bluuebunny/crossref_metadata_2025 huggingface dataset:
Telechelics, 7. Polytetrahydrofuran with acetate end groups
Authors: Kreß Hans‐Jürgen , Stix Wolfgang , Heitz Walter
Published: April 2003

Tetrahydrofuran (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

A 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

The 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

The 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

For 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

Acyl 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

The 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

The 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

Reduction 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

Hydrogel 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

The 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

Infrared 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

Oligoureas 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

Temperature 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

Oxidation 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

A 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

The 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

Pure 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

The 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

Blends 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

The 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

Polyamide‐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

The 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.
Adhesion behavior of rat lymphocytes on poly(γ‐benzyl L‐glutamate) derivatives having hydroxyl groups or poly(ethylene glycol) chains
Authors: Nishimura Takao , Sato Yuichi , Yokoyama Masayuki , Okuya Mashahiro , Inoue Shohei , Kataoka Kazunori , Okano Teruo , Sakurai Yasuhisa
Published: April 2003

Poly[γ‐benzyl L‐glutamate (BLG)‐co‐N5‐(3‐hydroxypropyl)‐L‐glutamine (HLG)] (3) and polyBLG/poly(ethylene glycol) (PBLG/PEG) block copolymers (6) were synthesized, and the adhesion behavior of rat lymphnode lymphocytes on these polymers was examined by the column method. An increase in the HLG content of polymer 3 caused a slight decrease in lymphocyte adhesivity. Lymphocyte subpopulation B cells were found to be more adhesive to polymers 3 than T cells, by a factor of 1,4 – 1,6. On the other hand, an increase in the PEG content of PBLG/PEG block copolymer caused a remarkable decrease inlymphocyte adhesivity and an increase in selectivity in the adhesivity between B cells and T cells up to a factor of 2,3.
Vapour pressures of the system tert‐butyl acetate/polystyrene
Authors: Schotsch Kurt , Wolf B. A.
Published: April 2003

An apparatus is presented for the precise measurement of vapour pressures. It is tested with diethyl ether and applied to the system tert‐butyle acetate/polystyrene (weight‐average molecular weight Mw = 110000) up to polymer concentrations of ca. 60 wt.‐% in the temperature range from 10 to 90°C; by means of the Redlich‐Kister equation the results can well be described analytically. The data are evaluated to yield the Flory‐Huggins parameter in the subsequent article in conjunction with other experimental information.
Structure and stability of poly(vinyl chloride), 4. Unsaturated ketones and their role in the initiation of thermal degradation
Authors: Světlý Jarmil , Lukáš Rudolf , Michalcová Jaroslava , Kolíanský Miloslav
Published: April 2003

The thermal dehydrochlorination of poly(vinyl chloride) (PVC) in an inert atmosphere was investigated by the continuous potentiometric method. The effect of the structure of alicyclic and aliphatic α,β‐unsaturated ketones on the rate of dehydrochlorination was examined, and a new mechanism of initiation for the dehydrochlorination of PVC was suggested. The results obtained demonstrate that the basic cause of the thermal instability of PVC are structures of the type of cisoid α,β‐unsaturated ketone, dienone, or polyenone which by the dehydrochlorination of regular structural PVC units form isolated double bonds which, in turn, initiate the chain dehydrochlorination of PVC by allyl activation.
Gemischte Diester von 2,2′‐Methylendiphenolen mit Methacryl‐ und Crotonsäure und ihre Polymeren. 13C NMR‐Untersuchungen zur Strukturaufklärung
Authors: Böhmer Volker , Funk Rüdiger , Vogt Walter
Published: April 2003

The structure of mixed diesters of three 2,2′‐methylenediphenols with crotonic acid and methacrylic acid was studied by 13C NMR‐spectroscopy. The position of the two acyl groups, expected from the synthetic pathway, was unambiguously confirmed by comparison with the corresponding mono‐ and diesters containing the same acyl group. In the same way, it was shown that the crotonoyl residue is not involved in the radical polymerisation of these esters.
Investigations on linear segmented polyurethane elastomers, 1. Temperature dependence of microphase segregated structure
Authors: Tagawa Hiroyuki , Kurita Kimio , Wada Eiichi
Published: April 2003

The temperature dependence of microphase segregation in polyester and polyether segmented urethane elastomers has been studied by small‐angle X‐ray scattering, viscoelasticity, and infrared spectroscopy. The mean‐square electron density fluctuations distincitly decrease with increasing temperature above about 60°C. Their value estimated from the location of the first peak of the electron density correlation function increases with increasing temperature; at the same time the peak becomes flat and finally disappears. The infrared absorbance for the NH vibration decreases above about 80°C. These results correspond to an increase of the mean distance between the centers of the nearest neighbouring microdomains, mainly composed of the hard segments, and to intermixing of hard and soft segments in the boundaries of the domains by heat treatment. This fact suggests that a domain structure is formed by casting in these polyurethane elastomers. The dynamic storage moduli G′ for both samples investigated decrease in the two temperature ranges, −70 to −20°C and 60 to 120°C, the former corresponds to the dispersion of soft segments and the latter to the dissociation of hydrogen bonds.
Résines époxydes, 3. Etude de quelques prépolymères époxydes bromés par GPC, HPLC et NMR
Authors: Gulino Danièle , Galy Jocelyne , Pascault Jean‐Pierre , Pham Quang Tho
Published: April 2003

Examinations by GPC, HPLC and NMR of several commercial prepolymers containing epoxy groups show that they are based on bisphenol A (DGEBA) and brominated bisphenol A (DGEBtBr). In some cases, brominated monepoxides are also added to the mixture to diminish its viscosity. Consequently, the three‐dimensional networks resulting from the polycondensation of brominated resins with diamines can be greatly affected by the presence of these monoepoxides that modify the epoxy/amine ratios.
Synthesis and investigation of the properties of polymers containing dicarbaundecaborate
Authors: Bekasova Nina I. , Komarova Ludmila G. , Kats Georgii A. , Korshak Vasilii V.
Published: April 2003

Polymides containing dicarbundecaborate moieties (1) are formed by nucleophilic degradation of polyamides containing 1,7‐dicarba‐closo‐dodecaborane(12) (m‐carborane) moieties in the polymeric chain. The formation of polyamides 1 is accompained by decomposition of the polymeric chain. Potassium cations in the dicarbundecaborate moieties were shown to be easily replaced by protons. The structure of polymers containing exclusively dicarbaundecaborate units (2) was investigated by IR and 1H NMR spectroscopy. Some chemical and physico‐chemical properties of these polyamides were studied.
Kinetics of deactivation in the BuOTiCl3/AlEt2Cl initiated polymerization of styrene
Authors: Sehra Jagdish C. , Gundiah Subbaraya
Published: April 2003

The deactivation of the catalytic activity of the BuOTiCl3/AlEt2Cl initiated polymerization of styrene in heptane was found to follow a second‐order rate law. The varying slopes in the second‐order plots observed with varying catalyst concentrations are due to the heterogeneous nature of these colloidally dispersed catalysts. Site poisoning by reversible adsorption of the AlEtCl2 formed, is proposed as the probable reason for the deactivation.
Conformational analysis and reactivity in isotactic specific polymerization of C‐3 branched α‐olefins
Authors: Ammendola Paolo , Guerra Gaetano , Villani Vincenzo
Published: April 2003

Quantitative conformational analysis of 3‐methyl‐1‐butene, 3‐methyl‐1‐pentene and 3‐ethyl‐1‐pentene seems to support the hypothesis that the conformation of these monomers in the active state of Ziegler‐Natta isotactic polymerization is either H‐skew + or H‐skew −. It seems, however, that the experimentally determined reactivities of the considered α‐olefins in the initiation steps of the isotactic polymerization could be accounted for quantitatively only by assuming somewhat different activation energies for the attack of the different monomers.
Synthesis of a propene—methyl methacrylate diblock copolymer via “living” coordination polymerization
Authors: Doi Yoshiharu , Koyama Tetsuya , Soga Kazuo
Published: April 2003

A new diblock copolymer of propene and methyl methacrylate (MMA) was prepared by adding MMA during the living coordination polymerization of propene together with the soluble catalyst V(acac)3/Al(C2H5)2Cl at −78°C and subsequently by raising the polymerization temperature up to 25°C. The homopolymerization of MMA with this catalyst exhibits the characteristics of a living polymerization at the initial stage of polymerization. From the copolymerization of MMA with styrene, it was concluded that the polymerization of MMA occurs via a radical intermediate. It is suggested that a propene‐MMA diblock copolymer is formed via the transformation of a living polypropylene end to a radical end.
Aldehydes and acetals based on esters of methacrylic acid as potential monomers
Authors: Zábranský Jiří , Houska Milan , Kálal Jaroslav
Published: April 2003

New monomers containing aldehyde groups in the alcohol component of methacrylates were prepared. The structure of these monomers prevents undesired spontaneous intramolecular cyclization reactions of pendant aldehyde groups of the corresponding polymers. 2,2‐Diethoxyethyl methacrylate (1) and its saturated analog, 2,2‐diethoxyethyl pivalate (3) and 3,3‐diethoxypropyl methacrylate (2) were prepared. The conditions for a selective hydrolysis of the acetal function of these compounds, leading to the corresponding aldehydes, were studied.
Cinétiques de télomérisation, 1. Determination des lois applicables à la synthèse des télomères à DPn moyens en télomérisation radicalaire
Authors: Boutevin Bernard , Piétrasanta Yves , Bauduin Gérard
Published: April 2003

The kinetics of free radical telomerization was studied. The theoretical relations that can be applied in reactions of this type, were evaluated. When transfer predominates, the equations giving the variations of monomer, telogen and initiator as a function of time were established. Moreover, instantaneous and cumulated number and weight average degrees of polymerization were calculated. The resulting relations were checked on the example of the telomerization of 2,3‐epoxypropyl methacrylate with bromotrichloromethane in the presence of two initiators and two different temperatures. Comparison of the experimental results with the theoretical ones revealed the scope of application of the general formulae giving the average degrees of polymerization.
Substitutions in polymer complex systems
Authors: Bekturov Esen A. , Khamzamulina Rimma E. , Belgibaeva Zein K.
Published: April 2003

The substitution in polymer1‐fluorescence dye‐competitor systems was investigated by measurement of the dye fluorescence. It is ascertained that the main factor affecting the direction of the possible reaction is the nature of the competitor. According to their ability to substitute dyes, different competitors can be arranged in the following series: polyelectrolytes > nonionic polymers ≥ surfactants > metal ions.
Effect of the acid dimer on the α‐relaxation process of the methyl methacrylate‐acrylic acid copolymer
Authors: Kihira Yasuharu , Yamamura Hitoshi , Murakami Ichiro
Published: April 2003

The dielectric and mechanical α‐relaxation process and the IR spectra of a methyl methacrylate‐acrylic acid copolymer, prepared by radical copolymerization, were investigated at a wide temperature range across the glass‐transition temperature. From the temperature dependence of the relaxation strength for the α‐process, the dissociation energy for the acid dimer in the copolymer was estimated by dielectric and mechanical methods, similar to the case of the methyl methacrylate‐methacrylic acid copolymer. The α‐relaxation shifts to lower temperatures with increasing number of acrylic acid monomeric units. The fact is due to the increase of more flexible acrylic acid monomeric units, released from the acid dimer into the methacrylate polymer chain.
Polymeric peroxycarbamates: Synthesis, characterization and their initiation of styrene polymerization
Authors: Yilgör İskender , Baysal Bahattin M.
Published: April 2003

Three different polymeric peroxycarbamates were synthesized using polyether glycols, a cycloaliphatic diisocyanate and a dihydroperoxide. The products were characterized by infrared spectroscopy, molecular weight measurements and isocyanate and peroxygen analyses. Thermal decomposition kinetics of these peroxycarbamates were studied in toluene or 1,4‐dioxane solutions at 80, 90 and 100°C. All reactions were found to proceed according to the first‐order kinetics with activation energies in the range of 123 to 145 kJ · mol−1, depending on the structure of the peroxycarbamate. One of the products was used to initiate styrene polymerization at 80°C, in bulk. The initiating activity of this polymeric peroxycarbamate was found to be better than that of some hydroperoxides.
Sequential analysis of polyesters by stepwise chemical degradation. Preparation of the reagent
Authors: Schmitz Franz P. , Windeln Johannes , Rossbach Volker
Published: April 2003

N‐{2‐[4‐(N‐tert‐Butoxycarbonylamino)benzoylamino]ethoxycarbonyl}anthranilic acid (1) was synthesized as a reagent for the stepwise elimination of monomeric units from the chain ends of oligoesters and polyesters, especially of poly(ethylene terephthalate) and poly(tetramethylene terephthalate) type. The reagent is supposed to be applied for a stepwise chemical degradation and thus for a sequential analysis of these polyesters.
Poly(vinyl acetate) as a test of the roedel mechanism for short branch formation
Authors: Viswanadhan V. N. , Mattice Wayne L.
Published: April 2003

Probabilities of configurations conducive to the intramolecular back‐biting abstraction of a hydrogen atom have been evaluated for growing unperturbed poly(vinyl acetate) chains. A realistic rotational isomeric state model was used for the chain statistics. Probabilities are found to be smaller than those seen in an earlier treatment of the polyethylene chain. The smaller probabilities of poly(vinyl acetate) contribute to the virtual absence of short branches. The present study therefore provides support for the validity of the Roedel mechanism for the formation of short branches in the free radical initiated polymerization of ethylene.
Continuous fractionation and solution properties of PVC, 2. Scrutiny of solvents, intrinsic viscosity
Authors: Geerissen Heinz , Roos Jürgen , Wolf B. A.
Published: April 2003

Investigations with ca. 100 organic liquids in a temperature range from −20°C to 90°C result in a survey of the solubility behaviour of PVC. The experimental results were compared with the predictions of the solubility parameter theory: Accepting δ = 9,75 (cal/cm3)1/2 as the solubility parameter for PVC, all solvents (except ketones in which PVC is soluble independent of their solubility parameters) are located within the range of δPVC ± 0,75. Only three of the 100 liquids examined turned out to be (endothermal) theta‐solvents, namely the aromatic solvents o‐xylene, phenetole and dimethyl phthalate. The theta‐temperatures in o‐xylene and phenetole were determined viscometrically by means of the temperature dependence of the Mark‐Houwink exponent to be 84 and 88°C, respectively. Viscosity measurements were also performed in the temperature range of 25 to 60°C with solutions of PVC 75 000 in 10 thermodynamically good solvents used for rheological investigations. In all cases the intrinsic viscosities decrease slightly with increasing temperature, i.e., all solutions are weakly exothermal. The binary cluster integral, β, was determined (taking the monomeric unit as the statistical segment) and the polar contribution, βe, was calculated from Yamakawa's theory. The correlations between the non‐polar part of (βn = β – βe) and the solubility parameter of the solvent, found by Utracki, were tested and found to be valid for the present systems, too.
Continuous fractionation and solution properties of PVC, 6. Pressure dependence of the viscosity — influence of molecular weight and composition
Authors: Geerissen Heinz , Roos Jürgen , Wolf B. A.
Published: April 2003

Viscosities were measured as a function of pressure and temperature with solutions of PVC 75 000 in cyclohexanone (CHO) and polymer contents ranging from 0,6 to 12 wt.‐%, by means of a Searle‐type (≥3 wt.‐%) and a rolling‐ball viscometer (<3 wt.‐%). Furthermore, the influence of molecular weight was determined with solutions of 8 wt.‐% of PVC 20 000, PVC 37 000 and PVC 100 000. (The numbers in the codes of the PVC specimens are their approximate molecular weights.) For all concentrations and molecular weights, the viscosity increases in a more or less exponential manner with increasing pressure. The ratio f1000 of the viscosity of the solution at 1 000 and 1 bar can be varied by the change of the polymer content from 2,5 (the value of the pure solvent, index s) to 3,5 (12 wt.‐% PVC 75 000) at t = 25°C and from 2,23 to 2,94 at t = 80°C. An increase of the molecular weight of the polymer raises f1000 in a similar manner as the polymer concentration. Using the reduced variables V≠/V≠ (ratio of the volumes of activation of the solution and the pure solvent) and c̃ (product of the polymer concentration and the intrinsic viscosity), all results obtained by variation of T, c and Mw can be represented by a master curve. This means that it is possible to calculate the pressure dependence of a given polymer solution of arbitrary polymer concentration from a mere measurement of the intrinsic viscosity at normal pressure. Criteria are presented which allow a forecast concerning the occurrence of minima in the concentration dependence of the energy of activation of the viscous flow E≠ and V≠.
Cinétique de télomérisation, 2. Détermination des lois applicables à la synthèse des télomères à DPn moyens par catalyse rédox
Authors: Boutevin Bernard , Piétrasanta Yves
Published: April 2003

Some theoretical relations concerning the kinetics of redox catalysed telomerization were studied. Assuming that the transfer termination reaction to the metallic cation is the main termination reaction, equations were established giving, as a function of time, monomer and telogen concentrations. Moreover, instantaneous and cumulated number‐ and weight‐average degrees of polymerization could be calculated. As an example the telomerization of ethyl acrylate with carbon tetrachloride as telogen and with ferric chloride/benzoin as catalyst at four concentrations were carried out. The theoretical and the experimental results are in good agreement with the predictions.
Studies on methoxycarbonylcellulose: Conductivity measurements of solutions, 1
Authors: Trivedi Harikrishna C. , Patel Raman D.
Published: April 2003

The conductivity behaviour of a partially neutralized methoxycarbonylcellulose (carboxymethylcellulose, CMC) solution was investigated at different frequencies using a home made conductance bridge. The equivalent conductance of CMC solutions has very poor dependence on frequency contrary to the behaviour of simple ionic compounds. The effect of concentration on the polyelectrolyte behaviour was investigated conductometrically and it was observed that the polymer concentration has little effect on polymer charge fraction and polymer counterion fraction. Sodium ion‐binding on the polymer molecule was also investigated.
Kinetics of irreversible, stoichiometric polycondensations
Authors: Elias Hans‐Georg
Published: April 2003

Equations are derived for the time dependence of the extent of functional group reaction, pA, for catalyzed and uncatalyzed, irreversible, stoichiometric polycondensations of the AB and AA/BB type following pseudo‐second‐order and third‐order chemical kinetics, resp., based on amount‐of‐substance concentrations. The resulting functions 1/(1 – pA) ‐ f(t) for pseudo‐second‐order polycondensations and 1/(1 – pA)2 ‐ f(t) for third‐order polycondensations are predicted to be non‐linear for low extents of reaction and practically linear for higher ones which agree with previous, hitherto unexplained experimental observations. The slope of the linear part does not give the true rate constant, contrary to traditional assumptions. The extent of non‐linearity at small conversions and the deviation of the apparent rate constant from the true one depends on the initial amount of A groups, the molar mass of the leaving molecules, and the initial mass of the reaction mixture, if the molar concentrations are based on masses (“molalities”). The density of the leaving molecules enters, in addition, if the molar concentrations are volume related (“molarities”). The equations predict, for a given system, that the range of the non‐linear region increases with decreasing rate constants, i.e., with decreasing temperature, in accordance with experimental observations.
Ziegler‐natta catalysis by Mg‐Ti complexes, 2 Ethylene polymerization by MgTiCl6·4CH3COOC2H5 and triisobutylaluminium
Authors: Giannetti Enzo , Albizzati Enrico
Published: April 2003

The reaction between the MgTiCl6·4CH3COOC2H5 complex and alkylaluminium compounds was studied. The solid samples, recovered after increasing reaction times, were analysed. Elemental analyses, X‐ray diffraction patterns, and IR spectra clearly indicated the formation of activated, high‐surface MgCl2. Polymerizations of ethylene were carried out employing, as the solid component of the catalyst system, both MgTiCl6·4CH3COOC2H5 and the recovered samples. The lower induction time in the latter case was related to the extent of MgCl2 formation and its degree of activation.
Hetero‐chain polymers based on natural amino acids. Synthesis of polyamides from Nα, Nε‐bis(trimethylsilyl)lysine alkyl esters
Authors: Katsarava Ramaz D. , Kharadze Darejan P. , Japaridze Nana Sh. , Omiadze Tina N. , Avalishvili Lamara M. , Zaalishvili Malkhaz M.
Published: April 2003

High‐molecular‐weight polyamides based on the natural amino acid lysine were synthesized by condensation of Nα, Nε‐bis(trimethylsilyl)lysine alkyl esters (1a–c) with derivatives of aromatic dicarboxylic acids (2a–c). The best results were obtained with diacyl dichlorides. However, in the case of aliphatic dicarboxylic acid derivatives, preference should be given to their active diesters. The properties of the resulting polyamides were shown to be determined, to a considerable degree, by the nature of the reaction medium. Polyamides with free carboxyl groups, capable of further polymeranalogous conversions, were obtained by means of saponification of the side chain alkyl ester groups. The substituted phenols, resulting from the polycondensation of 1a–c with active diesters, could be used for the synthesis of polyamides with active ester groups in the side chains.
Thermally stimulated depolarization currents in thiourea‐formaldehyde polycondensate
Authors: Nalwa Hari Singh , Vasudevan Padma
Published: April 2003

A thiourea‐formaldehyde polycondensate was synthesized in acidic medium using glacial acetic acid. It was characterized by elemental analysis, infrared spectroscopy and thermal techniques. The thermally stimulated depolarization (TSD) current characteristics were studied under different polarization and depolarization conditions. The TSD results indicate a transition at 126°C. Depolarization kinetics data of the thermoelectret are reported. The polarization and depolarization phenomena were correlated with physical as well as chemical changes occurring in the material.
Simultaneous dehydrochlorination and film formation of a vinylidene chloride copolymer by aqueous‐organic interface reaction
Authors: He Fei‐Feng , Kise Hideo
Published: April 2003

The interface reaction of a THF solution of a vinylidene chloride copolymer with an aqueous alkaline solution in the presence of a quaternary ammonium halide as a phase transfer catalyst affords a dehydrochlorinated polymer film with conjugated polyene structure. The degree of the reaction is dependent on the catalyst structure, and tetrabutylammonium bromide is the best among those used. KOH was found to be more effective than NaOH. The effects of the base and polymer concentration and of the nature of the solvent were also studied. The results are discussed in terms of the change of the rate of formation of ammonium hydroxide at the interface and of its diffusion in the organic phase. The doping of the obtained films with iodine vapor increases the electric conductivity up to 7 · 10−4 S · cm−1.