bluuebunny/crossref_metadata_2025_split huggingface dataset:
Telechelics, 7. Polytetrahydrofuran with acetate end groups
Authors: Kreß Hans‐Jürgen , Stix Wolfgang , Heitz Walter 
Published: April 2003

AbstractTetrahydrofuran (THF) was polymerized by protic and non‐protic cationic initiators in presence of acetic anhydride (Ac2O) in methylene dichloride. Due to a low transfer coefficient (CAc2o = 0,058) the molecular weight increases during the early part of the reaction. The consumption of Ac2O continues even when the THF concentration approaches zero, which results in a lowering of the number‐average degree of polymerization Pn. Degradation of poly(THF) continues until the Ac2O is exhausted. The equilibrium concentration of THF can reach almost zero at small Pn. The equilibrium constants K2, K3, K4, etc., up to K23 for the successive monomer additions are obtained from gel permeation chromatography. With the exception of K2 the equilibrium constants Kn are independent of n.
Thermodynamical description of deformation phenomena in rubbers
Authors: Kilian Hanns‐Georg , Vilgis Thomas 
Published: April 2003

AbstractA fundamental thermodynamical equation is presented for a Gaussian network in an analytically closed form (Gibbs function) for modified and extended network models in a parametric form. With this equation a complete description of the deformation phenomena in rubbers can be made, embracing strain‐dependent effects, related to short‐range properties like thermal expansion, rotational isomerism and rotatory oscillation degrees of freedom.
Molecular weight distribution studies, 4 Kinetics of the gamma‐ray induced free radical polymerization of vinyl acetate at low temperatures
Authors: Braks Jorma G. , Huang Robert Y. M. 
Published: April 2003

AbstractThe kinetics of the gamma‐radiation initiated free radical polymerization of vinyl acetate were studied in bulk over a temperature range of −60°C to 0°C. Four radiation dose rates of 0,83, 0,33, 0,26, and 0,079 Mrad were used. The overall rate of polymerization was found to vary with the 0,46 to 0,53 power of the radiation intensity, indicating a free‐radical polymerization mechanism. The overall activation energy was found to tie between 16 and 18 kj/mol. The values of ktrm/kp and (ktc + ktd)kp2 were evaluated from the overall polymerization rates and the number‐average molecular weights. The values of the radiation chemical yield GVAC were found to lie between 2,4 and 4,1.
Detection of a transition in diluted solution: polymer/solvent/non‐solvent mixtures
Authors: González Carmen , Zamora Fernando , Guzmán Gonzalo M. , León Luis M. 
Published: April 2003

AbstractThe behaviour of poly(N‐vinylcarbazole) (PNVC) in dilute solution of chlorobenzene/methanol and 1,3‐dichlorobenzene/methanol mixtures was studied. Theta compositions at 298 K were determined by using the cloud‐point method, giving values of 14, 1 vol.‐% methanol and 15 vol.‐% methanol, respectively. In both cases, viscometric measurements confirmed that the polymer was in the unperturbed state. A variation of several thermodynamic parameters, KΘl,γ and B with the solvent mixture composition and a transition in the coil state were detected at 5,0 vol.‐% methanol for the PNVC/chlorobenzene/methanol system and at 7,5 vol.‐% methanol for the PNVC/1,3‐dichlorobenzene/methanol system.
Structural study of compounds modelling elementary polymer units, 1. Molecular and crystal structures of 1,3,5‐tris(4‐biphenylyl)‐benzene and 1,3,5‐tris[4‐(C‐o‐carboranylmethyl)phenyl]benzene
Authors: Lindeman Sergey V. , Struchkov Valerii E. , Struchkov Yurii T. , Khotina Irina A. , Salykhnova Tunzil M. , Teplyakov Mihail M. , Korshak Vasilii V. 
Published: April 2003

AbstractFor elucidating the structural features of elementary units of polyphenylene type polymers, prepared by polycondensation of di‐ and mono‐acetylaromatic compounds, and X‐ray study of two model compounds was performed, viz. 1,3,5‐tris(4‐biphenylyl)benzene (1) and 1,3,5‐tris[4‐(C‐o‐ carboranylmethyl)phenyl]benzene (2) (diffractometer: R = 0,063 (1) and 0,061 (2))· 1 0,5 C6H6 crystals were found to be rhombohedral, a = 20,168 (3), c = 13,678 (3) Ǎ, space group R3c, Z = 6;2· CHCl3 crystals are triclinic, a = 15,7528 (2), b = 12,7004 (6), c = 15,460 (2) Å, α = 109,97(1) β = 111,92(1) γ = 100,69 (2) °, space group P1, Z = 2. In the crystal the molecule 1 has a 32 symmetry with a propeller‐like orientation of the biphenyl fragments with respect to the central ring (the rotation of the disubstituted benzene rings relative to the central one is 47,2° and relative to the therminal ones, it is 35,9°). In2 the disubstituted benzene rings are rotated with respect to the central one by different values (dihedral angeles are 31,7 ‐ 30,7, and 52,5°). In all benzene rings of both molecules a decrease of the endocyclic bond angles at the ipso‐atoms is observed which in 2 depends on the dihedral angeles between the planes of bonded benzene rings. All there carboranylmethylphenyl fragements in 2 have the same conformation: the CH‐group of the carborane skeleton “hangs” over the benzene ring plane. The crystal packing of 1and 2 is characterized by sufficiently large cavities which are occupied by solvent molecules. In crystals of 2 the carborane parts of the molecules are associated into separate structural motives.
UV‐Photometrische Analyse kationisch erzeugter Polystyrole, 2. Quantitative Bestimmung von Endgruppen in Polystyrolen, dargestellt mit Acylperchloraten
Authors: Kämmerer Hermann , Seyed‐Mozaffari Ahmad 
Published: April 2003

AbstractAcyl perchlorates generated in styrene without a solvent by acyl chlorides and silver perchlorate gave polystyrenes with covalently bonded acyl groups. In order to gain secured values their number average relative molecular masses (M̄n) were determined by different methods. The polystyrenes could be hydrogenated with hydrogen and Raney nickel at room temperature and under atmospheric pressure without attacking the phenolic nuclei. In addition IR data and a UV absorption at 294 nm of the polystyrenes revealed the presence of and olefinic bond, which was also found in a polystyrene obtained by polymerisation with perchloric acid. Also the quantitative evaluation of the hydrogeneation by UV absorption data gave number average relative molecular masses (M̄n,H), which are in accordance with other M̄n values. Furthermore, the UV absorption data of the polystyrenes gave correct M̄n values (M̄n,e) in combination with the molar absorption coefficients (ε) of model compounds. The number of covalently bonded acyl groups in a polystyrene sample could be determined by quantitative measurement of the UV absorption in combination with the ε‐values of model compounds and the M̄n values. This number was found to depend on the nature of the acyl perchlorate and it amounts to one acyl containing molecule per four to hundred molecules without an acyl group.
Anionic polymerization of β‐nitrostyrenes
Authors: Berry Robert W. H. , Mazza Robert J. , Sullivan Stuart F. 
Published: April 2003

AbstractThe rate of polymerization of β‐nitrostyrene initiated by sodium alkoxide was setudied gravimetrically. The rate was found to be first order with respect to monomer concentration and first order with respect to initiator concentration. Rate constants in the order of 0,25 dm3 · mol−1 · s−1 were obtained at 15°C, 20°C, and 25°C for the polymerization of β‐nitrostyrene, p‐methoxy‐β‐nitrostyrene, and p‐methyl‐β‐nitrostyrene initiated by sodium methoxide and by sodium ethoxide. The activation energy of polymerizations initiated by sodium methoxide and by sodium ethoxide was ∼24 kJ · mol−1 and ∼ 16 kJ · mol−1, respectively. The number average degree of polymerization of poly(β‐nitrostyrene)s was determined by polymerization of the monomer in the pressence of 14C‐alkanol. This is the first time that accurate number average molar masses of poly(β‐nitrostyrene)s have been reported since conventional methods of molar mass determination cannot be used owing to the insolubility of these polymers in most common organic solvents.
Dilute solution properties and unperturbed dimensions of poly(di‐ni‐alkyl itaconate)s
Authors: Veličković Jovan , Filipović Jovanka 
Published: April 2003

AbstractThe diesters of itaconic acid (methylenesuccinic acid) with higher C12 – C20 unbranched, saturated, aliphatic alcohols were prepared, purified, and polymerized in bulk or in solution with 2,2′‐azoisobutyronitrile as initiator. The transparent to waxy polymers obtained were fractionated and all fractions characterized by viscosity and light scattering measurements. The Kuhn‐Mark‐Houwink‐Sakurada relations were established and then extrapolated to thetaconditions, in order to calculate the unperturbed dimensions. High values of the steric factor σ, and the characteristic ratio C∞ were obtained. The results correlate well with those obtained previously for poly(di‐n‐alkyl itaconate)s from the corresponding lower C1 – C11 alcohols.
Darstellung einer homologen Reihe von oligoallylalkoholen mit 1‐cyano‐1‐methylethyl‐endgruppen. Beispiel einer mehrfachen matrizenreaktion und einer replicaoligomerisation
Authors: Kämmerer Hermann , Hegemann Günter 
Published: April 2003

AbstractReduction and hydrolysis of the ladder oligomers 1, 2, 3, 4, and 5 prepared from the acrylates of oligo (hydroxyphenylene‐methylene)s was found to lead to a homologous series of oligo (allylalcohol)s (6a, 7a, 8a, 9a and10a) with good yields. These alcohols were characterized by analytical and spectroscopic methods. The reaction sequences, starting with the esterification of the oligo[(hydroxyphenylene) methylene]s 11a – 11e with acryloyl chloride followed by the formation of the ladder oligomers and ending with their reduction and hydrolysis into the oligo(allyl alcohol)s and the starting compounds 11a – 11e, represent a simple matrix reaction. A mixture of multiple acrylates was also subjected to the same reaction sequences, resulting in a multiple matrix reaction. A mixture of matrix compounds 11b – 11e with a known mole ratio was esterified with acryloyl chloride, then transformed into a mixture of ladder oligomers and subsequently reduced and hydrolyzed to afford a mixture of oligo(allyl alcohol)s with the same mole ratio of the starting matrices as shown by gas chromatographic analysis. This represents a paradigm for a replica oligomerisation.
Functional monomers and polymers, 115. Permeability of hydrogel membranes consisting of copolymers containing pendant nucleic acid bases
Authors: Miyata Mikiji , Senda Shuji , Takemoto Kiichi 
Published: April 2003

AbstractHydrogel membranes consisting of copolymers from 2‐hydroxyethyl methacrylate (1a) and vinyl monomers (1b, 2b, 1c, 2c) containing nucleic acid bases such as adenine and uracil, were prepared by casting technique. The permeability measurement of these membranes for adenine and uracil revealed a selective transport which depends on the copolymer composition of the membranes and the permeation conditions. Transport of adenine based on the difference of proton concentration was also observed. The specific interaction between complementary nucleic acid bases seems to play an important role in the permeation behavior.
Polymer conformation and NMR chemical shifts, 9. Poly(α‐methylene‐γ‐butyrolactone)
Authors: Sato Kota , Koinuma Hideomi , Hirai Hidefumi 
Published: April 2003

AbstractThe conformational energies of poly(α‐methylene‐γ‐butyrolactone) are calculated and compared with those of poly(methyl methacrylate). In spite of the structural resemblance of these two polymers, the patterns of the energy contour maps are clearly distinguishable from each other; the energy barriers between rotational isomeric states are appreciably higher in the former than in the latter polymer. The calculation indicates large non‐bonded interactions between the protons in one lactone ring and those in the adjacent lactone rings. The broad NMR spectrum of poly(α‐methylene‐γ‐butyrolactone) apparently reflects its rigid conformational structure. 1H and 13C NMR chemical shifts are calculated by theoretical shielding calculations based on conformational analysis. Much lower magnetic field resonances of the OCH2 and α‐CH2 carbons in poly(α‐methylene‐γ‐butyrolactone) as compared with those of the OCH3 and α‐CH3 carbons in poly(methyl methacrylate) are well reproduced by the calculation. The shift to lower magnetic field is mainly attributed to paramagnetic shielding derived from the interaction between OCH2 carbon and α‐CH2 carbon. Tacticity‐ and conformation‐dependent 1H and 13C NMR chemical shifts of poly(α‐methylene‐γ‐butyrolactone) are well interpreted on the basis of the conformational analysis.
Investigation of molecular orientation and conformational change upon drawing for various ethylene/1‐butene copolymers by IR spectroscopy
Authors: Hosoda Satoru 
Published: April 2003

AbstractInfrared spectroscopy was used to investigate the molecular orientation and the conformational change upon drawing for various ethylene/1‐butene copolymers in a wide range of crystallinity (0 ≤ Xc ≤ 85% ). The degree of crystalline orientation at constant draw ratio decreases with increasing crystallinity. The orientation function for the amorphous CH2 sequence in the trans conformation, f(am), was calculated assuming additivity for the orientation functions of the trans bands. f(am) increases with drawing in a characteristical way for the different materials and reaches a value higher than that of the amorphous gauche bands. Furthermore, it was found that f(am) is strongly dependent on crystallinity. The relative concentration of the amorphous CH2 sequences in the trans conformation increases at the expense of that of the gauche sequences. The transformation from gauche to trans in the amorphous phase occurs simultaneously with the orientation of the amorphous CH2 sequences.
Poly(urethane‐parabanic acid)s
Authors: Caraculacu Adrian A. , Caraculacu Georgeta 
Published: April 2003

AbstractOligoureas with diisocyanato end groups (6a – f) were transformed into the respective parabanic acid derivatives (7a – f) with the aid of oxalyl chloride (2). In the reaction of 2 with certain diurea model compounds (12) in 1,2‐dichloroethane at room temperature besides the corresponding parabanic acids, diurea dihydrochlorides were formed. Their solutions in 1,2‐dichloroethane exhibit electrical conductivity. IR spectra confirm their structure. The reaction of the α,ω‐diisocyanatopoly(parabanic acid)s with diols (8a – e) led to copolymers and block copolymers, poly(urethane‐parabenic acid)s. The experimental conditions and the influence of the structure of the polymers on certain properties of the final products were investigated.
Thermodynamic properties of polylactones
Authors: Lebedev Boris , Yevstropov Alexei 
Published: April 2003

AbstractTemperature dependences of isochoric heat capacity, temperatures and enthalpies of physical transitions for polyglycolide, poly(β‐propiolactone), poly(γ‐butyrolactone), poly(λ‐valerolactone), poly(ε‐caprolactone), polyundecanolactone, polytridecanolactone, and polypentadecanolactone were studied between 13,8 and (340 – 550) K in a vacuum adiabatic calorimeter within a limit of experimental error of about 0,2%. From the results obtained the functions H0 – H0 (O), S0 (T), and G0 (T) – H0 (O) were calculated over the range 0 to (340 – 550) K. Zero entropy of glassy polymers, Sg0 (O), and difference in zero enthalpies of glassy and crystalline states, Hg (O) – Hc0 (O), were estimated also. Regularities of changes in thermodynamic properties of polylactones, in dependence of the number of atomic groups in a repeating unit, were found that made it possible to evaluate the properties of some polylactones the corresponding experimental data of which are not known.
Oxidation of poly(tetramethylene sulfide)
Authors: Marco Carlos , Fatou José G. , Bello Antonio , Pereña José M. 
Published: April 2003

AbstractOxidation of poly(tetramethylene sulfide) single crystals was carried out in a dispersion of distilled water at 25°C using trifluoroacetic acid and H2O2. The oxidation takes place in two different stages: the first one corresponds to preferential formation of sulfoxide groups and the second one, at higher concentrations of oxidizing agent, corresponds to formation of sulfone groups. Changes in crystallinity and melting behaviour of the intermediate polysulfones obtained were followed by X‐ray diffraction and calorimetry. Changes in the heat and temperature of melting and in the morphology are related to the different stages of oxidation.
New results in hydrolytic lactam polymerization
Authors: Bertalan György , Rusznák István , Anna Peter 
Published: April 2003

AbstractA new mechanism is proposed for the hydrolytic lactam polymerization. During reversible lactam addition to groups a considerable amount of amidines (ω‐amidinocarboxylic acids) is formed in addition to the polymeric homologous series. The amount of these ω‐amidinocarboxylic acids, can be determined quantitatively. They can participate in different reactions during the lactam polymerization leading to disproportionation of the amidino and carboxyl groups at a high rate, and to initiation. The proposed mechanism is valid for ε‐caprolactam and octanelactam.
Thermodynamic and hydrodynamic properties of aliphatic polyesters, 2. Intrinsic viscosity, radius of gyration and second virial coefficient of poly(β‐propiolactone) in 2,2,2‐trifluoroethanol
Authors: Rosenvasser Daniel , Figini Rubén V. 
Published: April 2003

AbstractThe molecular properties of poly(β‐propiolactone) in 2,2,2‐trifluoroethanol show that the poly(β‐propiolactone) molecule is highly expanded in solution due to unusually large excluded volume effects. The values of the exponents in the relationships between the radius of gyration, the intrinsic viscosity, the second virial coefficient on the one hand and the molecular weight on the other agree viscosity, the second virial coefficient on the one hand and the moleculer weight on the other agree with those deduced by scaling arguments with the value of the universal critical (exponent) v ≈ 3/5.
Ethylene glycol oligomers
Authors: Yeates Stephen G. , Teo Hoon Hong , Mobbs Richard H. , Booth Colin 
Published: April 2003

AbstractPure samples of the oligo(ethylene glycol)s 1a (n = 30 or 45), were prepared from the monosodium salt (1c) and the ditosylate (1b) of pentadeca(ethylene glycol). The Melting points of the samples were found to be higher than those of comparable materials prepared hitherto. The melting points of several pure oligo(ethylene glycol)s in the range n = 9 to 45, deriving from this and earlier work, were compared with those of commercially available poly(ethylene glycol)s of similar average chain lengths.
Relations between property versus molar mass relationships, 1. Sedimentation coefficient versus molar mass and diffusion coefficient versus molar mass relationships
Authors: Bareiss Rolf E. 
Published: April 2003

AbstractThe general validity of the “Exponents' Rule”, i.e. the interdependencies of the exponents from exponential property versus molar mass M relationships, is based on the general definition for the average of a molar mass dependent property. From this, the numerical value of the product KsD · Ks · KD‐1 of the pre‐exponential constants of the sedimentation constant (s) versus molar mass relationship, Ks, the diffusion coefficient (D) versus molar mass relationship, KD, and the constant of Svedberg's equation \documentclass{article}\pagestyle{empty}\begin{document}$ K_{sD} = {{RT} \mathord{\left/ {\vphantom {{RT} {(1 - \tilde \nu _2 \cdot 2\rho _1 )}}} \right. \kern-\nulldelimiterspace} {(1 - \tilde \nu _2 \cdot 2\rho _1 )}} $\end{document} is found to be dimensionally and numerically unity (\documentclass{article}\pagestyle{empty}\begin{document}$ \tilde \nu _2 $\end{document}: partial specific volume of polymer; ρ1 : density of solvent):

The experimental validity of this “Product of Constants” to be unity is proven by evaluating 26 different s versus M and D versus M relationships of 8 different polymer/solvent (temperature) systems from literature, which are based on mutually independent measurements of s, D, and M.
Glass transition temperatures in blends of poly(N‐vinyl‐2‐pyrrolidone) with a copolymer of bisphenol A and epichlorohydrin or with poly(vinyl butyral)
Authors: Eguiazabal Jose I. , Iruin Juan J. , Cortazar Mila , Guzmán Gonzaio M. 
Published: April 2003

AbstractBlends of poly(vinyl butyral) (PVB) and of a copolymer of bisphenol A and epichlorohydrin (Phenoxy) with poly(N‐vinyl‐2‐pyrrolidone) (PVP) were prepared by solution casting. The glass transition temperatures Tg for different compositions of the blends were measured by differential scanning calorimetry (DSC). The Tg behaviour of PVB/PVP blends suggests the existence of a single phase for blends containing less than 50 wt.‐% PVP, and of two phases in blends containing more than 50 wt.‐% PVP. Phenoxy/PVP blends showed to be miscible over the entire composition range. It was found that the Gordon‐Taylor equation predicts adequately the Tg‐composition dependence with a K parameter equal to 0,5 and 1,25 for PVB/PVP and Phenoxy/PVP blends, respectively.
Spectroscopic test of the pressure effect on complexes of poly(N‐vinylcarbazole) and derivatives with tetracyanoethylene
Authors: Pielichowski Jan , Sanetra Jerzy 
Published: April 2003

AbstractThe absorption spectra of the complexes of tetracyanoethylene with poly(N‐vinylcarbazole), poly(N‐vinyl‐3‐chlorocarbazole), and poly(N‐vinyl‐3,6‐dichlorocarbazole) were investigated in the visible range as a function of the pressure. The degree of complexation expressed by the equilibrium constant, the oscillator strength, and the excitation energy were determined. A significant increase of the oscillator strength was observed, when the pressure increases, this being in agreement with Mulliken's theory. With increasing pressure the absorption maximum of the CT complex was shifted towards the infra‐red. Two peaks were found as a consequence of a splitting of the absorption band under the influence of pressure. This effect is discussed in terms of the existence of orientational isomers. An influence of the substituents (chlorine) in 3‐and 3,6‐positions of carbazole on the spectral properties of the complexes was found.
Synthesis of segmented copolyamides by using telechelic prepolymers
Authors: Chujo Yoshiki , Hiraiwa Akihiko , Yamashita Yuya 
Published: April 2003

AbstractPolyamide‐polystyrene and polyamide‐poly(oxyethylene) segmented copolymers 6a, b of well‐defined structure and composition were synthesized using telechelic prepolymers. α,ω‐Dicarboxyl‐terminated polystyrene 2 was prepared by radical polymerization of styrene initiated by 4,4′‐azobis(4‐cyanovaleric acid) (1). α,ω‐Dicarboxyl‐terminated poly(oxyethylene) 3 was prepared by the reaction of commercially available hydroxyl‐terminated poly(oxyethylene) with excess succinic anhydride. These telechelic prepolymers were condensed with hexamethylenediamine in a 1:1 mole ratio together with nylon‐6,6 salt using the triphenyl phosphite/pyridine system. Similarly, α,ω‐diamino‐terminated polystyrene 5 was prepared and condensed with adipic acid and nylon‐6,6 salt. The segmented copolymers 6a and 6b were characterized by their 1H NMR and IR spectra.
Selective ring‐opening polymerization of 3,5‐anhydro‐1,2‐O‐isopropylidene‐α‐D‐xylofuranose synthesis of [3→5]‐D‐xylan
Authors: Uryu Toshiyuki , Koyama Yoshiyuki , Matsuzaki Kei 
Published: April 2003

AbstractThe ring‐opening polymerization of 3,5‐anhydro‐1,2‐O‐isopropylidene‐α‐D‐xylofuranose was studied to investigate the selectivity of ring‐opening mode under various polymerization conditions with a number of Lewis acids, anionic and coordinated catalysts. In all the conditions attempted here, the monomer attacks only the C‐5 methylene carbon of the active end of the growing chain to form a stereoregular [3→5]‐α‐D‐xylofuranan structure. With removal of the isopropylidene groups of the polymer, a new class of non‐hydrolyzable polysaccharides, [3→5]‐D‐xylan, is obtained.