bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthese schmelzspinnfähiger copolyoxadiazole für hochtemperaturbeständige faserstoffe
Authors: Strubl Rüdiger , Seyfarth Hans‐Eberhard , Taeger Eberhard
Published: April 2003

Poly(p‐phenylen‐1,3,4‐oxadiazol) entsteht aus Terephthalsäure und Hydrazinsulfat in Oleum und kann aus Schwefelsäurelösung durch Naßspinnen zu Faserstoffen mit hervorragender Temperaturbeständigkeit und guten textilphysikalischen Eigenschaften verformt werden. Da das Polymere weder schmilzt noch in ülichen organischen Lösungsmitteln löslich ist, steht bisher kein ökonomisch und ökologisch günstiges Verarbeitungsverfahren zur Verfügung. Ziel der vorliegenden Untersuchungen war die Synthese schmelzspinnfähiger Copolyoxadiazole durch chemische Modifizierung. Dazu wurden Dicarbonsäuren als Comonomere eingesetzt, die die Beweglichkeit der Polymerketten erhöhen und die zwischenmolekulare Wechselwirkung beeinflussen.

Die Cokondensation mit hinreichend stabilen Dicarbonsäuren erfolgte in Oleum order in einem Gemisch aus Amidosulfonsäure und Schwefelsäure. Völlig ohne Schwefelsäure entstehen Copolyoxadiazole aus Dihydraziden und Dichloriden auf dem Weg über die Polyhydrazide. Von den synthetisierten Copolyoxadizolen erwiesen sich solche als erweichungs‐ und schmelzfähig, die neben Terephthalsäure noch Isophthalsäure und ein oder zwei weitere Dicarbonsäuren enthalten. Gute Ergebnisse wurden mit 5‐Carboxypentyl‐N‐trimellitimid und anderen Dicarbonsäuren cyclischer Imide mit aliphatischen Segmenten erzielt. Eine zusätzliche Senkung der Erweichungs‐ und Schmelztemperatur gelang durch geringe Anteile an aliphatischen Dicarbonsäuren. Mit Bromterephthalsäure entstanden schmelzfähige Copolymere ohne aliphatische Kettensegmente. Die Erweichungs‐ und Schmelztemperaturen lagen zwischen 220 und 375°C. Die TG‐Analyse zeigte einen nur geringen Abfall der Thermostabilität im Vergleich zum Homopolymeren. Ausgewählte Copolyoxadiazole wurden in einer Kolbenspinneinrichtung verarbeitet. Die Fäden waren zum Teil spröde, andere flexibel und reckfähig.
Activation of the high pressure polymerisation of ethylene initiated with organic peroxides by means of organoaluminium compounds
Authors: Luft Gerhard , Batarseh Brigitte , Dorn Maximilian
Published: April 2003

In the course of this study, an activator system consisting of an aluminium trialkyl compound and a Lewis base was tested for its suitability for the radical polymerisation of ethylene at high pressure. The aim of reducing the initiator consumption and the polymerisation temperature was achieved with aluminium trialkyl alone without the use of a Lewis base.

Among the aluminium trialkyl compounds examined, triethyl aluminium proved to be the most effective. This effectiveness is due to the increased rate of decomposition of the peroxide as a result of which a larger amount of free radicals becomes available thus increasing the rate of polymerisation. By using an addition of 50 mole ppm triethyl aluminium to 50 mole ppm tert‐butyl‐perpivalate in the ethylene feed it was possible to almost double the monomer conversion at a given polymerisation temperature and to reduce by half the consumption of peroxide initiator per kg polyethylene produced. Compared with the non‐activated polymerisation, the polymerisation temperature was reduced from 150°C to 125°C, the initiator consumption remaining the same. The costs of the triethyl aluminium activator are more than offset by the increased yield and the decrease in initiator consumption.
Methoden zur bestimmung des maleinsäureanhydridgehaltes in acrylnitril‐copolymeren in gegenwart initialer carboxygruppen
Authors: Ziegler Hans‐Jörg , Lehmann Ingeburg , Abel Christiane , Malsch Günter
Published: April 2003

Zur Bestimmung des Maleinsäreanhydrid(MSA)‐Gehaltes in Acrylnitril(AN)‐Copolymeren des Typs Poly(AN‐co‐MSA) bzw. Poly(AN‐co‐Styrol‐co‐MSA) wurden drei verschiedene Titrationsmethoden hinsichtlich ihrer Richtigkeit, Reproduzierbarkeit sowie ihres Zeitaufwandes geprüft. Miteinander verglichen wurden (i) eine Methodenkombination A/H bestehend aus dem Teilschritt A, einer Umsetzung der Anhydridgruppen (AG) mit Anilin einschließlich der Titration der Monosäuregruppen mit methanolischer KOH, und dem Teilschritt H, einer vollständigen Hydrolyse der AG und Titration der Säuregruppen (SG) mit wäßriger NaOH, (ii) Methode B basierend auf der Reaktion der AG mit n‐Butylamin (BA) und der Rücktitration des nicht umgesetzten Amins mit Perchlorsäure (HClO4) in Eisessig und (iii) Methode C, beruhend auf der Umsetzung der AG mit p‐Chloranilin (pCA) und nachfolgender Chlorbestimmung durch Schöniger‐Aufschluß. Während sich alle genannten Methoden prinzipiell für die AG‐Bestimmung in Gegenwart initialer SG empfehlen, ist darüber hinaus über A/H eine simultane Bestimmung von AG und SG möglich. Wegen dieses zusätzlichen Informationsgewinns, ihrer besseren Reproduzierbarkeit, der erhöhten Richtigkeit sowie des geringeren zeitlichen und apparativen Aufwandes ist die Kombination A/H zu favorisieren. Mit Hilfe der FTIR‐Spektroskopie wurde der Gehalt an AG und SG qualitativ verfolgt und eine Korrelation zwischen den Bandenintensitäten der AG und den potentiometrisch erhaltenen Werten gefunden.
Influence of structural parameters on the dynamic mechanical properties of polyacetals
Authors: Braun Dietrich , Ross Stefan
Published: April 2003

The dynamic mechanical behaviour of various polyacetals was determined by means of torsion pendulum measurements. The products used had different structural parameters such as molecular weight distribution or comonomer nature and content, respectively; thus it was possible to investigate the influence of these parameters on the temperature dependence of the storage modulus G′, which is a measure for the rigidity of the material, and the loss tangent tan δ from ‐100 to 160°C.

The storage moduli G′ are not influenced by different molecular weight distributions, but correlate with the crystallinity in the samples, which is, beside others, dependent on the concentration of the incorporated comonomer components. A decreasing crystallinity ‐ i.e. an increasing comonomer content ‐ is combined with a loss in rigidity.

The distance between the peak location of the α‐relaxation in the loss tangent curves and the melting points (differential scanning calorimetry) of the investigated acetal resins is nearly constant; thus the molecular motions causing the β‐process take place in the crystalline regions. The α‐process (around −7°C) arises predominantly from molecular motions of the comonomer units, whereas the intensity of this relaxation can be correlated with the mobility of these units. The peak of the γ‐relaxation is located around −67°C and does not hardly shift despite of different structural parameters in the sample, whereas its intensity decreases with increasing both comonomer contents and contents of low‐molecular‐weight components.

For unimodally distributed polyacetals with different comonomer contents, the intensity of the β‐relaxation increases with increasing comonomer contents; simultaneously the intensities of the α‐ and γ‐relaxatìon decrease.
Melt free‐radical grafting of glycidyl methacrylate onto polypropylene
Authors: Sun Yi‐Jun , Hu Guo‐Hua , Lambla Morand
Published: April 2003

This paper concerns free‐radical grafting of glycidyl methacrylate (GMA) onto polypropylene (PP) in the molten state carried out in a batch mixer. This free‐radical grafting proceeds very rapidly as it goes to completion within two to three minutes at 200°C. The grafting yield of GMA alone is low and it is greatly enhanced upon addition of styrene as a second monomer with a reduced chain degradation of PP. Homopolymer and copolymer of GMA formed during grafting were quantified. It is suggested that in the presence of styrene, the dominating grafting mechanism is that styrene reacts with the PP macroradicals to form more stable styryl macroradicals which then react with GMA to form GMA‐grafted PP. The rate of this reaction is much greater than that between the PP macroradicals and GMA. Unlike grafting of mixtures of maleic anhydride and styrene, which is dictated primarily by formation of a charge transfer complex, free‐radical grafting of GMA in the presence of styrene follows a random copolymerization process.
Synthesis and characterization of a naphthoquinonediazide positive photoresist derived from bis(hydroxymethyl)phenol
Authors: Liu Jui‐Hsiang , Liu Huang‐Tsai , Tsai Fu‐Ren
Published: April 2003

A new photosensitive naphthoquinonediazide (NQD) was synthesized from 2,6‐bis‐(hydroxymethyl)‐3,4‐dimethylphenol and toluene diisocyante. NQD was identified by using IR, NMR and elemental analyses. Photobleachable characteristics were evaluated by UV spectrophotometry. Applications of the NQD on the photolithography as a positive working photoresist were investigated. The aqueous solution of NQD, novolak, cellosolve acetate, and DMF was used as a photosensitive material. It was found that NQD synthesized in this investigation can be used as an effective component in a positive photoresist. Optimal conditions of the UV dose, coating thickness, and development of the resist system were estimated. Resolution of the positive resist was evaluated by SEM technique. Effects of UV dose, exposure time, development time, and exposure UV wave length on the sensitivity and resolution of the photoresist were investigated.
Modified syndiotactic polypropene: Poly(propene‐co‐octene) and blends with atactic oligopropene
Authors: Jüngling Stephan , Mülhaupt Rolf , Fischer David , Langhauser Franz
Published: April 2003

Propene and 1‐octene were copolymerized with the syndiospecific homogeneous metallocene catalyst Me2C(Cp)(Flu)ZrCl2/MAO. Large amounts of octene were incorporated randomly. While catalyst activity was not affected markedly by low octene content, molecular weight, crystallinity, Young's modulus, and glass transition temperature were reduced with increasing octene content. Blends of atactic oligopropene with syndiotactic polypropene and poly(propene‐co‐octene) were prepared from toluene solution and compared with a reactor blend prepared with a hybrid catalyst containing a mixture of syndiospecific Me2C(Cp)(Flu)ZrCl2/MAO and non‐specific Cp2ZrCl2/MAO. Atactic oligopropene acted as plasticizer reducing Young's modulus and glass transition temperature of the blends.
Investigations on free radical polymerization of phenyl‐substituted 2‐methylene‐1,3‐dioxanes
Authors: Schulze Thomas , Klemm Elisabeth
Published: April 2003

We have investigated the free radical polymerization of phenyl‐substituted 2‐methylene‐1,3‐dioxanes. It was shown that there is a basic tendency of such ketenacetals to undergo exclusively a vinyl polymerization forming high‐molecular polyacetals without any detectable ring opening. The polymerization with the desirable ring opening reaction cannot be controlled by factors like resonance stabilized chain ends or steric hindrance in the growing step.

From densitometric measurements we got new information about the shrinkage behaviour. It was demonstrated that bulky substituents attached to the 2‐methylene‐1,3‐dioxane system result in a significant low shrinkage in homopolymerization and the shrinkage of common comonomers can be decreased by copolymerization.
Acrylamide polymerization in concentrated bicontinuous systems
Authors: Vašková V. , Klimová M. , Bartoň J.
Published: April 2003

The polymerization of acrylamide (AAM) in concentrated bicontinuous microemulsion systems was studied. The locus of initiation using radical initiators with various water‐solubility was investigated. It was found that water‐soluble and partially water‐soluble initiators initiate the AAM polymerization in the reaction systems under investigation very effectively. The polymers thus formed have special structures dependent on the composition of the original concentrated bicontinuous microemulsion.
Grundlagen der Festphasenpfropfung von Polypropylen: Diffusion und Sorption von Pfropfkomponenten im PP‐Granulat
Authors: Rätzsch Manfred , Bucka Hartmut , Wohlfahrt Christian
Published: April 2003

Bei der Festphasenpfropfung von Polymeren spielen die Diffusion und die Gleichgewichtssorption eine entscheidende Rolle bei der Bestimmung der örtlichen Konzentration der Monomeren in Polymerpartikeln. Mit den vorgestellten Arbeiten ist es gelungen, die Fragen der Gleichgewichtssorption und der Diffusion verschiedener Komponenten im Polypropylen (PP) zufriedenstellend zu klären. Die Kombination von kinetischen und thermodynamischen Messungen mit einem modernen thermodynamischen Modell hat sich bewährt. Die Annahmen und Näherungen bei der Modellierung haben sich als akzeptabel erwiesen und ein schlüssiges Gesamtbild des Verhaltens der Modifikatoren im Polypropylenpartikel ermöglicht. Für die Beschreibung der Diffusionsgeschwindigkeit hat sich ein einparametriges Modell als ausreichend erwiesen. Durch eine Trennung der Transportwiderstände in Poren‐Diffusion und Festphasen‐Diffusion im amorphen Bereich können die experimentellen Daten nicht besser beschrieben werden.
Fully aromatic copoly(ester‐imide)s with high thermal stability
Authors: Gedan‐Smolka Michaela , Jehnichen Dieter , Komber Hartmut , Voigt Dieter , Böhme Frank , Rätzsch Manfred
Published: April 2003

Fully aromatic copoly(ester‐imide)s of various compositions were synthesized in bulk by conversion of N‐(3‐acetoxyphenyl)trimellitic acid imide and N‐(2‐methyl‐4‐acetoxyphenyl)trimellitic acid imide with 4‐acetoxybenzoic acid as comonomer. The solid state properties, the melting and phase behaviour of the copoly(ester‐imide)s differ largely, but all of them show high thermal stability. Some of the copoly(ester‐imide)s form mesophases in the melt.

Most of the investigated copoly(ester‐imide)s of N‐(3‐acetoxyphenyl)trimellitic acid imide and 4‐acetoxybenzoic acid and some of the ternary systems could be processed from the melt. Copoly(ester‐imide)s of N‐(2‐methyl‐4‐acetoxyphenyl)trimellitic acid imide and 4‐acetoxybenzoic acid, however, do not melt before rapid degradation at temperatures above 480°C.
Orientierung von Bacteriorhodopsin in einer Polymermatrix
Authors: Balfanz Friedhelm , Schwarz Hans‐Hartmut , Richau Klaus , Elling Burkhard
Published: April 2003

Bacteriorhodopsin ist Bestandteil der sogenannten Purpurmembran des Mikroorganismus Halobacterium halobium. Es zeigt photochemische Aktivität und kann als biologischer Lichtwandler fungieren. Voraussetzung hierfür ist eine orientierte Anordnung der Purpurmembran in einer Matrix.

Das Prinzip der ionotropen Gelbildung, d. h. die geordnete Strukturbildung einer Polyelektrolytlösung infolge eines gerichteten Diffusionsstromes von mehrwertigen Ionen gestattet die orientierte Anordnung der Purpurmembran. Durch Lichteinwirkung werden elektrische Signale induziert. Es besteht ein Zusammenhang zwischen der Richtung des Strahlungseinfalls und der durch die Gelwachstumsrichtung festgelegten Orientierung der Purpurmembran.
Radiation‐induced copolymerization of methacrylic and acrylic acid with acrylamide
Authors: Georgieva M. , Arabadjieva T. , Tsankov C.
Published: April 2003

A study was made of the γ‐radiation‐induced bulk copolymerization of the methacrylic acid‐acrylamide (M2) (MA‐AAm) and acrylic acid‐acrylamide (M2) (AA‐AAm) monomeric pairs. The copolymerization reactivity ratios deterined according to the Kelen‐Tüdő method were: r1 = 1.35, r2 = 0.22 for the MA‐AAm pair, and r1 = 1.75, r2 = 0.10 for the AA‐AAm pair. It has been established that the polymerization rate depends both on the composition of the starting reaction mixture and on the reaction temperature. The differential kinetic curves obtained are unimodal ones, suggesting the occurrence of only one process, i.e. copolymerization. A second maximum in these curves, appearing at elevated temperature, is explained by crosslinking and formation of a water‐insoluble fraction. The copolymers obtained are white powders; in contrast to their water‐insoluble fractions, the water‐soluble ones are not toxic but they are less active as immunomodulators.
Metal ion sorption ability of poly(4‐vinylpyridine‐co‐N,N‐dimethylacrylamide)
Authors: Rivas B. L. , Maturana H. A. , Pereira E.
Published: April 2003

Resins containing amide and 4‐vinylpyridine moieties were synthesized by radical polymerization. All the resins were completely insoluble in water and characterized by FT‐IR spectroscopy, elemental analysis and thermal analyses. The ability to bind Cu(II), Fe(II), Fe(III) and U(VI) ions at different pHs was studied by batch equilibrium procedure. Uranium(VI) was adsorbed at pH 1 above 50% by the resins 1 and 2. The selectivity of uranium(VI) respect to copper(II) at pH 1.0 was 2.11. The uraniumloaded resin 2 could be partially recovered by treatment with H2SO4 and Na2CO3.
Synthesis and characterization of modified phenolics and their application as curing agent for epoxies
Authors: Patel R. T. , Patel S. P. , Patel R. D.
Published: April 2003

A series of novolak type resins were prepared by reacting formaldehyde with various phenoxy acetic acids using HCl as catalyst. All the synthesized resins were characterized by spectral studies (IR), viscometric measurements and by estimating the numberaverage molecular weight by vapour‐pressure osmometry. Two of these resin samples were used as curing agents for epoxy resins for studying the kinetics of curing by DSC technique. The cured epoxies were tested for thermal stability. These resins impart very good heat resistance to epoxy systems.
Tack of pressure‐sensitive adhesives with 4‐nonylphenol formaldehyde novolac resins as tackifiers
Authors: Roşu Dan , Caşcaval Constantin N. , Simionescu Cristofor I.
Published: April 2003

The tack, expressed as the rolling friction coefficient of some pressure‐sensitive adhesives obtained on the basis of natural rubber and 4‐nonylphenol formaldehyde novolac resins of viscosities in the range of 13.6–2065·7 Pa · s, was measured at 20°C by rolling motion of a ball as a function of the nature of the resin in adhesives, its concentration, thickness of the adhesive and velocity of the ball. The maximum amount of the tackifier resin to be used for a high tack of an adhesive depends on the type of resin and its solubility in the rubber phase. The tack of the tested adhesives is a function of the rheological properties. The correlation found between the apparent shear viscosity and the rolling friction coefficient showed that the best results are obtained for rubber‐resin mixtures with viscosities ranging within 1.7 · 106 and 3.4 · 108 Pa · s.
Synthesis and properties of fiber‐grade poly(trimethylene terephthalate)
Authors: Traub H. L. , Hirt P. , Herlinger H. , Oppermann W.
Published: April 2003

Poly(trimethylene terephthalate) was synthesized on a semi‐technical scale following the trans‐esterification route. Ester exchange as well as polycondensation were catalyzed by titanium tetrabutylate. The polymer formed shows a remarkable degree of whiteness, contrary to poly(ethylene terephthalate) when synthesized with the aid of titanium compounds. Polymers having molar masses up to 70000 (weight average) were obtained suitable for melt spinning. The Mark‐Houwink parameters for solutions in 1,1,2,2‐tetrachloroethane/phenol (1 : 1, w/w) were determined using static light scattering as a calibration. The melt volume index (235°C, 1.2 kg) was typically in the range 20–30 mL/10 min for a polymer having a weight‐average molar mass of 50000–60000 g mol−1.
Synthesis of chemically bonded poly(vinyl alcohol)‐starch composite
Authors: Hashem Mohamed M. , Bach Elke , Kesting Wolfgang , Hebeish Ali A. , Schollmeyer Eckhard
Published: April 2003

Poly(vinyl alcohol) (PVA) was grafted on hydrolysed starch through introduction of the chemically reactive bifunctional compound N‐methylolacrylamid (N‐MAm). The grafting reaction was carried out in two separate reaction steps. The first step was the reaction of PVA with N‐MAm in alkaline medium. The reaction mechanism and reaction conditions such as alkali concentration, temperature, reaction time as well as N‐MAm concentration were studied. According to the results obtained, the most appropriate conditions for the preparation of this reactive PVA are: treating PVA with N‐MAm (1.25 mol/mol PVA) in the presence of NaOH (6% based on solution volume) at 20°C for 8 h. Second step was the reaction of this reactive PVA (N‐MAm‐PVA) with hydrolysed starch in the presence of NH4Cl. The latter was carried out under different conditions including temperature, reaction time, catalyst concentration as well as N‐MAm‐PVA/hydrolysed starch ratio. The results obtained show that the extent of the grafting reaction is governed by each of these factors. Furthermore, GPC data showed that the molecular weight distribution and the apparent viscosity of PVA‐N‐MAm‐starch composite depend on the initial molecular weight of both PVA and hydrolysed starch used.
Sulfonated polyurethane ionomers in solution
Authors: Robilǎ Gabriela , Buruianǎ Tinca , Buruianǎ E. C.
Published: April 2003

Aqueous and DMF‐diluted solutions of polyurethane ionomers with sodium propanesulfonated groups at urethanic nitrogen atoms were studied by viscometry. A polyelectrolyte effect was evidenced at temperatures between 25 and 60°C, and it was preserved when NaCl was added to solutions.

The coulombic interactions between charged groups and a tendency to aggregation in separated domains (favoured by specific molecular architecture of polymers) explain the observed solution properties.
Synthesis and characteristics of chiral polymers with camphanediol moieties
Authors: Liu Jui‐Hsiang , Tsai Fu‐Ren , Lai Yuh‐Chung
Published: April 2003

Optically active exo,exo‐2,3‐camphanediol (CPO) was synthesized from (+)‐camphor. The chiral polymers poly(CPO‐co‐TDI) and poly(CPO‐co‐IPDI) were synthesized by step polymerization of chiral compound CPO with toluene‐2,4‐diisocyanate (TDI) and isophorone diisocyanate (IPDI). Effects of solvents, reaction time and temperature on the polymerization were investigated. To investigate the stereo structure of the chiral polymers, two kinds of model compounds, exo‐exo‐2,3‐bornylene N,N′‐diphenyldicarbamate and exo,exo‐2,3‐bornylene N,N′‐dipropyldicarbamate, related to the prepared polymers were synthesized. Chiroptical characteristics and stereo structures of the chiral polymers were investigated by using a circular dichroic spectrometer. Effects of temperature and solvents on the specific rotation of the chiral polymers were evaluated. The results obtained in this investigation suggest that the synthesized chiral polymers have no one‐handed helix conformation.
Effect of substitution of monoester by diester on titanium‐magnesium catalyst properties in propene polymerization
Authors: Talapatra Subhasis , Dudchenko Vyacheslav K. , Bukatov Gennadii D. , Zakharov Vladimir A. , Okkel Lidiya C.
Published: April 2003

Titanium‐magnesium catalysts (TMC), containing monoester (ethyl benzoate) as internal donor, can be transferred to the diester TMC by the treatment with TiCl4 and dibutyl phthalate. The activity and the stereospecificity of the transferred TMC in propylene polymerization are close to those of TMC prepared directly in the presence of diester. The surface area and the porous structure of both types of TMC were studied and the correlation with the activity of these catalysts is discussed.
Physical, dynamic‐mechanical and thermogravimetric analysis of aromatic and cycloaliphatic‐based poly(urethaneurea)s
Authors: Cascella Ciro , Malinconico Mario , Martuscelli Ezio , Piermattei Alessandro , Ragosta Giuseppe , Rizzo Adriana
Published: April 2003

Experimental batches of linear rubber‐like polyurethanes characterized by the presence of chemically different hard segments are studied and their thermal and dynamic‐mechanical properties are related to the differences in chemical compositions. Interesting correlations are found between the development of crystallinity in such elastomeric poly(urethaneurea)s and the aromatic or alicyclic nature of the diisocyanate. Moreover, for a fixed ratio between hard and soft segments, and for a given composition of the soft segment, the results seem to indicate a better degree of phase separation in cycloaliphatic‐based hard segment poly(urethaneurea)s than in aromatic‐based hard segment poly(urethaneurea)s.
Photopolymerization of styrene and methyl methacrylate using macro photoinitiators. Synthesis and characterization of PS‐PEG‐PS or PMMA‐PEG‐PMMA block copolymers
Authors: Cakmak Ismail
Published: April 2003

Macro photoinitiators based on poly(ethylene glycol)s (PEG) bearing benzoyl xanthate moieties were synthesized by the reaction of PEG xanthates with benzoyl chloride. These macro photoinitiators possessing PEGs of different molecular weights were used in the photoinduced radical polymerization of styrene (S) and methyl methacrylate (MMA) to yield block copolymers having an inner‐PEG segment. The influence of the concentration of reactants and polymerization time on the yield and intrinsic viscosities of block copolymers were also investigated. Characterization of block copolymers was carried out by fractional precipitation and IR, UV and 1H NMR spectroscopic methods.
The synthesis of pyridyl‐substituted polyurethanes and copolyurethanes
Authors: Dzo‐Song‐O  , Bouchal Karel , Bleha Miroslav , Kříž Jaroslav
Published: April 2003

New reactive polyurethanes with structure units substituted with pyridine rings were prepared by the polyaddition reaction of diphenylmethane‐4,4′‐diisocyanate or dicyclohexylmethane‐4,4′‐diisocyanate with 2‐methyl‐2‐(4‐pyridyl)propane‐1,3‐diol (MPyP). Copolyurethanes based on this diol were synthesized by a one‐ or two‐step procedure carried out in bulk or diglyme solution using hexane‐1,6‐diol (HD), α,ω‐dihydroxypoly(oxyethylene)s of various molecular weights (POE 400, 1000 and 2000) or α,ω‐dihydroxypoly(oxypropylene) (PPO 400) as comonomers.

Pyridyl‐substituted polyurethanes and copolyurethanes were characterized by their 1H and 13C NMR spectra and limiting viscosity numbers [η]. The pyridine units were determined acidimetrically (HClO4). The reactivity of the OH groups of the pyridine diol towards NCO groups was characterized by determining the rate constants of its reaction with phenyl isocyanate. The obtained value of 2.45 × 10−3 dm3 mol−1 s−1 (25°C) was by an order of magnitude greater than the rate constant for the addition of hexane‐1,6‐diol. This difference was interpreted in terms of a catalytic mechanism for the addition of MPyP.
Modell zur beschreibung der glasübergangstemperaturen binärer und ternärer mischungen von poly(styrol‐co‐n‐butylmethacrylat)en
Authors: Schellenberg Jürgen
Published: April 2003

Die Glasübergangstemperaturen binärer und ternärer Mischungen chemisch einheitlicher Poly(styrol‐co‐n‐butylmethacrylat)e mit einem mittleren n‐Butylmethacrylat‐Anteil von 30,8 Gew.‐% und unterschiedlichen zahlenmittleren Molmassen im Bereich von 4900 bis 67000 g/mol wurden in Abhängigkeit von der Zusammensetzung untersucht. Es wurden wesentliche Abweichungen vom idealen Verhalten bezüglich einer linearen Abhängigkeit zwischen Glasübergangstemperatur und Zusammensetzung festgestellt.

Dieses Verhalten konnte mit einem mathematischen Modell dargestellt werden, wobei sich insbesondere Polynome zur Beschreibung der teilweise über den Werten der Ausgangskomponenten liegenden Glasübergangstemperaturen der Mischungen als geeignet erwiesen. Schließlich wurden verschiedene Ursachen für diese Abweichungen diskutiert, wobei offensichtlich energetische Wechselwirkungen verbunden mit einer Nichtadditivität der Volumina von wesentlicher Bedeutung sind.
Stabilizer consumption and lifetime prediction in ageing of crosslinked polyethylene
Authors: Audouin L. , Langlois V. , Verdu J. , Rouyer E.
Published: April 2003

The thermal oxidation of β ray‐crosslinked polyethylene (XLPE) was studied in temperatures ranging from 90 to 180°C. Various analytical methods were used for determination of an end of the induction period on bulk samples: gravimetry, ultimate tensile properties, density and color change. On microtome slices of ∼30 μm thickness the depth distribution of oxidation products, phenolic antioxidant, density and tensile ultimate properties were followed as a function of exposure time by respectively IR and UV spectrophotometry, densitometry and Microfoil Tensile Testing.

Depending on the testing method different durations of induction period (DIP) were obtained. They increase in following order:

Phenol depletion < Ultimate elongation < Density < Carbonyl build‐up ≤ Color change < Weight loss.

The difference between phenol depletion DIP and carbonyl build‐up DIP can be considered as negligible at temperatures higher than the melting point (about 30%) but it reachs more than 100% at T< Tm.

Different kinetic regimes of phenol consumption were observed depending on the exposure temperature. A mechanistic interpretation is proposed explaining the role of the stabilizer system in initially homogeneous and later heterogeneous oxidation of the bulk material.

The Arrhenius law was applied to different durations of induction period. A discontinuity appeared in the melting point region (120–130°C) which is tentatively interpreted in terms of different stabilizer concentration in amorphous phase of semicrystalline material (T < Tm) and in melt material (T > Tm). On the basis of the presented complex study of polyethylene thermo‐oxidation, different aspects of lifetime predictions are discussed.
New trends in epr and epr kinetics studies in the stabilization mechanism by N‐oxyl radicals
Authors: Faucitano A. , Buttafava A. , Mongini G. , Martinotti F. , Berzero A. , Greci L. , Mar'in A. , Neri C. , Farris R.
Published: April 2003

The mechanism of the solid state oxidation of isotactic polypropylene films and the the mechanism of inhibition by HALS have been investigated by kinetic‐ESR and kinetic modelling with derivation of the rate constants for the sensitive steps in the reaction scheme. The results have shown the inadequacy of the Denisov cycle to account for the observed experimental kinetics of the intermediate nitroxyl radicals. The molecular dynamics associated with the oxidation inhibited by HALS in the polypropylene matrix has been investigated by applying the Liouville stochastic method to the analysis of the temperature effects of the ESR spectra of the intermediate nitroxyl radicals used as spin probes. The investigation on the nature and characteristics of the molecular motions available at the oxidation sites has also been carried out with nitroxyl spin labels bound to the PP chains. For this application a novel method of spin labelling was developed based on reactions with some of the oxidation products, namely the terminal and intrachain ketones (keana method), alcohols, peroxides and macroalkyl radicals.
Model studies on the mechanism of hals stabilization
Authors: Step Eugene N. , Turro Nicholas J. , Klemchuk Peter P. , Gande Matthew E.
Published: April 2003

Hindered Amine Light Stabilizers (HALS) are know to inhibit the photo‐oxidation of polymers. A key reaction in their stabilization mechanism is believed to be the conversion of a hindered aminoether into a nitroxyl radical. Several different possible mechanisms for this conversion were explored. One, the elimination of the aminoether to form an olefin and hydroxylamine (an intermediate in the formation of a nitroxyl), while possible at high temperatures, cannot account for the inhibitory activity we observed for secondary and primary aminoethers. Direct radical displacement by peroxy radicals was also considered. However, the products predicted by this reaction pathway were not observed. Finally, oxidation of the nitrogen by a peroxy radical, by either electron transfer or a radical attack on the nitrogen, was investigated. While electron transfer was shown to be unlikely, direct oxidation of the aminoether nitrogen was supported by our results. A detailed mechanism for the reaction of both alkyl‐ and acyl‐peroxy radicals with aminoethers is proposed.
FT‐IR emission studies of polymer oxidation
Authors: George G. A. , Vassallo A. M. , Cole‐Clarke P. A. , Celina M.
Published: April 2003

The theory and application of mid‐IR emission spectroscopy to the study of the oxidation of single reactor particles of unstabilized polypropylene (0.4 to 40μg) is described. The rate of formation of carbonyl and γ‐lactone oxidation products is followed by FT‐IR emission at 150°C and is interpreted within a heterogeneous model of solid state oxidation. The results are compared with the reported chemiluminescence from single polypropylene particles and evidence is presented for concerted oxidation when the particles are in close proximity.
Thermohydrolytic ageing of polynadimide IP960
Authors: Hilaire B. , Verdu J.
Published: April 2003

This study deals with the thermal ageing of a polynadimide matrix IP 960, developed for composite aircraft applications in the 250 −300°C temperature range. In a first chapter, it is tried to give a suitable representation of the network structure on the basis of literature data, analytical results and rubbery modulus measurements. Ageing in air at 300 −360°C is then studied. The role of diffusion control of degradation kinetics is shown from comparison of samples of various volume/surface ratios. The crucial role of sorbed water is put in evidence. Ageing in vacuum at 360°C allows to reveal the existence of at least three kinetics steps. The corresponding degradation mechanisms are discussed. Chemical (NMR, FTIR, UV) as physical (weight loss, water sorption or mechanical testing) are used to quantify the sample degradation.
Sulfonated polysulfone membranes with antifouling activity
Authors: Poźniak Gryzelda , Bryjak Marek , Trochimczuk Witold
Published: April 2003

The protein fouling phenomenon was investigated on modified polysulfone ultrafiltration membranes. The sulfonation degree was correlated to the extent of deposition of bovine serum albumin. It was shown that membranes prepared from modified polysulfone were less fouled than their off‐charge analogues. The fouling phenomenon was also investigated for membranes prepared from co‐cast blends. It was demonstrated that blends containing more than 50 wt.‐% of sulfonated derivative behaved like a membrane from pure sulfonated polysulfone. The effect was attributed to surface separation of polymers and formation of surfaces enriched with sulfonic groups.
Synthesis and characterization of UV curable acrylated urethane prepolymers, II. Effects of various diacrylates as diluents and relative humidity on mechanical properties of TDI/PEG/HEMA‐based polymeric films
Authors: Yildiz Emel , Güngör Atilla , Yildirim Hüseyin , Baysal Bahattin M.
Published: April 2003

Various UV‐curable acrylated urethane prepolymers based on tolylene‐2,4‐diisocyanate (TDI), poly(ethylene glycol) (PEG 400), and 2‐hydroxyethyl methacrylate (HEMA) were synthesized. The effects of reactive diluent types, the composition of the products and of different humidity conditions on mechanical properties of cured films were investigated. Effects of diethylene glycol diacrylate (DEGDA) and thiodiethylene glycol diacrylate (TDGDA) as reactive diluents on tensile strength, elongation and Young's modulus values of the UV cured films were examined systematically. The results show that the increase of relative humidity from 50 to 95% leads to a decrease in tensile strength and Young's modulus values of polymeric films. The decrease of these mechanical properties in high relative humidity is due to the formation of hydrogen bonding in the polymer chain caused by water molecules.
Photovieillissement d'un copolymère d'éthylène et d'acétate de vinyle en présence de sueur artificielle. I. Analyse de i'évolution chimique au voisinage des faces altérées
Authors: Rigny‐Bourgeois V. , Dubois C. , Mercier M.‐F. , Chambaudet A.
Published: April 2003

Une cellule de photovieillissement artificiel et accéléré est aménagée pour étudier le comportement de polyméres, en présence de sueur artificielle. Un copolymére d'éthyléne et d'acétate de vinyle (EVA) est soumis à un photoviellissement dans cette cellule. Parallélement, le photovieillissement est réalisé sans sueur artificielle afin de comprendre le rôle de ce substrat. Des études similaires sont également conduites sur cet EVA contenant des stabilisants lumière.

L'évolution chimique est suivie par spectrométrie IR‐ATR au voisinage des surfaces directement irradiées ou immergées. La comparaison des résultats obtenus selon les différentes voies fait principalement ressortir une combinaison des effets de la photooxydation et de l'hydrolyse, l'activation de l'hydrolyse par l'irradiation et l'action efficace des stabilisants lumière vis à vis de la photooxydation.
Unsaturated alcohols and glycols containing ionizable groups for synthesis of urethane acrylate graft copolymer latices
Authors: Saija Leo M. , Umiński Maciej
Published: April 2003

Unsaturated alcohols and glycols bearing carboxylic groups were synthesized from maleic anhydride (MA) and alcohols with 2 or 3 hydroxy groups. The halfester monomers were characterized by IR and NMR spectroscopy and were used for the preparation of urethane macroionomers and urethane acrylate graft copolymer latices. Obtained polymers were characterized by solubility and mechanical tests.
Zur bildung von polyepoxid‐polyamid‐netzwerken. Modelluntersuchungen am system phenylglycidether‐ε‐caprolactam
Authors: Tänzer Wolfram , Ludwig Ina
Published: April 2003

Es wurden Versuche zur Homopolymerisation von ε‐Caprolactam (CL) und Phenylglycidether (PGE) mit den Initiator/Beschleuniger‐Systemen Na‐Caprolactam/N‐Acetylcaprolactam (NaCL/AcCL) und Na‐Caprolactam/N‐Acetylimidazol (NaCL/AcImi) durchgeführt, um die für eine mögliche Copolymerisation von CL und PGE geeigneten Reaktionsbedingungen zu ermitteln. CL und PGE wurden in unterschiedlichen molaren Verhältnissen (CL : PGE = 1 : 5 bis 1 : 0,05) und bei Temperaturen zwischen 100°C und 140°C (max. 240°C) in einer Eintopfreaktion polymerisiert.

Die löslichen Produkte wurden mittels HPLC getrennt und spektroskopisch identifiziert. Die in Aceton unlöslichen Produkte wurden mit IR‐ und NMR‐Spektroskopie, Massenspektrometrie (MS) und Elementaranalyse untersucht.
Characteristics of permeation and separation of aqueous alcoholic solutions through a poly[bis(2,2,2‐trifluoroethoxy)phosphazene] membrane by evapomeation and pervaporation
Authors: Uragami Tadashi , Morikawa Takeshi
Published: April 2003

The characteristics of permeation and separation for aqueous solutions of methanol and ethanol through a poly[bis(2,2,2‐trifluoroethoxy)phosphazene] (PBTFP) membrane were studied by pervaporation and evapomeation. In pervaporation technique, methanol was preferentially permeated in all of the feed solution compositions and ethanol was permeated in lower ethanol concentrations of the feed solution. Water was predominantly permeated from the feed solutions with higher ethanol concentration. In evapomeation technique, water was selectively permeated in both all of the feed vapor compositions for aqueous methanol and ethanol solutions. These different permselectivities depended on the feed composition and the membrane permeation technique and could be discussed by a difference in the mechanisms of permeation and separation. It was found that the permeation rate was influenced remarkably by the degree of swelling of the PBTFP membrane and the permselectivity for water of aqueous alcoholic solutions was enhanced by an increasing degree of swelling of the membrane. When the degree of swelling of the membrane with rising permeation temperature was small, both the permeation rate and permselectivity for alcohol in pervaporation and evapomeation increased with the permeation temperature. The above results are discussed considering the PBTFP membrane structure in evapomeation and pervaporation.
Homogeneity of styrene‐maleic anhydride‐methyl methacrylate terpolymers in batch polymerization processes
Authors: Szirmai László
Published: April 2003

The formation of styrene‐maleic anhydride‐methyl methacrylate terpolymers was studied in batch polymerization process. The process of polymerization was investigated in quasi‐steady‐state time periods by the Markov statistics. The results of the calculations for high conversions were compared with the experimental results. Based on the advantage of the method, PVC blends were produced which (with 40% of blend component) increased the Vicat‐A and Vicat‐B heat‐resistance of PVC by 40–43°C and 18–21°C, respectively.
Structural investigations on low‐molecular‐weight polyisobutenes
Authors: Günther Wolfgang , Maenz Karsten , Stadermann Dietmar
Published: April 2003

Structural investigations of low‐molecular‐weight polyisobutenes synthesized by selective polymerization and of commercial polyisobutenes were made by 1H‐ and 13C‐NMR spectroscopy. It is possible to attribute the signals to “normal” and to some unusual olefinic structures. A comparison was made to literature data.
A novel process for the chlorination of polymers in solution
Authors: Friese K. , Hößelbarth B. , Reinhardt J. , Newe R.
Published: April 2003

A new uniform process for the solution chlorination of PVC, PE, and natural rubber has been developed with initiation by γ‐irradiation or radical initiators (azocompounds). The solvent used is dichloromethane instead of the industrially used tetrachloroethane or tetrachloromethane. The reaction is carried out in an autoclave with stirrer at temperatures between 70 and 100°C and pressures from 4 to 7 bar. As a result of the simultaneous chlorination of the solvent, trichloromethane is formed and only less than 1 wt.‐% tetrachloromethane. Characterization of the chlorinated polymers by DSC and NMR measurements showed no differences to conventionally chlorinated products.
Kinetik der polykondensation von natriumsulfidhydrat und 1,4‐dichlorbenzol zu poly(thio‐1,4‐phenylen)
Authors: Dauben Michael , Platkowski Kristina , Reichert Karl‐Heinz
Published: April 2003

Die Kinetik der Polykondensation von Natriumsulfidhydrat und 1,4‐Dichlorbenzol in 1‐Methyl‐2‐pyrrolidon zu Polyphenylensulfid

Systematischer Name: Poly(thio‐1,4‐phenylen).

im Temperaturbereich von 220 bis 280°C wurde mit Differential Scanning Calorimetry untersucht. Es wurde festgestellt, daß die Polykondensation autokatalytisch verläuft, wobei die Kinetik mit Modellansätzen einfacher Form über nahezu den gesamten Umsatzbereich gut beschrieben werden kann. In allen Fällen haben sich Gesamtreaktionsordnungen von etwa eins als optimal für die Anpassung der Geschwindigkeits‐Umsatz‐Verläufe erwiesen. Dieses wird mit der Tatsache erklärt, daß Natriumsulfid im untersuchten Temperaturbereich nur in geringen Mengen in komplexierter Form in 1‐Methyl‐2‐pyrrolidon löslich ist und dessen Konzentration näherungsweise als zeitlich konstant angesehen werden kann. Der autokatalytische Effekt wird erklärt mit der Zunahme der Geschwindigkeitskonstanten im Anfangsbereich der Polykondensation, wobei als Ursache hierfür eine wachsende Reaktivität der Oligomeren mit der Kettenlänge angenommen wird. Mittels stochastischer Methoden können Zahlen‐ und Massenmittelwert des Polykondensationsgrades der während des Reaktionsprozesses entstehenden Produkte modelliert werden. Dabei wird von einem einfachen Modell mit zwei verschiedenen Geschwindigkeitskonstanten im Kondensationsgeschehen ausgegangen. Für eine befriedigende Beschreibung der Molmassen muß die Konzentration von Natriumsulfid in der reaktiven Phase über nahezu den gesamten Umsatzbereich als konstant angesehen werden, wobei sie etwa 2–5% des Wertes der Dichlorbenzol‐Konzentration zu Reaktionsbeginn beträgt.
Synthesis and characterization of poly(vinyl alcohol)‐β‐cyclodextrin copolymer
Authors: Sreenivasan K.
Published: April 2003

A poly(vinyl alcohol)‐β‐cyclodextrin (PVA‐BCD) copolymer was prepared by successive reaction of BCD with toluylene diisocyanate and PVA. Copolymer formation was evidenced by infrared spectroscopy, differential scanning calorimetry and gel permeation chromatography. Scanning electron micrographs show morphological differences between PVA and the copolymer. The copolymer, being almost insoluble in common solvents with an equilibrium swelling in water of 50%, is a potential membrane material.
Study on electrorheological properties of semiconducting polyaniline‐based suspensions
Authors: Xie Hong‐Quan , Guan Jian‐Guo
Published: April 2003

Electrorheological (ER) fluids composed of a dispersing medium with a low dielectric constant and polyaniline particles, deprotonated with ammonia or sodium hydroxide at different concentrations for 24 h were studied. The effects of dielectric constant, conductivity and volume fraction of the polyaniline particles, the kind of dispersing medium, addition of surfactant, as well as the electric field strength and temperature on the ER properties of the ER fluids were investigated. The results showed that a moisture‐insensitive, highly ER‐active fluid can be obtained from chlorinated paraffin oil and polyaniline particles deprotonated with ammonia water at certain pH values and exhibited a static yield stress > 10 kPa and current density < 40 μA cm−2 at 2.8 kV mm−1 DC electric field.
Pultruded fiber‐reinforced polyurethane‐toughened phenolic resin, I. Reactivity and morphology
Authors: Wu Hew‐Der , Ma Chen‐Chi M. , Lee Ming‐Shiu , Wu Yin‐Don
Published: April 2003

A phenolic resin/polyurethane copolymer was synthesized by reaction of a phenolic resin, a blocked‐polyurethane and p‐toluene sulfonic acid. The copolymer provides a good balance between the processability (including pot life, reactivity) and toughness. The reactions that proceeded during the synthesis of the copolymer was investigated by IR spectroscopy. It was found that blocked polyurethane reacted with the hydroxy group of the phenolic resin. Glass fiber‐reinforced composites showed excellent bonding between fiber and matrix as revealed by SEM photographs. An overlap peak was found from the DMA diagram; it indicated that an interaction existed between phenolic resin and polyurethane and that improved the toughness of the phenolic resin.
Wasserabsorptionseigenschaften natürlicher polyionenkomplexe
Authors: Ichikawa Tomoko , Nakajima Toshinari
Published: April 2003

Die Wasserabsorptionseigenschaften natürlicher Makromoleküle, die als kationische Aminogruppen das Polysaccharid Chitosan oder das Polypeptid Polylysin und als anionische Carboxygruppen das Polysaccharid Carboxymethylcellulose oder das Polypeptid Polyglutaminsäure (PGA) enthalten, wurden untersucht. Bei Kombinationen von Polysacchariden oder Polyaminosäuren untereinander zeigten Gemische mit einem Ionenverhältnis von 1 : 1 die geringste durch Wasser hervorgerufene Quellung. Demgegenüber fand sich im Falle von Chitosan/PGA‐Gemischen bei Zusammensetzungen mit PGA‐Überschuß ein Minimalwert, während die Polyaminosäuren eine strukturell verhältnismäßig freie räumliche Anordnung einnahmen.

Durch Vergleiche der durch DSC‐Analyse bestimmten Enthalpien wurde bestätigt, daß die Komplexe mit Pyranose‐Ringstrukturen enthaltenden Filmkomponenten größere Mengen Wasser in Form von nicht ausfrierbarem Wasser halten können. Ferner ergab ein Vergleich der mechanischen Festkörpereigenschaften, daß sich bei Zusammensetzungen der Komplexe mit großen Mengen an Polysacchariden eine Tendenz zu einem erhöhten Elastizitätsmodul zeigt.