bluuebunny/crossref_metadata_2025_split huggingface dataset:
Über den thermischen abbau des poly(ε‐caprolacton)s
Authors: Lüderwald Ingo 
Published: April 2003

AbstractThe thermal and electron impact induced degradation reactions of poly(ε‐caprolactone) {poly[oxy(1‐oxohexamethylene)]} were investigated in a mass spectrometer. It can be shown that the favorated thermal degradation reaction is the cleavage of the ester bond and formation of ω‐hydroxyl and ketene endgroups (Eq. (iii)) and with a lower intensity the cleavage of the OCH2‐bond and formation of carboxyl‐and pentenyl endgroups (Eq. (vii)). After electron impact and fragmentation of the pyrolysis products to carboxonium ions an elimination of caprolactone via a “zip”‐mechanism can be observed (Eq. (v)).
Evaluation of the rate constant for primary radical termination in free radical polymerization
Authors: Mahabadi Hadi K. , O'Driscoll Kenneth F. 
Published: April 2003

AbstractStyrene and methyl methacrylate were polymerized with azodiisobutyronitrile (AIBN) at 50, 60, and 70°C. The average degree of polymerization was kept constant while changing the initiator concentration, by using 1‐butanethiol as a chain transfer agent. In these polymerizations, a deviation from the simple kinetic rate law was noticed. This deviation was explained in terms of primary radical termination considering the effect of size dependence of the termination rate constant on the kinetics of free radical polymerization and taking into account the fraction of thermal polymerization. The temperature dependence of the characteristic constant, Ktpr/KpKi, was estimated to be 5,408 · 10−5 exp (12915 cal mol−1/RT) and 7,52 · 10−3 exp (7791 cal mol−1/RT) for styrene/AIBN and methyl methacrylate/AIBN, respectively.
Thermal decomposition of γ‐ray irradiated poly(vinyl fluoride)
Authors: Hagiwara Miyuki , Ellinghorst Guido , Hummel Dieter O. 
Published: April 2003

AbstractThe thermal decomposition of γ‐irradiated poly(vinyl fluoride) has been investigated by means of thermogravimetry (TG), differential thermal analysis (DTA) and mass spectral analysis of the evolved gas. The polymer was found to lose its weight in two main steps. The first step was the elimination of hydrogen fluoride; during the second step various unsaturated hydrocarbons were evolved as a consequence of main chain scission. The kinetical analysis of TG for dehydrofluorination under N2 showed that the apparent overall activation energy decreases with increasing irradiation dose. Considerable heat release during the decomposition was observed when DTA was performed in the presence of air. This behaviour was attributed to a crosslinking reaction catalyzed by O2. The addition of potassium salts or CsCl markedly diminished dehydrofluorination. On the other hand, dehydrofluorination was accelerated by CuF2.
Aqueous polymerisation of acrylonitrile initiated by the V(V)‐ethylene glycol redox system
Authors: Nayak Padma L. , Mohanty Trijama R. , Samal Rajani K. 
Published: April 2003

AbstractThe kinetics of acrylonitrile polymerisation initiated by the redox system V(V)‐ethylene glycol were investigated in aqueous sulfuric acid in the temperature range 40–50°C. The rate of polymerisation, of V(V) disappearance, and the chain lengths of polyacrylonitrile were measured. The effect of certain water miscible organic solvents and certain neutral salts on the rate of polymerisation was investigated. The kinetics are consistent with the formation of an intermediate complex between the diol and the oxidant whose decomposition leads to the initiating radical. A suitable kinetic scheme is proposed and the various rate and energy parameters are computed.
Baker‐Williams fractionation of high molecular weight polyisobutylene and its evaluation by gel permeation chromatography
Authors: Mokhtari‐Nejad Esfandiar , Berger Knud C. , Hammel Reinhart , Lederer Klaus 
Published: April 2003

AbstractA sample from commercially available polyisobutylene with a viscosity average molecular weight of M̄v = 320 000 is fractioned according to Baker‐Williams. 9 Fractions are recovered and are characterized by viscometry and gel permeation chromatography (GPC). Molecularly very homogeneous fractions with an inhomogeneity U = (M̄w/M̄n)−1 ≈ 0,05 can be obtained in the range of molecular weights up to M̄v = 600 000. Inversion of molecular weight occurs in the last three fractions. A 3 wt.‐% portion with M̄v>106 is lost during the fractionation.
Chemische synthese verzweigter polysaccharide, 5. Kopplung von oligosacchariden und amylose an verschiedene träger durch hydrazonbindung
Authors: Andresz Holger , Richter Gabriele C. , Pfannemüller Beate 
Published: April 2003

AbstractThe coupling of glucose and maltooligomers by hydrazone linkage to carriers by means of acid hydrazide groups was investigated. The following carriers were used: (1) linear polymers such as (a) poly(ethylene glycol) with carboxymethyl (CM) end groups, (b) CM‐amylose and CM‐cellulose, 6‐COOH amylose and 6‐COOH cellulose, pectic acid, alginic acid, poly(acrylic acid); (2) multifunctional centers such as (c) CM‐cyclodextrin, 1,3,5‐benzenetricarboxylic acid, 1,3,4,5‐benzenetetracarboxylic acid, crosslinked poly(acrylamide) (BIO‐GEL). The hydrazone linkage which is formed preferably in borate buffer at pH 8,5 was stable above pH 6 and could be split by mild acid treatment at pH 4. Maltooligomeric grafts of degree of polymerization DP ≧ 4 may be extended enzymatically by phosphorolytic synthesis to amylose chains of variable length. Primer activity of the bound maltooligomers for phosphorylase was obviously not hindered by the hydrazone linkage, by free hydrazide groups, or by synthetic polymers as carriers. ABA‐Block copolymers may be derived from(a), comb‐like molecules from (b), and different kinds of star‐like molecules from (c).
Elektrokinetische untersuchungen an Fasern, 4. Über ein Adsorptionsmodell von ionen an ionenaustauschenden Polymeren
Authors: Aichele Wilfried , Schollmeyer Eckhard , Herlinger Heinz 
Published: April 2003

AbstractIn this part of our series, a thermodynamic description of the zeta‐potential is proposed, which leads under special conditions to the application of Nernst's equation on the Gouy‐Chapman‐layer. Thus the behaviour of the streaming current can be explained by adsorption of different electrolytes at solids. Finally, a relation of electrokinetic effects with redox electrodes is proposed, which might be able to result in the determination of absolute thermodynamic normal potentials.
Synthesis of block copolymers containing polybutyramide blocks
Authors: Nitadori Yoshiaki , Franta Emile , Rempp Paul 
Published: April 2003

AbstractSeveral methods were employed to synthesize block copolymers of a polyamide and polystyrene (or polyisoprene). The polystyrenes (or polydienes) were obtained anionically and were fitted with terminal acyllactam functions. In a second step the acyllactam groups were used as promoters for the polymerization of the corresponding lactam. The best results were obtained when the functionalization was carried out with toluene diisocyanate, followed immediately by protonation by means of the lactam itself. This method yields, the highest degrees of functionalization and low coupling rates; the subsequent polymerization of the lactam in the bulk leads to block copolymers which were characterized as such; they were found to contain only small amounts of homopolystyrene, easy to remove.
Dissociation behaviour of some mixtures of synthetic phenolic oligomers in nonaqueous media
Authors: Chatterjee S. K. , Chatterjee Nandita 
Published: April 2003

AbstractSome phenolic oligomers of uniform structure, molecular weight, and with additional functional groups have been prepared by stepwise synthesis. These synthetic novolaks when mixed in various molecular proportions resemble p‐cresol formaldehyde condensation polymers. A study has been made on the titration curves of the mixtures of synthetic compounds in nonaqueous media. A large number of breaks have been observed in the titration curves, and they occur in simple multiples of the calculated amount of base required to neutralize each acidic group in the various novolak molecules independently. An attempt has been made to interpret some of these observations in terms of intramolecular hydrogen bonding, ion‐association, and homoconjugation.
Deux phases »amorphes« dans les multifilaments préorientés de polyester. Essai d'interprétation à partir de l'analyse calorimétrique différentielle
Authors: Hagège Raoul , Mamy Catherine , Thiroine Claude 
Published: April 2003

AbstractThe reliability of a base‐line correction method—with the use of a computerized calculation—is considered in the case of Differential Scanning Calorimetry (DSC) of preoriented amorphous polyester yarns (POY); the method allows to measure the enthalpies of crystallization and fusion of those materials.An interpretation of the decrease of the enthalpy of crystallization with the increase of the amorphous orientation is then given; according to this interpretation, POY would be of a two‐phase character, with an oriented amorphous and a disoriented amorphous phase; the crystallization of the disoriented amorphous phase, which occurs at higher temperature, would require a part of the thermal energy liberated by the crystallization of the oriented phase, which takes place at lower temperature. Quantitative results are in good agreement with our working hypothesis, but they have to be supplemented by new experiments.
Effect of amine structure on the photopotential induced by dye / polyamine systems
Authors: Kaneko Masao , Sato Shunichi , Yamada Akira 
Published: April 2003

AbstractIt was found that the photoredox system, dye/poly(iminoethylene) (PEI) induces a remarkably higher photopotential than the corresponding dye/monoamine system. The relationship between the photopotential induced by thionine (TH)/PEI and the number of amino or imino groups in the amine molecule is characterized by an alternating pattern. From the dependencies of the photopotential and the ionic species of the amine on pH, it was concluded that the active species of the amine is the half‐protonated one. As a possible mechanism for the high photopotential induced by the polyamine system, an interaction between the dye and the half‐protonated species is proposed, based on the bifunctional behavior of the adjacent protonated and unprotonated imino groups of PEI.
Structure of polyethylene produced at high pressure by simultaneous ionic and radical mechanisms
Authors: Constantin Didier , Hert Marius , Machon Jean‐Pierre 
Published: April 2003

AbstractPolyethylene samples of intermediate density were prepared by high‐pressure polymerization with some Ziegler catalysts derived from titanium tetrachloride. These polymers were studied by characterization techniques (fractionation, gel permeation chromatography, viscometry, infrared spectroscopy, differential scanning calorimetry) and three types of macromolecules were identified.
On the polymerization of crystalline 1,4‐diethynylnaphthalene, 1 the structure of the photopolymer
Authors: Rohde Ottmar , Wegner Gerhard 
Published: April 2003

AbstractUpon irradiation with UV light crystalline 1,4‐diethynylnaphthalene (1) readily polymerizes in the solid state. The purple polymer formed has a polyene polymer backbone and a molecular weight of 9000. Only one ethynyl group of the monomer participates in the polymerization process, whereas the second ethynyl group remains unreacted. The structure of the photopolymer was proven by spectroscopic methods, and direct evidence was obtained from resonant Raman spectra by comparing the photopolymer of the title compound to poly(1‐ethynylnaphthalene) prepared by complex catalysis.
Strukturuntersuchung von Polyestern durch direkten Abbau im massenspektrometer, 5. Polyester aus Terephthalsäure und/oder Bernsteinsäure und Hydrochinon
Authors: Aguilera Carlos , Lüderwald Ingo 
Published: April 2003

AbstractThe structure and thermal degradation behaviour of polyesters from terephthalic and/or succinic acid and hydroquinone were investigated by pyrolysis mass spectrometry. Poly(oxysuccinyloxy‐1,4‐phenylene) (2) undergoes cleavage of the ester bond (Eq. (vii)) as a very selective pyrolysis mechanism at 310°C, whereas the thermally more stable poly(oxyterephthaloyloxy‐1,4‐phenylene) (1) starts to degrade above 400°C and yields pyrolysis products with phenyl (Eq. (iv)), p‐hydroxyphenyl (Eq. (iii)), benzoyl (Eq. (iiv)) and carboxylic end groups. A calibration curve of the intensities of monomer specific fragments, obtained from pyrolysis mass spectra of polyesters from terephthalic acid, succinic acid, and hydroquinone provides the exact determination of their compositions.
Darstellung und eigenschaften von chelatharzen mit pyrazol‐3,4‐dicarbonsäure bzw. 1,2,3‐triazol‐4,5‐dicarbonsäure als ankergruppen
Authors: Manecke Georg , Rühl Christian‐Steffen 
Published: April 2003

AbstractN‐vinylation of pyrazolecarboxylates and 1,2,3‐triazolecarboxylates with vinyl acetate leads to the formation of the N‐vinylpyrazoles and N‐vinyl‐1,2,3‐triazoles. The structures are determined by mass and NMR spectra. The syntheses of crosslinked poly[1‐(3,4‐dicarboxypyrazol‐1‐yl)ethylene] (12) and poly[1‐(4,5‐dicarboxy‐1,2,3‐triazol‐2‐yl)ethylene] (13) are described. The swelling behaviour, the time dependence of the uptake of Cu2+‐ions and the pH‐dependence of the uptake of Cu2+‐, Zn2+‐, and Mg2+‐ions of these resins were investigated.
The role of co‐operativity in determining the binding behaviour of hetero‐charged polyanions with metachromatic dyes
Authors: Cundall Robert B. , Lawton John B. , Murray David , Phillips Glyn O. 
Published: April 2003

AbstractThe binding of acridine orange to carboxyl and sulfate containing polyanions has been investigated by fluorescence spectroscopy. Particular attention has been given to solutions containing both carboxyl and sulfate groups in two different situations, first where both types of site are present attached to the same polymer backbone in a regular repeating structure (heparin), and secondly where individual polymer chains carry exclusively one type of site (hyaluronic acid/K‐carrageenan mixtures). Greatly differing behaviour of the binding profiles as the concentrations of components were reduced have been explained in terms of the strong co‐operativity of the dye‐binding process. The carboxyl and sulfate sites of heparin appear to be equivalent in binding strength, while those of the polycarboxylate polysulfate mixture are no longer equivalent, binding profiles being dominated by the strong binding sulfate group.
Polymerization of 5,6‐anhydro sugar derivatives, 2. Anionic polymerization of 5,6‐anhydro‐1,2‐O‐isopropylidene‐α‐D‐glucofuranose and synthesis of 5,6‐glucan
Authors: Uryu Toshiyuki , Kitano Kissho , Matsuzaki Kei 
Published: April 2003

AbstractPoly(5,6‐anhydro‐1,2‐O‐isopropylidene‐α‐D‐glucofuranose) (1) the main chain structure of which is poly(oxyethylene) was obtained by anionic ring‐opening polymerization of 5,6‐anhydro‐1,2‐O‐isopropylidene‐α‐D‐glucofuranose (2) which contains a pendent oxirane ring. Polymerization by strong bases such as sodium hydroxide, potassium hydroxide, cesium hydroxide, and potassium tert‐butoxide gave polymers with degrees of polymerization up to sixteen in high yield. The specific rotations of the polymers were almost constant, being mostly in the range from −44° to −40°. The factors affecting this polymerization were examined in order to elucidate the best conditions for polymerization. The polymer was hydrolyzed to 5,6‐glucan (3) with trifluoroacetic acid‐water at room temperature. The structures of the original polymer 1 and the hydrolyzed one were compared with those prepared by cationic ring‐opening polymerization of 2.
Chelation ion‐exchange properties of poly(8‐hydroxyquinolinediylethylene)
Authors: Patel Bhupendra S. , Patel Shanti R. 
Published: April 2003

AbstractThe polymer prepared from 8‐hydroxyquinoline and 1,2‐dichloroethylene by Friedel‐Craft's condensation, showed to be a selective chelating ion‐exchange resin for certain metal ions. A batch equilibration method was employed in the study of the selectivity of metal ion uptake. This method involved the measurement of distribution of a given metal ion between the polymer sample and a solution containing the metal ions. The study was carried out over a wide pH range and in media of various ionic strengths.
Polyoxirannes et polythiirannes comportant un centre chiral dans la chaine latérale, 1. Synthèse et pureté optique de diastéréoisomères des époxy‐1,2 méthyl‐3 pentane et épithio‐1,2 méthyl‐3 pentane
Authors: Goguelin Michel , Sepulchre Maurice 
Published: April 2003

AbstractIn order to study the polymerization of oxiranes and thiiranes containing an asymmetric carbon atom in the side chain a mixture (mole ratio 1:1) of the diastereoisomers 2R,3S and 2S,3S 1,2‐epoxy‐3‐methylpentane (1a et 2a) and 2R,3S and 2S,3S 1,2‐epithio‐3‐methylpentane (1b et 2b) as well as the almost pure diastereoisomers 2R, 3S (1b) and 2S, 3S (2a) were prepared. The diastereoisomeric composition of these compounds was established by 1H NMR spectroscopy, at 250 MHz for the thiiranes and at 90 MHz for the oxiranes (in the presence of a chiral shift reagent). The optical activities of the different pure diastereoisomers were determined, and the chiroptical properties of these new monomers were studied.
Synthesis of polyamide‐sulfonamides by ring‐opening polyaddition of 2,2′‐disubstituted bis(thiazetidinone 1,1‐dioxides) with aliphatic diamines
Authors: Imai Yoshio , Ueda Mitsuru , Okuyama Kazuo 
Published: April 2003

AbstractNew bifunctional, four‐membered heterocyclic monomers, 2,2′‐m‐xylylenebis(4,4‐dimethyl‐1,2‐thiazetidin‐3‐one 1,1‐dioxide) (1a) and 2,2′‐oxydi‐p‐phenylenebis(4,4‐dimethyl‐1,2‐thiazetidin‐3‐one 1,1‐dioxide) (1b), were synthesized from 2‐chlorosulfonyl‐2‐methylpropionyl chloride and the corresponding diamines. The ring‐opening polyaddition of these monomers 1a and 1b with aliphatic diamines in polar aprotic solvents afforded polyamide‐sulfonamides having inherent viscosities of 0,1–0,2 dl·g−1 in excellent yields. These polymers were soluble in polar aprotic solvents and both acidic and basic media. They began to lose weight at around 300°C in nitrogen under thermogravimetry.
Trans‐poly(butadiene‐co‐piperylene): Influence of temperature and molecular weight on bulk crystallization
Authors: De Chirico Aurelio 
Published: April 2003

AbstractBulk isothermal crystallization kinetics of a trans‐poly(butadiene‐co‐piperylene) sample (35 mol‐% of piperyleneSystematic name: 1,3‐pentadiene.
) and of its fractions were examined by dilatometry. Crystallization rates increase as crystallization temperature and molecular weight decrease. A solid/solid transition temperature, increasing with crystallization temperature, was observed. The nucleation free energy decreased with the crystallization temperature. This might be attributed to formation of less stable crystallites during the crystallization process.
Polystyrene as an inert medium in the synthesis of the styrene/divinylbenzene/acrylonitrile copolymers
Authors: Drăgan Stela , Nichifor Marieta , Petrariu Ioan 
Published: April 2003

AbstractSamples of styrene/divinylbenzene/acrylonitrile macroporous copolymers were prepared, using polystyrene as inert medium. The initial viscosity average molecular weight of the polystyrene samples were: M̄v.i=87000, 98000, 117000 and 218000. The polystyrene samples with the initial molecular weights M̄v.i=87000 and M̄v.i=117000 were reused as inert media, for many times, until they lost their capacity to produce permanent porosity of the copolymers. The macroporous copolymers were characterized by their permanent porosity and volume swelling. If a polystyrene sample is used for many times, the molecular weight of the polystyrene removed (extracted) is gradually diminished and therefore the permanent porosity of the macroporous copolymers decreases step by step. The reasons responsible for this behaviour are:

during the copolymerization process a polystyrene with a smaller molecular weight is formed.
polystyrene parts of high molecular weights are included in the network structure of the macroporous copolymers.
The evidence for this was given by plotting the differential and integral molecular weight distribution curves for six samples of polystyrene.
Mechanismus der photopolymerisation des styrols, 1. Zur desaktivierung elektronisch angeregten styrols durch chemische konzentrations‐löschprozesse: Photooligomere und photopolymere
Authors: Kauffmann Harald Friedrich 
Published: April 2003

AbstractElectronically excited styrene—in bulk or in concentrated solution—via intermolecular fluorescence self quenching processes undergoes a series of parallel and consecutive chemical reactions, leading to photooligomers and photopolymers. The oligomeric photoproducts, as shown by gas chromatography analysis, consist of dimers (M2) and trimers (M3) of styrene, whereby the quantity of M2 exceeds M3 by a factor of 20. The dimer fraction is built up of (a) 4 non olefinic cyclic C16‐hydrocarbons: cis‐1,2‐diphenylcyclobutane (c‐CB, 45–50 wt.‐%), trans‐1,2‐diphenylcyclobutane (tr‐CB, 8–10 wt.‐%), 1‐phenyl‐1,2,3,4‐tetrahydronaphthalene (1‐PhT, 7–9 wt.‐%), and 2‐phenyl‐1,2,3,4‐tetrahydronaphthalene (2‐PhT, 3–5 wt.‐%), (b) an open chain unsaturated compound–1‐vinyl‐2‐(2‐phenylethyl)benzene (VPEB, 5–7 wt.‐%), and (c) 5 highly unsaturated mono‐, bi‐, and/or tricyclic C16‐valence isomers (19–32 wt.‐%) which are considered to be the result of the participation of the aromatic benzene system in 1,2‐, 1,3‐ or 1,4‐photocycloaddition reactions, respectively. Among the numerous phototrimers, two saturated C24‐hydrocarbons were identified: 1‐phenyl‐4‐(1‐phenylethyl)‐1,2,3,4‐tetrahydronaphthalene (T1) and 2‐phenyl‐4‐(1‐phenylethyl)‐1,2,3,4‐tetrahydronaphthalene (T2). Under conditions where simultaneous thermal processes could be excluded (−20⩽T/°C⩽25), the presence of 1‐PhT, 2‐PhT, T1 and T2 gives strong evidence for the involvement of two 4π + 2π‐photointermediates, viz. 1‐phenyl‐1,2,3,8a‐tetrahydronaphthalene (1) and 2‐phenyl‐1,2,3,8a‐tetrahydronaphthalene (1′), which undergo two consecutive reactions: (a) a unimolecular, photo‐induced 1,3‐sigmatropic rearrangement (1‐PhT, 2‐PhT) and (b) a bimolecular, photo‐induced ene‐reaction with styrene as enophilic component (T1, T2). Because of the non‐concerted, stepwise nature of this photo‐ene‐process, the trimers have to be interpreted as the products of a cage reaction between two radical pairs |R1…R2| and |R1…R2′|. Their presence therefore gives strong evidence that the non‐concerted ene‐reaction is the most probable pathway for the production of the free radicals, which are responsible for the initiation of photopolymerization.
Einfluß einer orientierung der moleküle auf die kinetik der kristallisation von polyethylenterephthalat
Authors: Althen Gaby , Zachmann Hans Gerhard 
Published: April 2003

AbstractAmorphous samples of poly(ethylene terephthalate) were oriented by drawing at 92°C to different drawing ratios as well as by cold drawing. The kinetics of isothermal crystallization was determined in the range from 70°C to 115°C. The orientation of the samples was measured by the birefringence before crystallization. With increasing orientation also the rate of crystallization increases and the Avrami exponent n decreases from 3 to 1. The density obtained at the end of the crystallization process almost is not affected by the orientation. The results also indicate that some sort of order occurs already during the orientation process. The results are discussed. The birefringence does not change monotonically during crystallization.