bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and application of thermosensitive microcapsules containing azo groups
Authors: Nuyken Oskar , Dauth Jochen , Pekruhn Wolfgang
Published: April 2003

In view of applying thermolabile microcapsules with azo groups as thermosensitive sites it was necessary to study the preparation and the thermal behaviour of two reactive, symmetrical azo monomer‐compounds and model compounds. They are thermally and photochemically instable and the kinetics of their decomposition is of first order, comparable to that of AIBN.

Azo group‐containing polyamides and polyureas were prepared by interfacial polycondensation reaction from ethylendiamine, 1,6‐hexamethylenediamine, diethylenetriamine and azo monomer‐compounds.

These polymers were used to prepare thermosensitive microcapsules. Favourable conditions were found to obtain microcapsules of uniform size, in a high yield, and with good properties in thermo‐transfer‐print.
Microemulsion polymerization of vinyl acetate
Authors: Donescu Dan , Anghel Dan , Gosa Kristiana , Balcan Marieta
Published: April 2003

Vinylacetate (VAc) was polymerized with ammonium persulfate in microemulsions prepared from VAc, sodium dodecyl sulfate, n‐propanol and water. The polymerization rates were smaller than those in emulsion. The reaction orders versus the initiator and tenside concentration were 0.9 and −0.5, respectively. The polymerization rate and molecular weights decreased by increasing the surfactant and the cosurfactant concentrations. By cooling the finally obtained microemulsions, a polymer solution coacervation took place.
Filled compounds of the β‐modification of polypropylene
Authors: Varga József , Tóth Ferenc Schulek
Published: April 2003

Possibilities and thermal preconditions of the preparation of filled β‐PP composites were studied. Two types of mineral fillers (chalk and talc) were found considerably different. Chalk, as a weak α‐nucleating agent, exerts minimum influence on the rate of crystallization, on the polymorphic composition, and on the size of spherulites formed. Consequently, chalk‐filled β‐PP composite products can be manufactured in a wide range of composition. On the contrary, talc is a strong selective α‐nucleating agent, thus it has a great influence on the course of crystallization and on the polymorphic composition. Even at a low concentration (C ≥ 1%), talc suppresses the formation of the β‐modification. In its presence, only products of high proportion of β‐modification can be prepared.

Mechanical characteristics of the composites were determined.
Studies on hydride terminated methylhydro‐dimethylsiloxane copolymers
Authors: Joseph M. A. , Haque S. A. , Grover S. S. , Francis D. J.
Published: April 2003

Synthesis of hydride terminated methylhydro‐dimethylsiloxane copolymers from the hydrolyzates of 10, 20, 30, 50 and 70% vol.‐% dichloromethylsilane with dichlorodimethylsilane have been carried out. The copolymers were characterized by IR‐and 1H‐NMR‐spectroscopy and standard chemical analysis. They were used as curatives for a standard vinyl functional room temperature vulcanizing (RTV) silicone material based on addition cure, and the vulcanizate properties have been evaluated. The copolymers with high hydride content gave better mechanical properties and thermal stability to the vulcanizates.
Thermal behaviour of TiO2‐encapsulating polymers
Authors: Haga Yutaka , Watanabe Takanobu , Yosomiya Ryutoku , Isizawa Ryosyo
Published: April 2003

Comparing the thermal properties of TiO2 encapsulating polystyrene and poly(methyl methacrylate) with those of TiO2 dispersion polymers it was found that the encapsulating polymers have two thermal relaxation regions. The activation energy of those thermal relaxation regions was determined using the Wunderlich method and it was found that the values are similar to the activation energy for the dynamic dispersion. It is suggested that the low‐temperature thermal relaxation is caused by the local change of conformation of molecular chains, while the high‐temperature thermal relaxation is similar to that of the normal glass transition temperature including the interaction with TiO2. In addition, the thermal behaviour near the degradation point in different atmospheres indicates that the encapsulating polymer has a specific structure for adsorbing a large amount of oxygen.
Photooxidation of polyacetal copolymers, 1. A preliminary study of the long wavelengths photooxidation
Authors: Gardette Jean‐Luc , Sabel Hans‐Dieter , Lemaire Jacques
Published: April 2003

Photooxidation of three polyacetals is described. These copolymers present different structures, but it is shown that the presence of CC bonds vicinal to oxygen or the presence of tertiary carbon do not control their photoreactivity. The final photoproducts were identified by chemical treatments associated to IR spectroscopy. A mechanism involving primary hydroperoxides is proposed, which leads to the formation of carbonates, formates, and hydroxylated compounds.
Etude du vieillissement d'un assemblage métal/adhésif/métal par impédancemétrie électrique et viscoélasticimétrie
Authors: Bourahla Hamid , Lenoir Jeanine , Chauchard Jacques , Romand Maurice
Published: April 2003

L'évolution des caractéristiques électriques d'un assemblage collé acier inoxydable/adhésif en film/acier inoxydable est étudiée en fonction du temps de vieillissement en atmosphère chaude et humide. A partir de mesures non destructives d'impédance électrique, il est montré que l'absorption d'eau par le joint conduit à une diminution de sa résistance en basse fréquence et à un accroissement de sa constante diélectrique. La sorption d'eau dans le joint résulte de deux processus simultanés:

— La fixation de molécules d'eau sur les sites polaires de l'adhésif. Ce phénomène est caractérisé par une dispersion électrique croissante en basse fréquence.

— La migration d'eau libre dans des microcavités. Ce phénomène entraîne un accroissement de la permittivité en haute fréquence.

La proportion relative de ces deux phases (eau structurale et eau libre) est également donnée.

D'autre part, ce travail montre que la nature du traitement de surface du métal provoque une modification de la cinétique de sorption d'eau.

Ces résultats sont en accord avec ceux obtenus par analyse thermomécanique dynamique.
Aliphatisch‐aromatische polyethersulfone, II. Polykondensationsprodukte aus bis‐(4‐hydroxyphenyl)‐sulfon und bis‐(4‐chlormethylphenyl)‐verbindungen—synthese und struktur
Authors: Podkościelny Wawrzyniec , Dethloff Jadwiga , Dethloff Michael , Brunn Joachim
Published: April 2003

Durch Polykondensationsreaktionen von Bis‐(4‐hydroxyphenyl)‐sulfon mit Bis‐(4‐chlormethylphenyl)‐verbindungen der allgemeinen Formel (ClCH2Ar)2X, wobei X eine Einfachbindung oder eines der zweiwertigen BrückengliederCH2,CO,O,S oderSO2bedeutet, wurden neue aliphatisch‐aromatische Polyethersulfone erhalten.

Die Reaktionen wurden in hochsiedenden polaren Lösungsmitteln bei Anwendung äquimolarer Mengen an Substraten und eines 15proz. molaren Überschuses von Kaliumcarbonat als HCl‐Akzeptor unter einer Stickstoffatmosphäre durchgeführt.

Die verwendeten Bis‐(4‐chlormethylphenyl)‐verbindungen unterscheiden sich hinsichtlich ihrer Reaktivität. Für die gesamte untersuchte Monomerreihe wurden die folgenden günstigsten Reaktionsbedingungen ermittelt:

Lösungsmittel N,N′‐Dimethylacetamid, Reaktionstemperatur 120°C, Reaktionszeit 30 min, Konzentration der Lösung 0,8 mol/l.

Die erhaltenen Polykondensate besitzen ein mittleres Molekulargewicht M̄w von 10000–50000. Sie sind linear nach dem Typ A‐B‐A‐B aufgebaut.
Aliphatisch‐aromatische polyethersulfone, III. Eigenschaften der polykondensationsprodukte aus bis‐(4‐hydroxyphenyl)‐sulfon und bis‐(4‐chlormethylphenyl)‐verbindungen
Authors: Podkościelny Wawrzyniec , Dethloff Jadwiga , Dethloff Michael
Published: April 2003

Die thermischen, mechanischen und dielektrischen Eigenschaften von aliphatischaromatischen Polyethersulfonen, die durch Polykondensation von Bis‐(4‐hydroxyphenyl)‐sulfon mit Bis‐(4‐chlormethylphenyl)‐Verbindungen der allgemeinen Formel (ClCH2Ar)2X (X steht für eine Einfachbindung oder eines der zweiwertigen BrückengliederCH2,O,CO,SoderSO2) erhalten wurden, werden beschrieben. Die Polykondensate besitzen Glasumwandlungstemperaturen von über 145°C. Die Zersetzung der amorphen Polykondensate wird erst oberhalb 300°C beobachtet. Die Löslichkeit der aliphatisch‐aromatischen Polyethersulfone in verschiedenen organischen Lösungsmitteln wurde untersucht. Die mechanischen Eigenschaften von Preßlingen wurden bei Raumtemperatur und die dielektrischen in Abhängigkeit von der Temperatur und Frequenz bestimmt.

Ihrem Sauerstoff‐Index nach können diese Polyethersulfone zur Gruppe selbstverlöschender Kunststoffe gezählt werden.
Synthese und charakterisierung von telechelen oligosiloxanen
Authors: Klemm Elisabeth , Beil Ulrike
Published: April 2003

Photopolyaddition von 1,8‐Dimercaptooctan an 1,1,3,3‐Tetramethyl‐1,3‐divinylsiloxan führt zu SH‐ oder vinylterminierten Telechelen. DC und HPLC‐Untersuchungen zeigen, daß die Telechelen Mischungen von Oligomeren mit wachsender Kettenlänge sind, deren Verteilung nur vom Molverhältnis r der Monomeren abhängt. Die Antimarkownikow‐Struktur ist durch NMR‐Analyse belegt.
Copolymerization of tri‐n‐butyltin‐α‐chloroacrylate with 2‐hydroxyalkyl methacrylates
Authors: Joshi Ravi R. , Gupta Sudhir K. , Dharia Jayesh R.
Published: April 2003

Copolymers of tri‐n‐butyltin‐α‐chloroacrylate (TCA) with 2‐hydroxyethyl methacrylate (HEMA) and 2‐hydroxypropyl methacrylate (HPMA) were synthesized in solution at 55°C using azobisisobutyronitrile as initiator. Copolymer compositions were determined by tin analysis. Monomer reactivity ratios were calculated by the Kelen‐Tüdős method. The copolymers were further characterized by IR, 1H‐NMR, TGA, DSC, XRD and solubility. Biotoxicity studies of the copolymers are also reported. The copolymer system is compared with similar copolymers of tri‐n‐butyltín methacrylate.
Mechanical properties of polymers filled with alkyl dihydrogen phosphate treated calcium carbonate
Authors: Mitsuishi Kazuta , Nishi Katsushi , Kodama Souji , Kawasaki Hitoshi
Published: April 2003

Poly(ethylene) (PE) or poly(ethylene‐co‐vinyl acetate) (EVA) and alkyl dihydrogen phosphate ester (APEn, CnH2n+1OPO(OH)2, n = 1, 4, 10, 12, 16) treated calcium carbonate (CaCO3) were mixed on a two roll mill. In order to improve the affinity of polymer‐CaCO3 interface, the CaCO3 surface was treated through chemical reaction with various APEn types. The effect of carbon number of APEn on the tensile elongation and the adhesion properties between CaCO3 particles and polymer matrix was investigated. In the case of PE/CaCO3 series, tensile elongation, modulus of oriented samples and adhesion of polymer‐CaCO3 interface increased with carbon number of APEn (n ≦ 12). In the EVA/CaCO3 series, the dependence of the tensile elongation on the carbon number of APEn was not clearly recognized; the adhesion at the phase interface was improved with the decrease of carbon number of APEn (n ≦ 12).
Synthesis and characterization of a new bismaleimide resin matrix for composites
Authors: Dolui S. K. , Mandal B. K. , Maiti S.
Published: April 2003

A bismaleimide monomer containing etherimide linkages was synthesized from 3‐nitrophthalic anhydride, diamino diphenyl ether and bisphenol‐A by the principle of activated nucleophilic displacement reaction and finally reacting the produced diamine with maleic anhydride. The monomer was characterized by elemental analysis, IR and NMR spectroscopy. It is highly soluble in low boiling solvents such as chloroform, tetrahydrofuran, etc. It forms a cross‐linked polymer on heating to 200°C and higher. The cured product is completely insoluble in usual solvents including conc. H2SO4. The thermal behaviour of the bismaleimide was studied by TGA, DTA and isothermal aging. The polymer is stable up to 300°C. Laminates prepared with this resin and carbon fiber are almost void‐free and possess good mechanical and thermal properties. These properties are compared with earlier reported bismaleimide imide prepolymer based composite.
Untersuchungen zum Einfluß von Modifikatoren auf die Thermostabilität von PE‐HD/CaCO3‐Verbunden
Authors: Lühr Jens , Beismann Ruth , Janowski Frank
Published: April 2003

Der Einfluß der Füllstoffmodifizierung mit nichtkoppelnden Modifikatoren wie Stearinsäure und Isopropyltriisostearyltitanat (ISTT) auf die thermische Stabilität von PE‐HD/CaCO3‐Verbunden wurde untersucht. Mit Hilfe der thermischen Analyse wurde eine erhöhte Sauerstoffaufnahme für gefülltes PE‐HD nachgewiesen. Eine Zunahme der Modifikatorkonzentration erniedrigt die Temperatur für den Oxidationsbeginn. Dieser Effekt ist für Stearinsäure ausgeprägter im Vergleich zu Titanat.

Die zusätzliche thermische Stabilisierung von PE‐HD/CaCO3‐Verbunden ist daher notwendig.
Polycondensation using alkyl chlorosilanes/silicon tetrachloride: Preparation of poly(1,4‐benzamide)
Authors: Galioǧlu Oya , Akar Ahmet
Published: April 2003

Mixtures of alkyl chlorosilane and silicon tetrachloride were used as condensation agents for the preparation of poly(1,4‐benzamide). Both high yield of polyamide and soluble side products were obtained. This method may be used to regulate the surface structure and the particle size of silicon dioxide side product if a minimum amount of trimethyl chlorosilane was added to silicon tetrachloride catalyst.
Effect of crosslinking on the properties of poly(2‐hydroxyethyl methacrylate) hydrogels
Authors: Davis Thomas P. , Huglin Malcolm B.
Published: April 2003

By means of γ‐irradiation 2‐hydroxyethyl methacrylate has been copolymerized in bulk with two different tetrafunctional monomers, ethylene glycol dimethacrylate and 1,3‐bis(acryloxymethyl) tetramethyl disiloxane and with a hexafunctional monomer, 1,1,1‐trimethylolpropane trimethacrylate. The resultant xerogels were subsequently swollen to equilibrium in water. In order to allow a comparison among the three crosslinkers, their molar masses and funtionalities were taken into account, the theoretical crosslink concentrations being varied from 0.032 to 0.644 mol dm‐3. The relative hydrophobicity of the three crosslinkers was found to have a significant effect on both the equilibrium swelling and elastic modulus of the swollen gels. Non‐freezing water in several gels crosslinked with 1,1,1‐trimethylolpropane trimethacrylate was analysed by differential scanning calorimetry (DSC). The proportion of non‐freezing water in the gel relative to the overall water content was found to increase with increasing crosslink density.
Synthesis and properties of cationic resins derived from aniline/benzylamine‐modified epoxy resins and diethylamines
Authors: Lee Lung‐Ta , Yang Chin‐Ping
Published: April 2003

Aniline/benzylamine‐modified epoxy resins with different molecular weights, which contain tertiary amines in the middle of the polymer chain, were synthesized by the reaction of aniline/benzylamine with epoxy resin at various molar ratios. The resulting aniline/benzylamine‐modified epoxy resins were reacted with diethylamine and subsequently reacted with 2‐ethylhexanol‐blocked toluene diisocyanate to obtain thermally crosslinkable resins which contain tertiary amines at the end and in the middle of the polymer chain. These resins were partially neutralixed with acetic acid to give thermally crosslinkable cationic resins. The resulting cationic resins were dissolved in suitable solvents and mixed with deionized water to form various emulsions. The emulsion and electrodeposition properties of these resins were studied in some detail to compare the properties of these cationic resins. The results show that the deposition yields and throwing power of the emulsions prepared from benzylaminemodified epoxy resins are higher than those of the emulsions prepared from anilinemodified epoxy resins. The emulsion having proper pH values can give a high throwing power. High throwing power is the characteristic property of these modified cationic resins. Factors determining the throwing power and deposition yield of the emulsions were also investigated.
Thermosensitive microcapsules, II. New azomonomers, homo‐ and cocondensation, microencapsulation, release measurements, size distribution and thermo‐printing
Authors: Nuyken Oskar , Dauth Jochen , Pekruhn Wolfgang
Published: April 2003

Thermolabile microcapsules are formed by interfacial polycondensation in which one of the wall‐forming reactants contains azo functions. These reactants are compounds of the general structure XRNNRX (X = OH, NH2, NCO, COCl). Their properties are described in detail.

Experimental details of the microencapsulation such as particle size, dependence from stirrer speed and stability of the capsules are given. An ink ribbon containing a carrier covered with dye filled microcapsules is applied for thermal‐transfer‐printing.
Mechanisms of photostabilization of polyolefins with N‐alkyl(methyl) HALS. 1. Comparison of the performance of unsubstituted with N‐substituted HALS in polyolefins
Authors: Gugumus F.
Published: April 2003

There is still controversy over the relative efficiency and stabilization mechanisms of secondary and tertiary HALS. In this study the performance of secondary HALS is compared with that of corresponding hindered amines bearing various substitutents at the sterically hindered nitrogen atom. The bulk of the stabilization data concerns unpigmented polypropylene and the comparison of N‐H and N‐methyl derivatives. It is found that in PP films, PP multifilaments, PP tapes and injection molded PP plates the secondary HALS and the corresponding N‐methyl derivatives give the same performance within experimental error. The results available, so far, with PE‐HD films, PE‐HD tapes and PE‐LD films lead to the same conclusion. Saturated alkyl groups other than methyl show also comparable performance. The effect of unsaturated groups such as allyl and benzyl and of oxygen atoms (nitroxyl radicals) varies. Depending on the particular polypropylene batch used, the performance can be comparable, superior or inferior to that of the corresponding NH/N‐methyl compounds.
Study of the acetoxy‐hydroxide transformation in ethylene‐vinyl acetate copolymers
Authors: Fonseca Carmen , Fatou Jose G. , Pereña Jose Manuel
Published: April 2003

Ethylene‐vinyl alcohol (EVAL) copolymers and ethylene‐vinyl alcohol‐vinyl acetate (EVALVA) terpolymers with different VA content were achieved by hydrolysis of ethylene‐vinyl acetate (EVA) copolymers of low vinyl acetate content. Several experimental techniques (elemental analysis, thermogravimetry, NMR and IR spectroscopy) were used for the analysis of the composition of copolymers and terpolymers. The results have been critically discussed. Kinetic aspects of the acetoxy‐hydroxide transformation of the EVA copolymers have been analysed, such as the influence of steric and neighbouring group effects on the rate of this transformation. The kinetics can be expressed by a second order kinetic equation and the acetoxy groups joined to hydroxy groups are rapidly transformed. The reaction rate depends on the vinyl acetate content; the higher the vinyl acetate content of the EVA copolymer, the higher is the rate of the transformation process. Another important conclusion is related with the dependence of the rate constant on the concentration of the EVA copolymer in the reaction, on the base of equivalent ester group concentration.
A nonionic hydrogel from the telechelics by utilizing living polymerization of 2‐oxazolines
Authors: Park In‐Hwan , Han In‐Su , Kim Dong‐Kuk , Saegusa Takeo
Published: April 2003

N,N′‐dimethyl‐2,2′‐tetramethylene‐bis(2‐oxazolinium) bis(methyl‐p‐toluene sulfonate) (II), a cationic polymerization initiator, was synthesized by the reaction of methyl p‐toluene sulfonate with 2,2′‐tetramethylene‐bis‐2‐oxazoline (I) and a cationic ring‐opening polymerization of 2‐methyl‐2‐oxazoline [MeOZO] in the presence of (II) was carried out to produce poly(MeOZO) telechelics with various molecular weights. These telechelics were hydrolyzed with an aqueous solution of sodium carbonate to obtain hydroxy terminated telechelics of poly(MeOZO). A series of nonionic polyurethane hydrogels was prepared by the crosslinking reactions of the poly(MeOZO) glycol with pluriisocyanates in the presence of ferric acetylacetonate and DMF as the catalyst and reaction medium, respectively. The hydrogels showed good swelling degrees for water and hydrophilic solvents such as DMF, and bad swelling degree for a hydrophobic solvent such as toluene.
Conformation and electrical conductivity of poly(γ‐methyl‐L(LD)‐glutamates) reticulate‐doped with 1,3‐dimethylimidazolium‐7,7,8,8‐tetracyano‐p‐quinodimethane complex salt
Authors: Šorm Miloslav , Dědek Petr , Nešpůrek Stanislav , Kotva Rudolf , Pivcová Hana
Published: April 2003

Polymeric composites were prepared by reticulate doping of poly(γ‐methyl‐L‐glutamate) (PMLGA) and poly(γ‐methyl‐LD‐glutamate) (PMLDGA, 1 : 1) having different conformation forms with 1,3‐dimethylimidazolium‐TCNQ complex salt. The heat induced α‐helix to coil transition in PMLGA and α‐helix to β‐form and coil transition in PMLDGA were carried out in chlorobenzene and o‐dichlorobenzene at temperatures between 70 and 150°C. The conductivity of polyglutamate composites thermally treated and prepared at 70°C is higher by approximately two orders of magnitude than that of thermally not treated films cast at ambient temperature. The conductivity of the most conductive reticulate‐doped PMLGA film is higher by more than four orders of magnitude than that of the 1,3‐dimethylimidazolium‐TCNQ complex salt in pressed pellets.
Preparation of block and graft copolymers by peroxycarbamates
Authors: Uyanik Nurseli , Yildirim Hüseyin , Kizilcan Nilgün , Akar Ahmet
Published: April 2003

Block copolymers of cyclohexanone‐formaldehyde resin (CF‐resin) and polystyrene and graft copolymers of styrene on ethyl cellulose, respectively, were prepared via peroxycarbamates. NCO/OH ratio was the important parameter during preparation of polymeric peroxycarbamates from prepolymeric isocyanate‐terminated peroxycarbamates and CF‐resin. Cross‐linked copolymers were produced if NCO/OH ratio was above 2:9. Ethyl cellulose with low hydroxy value was used as hydroxy compound for the preparation of peroxycarbamate. About one of every two anhydroglucose units of ethyl cellulose was grafted with polystyrene.
Functionalization of polyethylene and ethylene propylene diene terpolymer in the bulk through dibutyl maleate grafting
Authors: Sen Achintya K. , Mukherjee Bibha , Bhattacharyya A. S. , De P. P. , Bhowmick Anil K.
Published: April 2003

Functionalization of polyethylene (PE) and ethylene propylene diene terpolymer (EPDM) in the bulk through dicumyl peroxide (DCP) initiated grafting of dibutyl maleate (DBM) has been studied in the temperature range from 140 to 200°C. The degree of grafting has been determined by infrared spectrophotometry and DSC. The concentration of DBM and DCP has been optimized. 0.5 wt.‐% and 0.2 wt.‐% DCP for PE and EPDM, respectively, and 10% DBM for both have been found to be the optimum. The kinetics of the grafting reaction is comparable for PE and EPDM. The activation energy of grafting is ca. 145 kJ/mol for PE and ca. 130 kJ/mol for EPDM. The influence of structure of polyolefins on the degree of grafting has also been studied. A higher degree of grafting is obtained for PE than for EPDM. For PE/EPDM blends, the degree of grafting increases with increasing PE content in the blends. A through discussion and proposed mechanism for grafting and other competitive secondary reactions has been provided.
Interfacial adhesion in short‐fibre composites
Authors: Rybnikář František
Published: April 2003

For the evaluation of the interfacial adhesion in short‐fibre composites, a simple method based on fibre pull‐out length distribution was proposed. The experiments with three composites of isotactic polypropylene with 32 wt.‐% of short‐glass fibres confirm the potentials of the method for a sensitive determination of differences in the interfacial adhesion. The effects of temperature, crystallinity and fibre orientation angle on the interfacial adhesion were investigated.
Pervaporation separation of pentane‐alcohol mixtures through ionically crosslinked blended membranes. I. Thermal measurements, electron microscopy and tensile studies
Authors: Balakrishnan Malini , Huang Robert Y. M.
Published: April 2003

Ionically crosslinked blended membranes were prepared from blends of nylon 6 and poly(acrylic acid) (PAA) with the proportion of PAA ranging from 25 to 45 wt.‐%. The technique consists of casting a film of the blend, followed by drying and immersion in an aluminum salt crosslinking solution for a predetermined time. The glass transition temperature (Tg) of the membranes was determined by differential scanning calorimetry (DSC). All the samples exhibited a single Tg, which is higher than that of either polymer. There is also a shift in the Tg with increasing scanning time. This phenomenon is attributed to the elimination of water molecules and the formation of anhydrides in the non‐crosslinked PAA portion of the membrane. The membrane morphology was studied using scanning electron microscopy (SEM) and shows a dense structure without any pores. No phase separation is observed by scanning cross‐sections of the samples, indicating that nylon 6 and PAA are completely miscible in the ranges studied. The membrane material strength lies in the range of 5 to 26 MPa and varies with the amount of PAA in the membrane. Samples with higher PAA content show lower tensile strength in spite of increased crosslinking density. This is due to the inherent low strength of PAA, coupled with increasing swelling of the membrane with increasing PAA content. The latter is confirmed by the measurement of water uptake into a dry membrane which increases from 23.6% to 76.3% with the membrane PAA content increasing from 25 to 45 wt.%.
Effect of surface structure of porous silica microballoons on dynamic mechanical properties of amine cured epoxy resin composites
Authors: Tanaka Yuko , Nakahara Yoshiko , Takemoto Kiichi
Published: April 2003

Dynamic mechanical properties were studied for epoxy resin filled with porous silica microballoons with varying surface area, pore radius, pore volume and adsorbed water. The glass transition temperature (Tg) of the composites is 12–14°C lower than the Tg of the unfilled epoxy resin. This Tg depression is attributed to the preferential adsorption of curing agents on the porous silica microballoons. Tg of the composite increases with increase in the adsorbed water on fillers. The storage modulus has a distinct correlation with the Hg‐surface area of silica microballoons, which corresponds to the sum of the surface area of pores with radii larger than about 4 nm.

Tan δc tan δm decreases with increasing Hg‐surface area.
Zur reaktionstechnischen und fluiddynamischen stabilität von multirohrreaktoren für die massepolymerisation
Authors: Weickert G.
Published: April 2003

Infolge der sich mit steigendem Monomerumsatz stark verändernden Viskosität der Reaktionsmasse existieren im Multirohrreaktor mit Kühlung mindestens drei stationaäre Punkte bezüglich des Einzelrohrmassenstromes gleichzeitig. Als Konsequenz ergibt sich eine Ungleichverteilung der Rohrbelastung, die sowohl die Reaktorstabilität als auch die Polymerqualität negativ beeinflußt. Das Betreiben einer Rückführung kann das Reaktorverhalten stabilisieren. In der vorgelegten Arbeit werden einige fundamentale Aspekte der Anwendung von Multirohrreaktoren für die Massepolymerisation von Styrol untersucht.
Oberflächenstrukturierung polymerer fasern durch UV‐laserbestrahlung. 11. Oberflächenstrukturierung von polypropylen‐folien und ‐geweben
Authors: Kesting Wolfgang , Knittel Dierk , Schollmeyer Eckhard
Published: April 2003

Es wird aufgezeigt, daß Materialien, die UV‐Licht nur schwach absorbieren, wie z. B. Polypropylen (PP), durch eine Imprägnierung mit starken Absorbern wie Benzophenon einer Bearbeitung mit UV‐Lasern zugänglich gemacht werden können. Durch die dann erzielbaren hohen Absorptionskoeffizienten der so dotierten Polyolefine lassen sich hohe Ätzraten durch die Laserbestrahlung erzielen. Darüber hinaus können rollenähnliche Oberflächenstrukturen erzeugt werden, so wie diese von z. B. Polyester‐ und Polyamidfasern bekannt sind. Die Dimensionen dieser Strukturen liegen im Bereich von 10 bis 25 μm bei einer Tiefe von etwa 3 μm. Dagegen werden an biaxial verstreckten PP‐Folien tropfenförmige Strukturen erzeugt, die auf eine Dominanz thermischer Effekte schließen lassen. An schwach absorbierenden Systemen wie etwa an gefärbten PP‐Fasern lassen sich nur Verschmelzungen von Einzelfilamenten erreichen. Durch einen mechanischen Kontakt einer undotierten PP‐Probe mit einer Poly(ethylenterephthalat) (PETP)‐Folie lassen sich durch die Laserbestrahlung ebenso rollenähnliche Strukturen an der PP‐Oberfläche gewinnen.
Synthesis, dielectric and X‐ray powder diffraction studies of Fe(III), Co(II) and Ni(II) chelate polymers with 5,8‐dihydroxy‐1,4‐naphthoquinone
Authors: Rao T. Ramkrishan , Rao P. Raghunath , Lingaiah P. , Deshmukh Lalitha Sir
Published: April 2003

Coordination polymers of Fe(III), Co(II) and Ni(II) with 5,8‐dihydroxy‐1,4‐naphthoquinone have been synthesized and characterized by elemental analysis, IR and magnetic moment studies. From DSC data, the order of the decomposition reaction and the activation energy for the decomposition of the different polymers have been evaluated. Electrical properties like the dielectric constant and the dc conductivity of the polymers have been measured. From x‐ray powder diffractograms cell parameters were calculated, the pattern indexed, and the symmetry determined.
Porous copolymers of N‐vinylcarbazole and divinylbenzene
Authors: Kolarz Bożena N. , Wojaczyńska Maria , Pielichowski Jan
Published: April 2003

Porous copolymers of N‐vinylcarbazole (NVC) and divinylbenzene (DVB) of different composition (crosslinking degree) have been studied. The copolymers were obtained by suspension polymerization carried out in the presence of diluents, mixtures of ‘good’ (isopentanol and toluene) and ‘bad’ solvents (dodecane and toluene).

The supermolecular structure of the copolymers was found to depend not only on the crosslinking degree, but on the thermodynamic quality of diluents. In the presence of good solvents, copolymers of the porous‐gel type were formed at relatively small crosslinking degree (<20% DVB).

Sorption properties of porous NVC‐DVB copolymers with respect to p‐nitrophenol were found to be similar to those of acrylonitrile‐DVB copolymers.
Copolymerization reactivity ratios of N,N‐dimethyl acrylamide and isopropyl methacrylate determined by 1H‐NMR spectroscopy
Authors: Srinivasulu B. , Rao P. R. , Sundaram E. V.
Published: April 2003

Copolymers of N,N‐dimethyl acrylamide (DMA) and isopropylmethacrylate (IPM) were prepared in dimethyl formamide using azoisobutyronitrile as initiator. The composition of copolymers was determined by 1H‐NMR analysis. Reactivity ratios (rDMA = 0.58, rIPM = 2.76) were calculated from these values by using the Kelen‐Tüdős differential linear equation.
Polymer molecular properties and hydrodynamic lubrication
Authors: Figini Ruben Victor , Tinta Clotilde Goday
Published: April 2003

A general numerical procedure is presented to calculate the modification of the basic equation for hydrodynamic lubrication brought about by the use of polymeric fluids with shear depending viscosity. The procedure is based on the generalized Newtonian fluid model and allows to treat continuously all the flow regions between the pure Newtonian and the power law behavior. The results show that the influence of the viscosity depending on shear stress is completely characterized by one dimensionless number, namely U.·τ*/h*, where U is the relative sliding velocity, h* is the characteristic film thickness, and τ* is a characteristic time of the lubricant. The procedure is exemplified by applying it for the determination of the influence of the molecular weight and concentration of the polymeric component of the lubricant on the hydrodynamic lubrication. This influence is brought about by the strong relation between the polymer properties and τ*.
Oxygen permeability in polymers, III. Dependence of the oxygen permeability on the chemical structure of styrene‐maleic acid‐copolymers
Authors: Kraus N. , Israel G. , Müller F. W. , Schiller K. , Rätzsch M.
Published: April 2003

The paper gives a report on the oxygen permeability in films of poly(styrene‐comaleic acid) halfesters and halfamides as well as other polymers containing carboxylic groups in comparison with commercially available glass forming polymers at room temperature. The presence of oxygen in the polymer layers was proved by the quenching of the delayed fluorescence of pyronin B. The permeability of the halfesters/halfamides (Pox = 2…7.10‐14 cm2/Pa .s) corresponds to that of common polymers like poly(methyl methacrylate) (PMMA) or poly(vinyl acetate) (PVAc), and is nearly one order of magnitude higher than that of poly(acrylic acid) (PAAc), poly(styrene‐comaleic acid) (SMAc) and carboxymethylcellulose (CMC). Presumably, intramolecular hydrogen bonds in the halfester/halfamides compete successfully with the intermolecular interactions and hence cause an increase in permeability as also do bulky substituents. Addition of bases like dimethyl aminopropanol (DMAP) and dimethyl aminopropyl acrylamide (DMAPAA) decreases the permeability to about 1/40 of the initial value. The permeability is then similar to the low permeability of polymers with predominant ionic interaction sodium polyacrylate (NaPAAC), sodium carboxymethylcellulose (NaCMC)).
Solid‐state polycondensation of poly(ethylene terephthalate) films
Authors: Karayannidis George , Sideridou Irini , Zamboulis Demetris , Stalidis George , Bikiaris Demetris , Lazaridis Nicolaos , Wilmes Aloyse
Published: April 2003

The solid‐state polycondensation of poly(ethylene terephthalate) (PET) amorphous and unoriented films from Du Pont (precursor for their Mylar®

Du Pont's registered trade mark for the polyester film.

polyester film) prepared from a specified catalyst and monomer system has been studied. The effect of various reaction parameters such as reaction temperature and time on inherent viscosity (ηinh) and number of carboxy and hydroxy end‐groups has been investigated. From ηinh measurements an empirical equation was taken which allows the calculation of (M̄n) of PET film after solid‐state polycondensation at a certain temperature and time. The melting behaviour of the solid‐state polycondensated samples was also studied.
Pervaporation separation of water‐ethanol through modified chitosan membranes, II. Carboxymethyl, carboxyethyl, cyanoethyl, and amidoxime chitosan membranes
Authors: Lee Young Moo , Shin Eun Mi , Noh Si Tae
Published: April 2003

The present study investigates the pervaporation performance of four kinds of modified chitosan membranes to separate water from aqueous ethanol solution. Chitosan was prepared from chitin abstracted from the crab shell and subsequently deacetylated with aqueous NaOH solution. Modified chitosan membranes examined in this study include carboxymethyl chitosan, carboxyethyl chitosan, cyanoethyl chitosan, and amidoxime chitosan. The incorporation of hydrophilic functional groups into the 6‐O position of chitosan enhances the selectivity of modified chitosan membrane compared to the previously reported chitosan‐acetic acid complex membrane. Among the modified chitosan membranes, membranes containing carboxy groups show the best pervaporation performance. Carboxymethyl chitosan membranes show the maximum swelling and ethanol flux at approx. 15 wt.‐% feed ethanol concentration due to the coupling and plasticizing effect.
Cationic polyelectrolytes, XI. Polymers with quaternary N‐atoms in the main chain obtained by condensation polymerization of epichlorohydrin with amines
Authors: Dràan Stela , Ghimici Luminita
Published: April 2003

Water soluble cationic polyelectrolytes containing quaternary nitrogen atoms within the main chain were prepared via condensation polymerization of epichlorohydrin (ECH) with dimethylamine (DMA) and N,N‐dialkylaminoalkylamines. The main parameters of the reaction that influence the polymer properties are: DMA/asymmetrical diamine molar ratio, the initial concentration of amine solution, NaOH/amine molar ratio, ECH/amine molar ratio, and asymmetrical diamine structure. The feature of flexible polyelectrolyte own to the investigated polymers was emphasized by the viscosimetric behaviour in dilute aqueous solutions with and without salt presence.
Study of the conduction mechanisms in polycarbonate
Authors: Amin M. , El‐Shekeil A. , Mounir M. , Elez M. Abu
Published: April 2003

Current‐voltage characteristics of polycarbonate samples (PC) have been studied in the voltage range 50–1000 V. The effect of UV‐irradiation at λ = 225 and 300 nm, and thermal annealing on the electrical conductivity (σ) of PC was studied. The σ vs. 1/T relationship shows two slopes, i.e. two possible conduction mechanisms. The obtained results made it possible to determine a complete set of conduction parameters including activation energy and jump distance.
Porous terpolymers: Poly(acrylonitrile‐co‐vinyl acetate‐co‐divinylbenzene)
Authors: Kolarz Bożena N. , Trochimczuk Andrzej , Wojaczyńska Maria
Published: April 2003

Terpolymers of acrylonitrile (AN), vinyl acetate (VA) (7.5–30 mol‐%, related to AN), and divinylbenzene (DVB) (10 wt.‐%) were prepared by suspension polymerization. The diluents used were mixtures of toluene or cyclohexanol (90 vol.‐%) with solvents (10 vol.‐%) such as hexadecane (HD), octane (O), dodecane (D), 2‐ethylhexanol (E) or benzyl alcohol (B).

It has been found that AN‐VA‐DVB terpolymers have a higher porosity, about 0.61–0.68, than corresponding AN‐DVB copolymers. The terpolymers obtained with mixtures of various diluents differ in their supermolecular structure although they had similar porosity characteristics.

The thermal effects accompanying heating of the terpolymers above 200°C significantly exceed that of nitrile groups cyclization observed of the other AN polymers.
Monothiirane als reaktive Verdünner für Epoxidharze
Authors: Večeřa Miroslav , Milič Richard , Mleziva Josef
Published: April 2003

Langkettige aliphatische Monothiirane können als reaktive Verdünner für Epoxidharze benutzt werden. Die Eigenschaften der ausgehärteten Produkte entsprechen denen, die bei der Verwendung von entsprechenden Monooxiranen (Monoglycidylethern oder ‐estern) gewonnen werden. Von Vorteil ist die Beschleunigung des Aushärtungsprozesses mit aliphatischen Polyaminen und Säureanhydriden sowie die geringere Toxizität.
Zur Bestimmung von funktionellen Gruppen in Polymeren mit elektroanalytischen Methoden
Authors: Peter Ralf
Published: April 2003

Im Zuge der ionischen Modifizierung von Polymeren bieten sich elektroanalytische Charakterisierungsverfahren an. Die Palette der analytischen Probleme reicht dabei von der Bestimmung saurer oder basischer funktioneller Gruppen bis hin zur Quantifizierung reduzierbarer und oxidierbarer Spezies — und dies teilweise im spurenanalytischen Bereich. Praktisch relevante und theoretisch interessante Beispiele hierfür sind unter anderen die Ermittlung des Hydroxy‐Gruppengehaltes in Ethylen‐Vinylacetat‐Copolymeren und Epoxidharzen sowie die Bestimmung von als Restmonomerem vorliegenden Doppelbindungseinheiten in Acrylsäure‐Styrol‐Polypropylen‐Compounds und in Maleinsäureanhydrid‐Polyolefin‐Pfropfcopolymeren. Es werden konkrete Lösungsvarianten zu den genannten Problemstellungen beschrieben und die entsprechenden Ergebnisse diskutiert.
Synthesis of a thiol‐terminated poly(L‐glutamic acid) by polymerization of N‐carboxyanhydrides on solid supports
Authors: Palacios Paul , Bussat Philippe , Bichon Daniel
Published: April 2003

A novel method of synthesizing a thiol‐terminated poly(L‐glutamic acid)

IUPAC name: α‐hydro‐ω‐(2‐mercaptoethyl)amino‐poly{sodium imino‐[1‐(2‐carboxylatoethyl)‐2‐oxo]ethylene}.

(PLGA) is reported. Synthesis of this compound is accomplished with the aid of a solid phase support. The procedure consists of first preparing aminoethyl disulfide‐functionalized silica, glass or polystyrene solid supports. The support thus prepared is then reacted with ester‐protected γ‐benzyl‐L‐glutamate or γ‐piperonyl‐L‐glutamate N‐carboxyanhydride (NCA) to obtain the conjugated poly(γ‐ester‐L‐glutamate)‐support. Then the protected ester group is acidolyzed by adding hydrobromic acid or trifluoroacetic acid (TFA). Finally, the disulfide bond of the resulting acid is cloven by reacting it with mercaptoethanol thus producing the desired end product, the thiol‐terminated poly(L‐glutamic acid) (yield 64%).
Preparation and properties of poly(p‐nitrophenylquinoxaline‐imide‐amide)s
Authors: Bruma M. , Sava I. , Hamciuc E. , Belomoina N. M. , Krongauz E. S.
Published: April 2003

New thermostable polymers containing p‐nitrophenyl substituted quinoxaline units and imide rings as well as flexible amide groups have been synthesized by polycondensation reaction of a diaminoquinoxaline derivative carrying p‐nitrophenyl substituents with diacid dichlorides incorporating preformed imide cycles. These polymers show better solubility compared to related products which do not contain nitro groups. They have also a high thermal stability and good electrical insulating properties.
Light‐induced polymer and polymerization reactions, 48. Photo‐induced reactions in novolac resins containing onium salt photoinitiator systems
Authors: Timpe Hans‐Joachim , Rautschek Holger
Published: April 2003

The exposure of photoinitiators contained in novolac layers, which give protonic or Lewis acids by irradiation, leads to the degradation of these resins. Benzylic carbocations are formed as intermediates, which can be detected by their long wavelength absorptions between 525 and 545 nm. These intermediates react either with nucleophiles (e.g. anions, water) to benzyl derivatives, or with phenols to novolacs (back reaction), or they yield, under abstraction of protons, ortho‐quinone methides, also coloured (absorption maxima at ∼400 nm). Altogether, a complicated system of competitive reactions occurs and, therefore, kinetic calculations are very difficult. Due to changes caused in solubility, this photoinduced degradation of novolacs can be used for photolithographic purposes. But problems arise in negative working resists using novolac resins as polymeric binders.
Synthesis and characterization of polymers containing naphthyl‐2H‐benzotriazoles, 1. Monomer synthesis and characterization
Authors: Shuhaibar K. F. , Rasoul F. A. , Pasch H. , Mobasher A.
Published: April 2003

2‐(2‐Hydroxynaphthyl)‐2H‐benzotriazoles were synthesized by azo coupling of o‐nitrobenzene diazonium chloride with 2,3‐, 2,5‐, and 2,7‐dihydroxynaphthalenes, respectively, followed by reductive cyclization with zinc powder and sodium hydroxide. The mode of coupling reactions has been elucidated using NMR spectroscopy and showed that the coupling occurred at the α‐position of the dihydroxynaphthalenes. The treatment of 2‐(2,7‐dihydroxynaphthyl)‐2H‐benzotriazole with acryloyl or methacryloyl chloride, respectively, gave the corresponding (meth)acryloyloxynaphthyl‐2H‐benzotriazoles, which, along with their methoxy and chloro derivatives, provide a new class of polymerizable UV absorbers.
Oberflächenstrukturierung polymerer Fasern durch UV‐Laserbestrahlung. 12. Pulszahlabhängige phänomenologische Untersuchungen zur UV‐laser‐induzierten Oberflächenstruktur von Poly(ethylenterephthalat)‐Fasern,
Authors: Kesting Wolfgang , Schollmeyer Eckhard
Published: April 2003

Durch die Bestrahlung von verstreckten Poly(ethylenterephthalat)(PETP)‐Fasern mit einem gepulsten UV‐Excimer‐Laser entstehen charakteristische Strukturierungen auf der Faseroberfläche. In einem Experiment, bei dem PETP‐Fasern unter einem Mikroskop bestrahlt werden, wird die Änderung der Oberflächenstrukturierung pulszahlabhängig untersucht. Diese Untersuchungen werden für verschiedene Pulsenergiedichten, Wellenlängen und unterschiedliche Verstreckungen der Faser durchgeführt. Mit zunehmender Anzahl von Laserpulsen kommt es zu einer gröberen Ausbildung der Strukturierung, in der feiner ausgeprägte Strukturen verschwinden. Nach einer ausreichenden Anzahl von Laserpulsen zerfällt die Faser in ellipsenförmige Segmente. Quantitative Untersuchungen ergeben eine logarithmische Abhängigkeit zwischen dem mittleren Abstand der Aufwerfungen und der Anzahl der angewandten Laserpulse.
Modifikation von Harnstoff‐Formaldehyd‐Schäumen mit einem Stärkehydrolysat
Authors: Braun Dietrich , Rösinger Sabine , Unvericht Reinhard
Published: April 2003

Der Einsatz eines hauptsächtlich aus Glucose, Maltose und Maltotriose bestehenden Stärkehydrolysates bei der Herstellung von UF‐Schaumstoffen führt zu einer sichtbaren Verminderung von Partikelagglomerationen ohne eine Verschlechterung der Morphologie und damit der mechanischen Eigenschaften. Dadurch kann die begrenzte Lagerstabilität der bei niedrigem Formaldehyd/Harnstoff‐Verhältnis produzierten Harze verbessert werden. Dagegen ist es nicht möglich, den Gehalt an freiem oder acetalisch gebundenem Formaldehyd im Vorkondensat durch solche Zusätze zu erniedrigen.
Properties of cationically polymerized aromatic monomers which are present in C9 resinfeed. Properties influencing printing ink compositions
Authors: Salemis Philippe , van Eikenhorst Rita
Published: April 2003

The main components of the “C9 cut”, a by‐product from steam cracking of gasoil or naphtha, have been cationically homopolymerized. The properties of the resulting homopolymers have been related to their structure. As some of the main application areas of the C9 resins are printing ink resins and adhesives, we focused primarily on these fields of application when considering the properties of these homopolymers.
Functionalization of dextran: Incorporation of carboxy groups by O‐succinoylation
Authors: Arranz F. , Sanchez‐Chaves M. , Ramirez J. C.
Published: April 2003

The modification reaction of dextran with succinic anhydride using pyridine as catalyst and N,N‐dimethylformamide/lithiumchloride system as solvent was studied. The structure of the resulting polymers was determined by means of 1H and 13C NMR spectroscopy. A linear dependence of the reaction rate on succinic anhydride concentration was found. The orders with respect to pyridine and polymer concentrations were 1 and 2, respectively. The activation energy was found to be 69.0 kJ/mol. 13C NMR spectra at 75.4 MHz of partially modified dextran with monosuccinate groups were studied in order to evaluate the selectivity of the reaction of dextran with succinic anhydride in the homogeneous phase. Analysis of the spectra of ring carbons in the anhydroglucose units shows that the reactivity of individual hydroxy groups decreases in the order C‐2 ∽ C‐3 > C‐4. For samples with higher degree of substitution the order is C‐4 > C‐3 > C‐2. The results were explained by considering the formation of intramolecular hydrogen bonds as well as by steric considerations.
Struktur und eigenschaften von simultanvernetzten bismaleimidmodifizierten novolak‐epoxidharzen
Authors: Lüders Günter , Goering Harald , Pohl Martina , Raubach Heinz
Published: April 2003

N,N′‐4,4′‐Diphenylmethan‐bismaleimid (BMI) wurde in halbfesten Phenolnovolak‐Epoxidharzen (EP) bis P̄, = 10 oligomerisiert. Die novolakgehärteten EP‐BMI‐Festharze bilden eine Zweiphasenstruktur, bestehend aus einer EP‐BMI‐Mischphase der beiden sich durchdringenden Netzwerke (interpenetrating polymer network, IPN) und einer BMI‐Phase. Die dynamisch‐mechanischen Eigenschaften hängen vom Gesamt‐BMI‐Anteil w2 und vom Oligomerisierungsgrad P̄n des BMI ab. Der relative Schubmodul des EP‐BMI‐Harzes im kautschukelastischen Zustand zeigt, daß beide Phasen kohärent sein können. Die Glastemperatur Tg korreliert mit dem Oligomerisierungsgrad, z. B. entspricht ΔPn ≡ 10 einem ΔTg ≡ 35 K und einem BMI‐Anteil Δ wx2 ≡ 0,25 in der Mischphase. Die Bruchzahigkeit bleibt unerwartet konstant.