnicǎ
Published: April 2003

Abietic acid and paraformaldehyde, taken in various molar ratios, were condensed in acid catalysis (p‐toluenesulfonic acid). Toluene was used both as reaction medium and carrier for aqueous condensate. The obtained polymeric products (resins) were characterized by determination of acid number, melting point, molecular weight and viscosity. Spectral methods, e.g. I. R. and 1H‐NMR, were also used in the same scope. The experimental data evidence the fact that abietic acid is a substance with a functionality of minimum 3 as against formaldehyde. There have been obtained some condensation products with three‐dimensional structure and low molecular weight. The polymerization average degree of the resins was found to be 3, although some fractions with polymerization average degree of 6 have been observed. The chemical bonds established between the structural units can be of both methylenic and dimethylene ether type, depending on the molar ratio of reacting substances.
The effects of the proportion of biphenyl‐AlCl3‐CuCl2 polymerization system on structure and electrical conductivity of insoluble polyphenylenes
Authors: Simitzis J. , Zoumboulakis L. , Stamboulis A. , Hinrichsen G.
Published: April 2003

Polyphenylenes insoluble in chlorobenzene were prepared by cationic oxidative polymerization of biphenyl with aluminum trichloride as catalyst and cupric chloride as oxidizer. The fraction insoluble in chlorobenzene was doped in a solution of FeCl3 in acetonitrile. The alternating electrical conductivity, the X‐ray diffractograms and the FTIR‐spectra of undoped and doped polyphenylenes were measured. The undoped material was observed to be an insulator. Only one sample exhibited different behavior which was similar to the doped material, that was found to be semiconducting. Both undoped and doped polyphenylenes were found to have a monoclinic crystallographic unit cell. For the preparation of polyphenylenes with maximum electrical conductivity after doping, the stoichiometric proportion of biphenyl/CuCl2 = 1/2 has to be chosen. Similarly, the catalyst proportion biphenyl/AlCl3 has to be either 1/0.75 or 1/1.5. Under these conditions the undoped polyphenylenes had a ratio of para/meta substitution of about 1, the degree of crystallinity was below 60% and the unit cell volume was quite low. The results were discussed according to the reactions taken place during polymerization.
New polymer additives, 3. Telechelic additives for polyolefins
Authors: Wanicek Helmut , Gruber Heinrich , Greber Gerd
Published: April 2003

A series of telechelic additives with molecular weights of 500–1500 for polyolefins was prepared by reaction of telechelic polyolefins with amino‐, carboxy‐and aldehyde end groups were obtained by hydrogenation of the corresponding telechelic polybutadienes which were prepared by radical polymerization of butadiene with appropriate functional initiators as well as by anionic polymerization of butadiene and termination with carbon dioxide, ethylene oxide and chloroacetaldehyde dimethyl acetal. Oligomeric polyolefins with stabilizer end groups attached by non‐hydrolyzable CC‐bonds were obtained by end‐capping of living polybutadiene with appropriate functional additive components and subsequent hydrogenation. Preliminary tests of some of the telechelic additives demonstrated excellent compatibility with polypropylene and efficiencies similar to low‐molecular standard additives.
Electroluminescence of poly(phthalidylidene arylene)s
Authors: Lachinov Alexey N. , Zolotukhin Mikhail G. , Antipin Vyacheslav A. , Valeeva Irina L.
Published: April 2003

Electroluminescence of thin films of poly(3,3‐phthalidylidene‐4,4′‐biphenylylene) (PPB) and poly(3,3‐phthalidylidene‐2,7‐fluorenylylene) (PPF) was studied. In both cases, electroluminescene was found to be of a threshold origin. Emission maxima and quantum efficiencies for PPB and PPF are 490 and 525 nm, 0.01 and 0.1%, respectively. The electroluminescent characteristics were found to be strongly dependent on the polymer used.
Block/graft copolymer synthesis via ceric salt
Authors: Galioǧlu O. , Soydan A. B. , Akar A. , Saraç A. S.
Published: April 2003

Acrylamide and acrylonitrile were polymerized with water‐soluble organic reducing compounds containing hydroxy groups such as methyl cellulose (MC), methyl hydroxy‐propyl cellulose (MHPC) and poly(ethylene glycol)s (PEG) in the presence of Ce(IV) in order to produce graft/block copolymers. The effect of cerium(IV) concentration, temperature, time and monomer concentration on the yield was studied. Copolymers of cellulose derivatives and polyacrylonitrile showed solubility properties similar to polyacrylonitrile. Both cellulose derivative‐polyacrylamide and poly(ethylene glycol)‐polyacrylamide copolymers were soluble in water.
Interpenetrating polymer networks of polyurethane and furfuryl alcohol. I. Morphology and mechanical properties
Authors: Ma C.‐C. M. , Goang D. Y. , Han J. L. , Hsieh K. H.
Published: April 2003

Polyurethane/furfuryl alcohol (PU/FA) interpenetrating polymer networks (IPNs) were synthesized from furfuryl alcohol using p‐toluene sulfonic acid as a catalyst and blocked NCO‐terminated PU prepolymer with m‐xylylenediamine (MXDA) as a chain extender. From IR spectrum analysis it was found that the major reactions in the PU/MXDA/FA system are the polymerization of PU/MXDA and the self‐polymerization of FA. The tensile strengths of PU/FA IPNs that contain 5 p.h.r. PU are greater than those of the pure components. The flexural strength, flexural modulus, Shore D hardness and HDT decrease and the notched Izod impact strength increases with the polyurethane content. The compatibility of the compounds in these PU/FA IPNs was investigated by dynamic mechanical analysis and scanning electron microscopy. It was found that glass transition temperatures are shifted inwardly which indicated that the PU/FA IPNs were semicompatible. It was confirmed from scanning electron micrography that the system was heterogeneous.
Image formation of alkyl‐pendent aromatic polyimide by photocoupling with aromatic ketones
Authors: Chiang Wen‐Yen , Mei Wang‐Ping
Published: April 2003

Positive and negative photostructures are formed after the polyimide (PI) of 4,4′‐biphthalic anhydride (BPA) and 4,4′‐diamino‐3,3′‐dimethyldiphenylmethane (DADMDPM), PI(BPA/DADMDPM) is doped with Michler′s ketone (MK) and benzophenone (BP), respectively, and is subjected to UV light (400 ± 50 nm) irradiation and solvent development. The principle of positive feature formation is based on the photocoupling of MK with PI, which increases PI solubility and thus enables a positive pattern to be developed. The phenomenon of negative photopatterning results from intermacromolecular H‐bonding between the carbonyl group of the imide ring and the hydroxy group which is formed in the photoinduced coupling reaction between BP and PI. Lithographic evaluation shows that the MK‐doped positive‐acting PI film cannot form useful patterns because UV wavelengths are strongly absorbed by MK, which limits the depth of photocoupling in the film. On the other hand, 2‐μm‐wide lines can be resolved in the BP‐doped negative‐acting 0.6‐μm‐thick PI film.
Sulfobetaine polyurethane ionomers, 4. Study of interactions between polymers and methyl orange
Authors: Buruianǎ T. , Airinei A. , Buruianǎ E. C. , Robilǎ G.
Published: April 2003

The photochemical behaviour of some polyurethane zwitterionomers containing azoaromatic structures of dye type was studied both in solution and polymer film. The interaction between methyl orange and the sulfobetaine structures of the polyurethane chain was followed by electronic absorption spectra.
Mechanical properties of talc‐filled polypropylene. Influence of filler content, filler particle size and quality of dispersion
Authors: Švehlová Vítězslava , Polouček Eduard
Published: April 2003

Mechanical properties of polypropylene‐talc composites are measured as a function of talc concentration up to 40 wt.‐%, Young's modulus of filled polypropylene shows linear increase with talc concentration up to double the value of unfilled polymer. Yield stress and Charpy notch toughness decrease with increasing talc content below matrix level at the highest filler content. Composite ultimate tensile elongation and tensile impact strength decrease sharply beginning at the lowest filler concentration. The influence of the talc particle size on the mechanical properties, especially composite toughness, mentioned above, is investigated. Four type of talc were used. Notch toughness decreases according to a linear dependence with mean size of talc particles. Evaluating impact strength possible content of agglomerates of filler and other additions is necessary to be included: tensile impact strength gives slow linear dependence with increasing content of filler particles and/or agglomerates above about 10 μm. The influence of talc particle size on the toughness of filled polypropylene becomes strong if the rubber particles are present.
Blends of polyamide 6 and poly(etheraroylhydrazide)s prepared concurrently with polyhydrazide polymerization
Authors: Aslan S. , Lanzetta N. , Laurienzo P. , Malinconico M. , Martuscelli E. , Volpe M. G.
Published: April 2003

Poly(etheraroylhydrazide) is synthesized in the presence of PA6 by means of low‐temperature condensation polymerization of 4,4′‐dichloroformyl‐α,ω‐diphenoxydodecane with terephthaloyl dihydrazide (TDH) in order to prepare polyhydrazide/poly‐amide 6 (PEHZ12/PA6) blends. The thermal analysis of the blends by DSC seems to indicate that the two polymers are not interacting. Nevertheless, when the blends are subjected to an extraction process with formic acid in order to remove the PA6, the characterization of the residual PEHZ12 reveales that some interactions do occur between the constituent polymers, at least for selected compositions. Model experiments permit to hypothesize that the polymerization of PEHZ12 proceeds with a chemical interaction between amino end groups of PA6 and growing PEHZ12 chains.
On the synthesis of acrylamide oligomers
Authors: Bortel Edgar , Kochanowski Andrzej , Kowalski Antoni
Published: April 2003

The synthesis of low‐molecular‐weight poly(acrylamide)s (M̄n = 500 – 1 000) is described. Metal‐activated and non‐activated polymerization in aqueous solution was investigated employing hydrogen peroxide as initiator. Among four transition metal salts considered, Cu2+ cations proved to be the most efficient in decomposing H2O2 molecules and were used as activator. The experiments were run at three reaction temperatures (60, 80 and 95°C), at three H2O2 levels (4, 5 and 6 wt.‐% on monomer), and at four Cu2+ levels (900, 600, 300 and 0 ppm by weight of metal on monomer). Thus, ist was possible to prepare acrylamide oligomers with monomer conversions exceeding 95%, and with Mn values covering the narrow range indicated above. Within these low limits a molecular weight control is impossible, even with inclusion of the differentiated levels of Cu2+cations. Intrinsic viscosities are very low, too ([η]) = 20 – 50 cm3/g, without any relations of the individual values to variations of the given process parameters. The work provides an industrial route to very‐low‐molecular‐weight acrylamide oligomers.
Preparation and investigation of silicon rubber containing imide‐siloxane copolymers
Authors: Ghadir M. , Zimonyi E. , Nagy J.
Published: April 2003

A study has been carried out on the preparation of some modified imide‐siloxane copolymers. This has been accomplished by means of addition of α,ω‐dihydropoly(di‐methylsiloxane)s to N,N'‐diallyldiimides by hydrosilylation reaction. The copolymers were characterized by IR and NMR spectroscopy methods. Molar mass, molar mass distribution, thermal and mechanical properties of copolymers were determined. These copolymers are used as additives, mixing them in different ratios with a silicone polymer and filler to obtain imide‐silicone rubbers of high temperature vulcanizing (HTV) type. Mechanical properties of the vulcanized rubbers were evaluated.
Polymerization and application of 2‐methacryloyloxyethyl phenyl phosphate in coatings
Authors: Liaw Der‐Jang , Shen Wen‐Chang
Published: April 2003

2‐Methacryloyloxyethyl phenyl phosphate (MEPP) was synthesized by reacting 2‐hydroxyethyl methacrylate (2‐HEMA) with phenyl dichlorophosphate (PDCP) followed by hydrolysis. This acrylic monomer containing the phosphate group was introduced into a typical UV‐curable acrylated epoxy system as an adhesion promoter. Good adhesion properties and solvent resistance of the films after UV curing were obtained in the presence of MEPP, although there was a decrease in the curing rate. When MEPP was introduced into acrylated epoxy resin, the contact angle remarkably decreased indicating that the wetting ability was improved. When MEPP was applied to the synthesis of the water‐soluble acrylic resins cured with various water‐soluble epoxy resins at 25°C, the adhesion and corrosion resistance of coating films was improved.
Photoreactions in halogen‐containing negative‐tone novolac resists
Authors: von Lampe Irene , Reinhardt Michael , Lorkowski Hans‐Joachim , Schnabel Wolfram
Published: April 2003

The photolysis of halogenophenol novolacs is determined by the substitution of halogens by hydrogen and the formation of quinoid groups and intermolecular crosslinks. This is concluded from elemental analysis, NMR, IR and optical absorption measurements. The rate of halogen release depends on the chemical nature of the halogen. It increases in the order F < Cl < Br < I. Chlorine elimination from 4‐position is favored over that from 2‐ and 3‐position. Moreover, dimers release chlorine from 4‐position much more readily than trimers and tetramers. ESR measurements at 77 K and flash photolysis studies at 296 K yielded evidence for the intermediate existence of phenoxyl and aryl radicals. Lithographic tests demonstrated the high UV‐sensitivity of resist formulations based on halogen‐containing novolacs. The increase in sensitivity relative to that of formulations based on nonhalogenated novolacs is 6 to 10fold system: 4‐chlorophenol novolac/4,4′‐bisazidobiphenyl (5%) and ca. 25fold system: 4‐chlorophenol/m‐cresol novolac/hexamethoxymethylmelamine (5%). A postulated reactions mechanism concerning the sensitivity increase takes into account that halogen elimination results in the formation of additional radicals that accelerate the rate of crosslinking. Moreover, hydrogen halide generated by hydrogen abstraction of halogen radicals (Hal˙ + RH → H‐Hal + R˙) provides for the acid required to catalyze the reaction of the melamine compound with the novolac matrix.
Silica gel supported zirconocene dichloride/methylalumoxane catalysts for ethylene polymerization: Effects of heterogenation on activity, polymer microstructure and product morphology
Authors: Janiak Christoph , Rieger Bernhard
Published: April 2003

The system zirconocene dichloride/methylalumoxane was supported on silica in order to provide ethylene polymerization catalysts for suspension or gas phase processes. Highest activity was found for a sandwich‐like, three layer anchoring of the zirconium centers on the support surface. The new catalyst systems show a decrease of activity compared to polymerization experiments in homogeneous phase. However, the molecular weights are increased and the weight distributions remain narrow by immobilization of the active catalyst sites. Those supported metallocene catalysts could find application for the synthesis of polyethylene materials with controlled rheology.
Effect of the chemical structure of some hydrogels on their characteristic properties. I. Effect of comonomer composition
Authors: Koßmehl G. A. , Abdel‐Bary E. M. , Sarhan A. A. , Abdelaal M. Y.
Published: April 2003

Some hydrogels of different chemical composition were synthesized using 2‐hydroxyethyl methacrylate, methacrylic acid, acrylic acid, and acrylamide in different ratios and crosslinked by ethylene dimethacrylate. Effects of the copolymer composition as well as the type of monomers on some hydrogel characteristics were evaluated. Some characteristic properties, namely soluble fraction percentage, swelling degree, solution uptake, and salt uptake were found to be markedly affected by the hydrogel composition.
pH control of the condensation reaction and its effect on the properties of formaldehyde/urea resins
Authors: Szesztay M. , László‐Hedvig Zs. , Takács C. , Gács‐Baitz E. , Nagy P. , Tüdős F.
Published: April 2003

The conditions of the preparation of formaldehyde/urea (F/U) resins have been supervised with the aim to reduce formaldehyde emission by influencing the ratio of methylene/dimethylene‐ether‐bridge linkages in the product.

The most crucial point of this task is to keep the pH values of the reacting mixtures on the required level. The effect of formic acid, unevitably present in industrial formaldehyde solutions, was neutralized by applying a new buffer system, containing boric acid and ethylene glycol.
Determination of the substituent pattern of heterogeneously and homogeneously synthesized carboxymethyl cellulose by using high‐performance liquid chromatography
Authors: Heinze Thomas , Erler Ulrich , Nehls Irene , Klemm Dieter
Published: April 2003

A rapid and convenient procedure was developed for the determination of the substituent pattern of carboxymethyl cellulose (CMC) by means of high‐performance liquid chromatography. The hydrolysates of CMC are separated on a polystyrene‐based strong cation‐exchange resin into glucose, 2,3,6‐tri‐O‐carboxymethyl glucose and groups of 2‐, 3‐and 6‐mono‐O‐ and 2,3‐, 2,6‐, and 3,6‐di‐O‐carboxymethyl glucoses. By this method the determination of the average degree of substitution as well as the substituent pattern is possible. In this way we found that CMC samples which were synthesized in LiCl/N,N‐dimethylacetamide as a cellulose solvent, contain a significantly higher amount of both tricarboxymethylated and unsubstituted units than those obtained in a slurry of cellulose in isopropanol/water at comparable DS values. The substituent pattern of heterogeneously synthesized CMC is mainly determined by statistics.
Evaluation of poly(butyl acrylate‐co‐ethylene glycol dimethacrylate) sorbents for chromatographic separation of biomolecules
Authors: Bryjak Marek
Published: April 2003

Copolymers of butyl acrylate (BA) crosslinked with ethylene glycol dimethacrylate (EGDMA) were evaluated as potential chromatographic packings. It was found that slightly crosslinked copolymers (up to 30 wt.‐% EGDMA) did not provide porous material, while for matrices which exceeded 40 wt.‐% of EGDMA the porous structure remained unchangeable. The increase of crosslinker content mostly affected the surface hydrophobicity. Two methods of measurement of this property were discussed: Sorption of alkyl alcohols and amino acids. Taking the latter for testing, a polymer matrix hydrophobicity index was calculated as the slope of dependence of column capacity vs. amino acid hydrophobicity parameter. The indices were verified against well‐established interaction energies of CH2 groups of alkyl alcohols and polymer surfaces. Some benefits of the use of the hydrophobicity index in evaluation of polymer sorbents were demonstrated.
Infrared study of the catalytic degradation of a commercial epoxy adhesive on metal surfaces
Authors: Hong Shinn‐Gwo
Published: April 2003

Reflection absorption infrared spectroscopy (RAIR) has been used to investigate the effects of different surface materials (interstitial free steel (IFS), aluminium (2024‐A1) and copper) on the thermo‐oxidative degradation of a commercial two part epoxy adhesive system. The epoxy resin was spin‐coated on polished metal substrates and aged at 125°C for different periods of time. Based on the relative changes in intensities of the amide, ether and alcohol bands during exposure, it was found that the fastest degradation took place on the Cu surface, whereas the slowest happened on the 2024‐Al surface. The accelerated degradation observed on the Cu surface was partly attributed to the preferential adsorption of labile amino and amide groups on the Cu surface.
Cetylpyridinium chloride‐modified poly(ethyleneimine) for the removal and separation of inorganic ions in aqueous solution
Authors: Palmer Valentina , Zhou Rongnong , Geckeler Kurt E.
Published: April 2003

The removal and separation of a series of ions by the water‐soluble cetylpyridinium chloride‐modified poly(ethyleneimine) (PEI‐CPC) in conjunction with membrane filtration were investigated. The Liquid‐Phase Polymer‐Based Retention (LPR) method was applied to study the removal of the low‐molecular species at different pH values and at several element concentrations. The study comprises aqueous solutions of the anions chromate and phosphate, and of the cations Cu(II), Zn(II), Co(II), Ni(II), Cr(III), Fe(III), Cd(II), Pb(II) and Sr(II). The results show that a high retention was attained in neutral solutions for both anions and also for most metal ions investigated. PEI‐CPC exhibited good removing abilities for chromate and phosphate ions even at relatively high concentrations of anions (85 and 150 mg · L −1, respectively) and also for most of the metal ions studied. In the case of Cu(II), Ni(II), Cd(II), and Sr(II) ions, selective interactions were observed. The polymer reagent and its interaction products were characterized by IR, UV/VIS spectrometry, and viscometry. In addition, the interaction behaviour was investigated by the retention ability. A good correlation was found between the retention data and the IR and UV/VIS spectra of the interaction products of the polymer reagent with the metal ions.
Effect of addition of cellulose powder on the viscometric behavior of liquid crystalline solutions of ethyl cellulose in m‐cresol
Authors: Suto Shinichi , Murokoshi Katsunobu
Published: April 2003

Steady‐state shear viscosity for the liquid crystalline ethyl cellulose solution filled with cellulose powders was determined using a cone‐plate‐type viscometer and the effects of cellulose powder content, powder aspect ratio and temperature on the viscometric behavior and phase transformation were discussed. The addition of powder increased the viscosity and decreased the activation energy (Ea) for flow, but did not affect the phase transformation. The viscosity and Eadepended on the aspect ratio; with greater aspect ratio, the viscosity enhancement was accelerated and Eaas well as the decrease in Eawith powder content increased. The phase transformation did not depend on the aspect ratio, the dependences of viscosity and of Eaon powder content depended on the solution phase; the dependences for the anisotropic phase were smaller than those for the isotropic one. The findings appeared to originate from the alignments of powders and rod‐like molecules.
Oxygen uptake methods as a tool to determine the mechanism of action of hindered amine light stabilizers1
Authors: Gijsman Pieter , Hennekens Jan , Tummers Daan
Published: April 2003

The UV‐degradation of an unstabilized and two HALS stabilized polyethylene (PE) films is described. The degradations are characterized by measuring the oxygen uptake, the formation of CO and CO2, the FT‐IR spectra, the mechanical properties, the stabilizer concentration and the oxygen content of the film.

The oxygen uptake of the unstabilized PE film led to the expected changes in the IR spectra and embrittlement of the film, while the oxygen uptake by the HALS stabilized films caused only minor changes. The differences between the results for the unstabilized and the HALS stabilized polymers are explained assuming that the initiation of the photodegradation of PE is due to charge transfer complexes.
Studies on controlled oxidation of low molecular weight polyethylenes
Authors: Munteanu D. , Toma F.
Published: April 2003

The low molecular weight by‐product of a high‐density polyethylene plant (slurry process in hexane, Ti‐based highly active catalysts) was subjected to controlled oxidation by air bubbling into the polymer melt maintained under stirring at constant temperature (130–170°C). Oxidized polyethylene waxes having various oxidation degree, i.e. acid number up to 60 mg.KOH/g and saponification number up to 120 mg.KOH/g have been obtained under different reaction conditions. Oxidation temperature and polymer/air ratio proved to be the main parameters that control the process. Inhibition and catalytic effects have been also studied as well as the dependence of the oxidation process on the like of the starting low molecular weight polyethylene. the results have been used to develop an industrial process for producing oxidized polyethylene waxes with useful properties and applications.
Photo–degradation of high performance polymers and application of a novel technique to degraded polymers
Authors: Narisawa I. , Kuriyama T.
Published: April 2003

Outdoor weathering at three locations in Japan has been carried out for new engineering plastics; PPO, PPS, PA and PEI. The degradation results were compared with those exposed in the Sunshine and Xenon Weather simulation machines. The half‐time of these materials, which was the time to give a 50% decrease of some property, strongly depended on a property to be noted. The elongation to break and impact energy, i.e. fracture energy, reflected the degradation process of neat polymers and they were closely related to the condition of a very thing degraded layer. The half‐amount of ultraviolet radiation also depended both on a property and material. The acceleration rate of the weather simulating machines has been obtained by this half‐amount. The loss in mechanical properties of fiber‐filled materials is much smaller than that of neat polymers. The fibers could reduce the embrittlement of the degraded layer. It has been demonstrated that a micro‐cutting technique to measure cutting resistance is a useful method to monitor a continous change in mechanical properties from the surface to the interior of the degraded layer. The effect of stabilizer has been clearly shown by this technique.
The kinetics and mechanism of polyethylene photo‐oxidation
Authors: Cruz‐Pinto J. J. C. , Carvalho M. E. S. , Ferreira J. F. A.
Published: April 2003

The kinetics of the natural and accelerated photo‐oxidation of low‐denisty polyethylene (LDPE) films have been studied; different geographical locations have been selected for the natural tests, and a range of temperatures used in the accelerated experiments in a specially built temperature‐controlled ultraviolet radiation enclosure. A meaningful correlation between natural and accelerated weathering results was established, by means of an adequate superposition of the effects of UV radiation exposure and temperature. Reasonably detailed and accurate, lumped‐parameter, kinetic models of the photo‐oxidation process have also been developed, to interpret and predict the results of measurements of carbonyl, hydroperoxide and vinyl absorbances as functions of time and temperature; the models predict the general experimental behaviour, and also that both the formation of hydroperoxides and carbonyl Norrish‐I reactions are important initiation steps. More complex models have the potential of interpreting other fine details of the degradation behaviour, namely the generation of other chemical species, and the chain scission and cross‐linking process which are directly related to changes in the mechanical properties.
Current of status of exploitation of radical scavenging stabilizers in advanced polymer stabilization
Authors: Pospíšil Jan
Published: April 2003

Principal chemical pathways characteristic of active participation of radical scavenging polymer stabilizers (phenols, aromatic, hydroaromatic and hindered aliphatic amines) are outlined. Pathways resulting in a partial depletion or distortion of activity of stabilizers, in formation of polymer discolouring products, or in interactions in bifunctional stabilizers are involved.