bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microneck formation in polymer single crystals
Authors: Jones Janice Breedon , Geil Phillip H. 
Published: April 2003

AbstractElectron microscopy has been used to investigate the deformation by micronecking in single crystals of polyoxymethylene (POM), poly(4‐methyl‐1‐pentene) (P4M1P), and poly[3,3‐bis‐(chloromethyl)oxacyclobutane] (BCMO). When drawn on Mylar, all three polymers form micronecks bridged by microfibrils pulled from the crystal. The results of this study indicate that there is a region approximately 200 Å wide along the microneck edge that has properties different from those of the rest of the crystal. This difference appears as a change in the character of the gold particles along the microneck edges in crystals of all three polymers decorated with gold after stretch and as a gold‐free area along the edges in crystals decorated before stretch. In P4M1P and BCMO vertically shadowed with platinum after stretch, a lighter region was often seen at the edge that seemed to be due to a local lack of platinum. POM crystals subjected to any of the shadowing techniques used often had definite darkening along the edges of the micronecks which seemed to be due to decoration by residual poly(acrylic acid) used in preparation.
Orientierung und Bewegungsverhalten von Fluoreszenzsonden in nichtkristallinen Bereichen verstreckter Polyethylenfolien
Authors: Fuhrmann Jürgen , Hennecke Manfred 
Published: April 2003

AbstractInvestigations of molecular orientation and mobility within non‐crystalline regions of semicrystalline polymers yield different results depending on the experimental method used. Starting from criteria classifying the measured specific polymer property, the polarized fluorescence method is applied to investigate low density polyethylene during drawing. The measured orientation factors coincide with results acquired by other methods if the geometry of the fluorescent probe and the type of indication within the non‐crystalline regions are considered. Fluorescent probes, the quantum yield of which is enhanced in deformed, rheologically effective microregions within the non‐crystalline regions during drawing, allow to separate between the orientation and cooperative mechanism of displacement in these microregions and the behaviour of the unaffected part of the non‐crystalline phase. The volume fraction of the rheologically effective microregions is estimated. Fluorescent probes yield polymer informations, which can be understood as a result of averaging the orientation and mobility behaviour of the adjacent polymer chains.
Molecular weight distributions, 3. Gamma‐ray induced polymerization of methyl methacrylate in the solid state
Authors: Mayer Gunter , Huang Robert Y. M. 
Published: April 2003

AbstractThe kinetics and molecular weight distributions of the gamma‐ray induced polymerization of methyl methacrylate were investigated in the solid state in the temperature range of −50°C to −65°C. The polymerization reaction rate was found to be proportional to the amount of polymer formed. The polymerization at the freezing point did not show any special features. With increasing dose rate the radiation efficiency was found to drop faster in the solid than in the liquid state. The molecular weights showed the same features as in the liquid state polymerization previously reported and increased with percent conversion. A kinetic model for the solid state polymerization is proposed. The molecular weight distribution function could be expressed by a log‐normal distribution.
Influence of composition on the melt crystallization of isotactic random propylene/1‐butene copolymers
Authors: Crispino Luigi , Martuscelli Ezio , Pracella Mariano 
Published: April 2003

AbstractThe influence of composition on the overall rate of isothermal crystallization of isotactic random propylene/1‐butene copolymers is investigated. At a constant crystallization temperature a small fraction of 1‐butene co‐units inserted along a polypropylene chain causes a drastic reduction in the overall rate of crystallization. Further it is found that for a given rate of crystallization it is possible to crystallize the isotactic polypropylene at lower crystallization temperature by adding along the chain a small amount of 1‐butene as comonomer. The equilibrium melting temperature, the surface free energy of folding, the enthalpy and the entropy of fusion decrease with increasing the contents of 1‐butene in the copolymer samples.
Transcrystallization of isotactic polypropylene
Authors: Goldfarb Louis 
Published: April 2003

AbstractTranscrystallization of isotactic polypropylene — on polymer, metal, and metal‐oxide substrates — has been investigated by hot‐stage polarizing microscopy. A measure of the extent of transcrystallization was obtained from a count of spherulites per unit length of substrate, the linear nucleation density. Classical free‐energy models were used to interpret variations in linear nucleation densities, in which the degree of supercooling and surface‐energy expressions were emphasized.
Einige Modelluntersuchungen zur Chemie und Struktur von Polyvinylpyrrolidon‐Halogenophoren
Authors: Schenck Hans‐Uwe , Simak Peter , Hädicke Erich 
Published: April 2003

AbstractPolyvinylpyrrolidone forms complexes with hydrogen halides (HX; X = Cl, Br, I) and halogen molecules (Y2; Y = Br, I). For these compounds a structure is proposed in which the proton is coordinated to the carbonyl groups of two pyrrolidone rings by strong hydrogen bonds. The \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm XY}_{\rm 2}^ \ominus $\end{document}‐anion is attached ionically to this complex cation. The structure of these complexes could be elucidated by comparative examination of the Lig2 · HX · Y2‐complexes of model compounds such as N,N‐dimethylacetamide, N‐alkyl‐2‐pyrrolidones (2a – d), and 1,3‐bis(2‐oxo‐1‐pyrrolidinyl)butane (3) and the analogous polyvinylpyrrolidone complexes. The structure of the (N‐methyl‐pyrrolidone)2 · HI3‐complex was examined by X‐ray structure analysis. In a similar way the potassium salts (Lig2 · KX · Y2) of the complex acids could be prepared from the ligands, potassium halides, and halogen molecules. Unlike the proton, the potassium cation appears to be only weakly attached to the carbonyl groups of the ligands.
Die Messung der Dichte zur Umsatzbestimmung bei Polymerisationsreaktionen, 1. Untersuchungen an dem System Styrol‐Polystyrol in Tetrahydrofuran
Authors: Trathnigg Bernd 
Published: April 2003

AbstractIt is shown, that the density of a dilute solution of styrene and polystyrene of known total concentration represents the composition with high accuracy. An equation relating the density of a solution to the extent of polymerization is derived. A density measuring device according to the mechanical oscillator method proves to be a sufficiently sensitive instrument for determining the conversion in polymerization solutions even of very low concentrations.
Cinétique de cristallisation de la gélatine en solution aqueuse. Influence des différents composés moléculaires
Authors: Godard Pierre , Biebuyck Jean‐Jacques , Barriat Paul‐André , Naveau Henry , Mercier Jean‐Pierre 
Published: April 2003

AbstractThe gelation kinetics of gelatin of various molecular structures and also of different molecular components is studied by polarimetry. The gelation phenomenon can be analyzed as a conventional crystallization process assuming predetermined primary nucleation and unidirectional growth. The study of gelation kinetics of the different fractions displayed important alterations induced by the manufacturing process on the molecular structure and on the number of nucleation sites.
A convenient synthesis of poly[sulfonylmethylene‐1,4‐phenylenemethylene] directly from sulfur dioxide
Authors: Soga Kazuo , Nagata Ko‐ichi , Hattori Iwakazu , Ikeda Sakuji 
Published: April 2003

AbstractPoly[sulfonylmethylene‐1,4‐phenylenemethylene] (2) was obtained from 4‐chloromethylbenzyl chloride (1), potassium and sulfur dioxide by using 1,4,7,10,13,16‐hexaoxacyclooctadecane (18‐crown‐6‐ether) as catalyst. On the other hand, the reaction of 1, potassium and sulfur dioxide in the absence of 18‐crown‐6‐ether gave preferentially poly[1,4‐phenyleneethylene] (3) by the Wurtz reaction between 1 and potassium. A detailed study was carried out on these reactions.
Alternating copolymerization of cyclohexene oxide and sulfur dioxide
Authors: Soga Kazuo , Kiyohara Kazuto , Hattori Iwakazu , Ikeda Sakuji 
Published: April 2003

AbstractCopolymerization of cyclohexene oxide (CHO) and sulfur dioxide (SO2) was conducted at 80°C by using a variety of catalysts both in the presence and absence of solvent. Aromatic tertiary amines such as pyridine gave an alternating copolymer of CHO and SO2 in the presence of solvents such as 1,2‐dimethoxyethane. The alternating copolymer obtained was a white thermoplastic which could readily be thermoformed. It was soluble in acetone and chloroform but insoluble in water and hexane. From the reaction of the equimolar mixture of CHO, SO2 and pyridine at 20°C, an 1 : 1 : 1 adduct of CHO, SO2 and pyridine (see formula 2) could be isolated. This adduct was confirmed to be the active species for the present copolymerization.
Thermodynamic studies on DNA‐dye complexes
Authors: Tanaka Shigeyuki , Baba Yoshihiro , Kagemoto Akihiro , Fujishiro Ryoichi 
Published: April 2003

AbstractThe interaction between DNA and dyes such as acridine orange (1), proflavine (2), and 3,8‐diamino‐5‐ethyl‐6‐phenylphenanthridinium bromide (3) were studied by means of the heat of mixing and UV spectra. From the results obtained, the thermodynamic quantities of DNA‐dye complexes were estimated. It is concluded that the intercalation process forms a more stable binding than the stacking process does. Further, in each process, ΔG of DNA‐2 and DNA‐3 systems is nearly equal to that of the DNA‐1 system, but their — ΔH and — ΔS values are higher than those of the DNA‐1 system. The stability of binding in DNA‐2 and DNA‐3 systems may be governed largely by ΔH, while in the DNA‐1 system ΔS may contribute largely to the stability of binding.
Donor acceptor interactions in polymeric systems, 5. A polyurethane with pendant carbazolyl groups
Authors: Tazuke Shigeo , Nagahara Hajime , Matsuyama Yujiro 
Published: April 2003

AbstractA polyurethane having pendant carbazolyl groups separated by four methylene groups was prepared and the EDA complex formation with 2,4,7‐trinitrofluorenone (TNF) was studied in chloroform. EDA complexes of the polymer and the monomer model compound are spectroscopically indistinguishable. The formation constant (K) of the polymer complex is about equal to that of the monomer model compound in the oligomeric range whereas K increases with increasing molecular weight of the polymer. This trend of polymer effect is the same for the complex formation with other acceptors such as tetracyanoethylene (TCNE) and 1,3,5‐trinitrobenzene (TNB). The formation of the polymer complex is entropically favoured although the negative enthalpy change is larger for the monomer model compound. The reasons are discussed.
Polymerization of bicyclic acetals, 8. Cationic polymerization of 6,8‐dioxabicyclo[3.2.1]oct‐2‐ene
Authors: Okada Masahiko , Sumitomo Hiroshi , Kanie Masakazu , Komada Hajime 
Published: April 2003

AbstractPoly(5,6‐dihydro‐2H‐pyran‐2,6‐diyloxymethylene) (6), a new polyacetal having a dihydropyran ring in its repeating unit was prepared by selective ring‐opening polymerization of 6,8‐dioxabicyclo[3.2.1]oct‐2‐ene (5) at temperatures between −60 and −90°C in dilute methylene chloride or toluene solutions using boron trifluoride etherate as initiator. The resulting polymers, having a number average molecular weight up to 1,5 · 104, melted at 110 – 130°C and decomposed at ≈ 170°C in air. The isotactic dyad content of the polymers, estimated by 13C NMR spectroscopy, was found to be in the range of 70 to 77 mole‐%, somewhat lower than that of its saturated analogue, poly(tetrahydropyran‐2,6‐diyloxymethylene), (2). The preferred formation of the isotactic sequence along the polymer chain is rationalized in terms of the enantiomer selection by the growing chain end control mechanism as previously proposed for the polymerization of 6,8‐dioxabicyclo[3.2.1]octane, (1).
On the molecular weight determination by vapour pressure osmometry, 1. Consideration of the calibration function
Authors: Marx‐Figini Marianne , Figini Rubén Victor 
Published: April 2003

AbstractA detailed study on the calibration of vapour pressure osmometry (VPO) using thirteen different samples (eight of them polystyrenes) in a range of molecular weights up to 50 000 as solutes and chloroform, dichloromethane, ethyl methyl ketone, cyclohexane, and acetone as solvents is carried out. The results show that contrary to the commonly used calibration equation M = K · (ΔV/c), the relationship between the measuring result (ΔV/C)c=0 and molecular weight M obeys a function of the type M = K · (ΔV/c) in which the exponent a differs from 1. For each of the above mentioned solvents the values of K and a are determined. The limits of applicability of VPO with respect to polymers are discussed in view of these terms and recent theoretical considerations.
Long‐lived polymer radicals, 2. An ESR study on the reactions of the propagating polymer radicals of N‐methylacrylamide and N‐methylmethacrylamide with vinyl monomers at room temperature
Authors: Tanaka Hitoshi , Sato Tsuneyuki , Otsu Takayuki 
Published: April 2003

AbstractAcrylamide (AAm), methacrylamide (MAm), N‐methylacrylamide (NMAAm) and N‐methylmethacrylamide (NMMAm) were found to yield long‐lived propagating polymer radicals in the photo‐sensitized polymerizations in 1,4‐dioxane or benzene. The concentration of poly(NMAAm) radicals reached 1.10−3 mol/l. Some post‐effect was observed at room temperature in the photo‐sensitized polymerization of AAm with di‐tert‐butyl peroxide in 1,4‐dioxane, while no post‐polymerization proceeded at room temperature in the polymerization of NMMAm in benzene. The reactions of poly(NMAAm) and poly(NMMAm) radicals with various vinyl monomers were found to produce long‐lived propagating polymer radicals of the second monomers at room temperature. Polymer radicals of non‐homopolymerizable monomers such as α‐methylstyrene and 1,1‐diphenylethylene were easily formed in such a block‐copolymerization matrix. The formation of the propagating polymer radicals of the vinyl monomers was investigated by means of ESR spectroscopy.
Polymerization of ethylene catalyzed by titanocene systems, 1. Catalytic systems Cp2TiEtCl/AlEtCl2 and Cp2TiEtCl/(AlEtCl2 + H2O)
Authors: Cihlář Jaroslav , Mejzlík Jiří , Hamřík Oldřich , Hudec Pavel , Majer Josef 
Published: April 2003

AbstractThe kinetics of the ethylene polymerization catalyzed by the Cp2TiEtCl/AlEtCl2 system in toluene were investigated. Hydrolysis of AlEtCl2 in benzene was studied and the resulting oxyaluminium compounds were used as cocatalysts together with Cp2TiEtCl as catalyst for ethylene polymerization. A strong enhancement of the cocatalytic activity for the formation of oxyaluminium compounds was observed, accompanied by an increase of molecular weight. The catalyst efficiencies were found to be rather high in both the Cp2TiEtCl/AlEtCl2 and the Cp2TiEtCl/(AlEtCl2 + H2O) system. Transfer reactions are suppressed under the applied experimental conditions, but termination reactions, leading to non‐stationary kinetic patterns, may be assumed for both systems.
Preparations and asymmetric, reducing abilities of chiral polymeric amine‐boranes
Authors: Yamashita Tetsushi , Mitsui Hitoshi , Watanabe Hiroyuki , Nakamura Nobuo 
Published: April 2003

AbstractPolymeric amine‐boranes 2b, 4b, and 8c and their corresponding low‐molecular‐weight model compounds 3b, 5b, and 6b were obtained by reaction of chiral amines with diborane; these amines were poly(pyrrolidine‐1,2‐diylmethylene) (2a), poly(imino‐1‐isobutylethylene) (4a), poly{[1,2‐bis(4‐vinylphenyl)ethyl]amine} (8b), 1‐methylpyrrolidin‐2‐yl‐1‐pyrrolidinyl‐methane (3a), N1‐isopentyl‐N2‐methyl‐4‐methyl‐1,2‐pentanediamine (5a), and α‐phenylphenethylamine (6a). The polymeric amine‐boranes are white powders, stable to be kept for several weeks at room temperature, whereas the low‐molecular‐weight model compounds are less stable syrup‐like materials. The reduction of acetophenone to optically active 1‐phenylethanol was carried out with the chiral amine‐boranes in the presence of boron trifluoride etherate at various reaction temperatures. The product resulting from the reduction with 8c can easily be separated from the reaction mixture by filtration. The optical yield of the product obtained with 8c was 8,9% at −40°C. The highest optical yield (25,3%) was obtained with α‐phenylphenethylamineborane 6b at 0°C.
A study of the origins of colour in alkali degraded polyacrylonitrile and polymethacrylonitrile, 3. Computer predicted structures for the degradation products
Authors: Batty Norman S. , Guthrie James T. 
Published: April 2003

AbstractPossible structures for the products obtained on alkali treatment of polyacrylonitrile are considered. The Pariser‐Parr‐Pople (PPP) self‐consistent field method was applied to give λmax values for the proposed structures. The colouration of PAN by alkali was found to occur in two stages. There is a temporary colour which is destroyed by acids and a permanent colour which is not. The colour of alkali treated PMAN is entirely destroyed by acids. This temporary colouration may arise from n → π* transitions. We believe that the permanent colour of degraded PAN arises from π→π* transitions via a free radical activition mechanism and use of molecular oxygen.
Catalytic activity of polynuclear manganese‐thiolato complexes for oxidative polymerization of 2,6‐dimethylphenol
Authors: Kaneko Masao , Yamada Akira 
Published: April 2003

AbstractChelating thiolato‐manganese complexes of 1,2‐dimercaptoethane (DME), 3,4‐dimercaptotoluene (DMT), cystein (Cys), β‐mercaptoethyl alcohol (ME), β‐mercaptoethylamine (MEA), and mercaptoacetic acid (MAA) showed high activity for the oxidative polymerization of 2,6‐dimethylphenol (DMP) as heterogeneous catalysts. The complexes caused only CO coupling to give poly[oxy(2,6‐dimethyl‐1,4‐phenylene)] selectively. From the reaction in the absence of oxygen it was concluded that oxygen acts as electron‐accepting ligand. The much higher activity of DMT complex, compared with that of DME complex, was considered to be due to the π‐accepting character of the ligand. The MEA complex which showed especially strong spin‐spin interaction in the ESR spectrum exhibited also high activity.
The partial specific volume of lysozyme chloride in water under pressure
Authors: Chiri Rose‐Marie , Abétino François , Baret Jean‐François , Catella Robert , François Jeanne , Dayantis Jean 
Published: April 2003

AbstractThe apparent specific volume ν of lysozyme chloride dissolved in pure water has been measured from 1 to 4000 bar using the Adams‐Gibson‐Anderson method of trapped mercury. A parametric expression for ν as a function of solute weight fraction X2 is given for the various pressures at which the experiments have been performed. This parametric expression is valid when the densities of the solutions at atmospheric pressure and their compression at pressure P can be considered to be linear functions of the solute weight fraction X2. The relation between ν and the partial specific ν2 is discussed and it is shown that within the range of concentrations considered and given the precision of the experiments under pressure, the two quantities are indistinguishable.
Polymerization of tetrahydrofuran by bifunctional cationic initiators: Terephthaloyl perchlorate
Authors: Alamo Rufina , Guzmán Julio , Fatou José G. 
Published: April 2003

AbstractThe kinetics and mechanism of the polymerization of tetrahydrofuran with terephthaloyl perchlorate in methylene chloride or cyclohexane were analyzed. This polymerization produces dicationically active polymers and takes place without induction period. Propagation in both solvents proceeds as a reaction being first order in monomer, and it changes with the polarity of the solvent because ionic and covalent species take part with different growing rates. The macroester mole fractions in cyclohexane and methylene chloride are 0,99 and 0,86, respectively.
Reduction of nitrogen coordinated to polymer bound chlorobis(η‐cyclopentadienyl)titanium
Authors: Koide Mikio , Tsuchida Eishun , Kurimura Yoshimi 
Published: April 2003

AbstractDinitrogen complexes of poly{1‐[4‐(chlorodicyclopentadienyltitanio)phenyl]ethylene‐co‐1‐(4‐bromophenyl)ethylene‐co‐1‐phenylethylene} (2a – e) were synthesized. It was found that there is an equilibrium between the mononuclear and binuclear complex. Ammonia was formed after hydrolysis of the reaction mixtures resulting from 2a – e and lithium naphthalide in a nitrogen atmosphere. The yield of ammonia increased extremely with decreasing content of titanocene in the polymer. In the system with 2a 41,7 mol ammonia were formed per 1 mol of titanium.
Über den thermischen Abbau des Polypivalolactons in cyclische Oligomere
Authors: Lüderwald Ingo , Sauer Werner 
Published: April 2003

AbstractPyrolysis‐mass spectra have indicated that polypivalolactone degrades thermally into cyclic oligomers. To confirm this degradation behaviour polypivalolactone was pyrolyzed in a glass apparatus and the degradation products trapped at 0°C. After separation by preparative gel chromatography the isolated fractions could be identified as cyclic trimers to undecamers of pivalolactone and characterized by independent analytical methods. With the exception of the cyclic heptamer all odd oligomers have a lower melting point and enthalpy than the next bigger and smaller even cyclics.
Lamellar crystalline structure of block copolymers with an amorphous and a crystallizable block: Effect of the nature of the crystallizable block
Authors: Gervais Monique , Gallot Bernard , Jérome Robert , Teyssié Philippe 
Published: April 2003

AbstractBlock copolymers of styrene and ethylene oxide (SEO) and of styrene and ε‐caprolactone (SCL), in the dry state and in the presence of a preferential solvent of the amorphous block, exhibit a lamellar crystalline structure at temperatures below ≈50°C. In this structure the crystallized chains are folded in two superposed layers. To investigate the effect of the nature of the crystallizable block, two copolymers SEO and SCL of the same relative molecular mass and composition were studied by X‐ray diffraction and differential scanning calorimetry. It is established that the nature of the crystallizable block influences the crystallinity and the number of folds of the crystallized chains and the swelling of the amorphous polystyrene block.
Solid phase photoreduction of methylviologen on cellulose
Authors: Kaneko Masao , Yamada Akira 
Published: April 2003

AbstractMethylviologen (1,1′‐dimethyl‐4,4′‐bipyridinium dichloride, MV2+) absorbed on cellulose paper can be reduced photochemically in solid phase. The ESR spectrum (singlet; g = 1,967, ΔHmsl = 13,5 gauss) shows the photochemical formation of its cation radical (MV•+). The MV•+ formed on cellulose is unusually stable against oxidation by oxygen. Photochemical formation and slow oxidation of MV•+ under air occur fairly reversibly. The concentration of MV•+ and the optical density (O.D.) at 620 nm show a linear relationship. The concentration of MV•+ at 1 O.D. corresponds to 1,07.10−8 spins/cm2 cellulose paper. The formation of carbonyl groups in MV2+/cellulose after irradiation indicates that cellulose acts as electron donor. The mechanism of the solid phase photoreduction is discussed in relation to the effect of other carbohydrates or inorganic materials as adsorbents.