bluuebunny/crossref_metadata_2025 huggingface dataset:
Potassium hydroxide inhibition in poly(propylene oxide) autoxidation
Authors: Griffiths Peter J. F. , Hughes John G. , Park Geoffrey S.
Published: April 2003

A systematic study of the effect of potassium hydroxide on the autoxidation of poly(propylene oxide)s with number average molecular weights, M̄n, in the range 400–3000 has been made in the range of temperature 110–140°C. For all the polymers a considerable increase in the induction time was produced by KOH in solution in the polymer, the increase being most marked for the polymer of lowest molecular weight. For the polymers of molecular weight 1000 and lower, the rate of the subsequent autoxidation was considerably reduced by the KOH, the effect being greatest for the polymer of molecular weight 400. For polymers of molecular weight 2000 and above no change in rate was observed. The effectiveness of KOH as an antioxidant is shown to depend on the concentration of terminal hydroxyl groups and is explained by the non‐radical decomposition of RO ions.
Kinetics of oxidative dimerization of ethynylbenzene catalyzed by copper complexes of 2‐phenylpyridine and a polymeric pyridine derivative
Authors: Meinders Herman Casper , Prak Nanno , Challa Ger
Published: April 2003

The kinetics of the oxidative dimerization of ethynylbenzene (1) at 25°C was studied in a mixture of 1,2‐dichlorobenzene and pyridine, catalyzed by soluble complexes derived from copper(I) chloride and pyridine derivatives. The influence of the concentrations of cosolvent pyridine, of copper salt, of 1, and of the ligands 2‐phenylpyridine (4) and partially 2‐pyridyl substituted atactic polystyrene (3) on the initial reaction rate was determined. In the initial stages the reaction is first order in [CuCl]0 up to the solubility limit of the complex at [CuCl]0 = 2,8 · 10−3 mol dm−3. The order in 1 is 0,5 in the case of the pyridine complex and 2 in the case of the complex with the polymeric ligand 3. These results are in agreement with a previously proposed reaction scheme. It was also found that the cosolvent pyridine acts as a slightly activating ligand reaching a maximum reaction rate only for very high N/Cu ratios. The above mentioned ligands 3 and 4 can rapidly displace a pyridine ligand from the complex yielding much more active complexes.
The electro‐initiated cationic polymerization of indene, 1
Authors: Bhadani Suraj N. , Baranwal Panchdeo P.
Published: April 2003

The electro‐initiated anodic polymerization of indene in ethylene dichloride solutions of tetraethylammonium hexachloroantimonate and tetrabutylammonium perchlorate as background electrolytes was studied. The polymerization was conducted either under continuous electrolysis or by addition of the monomer to the pre‐electrolysed solution of the salt. The polymer formation was affected by the amount of electricity, the monomer concentration, and the nature of the electrolytes. The rate and degree of polymerization with the hexachloroantimonate salt are relatively high in comparison with the perchlorate salt. The characteristically colored species, formed during polymerization, were investigated spectrophotometrically. Mechanisms for the initiation processes of both procedures were elucidated.
Spektroskopische analyse mehrfacher methacrylsäureester von oligo[(2‐hydroxy‐1,3‐phenylen)methylen]en mittels UV‐, IR‐, 1H NMR‐ und massenspektren
Authors: Kämmerer Hermann , Pachta Jiri , Ritz Jürgen
Published: April 2003

The structures of two homologous series of oligo[(2‐hydroxy‐1,3‐phenylene)methylene]s completely esterified with methacrylic acid, were spectroscopically analysed. The molar decadal absorption coefficients of ultraviolet absorption maxima of the two homologous series confirm Hunter's relation. The vinylidene, ester, and substitution bands of the infrared spectra as well as the mass spectra agree with the accepted structures. The 1H NMR spectra permit to differentiate between exterior and interior groups of the molecules.
Application of spin trapping technique to radical polymerization, 12 The polymerization of N‐vinylcarbazole with benzoyl peroxide
Authors: Sato Tsuneyuki , Abe Masao , Otsu Takayuki
Published: April 2003

To clarify the initiation and propagation mechanisms of the polymerization of N‐vinylcarbazole (1) initiated by benzoyl peroxide (2), the spin trapping technique using 2‐methyl‐2‐nitrosopropane (5) was applied. From the ESR spectrum observed from this system, the 1‐(N‐carbazolyl)‐2‐benzoyloxyethyl radical (6a) was found to be trapped as its nitroxyl radical 6b, which was confirmed by a comparison with similar nitroxyl radicals (7b and 8b) derived from the systems, di‐tert‐butyl peroxalate/1/5 and 2/N‐ethylcarbazole/5, respectively. Therefore, it was concluded that the 1/2 system produces easily a primary propagating radical of 1 viz. 6a. Further, the monomer 1 was found to show a remarkable accelerating effect on the radical decomposition of 2. From the copolymerization of 1 with styrene initiated by 2, it was concluded that 6a propagates by ordinary successive ß‐attack to the monomer 1.
Application of spin trapping technique to radical polymerization, 13 Polymerization of methyl methacrylate with 1,2,3,10a‐tetrahydrophenanthrene‐1,2‐dicarboxylic anhydride
Authors: Sato Tsuneyuki , Abe Masao , Otsu Takayuki
Published: April 2003

The polymerization of methyl methacrylate (MMA) with 1,2,3,10a‐tetrahydrophenanthrene‐1,2‐dicarboxylic anhydride (TH) (10), which is a stable Diels‐Alder adduct of α‐vinylnaphthalene and maleic anhydride, was investigated by kinetic and spin trapping methods. TH could induce radical polymerizations of MMA and methyl acrylate with a considerably high rate, and the rate of polymerization (Rp) of MMA was found to follow the equation: Rp = k[TH]0,3 [MMA]1,6. The overall activation energy and the chain transfer constant to TH for this polymerization were determined to be 47,7 kJ/mol and 0,52, respectively. From these results, an initiation mechanism involving a hydrogen‐transfer from TH to MMA was proposed, which is similar to Mayo's initiation mechanism for the thermal polymerization of styrene. To confirm this mechanism, the spin trapping technique was applied. The results obtained regarding the trapping of the initiating radicals supported this hydrogen‐transfer initiation mechanism.
The oxidative coupling of 2,6‐xylenol catalyzed by polymeric complexes of copper, 2. Physicochemical study on copper(II) complexes of partially dimethylamino‐methylated polystyrene
Authors: Schouten Arend Jan , Wiedijk Dick , Borkent Jan , Challa Ger
Published: April 2003

The polymeric catalyst formed by complexation of copper(II) chloride and partially dimethylaminomethylated polystyrene was investigated to explain its behaviour in the oxidative coupling of 2,6‐xylenol (3). Viscometric studies indicated that at low polymer concentrations coordination of tertiary amine groups to copper(II) causes an intramolecular crosslinking. UV measurements and preliminary results of ESR point to a dimeric structure of these complexes with two amine groups per copper. A mechanism for the action of this polymeric catalyst is suggested, based on these results and on those described in Part 1. It appeared that some “free” copper(II) is essential for the catalytic activity, without which the reoxidation of copper(I) cannot take place.
The heats of dilution of polystyrene solutions
Authors: Baba Yoshihiro , Fujimoto Kenji , Kagemoto Akihiro , Fujishiro Ryoichi
Published: April 2003

The heats of dilution of atactic polystyrene‐anisole, ‐dibenzyl ether, and ‐acetophenone systems were measured in the concentration range of 0,168 to 0,02 in volume fraction of the polymer, by adding successively 1 ml of the solvent to the solution of a known concentration by using an isothermal calorimeter at 303K. The heats of dilution of all systems obtained proved to be exothermic.

The interaction heat parameter depends considerably on the concentration of the polymer and also on the molecular weight of the polymer. In polystyrene‐anisole and ‐dibenzyl ether systems an interesting fact was found: the χ1‐parameter is negative and its absolute value increases at first, reaches a maximum and then decreases as the molecular weight of the polymer increases.
Bindungsfähigkeit von casein für natriumchlorid bei hohen wasseraktivitäten. Untersuchungen mit einer neuartigen isopiestischen sorptionsapparatur
Authors: Gál Stefan , Hunziker Max
Published: April 2003

A new isopiestic sorption apparatus and its application to the determination of the binding capacity of casein for sodium chloride are described. The method provides reliable binding values in equilibrium with salt solutions of medium and high concentrations.
Homopolymerization of maleic anhydride
Authors: Bhadani Suraj N. , Prasad Jagdeo
Published: April 2003

Pyridine and picoline initiated polymerizations of maleic anhydride were investigated in acetic anhydride. It was found that the electrical conductivity of the polymerizing mixture increases in the course of the reaction, and that the initial rate of polymerization increases with increasing monomer and pyridine concentrations, and its values, measured at different temperatures, show the apparent overall activation energy to be about 10 kcal/mol (41,87 kJ/mol). The rates of polymerization and the increase of specific conductivities of the reaction mixtures show the following order of initiator activity: γ‐picoline > β‐picoline > pyridine > α‐picoline. Therefore, the results of the kinetic and conductivity measurements suggest that the polymerization rate depends on the basicity of the initiator.
Synthesis of a metal containing ladder‐polymer by solid‐state polymerization of bis(1,3‐pentadiynyl)mercury
Authors: Steinbach M. , Wegner G.
Published: April 2003

Bis(1,3‐pentadiynyl)mercury (3) polymerizes quantitatively in the solid‐state if irradiated with UV‐light or annealed at 100–200°C. The polymer shows resonant Raman frequencies at 1412, 1454, 2024, and 2070cm−1 typical for polymers containing butadiynyl (diacetylene) groups. The intensity of IR peaks due to the monomer triple bonds at 2098 and 2220 cm−1 decreases during polymerization and vanishes at completion. From experimental evidences it is inferred that the polymerization is lattice controlled and can be described, similar to the solid state polymerization of butadiynyl derivatives, by the formation of a ladder polymer of two strands of a poly(2‐butynediylidene) linked together by mercury.
The color reaction between partially saponified poly(vinyl acetate) and iodine‐iodide in the presence of boric acid
Authors: Hayashi Sadao , Tanabe Youichi , Hojo Nobumasa
Published: April 2003

The effect of the boric acid concentration on the color reaction between partially saponified poly(vinyl acetate), which is dissolvable in water, and iodine‐iodide was investigated. As the concentration of boric acid increased, the absorbance at λmax = 488 nm of the red‐violet complex, which is due to a long sequence of vinyl acetate units distributed along the polymer chain, increased gradually, reached a maximum, and then decreased from the point in which the absorbance at λmax = 656nm of the blue complex, based on the vinyl alcohol units in the polymer, was observed. The color complex in an excess of boric acid transferred from red‐violet to red‐tinged blue with time. From the color change, the molar absorption coefficient at λmax = 656 nm for the iodine molecule in the blue complex was found to be 3,92.104l/(mol cm).
Reduction of nitrile end groups in styrene polymers and their subsequent determination by dye partition technique
Authors: Kanjilal Chinmay , Mitra Bhairab C. , Palit Santi R.
Published: April 2003

Nitrile groups were incorporated in polystyrene through (i) initiation with azoisobutyronitrile (AIBN) and (ii) copolymerization with a trace of acrylonitrile. Their detection and estimation by dye partition technique were experimentally realized. The method consists in first converting nitrile end groups magnified image to primary amino end groups magnified image by reducing with lithium aluminium hydride in tetrahydrofuran medium followed by testing and quantitatively estimating the amino end groups in the resultant polymer by the usual dye partition technique. AIBN initiated polystyrene was found to contain on the average 2 nitrile end groups per polymer molecule supporting the fact that combination is the predominant mode of termination in styrene polymerization. The copolymer reactivity ratio (r1) for styrene (M1) – acrylonitrile (M2) copolymers as determined by this technique agrees fairly well with the existing literature values. This verifies the quantitative applicability of the dye partition method for the study of macromolecular reactions.
Electrical conductivity variation of native and denatured DNA in the solid state as a function of acidity and structure
Authors: Lecompte Marie‐France , Jozefowicz Marcel
Published: April 2003

D. c. electrical solid state conductivity of either native or heat‐denatured calf thymus DNA sodium it has been studied as a function of the acidic state of the samples. Conductivity implies major ionic carriers and depends on the secondary structure of the DNA sample. Its variation is correlated to the ion exchange properties of DNA solid phase suspension in a solvent. Partial renaturation of heat denatured DNA samples, induced by salt addition, increases the DNA solid state d.c. conductivity.
The effect of complexing agents on the radical polymerization of polar vinyl monomers
Authors: Kuran Witold , Pasynkiewicz Stanisław , Nadir Riad , Florjańczyk Zbigniew
Published: April 2003

Radical polymerizations of acrylonitrile, methacrylonitrile, methyl acrylate, and methyl methacrylate in the presence of Lewis acid type complexing agents like ZnCl2, SnCl4, or (C2H5)nAlCl3−n (n = 1,2,3) were investigated. The accelerating or inhibiting effects of the complexing agents on the polymerization of individual monomers were observed depending on the concentration and the character of the complexing agent. These effects were found to be also influenced by the monomer structure. The polymerization mechanism is discussed.
Vinyl polymerization by a cobalt complex
Authors: Kothandaraman Harimurthi , Sundaram Periannan Gnana
Published: April 2003

The rate of decomposition of the complex, sodium bis(diethanolamine)cobaltate octahydrate was studied at pH 7 and pH 1,6, respectively. This complex was found to initiate the vinyl polymerization (polymerization of acrylamide and methacrylamide) at pH 1,6 in aqueous medium. There was no polymerization at pH > 4. The dependences of the rate of polymerization on monomer concentration, initiator concentration, temperature, and pH were studied. The overall activation energy of the polymerization reaction was calculated. A kinetic reaction scheme is proposed on the basis of the experimental data.
The stability and chemical stress relaxation of peroxide cured polyurethane elastomers
Authors: Barrie James A. , Ludbrook Bryan D. , Thomas David K.
Published: April 2003

The chemical stress relaxation of two polyurethane elastomers Genthane S and Adiprene CM has been studied in air and in nitrogen in the temperature range 60 to 150°C. Both continuous and intermittent stress relaxation measurements were made on well characterized samples covering a range of crosslink densities. Scission and crosslinking reactions were observed for both the polyester based Genthane S and the polyether based Adiprene CM. The degradation of Genthane S is largely non oxidative and the scission reaction involves the main chain. The behaviour of Adiprene CM under nitrogen broadly resembles that of Genthane S; it differs from Genthane S in that it also undergoes an oxidative reaction. Activation energies for the scission and crosslinking processes were evaluated from kinetic analysis. Pretreatment of the elastomers with isocyanates inhibits both of these reactions. A mechanism involving the urethane group is proposed to account for the degradation behaviour and the role of water in this respect is discussed briefly.
On the mechanism of the carbon dioxide/propylene oxide alternating copolymerization in the presence of organozinc catalysts
Authors: Kuran Witold , Pasynkiewicz Stanisław , Skupińska Jadwiga
Published: April 2003

Carbon dioxide and propylene oxide were copolymerized in the presence of the catalytic systems diethylzinc/polyhydric phenols modified by pretreatment with one of the monomers. The mechanisms of initiation, propagation, termination, and chain‐transfer reaction in the copolymerization are suggested and discussed.
Aminolyses of monomeric and polymeric 4‐nitrophenyl esters of N‐methacryloylamino acids
Authors: Rejmanová Pavla , Labský Jiří , Kopeček Jindřich
Published: April 2003

4‐Nitrophenyl esters of N‐methacryloylamino acids and their copolymers with N‐(2‐hydroxypropyl)‐methacrylamide were synthesized. The effect of the ester and amine structure and of the reaction medium on the rate constant of aminolysis was studied.
Polymer effect on the electron‐donating character of a polymeric donor, 3. Formation of charge‐transfer complexes between polymer containing carbazolyl groups and three kinds of common acceptors
Authors: Iwatsuki Shouji , Arai Kiyotaka
Published: April 2003

Charge‐transfer complex formations with carbazole containing polymers are studied by using copolymer donors. Donors employed are poly(N‐vinyl carbazole) (poly[1‐(N‐carbazolyl)ethylene]), (PVK), copolymers of N‐vinyl carbazole (VK) and vinyl acetate (VAc) with various compositions, and N‐ethyl carbazole (NEK). As acceptor are used p‐chloranil (2,3,5,6‐tetrachloro‐2,5‐cyclohexadiene‐1,4‐dione) (CA), tetracyanoethylene (ethylenetetracarbonitrile) (TCNE) and 2,4,5,7‐tetranitrofluorenone (TNF). A smooth bathochromic shift in the wave length of maximum absorption λmax was observed with increasing the VK content in copolymers when CA and TCNE were used as common acceptor. In the case with TNF, since PVK and the copolymers give too broad charge transfer absorption bands, their λmax cannot clearly be read. In both cases with CA and TCNE, the association constant of charge‐transfer complex formation KCT was found to decrease with increasing the VK content in the copolymers, whereas in the case with TNF it increases. The thermodynamic parameters of complex formation were also discussed: ΔH and ΔS were found to decrease with increasing VK content in all cases with three common acceptors. Differences in their degrees of contribution to the free energy of the complex formation between enthalpy and entropy probably causes two types of variation of KCT with the VK content in the copolymers. In addition, effects of acceptors and solvents on the charge‐transfer complex formation were studied. A difference in λmax between with NEK and with PVK, corresponding to the so‐called polymer effect, was observed to be largest when CA was used as common acceptor and also to become larger as the dielectric constant of the solvent is increased.
Conformational flexibility of isotactic poly‐1‐olefins
Authors: Ajò David , Granozzi Gaetano , Zannetti Roberto
Published: April 2003

The conformational flexibility of isotactic polypropylene, isotactic poly‐1‐butene and isotactic poly(3‐methyl‐1‐butene) has been studied by theoretical methods, especially in relation to their polymorphism. The energy calculations show the predominant contribution of intramolecular effects and allow a valid interpretation of polymorphous behaviour. Furthermore, the conformational mobility of the side chains of the macromolecules plays a very important role in establishing the lowest‐energy structure.
Über die polymerisation von 1‐chlor‐2,3‐epoxypropan
Authors: Mateva Rosa , Kabaiwanov Wl.
Published: April 2003

The kinetics and the thermodynamic features of the polymerization of 1‐chloro‐1,3‐epoxypropane with the complex \documentclass{article}\pagestyle{empty}\begin{document}${\rm Cl}_{\rm 5} \mathop {{\rm Sb}}\limits^ \ominus \cdots \mathop {\rm S}\limits^ \oplus {\rm O}_2$\end{document} were studied. It was found that the process proceeds with a negative temperature coefficient, Ea=−51,29 kJ/mol ( − 12,25 kcal/mol), ΔHp=−18,8 kJ/mol (−4,5kcal/mol), ΔSp=−74,5 J mol−1 K−1 (−17,8 cal mol−1 K−1), and with the ceiling temperature of 52,6°C. The molecular masses of the polymers were determined and a possible mechanism of the polymerization process was suggested.
Molekulare und chemische uneinheitlichkeit von copolymeren aus trübungstitrationen von GPC‐eluaten
Authors: Hoffmann Martin , Urban Heinrich
Published: April 2003

The distributions of molecular weights and of chemical compositions of a binary linear copolymer may be determined by gel permeation chromatography (GPC) followed by turbidimetric titration of the eluates. Eluate fractions of 5,0ml are automatically collected and titrated within 7 min. The intensityRof the scattered light at a wavelength λ0=940nm is measured at an angle of 19° to the primary beam and corrected for the change of solution volumeVduring titration. The solubilities of chemically different molecules of a mixture are influenced somewhat but not substantially by the components of the mixture.

During the titration the turbidity of the eluates from graft copolymers often increases with time discontinuously, the points of inflection indicating the precipitation of a new species of molecules. If the dependence of solubility on chemical composition and concentration is known for the particular elution volume, the chemical composition of each species of the titrated molecules may be evaluated from these points of inflection. The elution volumeVEand the chemical composition are used for obtaining the molecular weightMfrom plots ofMvs.VEfor different chemical compositions. The concentration of a certain species of molecules in the eluate cannot be derived fromRitself as has been tried up to now because the turbidity continues to increase after complete precipitation of the polymer. However the rate of coagulation is proportional to the concentrationcof precipitated polymer. This leads to a nearly linear dependence ofR·V/V0on logVwith a slope porportional toc2. The velocity constants of this coagulation are nearly independent of molecular weight and chemical composition. Therefore the concentration of the first precipitated component of a mixture may be determined absolutely with a relative error of about ±4% at a concentration of 50 mg/l of the mixture. The molecules of a second component of the mixture precipitated at a later stage of the titration are quickly adsorbed by the particles of the first component. After this the enlarged particles coagulate with the coagulation constant of the second component. The velocity of coagulation is now proportional to the sum of the concentrations of the first and second components. The distribution of chemical compositions of the molecules in an eluate may therefore be derived from the increase of turbidity with volume at different points of the titration curve. By plotting such distribution perpendicularly over the curves representing constant elution volume in theM‐composition‐plane one obtains a three‐dimensional surface resembling a mountain range which characterises completely the molecular and compositional distribution of a binary copolymer.
1H NMR spectroscopic studies on the reaction of methoxymethyl isocyanate with alcohols and the side reactions
Authors: Sikorski Ryszard T. , Kowalczyk Mieczysław , Krzywański Jan , Mikołajczyk Marian
Published: April 2003

Alkyl N‐methoxymethylcarbamates (3) were synthesized by treating methoxymethyl isocyanate (1) with alcohols 2 in the presence of triethylamine. By means of 1H NMR spectroscopy and using the deuterated carbamate 3b it could be demonstrated that carbamates 3 undergo decomposition, accompanied by elimination of methanol from the methoxymethylene grouping and by the formation of polycondensates 5. It was found that 1 and 3 react in the presence of basic catalysts to give polyadducts 7.
Synthese und Strukturuntersuchung des Poly(1‐hydroxytetramethylen)s
Authors: Ritter Wolfgang , Eichin Karl‐Heinz , Elgert Karl‐Friedrich
Published: April 2003

Poly(1‐hydroxytetramethylene) was prepared via hydroboration of cis‐1,4‐poly(butadiene). The structure of the polymer chain generated by a random hydroxylation of the carbon double bonds of the butadien units was determined by 13C NMR spectroscopy.
Photochimie de la polyacrylophénone en solution, 2. Courbe d'inhibition à fortes concentrations en inhibiteur. Désactivation statique et solvatation préférentielle
Authors: Salvin Roger , Meybeck Jean
Published: April 2003

Static quenching performed on the type II cleavage of polyacrylophenone, poly(1‐benzoylethylene), (PAP) in 1‐methylnaphthalene, (MeN) as solvent and as quencher, has allowed us to evaluate the rate constant of electronic triplet‐triplet energy transfer Kel for the system PAP‐MeN.

This value is similar with the value determinated for the system valerophenone‐MeN. indicating that Kel is independant of the carbonyl position free or bound to a polymer chain.

The aspect of the quenching curve at high concentration of MeN in benzene has been associated with phenomenona of preferential solvation of benzene in the ternary system PAP‐MeN‐benzene which has been determinated by the method of dialysis equilibrium.
Polymorphie, Kristallinität und Schmelzwärme von Poly(ε‐caprolactam), 1. IR‐spektroskopische Untersuchungen
Authors: Simak Petr
Published: April 2003

Poly(ε‐caprolactam), (polyamide‐6) crystallizes in different modifications, which show different characteristic IR absorption bands. The absorption coefficients of the bands were evaluated from the dependence of their intensity on temperature and specific volume of different polyamide‐6 samples. A method is described how to determine quantitatively the amounts of α‐ and γ*‐modifications and of the amorphous phase. On the basis of these data the densities of the samples were calculated and shown to agree with the values determined experimentally. The specific volume of the amorphous phase is v = 0,917 cm3/g, and is independent of any contents of α, γ*‐, or γ‐modifications the samples may contain.
Effects of trivalent phosphorus compounds on vinyl polymerizations, 4. Radical reactivities of chlorophosphines
Authors: Nigenda Socorro E. , Caballero Deyanira , Ogawa Takeshi
Published: April 2003

In order to study the radical reactivities of trichlorophosphine, dichloro(phenyl)phosphine, and chlorodiphenylphosphine, the polymerizations of various vinyl monomers were carried out in the presence of these chlorophosphines using 2,2′‐azodiisobutyronitrile as an initiator. The reactivities were discussed from the results obtained for the rates and the degrees of polymerization and for the phosphorus contents of the polymers obtained. It was found that the tertiary radicals (such as that derived from methacrylonitrile and methyl methacrylate) were inert to these chlorophosphines, but the secondary radicals (such as those from vinyl acetate, methylacrylate, acrylonitrile, styrene, etc.) reacted with the chlorophosphines, and their reactivities depended on the stabilities of the polymer radicals. Only styrene gave copolymers. As a general mechanism the addition of the polymer radical to the phosphine followed by elimination of one of the four substituents on the phosphorus, was suggested.
Kinetics of the heterogeneous acid hydrolysis of regenerated cellulose
Authors: Vrhovac Ljubica P. , Rašajski Slavko N.
Published: April 2003

The kinetics of the early stage of acid catalyzed heterogeneous hydrolysis of different samples of regenerated cellulose at low temperatures (0, 20, and 30°C) was studied. The degradation of macromolecules was followed by determining the decrease of the degree of polymerization by measuring the viscosity of cellulose solutions in cadoxen. Interpretation of the experimental results using equations for first order reactions showed that in the studied experimental range first order kinetics cannot be applied. It was found that the rate constant decreases during the course of the hydrolysis at constant temperature. However, the experimental results could be explained by kinetic equations for heterogeneous processes with a solid and a liquid phase in the heterogeneous system. Kinetic parameters calculated from these equations point out that the process could be described as a diffusion controlled process.
Effect of carbonyl compounds on long‐wave UV photooxidation of polystyrene films
Authors: Kubica Joanna
Published: April 2003

It was found that the rate of secondary photooxidation reactions initiated by light not absorbed by polystyrene (PS) is related to the concentration of carbonyl compounds produced initially in pure PS films. Photochemical experiments carried out with a group of twelve low‐molecular‐weight compounds as models of the most likely carbonyl products of PS photooxidation showed that mainly diketones sensibilize the long‐wave UV photooxidation of polystyrene.
Zur Taktizität von Poly(α‐methylstyrol), 5. Die Abhängigkeit der Taktizität von der Reaktionstemperatur und der Anfangsmonomerkonzentration
Authors: Wicke Reinhard , Elgert Karl‐Friedrich
Published: April 2003

The tacticity of poly(α‐methylstyrene) was measured by 1H NMR spectroscopy. The polymerisation initiated in tetrahydrofuran by butyllithium gives a dependence on the initial monomer concentration and a S‐shaped plot of log(m/r) vs. 1/T, which is not influenced by a stronger reaction medium like 1,2‐dimethoxyethane or hexamethylphosphoric triamid or by addition of LiB(C6H5)4. The activation parameters of the two straight lines A and B limiting the experimental curve are according to the equation

The temperature dependence of the propagation rate constant kw measured dilatometricly between −11°C and −75°C gives a linear Arrhenius plot. The rate constant of depolymerisation kd was calculated using the equilibrium monomer concentration. The activation parameters are

The influence of ionic dissociation on the tacticity is discussed. The results lead to the conclusion, that the contact ion pair, the solvent separated ion pair, and the free anion generate tacticities, which are undistinguishable by the applied experimental methods.
Molecular weight distribution of polysarcosine obtained by NCA polymerization
Authors: Sisido Masahiko , Imanishi Yukio , Higashimura Toshinobu
Published: April 2003

Polymerization of sarcosine N‐carboxyanhydride was carried out in N,N‐dimethylformamide solution with some primary and secondary amines as initiators. The polymerization obeyed the first‐order kinetics. Polysarcosines obtained were fractionated by gel‐chromatography. For lower oligomers, individual oligomer components were isolated and the distribution of the degree of polymerization was calculated directly from the area of each peak. The elution diagram for higher polymers showed a single broad envelope which was analyzed by the method of Fourier analysis. In either case, the Poisson‐type distribution was observed.
Polymerization of methyl methacrylate in the presence of the system ethylaluminium dichloride—p‐chloranil
Authors: Florjańczyk Zbigniew , Kuran Witold , Lusztyk Ewa
Published: April 2003

The polymerization of methyl methacrylate (5) in the presence of the system ethylaluminium dichloride (2)—p‐chloranil (1) was found to proceed much easier than in the presence of only 2. The polymerization is initiated by ethyl radicals resulting from the reaction of 2 with 1. The effects of mole ratio of reactants, temperature, and reaction time on the polymerization yield and intrinsic viscosity of the polymer was studied and the results are discussed.
Studies on aqueous polymerization of acrylamide, 4. Potassium persulfate/thioglycolic acid redox system
Authors: Husain M. M. , Misra S. N. , Singh R. D.
Published: April 2003

Aqueous polymerization of acrylamide, initiated by the potassium persulfate‐thioglycolic acid redox pair, was studied at 30°C under introgen. The initial rate of polymerization R was found to be approximately proportional to the 0,5th power of potassium persulfate concentration within the range of 0,6 to 1,0 mmol−1. R was also found to vary linearly with the monomer concentration between 0,8 · 10−1 and 1,0·10−1 mol l−1 and to increase with the thioglycolic acid concentration in the interval of 3,0 to 4,0 mmol l−1. The activation energy was estimated to be 126 kJ mol−1. Addition ot NaCl, NaF, and (CH3)4NI lowered the initial rate R while MnSO4 increased it. Some aliphatic alcohols were observed to be polymerization retarders.
Polymérisation et copolymérisation d'acétoxy‐2 alcadiène‐1,3: L'acétate de (cyclohexène‐1 yle)‐1 vinyle. Synthèse d'une δ‐polycétone
Authors: Plaisance Chantal Bonnans , Levesque Guy
Published: April 2003

1‐(1‐Cyclohexenyl)vinyl acetate (1c) was polymerized in bulk under radical conditions. The homopolymers consist only of 1,4‐units (4) which can be hydrolysed into δ‐polyketone. Reactivity ratios in radical copolymerization with styrene and acrylic comonomers were determined. The photochemical degradation of the copolymer with styrene was studied in solution.
Limiting viscosity number—molecular weight relationships for phenol‐formaldehyde resin in solution
Authors: Kamide Kenji , Miyakawa Yoshiye
Published: April 2003

The effect of molecular structure of phenol‐formaldehyde resin on the Mark‐Houwink‐Sakurada equation for solutions in acetone is systematically studied. Random and high‐orthophenol‐formaldehyde resins are prepared by conventional, acid‐catalyzed and Zn++‐catalyzed condensations, respectively. The relative contents of 2,2′‐, 2,4′‐ and 4,4′‐methylene linkages are determined by 13C NMR spectroscopy. From these the detailed distribution of structural isomers is calculated. Several fractions having number‐average molecular weights (by vapor pressure osmometry) M̄n≥104 are isolated by a successive solutional fractionation run from whole random polymers. For solutions of random polymer in acetone at 30°C, [η]=0,631 · M̄ (where [η] is limiting viscosity number) and for high‐ortho polymer [η]=0,0813 · M̄ are established. The former equation can be interpreted in terms of the Zimm‐Stockmayer theory of branched polymer solutions.
Untersuchungen zum oxidativen abbau nativer cellulose, 4. Stöchiometrische verhältnisse zwischen der anzahl der entstehenden spaltstellen, dem sauerstoff‐verbrauch, der CO2‐entwicklung und den materialverlusten während des abbaus
Authors: Palma A. , Jovanović S. , Schulz G. V.
Published: April 2003

An investigation of the kinetics of cellulose degradation confirms the scheme proposed by G. V. Schulz and Mertes with the following modifications: the fast pre‐stage of the degradation is missing, because there are no faster cleaving bonds in the native cellulose; the first step of the degradation (pre‐oxidation) in agreement with the above mentioned authors consists in the uptake of an oxygen atom: in the second step, the scisson proper, the scheme of Staudinger and Roos is replaced by the newer and better founded scheme of Haskins and Hogsed, assuming an alkoxy‐elimination; the third step (post‐oxidation) finally consists in a limited number of substeps leading to a splitting off of about three glucose units which becomes evident in the losses of material. The values of the rate constants of the three characteristic reactions determined from the steady‐state and the non steady‐state period of the reaction practically coincide.
Strukturuntersuchung von polyestern durch direkten abbau im massenspektrometer, 4. Polyester und copolyester der milchsäure und glykolsäure
Authors: Jacobi Erhard , Lüderwald Ingo , Schulz Rolf C.
Published: April 2003

Polyesters and copolyesters of 2‐hydroxyacetic acid (glycolic acid) and 2‐hydroxypropionic acid (lactic acid) were investigated by direct pyrolysis in the ion source of a mass spectrometer. Thermal degradation of these polyesters and copolyesters at 10−6 mbar yields cyclic oligomers which are further degraded by an electron impact induced mechanism by elimination of formaldehyde or acetaldehyde and CO2 to give characteristic series of linear ions. In the pyrolysis mass spectrum of a copolyester (mole ratio of monomeric units ≈1:1) intact sequences up to 8 monomeric units can be observed.
The crystal structure of polycapryllactam (nylon 8) and of polycapriclactam (nylon 10)
Authors: Cojazzi Gianna , Fichera Annamaria , Malta Viscardo , Zannetti Roberto
Published: April 2003

From X‐ray diffraction patterns of uniaxially oriented fibers, the structures of Nylon 8 and Nylon 10 were determined. They crystallize in the monoclinic system (pseudohexagonal), space group P21/b, with four monomeric units in the unit cell. The crystallographic parameters of Nylon 8 are: a=4,77; b=9,54; c=21,9 Å; γ=120°, and those of Nylon 10: a=4,78; b=9,56; c=26,9 Å; γ=120° (c fiber axis). Both structures show a γ‐type molecular packing, characterized by a shortening of the fiber repeat distances and by a twisting of the amide groups. Therefore, pleated sheets of parallel chains joined by hydrogen bonds are formed and the direction of the chains in adjacent sheets is alternately “up and down”. These structures result very similar to those of Nylon 6 and Nylon 12 in γ‐form, demonstrating once more that, in this series, by increasing the number of methylene groups, the usual crystal structure becomes the γ‐form.
Die Fraktionierung von Styrol‐Acrylnitril‐Copolymeren nach dem Acrylnitrilgehalt in zweiphasigen Lösungsmittelgemischen
Authors: v. Tavel Peter , Schaller Johann
Published: April 2003

Liquid phase pairs were found in which polystyrene (PS) and styrene‐acrylonitrile (SAN)‐copolymers with an AN‐content up to 13 wt.‐% can be partitioned. They could be used for the fractionation of the copolymers according to chemical composition. The phase pairs are composed of 4 solvents, cyclohexane and nitromethane to form the phases and two solvents for the polymers. The partition ratio was measured as a function of the composition of the phase pairs, the molecular weight of PS, and of the AN‐content of the copolymers. The phase composition at which a polymer is equally distributed into both phases depends on the chemical composition of the polymer but not on its molecular weight. With other phase compositions the partition equilibrium is shifted to one phase or the other the more the degree of polymerisation increases. Based on the partition equilibrium, fractionation methods are proposed to separate the SAN‐copolymers according to their chemical composition if their molecular weight is high enough (>about 105). The conditions which determine fractionation more by molecular weight or more by chemical composition are discussed.
Photochemical reactions and stabilizing properties of 2,6‐Di‐tert‐butyl‐4‐methylphenol, 2. Photochemical processes of 2,6‐Di‐tert‐butyl‐4‐methylphenol in polystyrene films
Authors: Kowal Joanna , Waligóra Bolesław
Published: April 2003

Photochemical reactions of 2,6‐di‐tert‐butyl‐4‐methylphenol (BHT) were investigated in polystyrene films. It was found that the stabilizing effect of BHT on polystyrene photooxidation process consists in lowering the rate of the formation of low molecular weight carbonyl products and the yield of polymer chain scissions.
Micellar solubilization of apolar molecules
Authors: Sepulveda L. , Soto R.
Published: April 2003

The solubilization of anthracene, naphthalene and Orange OT by micelles of cetyltrimethylammonium bromide (hexadecyltrimethylammonium bromide), sodium laurylsulfate (sodium dodecylsulfate) and dode‐cylamine hydrochloride has been measured at 30°C. These data and others obtained from the literature are interpreted in terms of the solubilization number n and the aggregation number N by using a very simple equation relating n, N, the critical micelle concentration (CMC) and the molar solubility of the solutes. The interpretation of the solubilization leads to a new, simpler and less empirical method of finding the CMC from solubilization data. Values of n less than 1, close to 1 and much greater than 1 were found.
Studies on formaldehyde resins, 15. Base‐catalyzed hydrolysis of bis(hydroxymethyl)melamine
Authors: Sato Kenji , Yamasaki Kazumi
Published: April 2003

The hydrolysis of N,N′‐bis(hydroxymethyl)melamine [6‐amino‐2,4‐bis(hydroxymethylamino)‐1,3,5‐triazine] to N‐(hydroxymethyl)melamine [2,4‐diamino‐6‐(hydroxymethylamino)‐1,3,5‐triazine] was studied in dimethyl sulfoxide/water (volume ratio 1:9) using sodium hydroxide as a basic catalyst, in the region [Sodium hydroxide]0=0 to 2 mol·1−1. The study of the dependence of logk on the pH revealed that logk is nearly constant in the range of pH≈8–10 and increases with the slope of d(logk)/d(pH)≈1 in the region of pH≈11–13,5, followed by a gradual saturation at a stronger basic region where k is a first order rate constant. A rate equation for the hydrolysis is proposed, and the hydrolysis mechanism was elucidated by comparison of the theoretical curves resulting from this rate equation with the corresponding experimental curves.
Syntheses and condensation polymerizations of 3‐hydroxybutyric acid derivatives of pyrimidine bases
Authors: Hattori Masahira , Takai Hiroshi , Kinoshita Masayoshi
Published: April 2003

4‐(1,2,3,4‐Tetrahydro‐5‐methyl‐2,4‐dioxo‐1‐pyrimidinyl)‐3‐hydroxybutyric acid (1a) and 4‐(1,2,3,4‐tetrahydro‐2,4‐dioxo‐1‐pyrimidinyl)‐3‐hydroxybutyric acid (1b) were synthesized via the addition reaction of thymine (3) and 4‐ethoxy‐1,2‐dihydro‐2‐oxopyrimidine (7), respectively, to 1‐chloro‐2,3‐epoxypropane and subsequent cyanization, followed by acid hydrolysis of the products. Condensation polymerizations of 1a and 1b were carried out using dicyclohexylcarbodiimide, 2,4,6‐triisopropylbenzenesulfonyl chloride or p‐toluenesulfonyl chloride as dehydrating agents. The resulting oligoesters 2a and 2b are light‐yellow powders with molecular weights of about 700, according to gel filtration measurements. Their UV spectra show a hypochromicity of 3–4% when mixed with denatured yeast RNA in 0,1 M Na2HPO4 solution.
Circular dichroism and structure of Schiff's bases of hydroxybenzaldehydes anchored to poly(L‐lysine) and poly(L‐α,γ‐diaminobutyric acid)
Authors: Dentini Mariella , De Santis Pasquale , Savino Maria , Sforza Maria Pia , Verdini Antonio Silvio
Published: April 2003

Schiff's bases of ortho‐, meta‐ and para‐hydroxybenzaldehydes with poly(L‐α,γ‐diaminobutyric acid) and poly(L‐lysine) were investigated in solution of methanol and methanol‐water mixtures by circular dichtroism, absorption spectroscopy and equilibrium dialysis techniques. The results so far obtained allow us to propose a molecular model, which fully justifies the stereospecific binding of ortho‐hydroxybenzaldehyde with the polypeptide chain; moreover it is able to explain the dramatic change of the chemical equilibrium in the hydrolysis reaction.
Solvatation préférentielle des polymères: Effet de la masse moléculaire sur les résultats expérimentaux et comparaison avec les prévisions théoriques
Authors: Dondos Anastasios , Benoît Henri
Published: April 2003

The preferential solvation coefficient λ′ has been studied as a function of the molecular weight of the polymers and the composition of the mixed solvents for the following ternary systems: polystyrene/benzene/cyclohexane, poly(2‐vinylpyridine)/benzene/cyclohexane, polystyrene/benzene/methanol, polystyrene/carbon tetrachloride/methanol and poly(2‐vinylpyridine)/chloroform/ethanol.

It is shown that the extrapolated value λ′∞ for infinite molecular weight better obeys the theoretical expressions established by Read and Pouchly than the value for a finite molecular weight.

When interactions are weak the Read formula can be used, when they are stronger one has to use the formula on Pouchly et al., but all these theories give just a qualitative description of the phenomenon and cannot be used quantitatively in the presence of strong interactions such as hydrogen bonds.
Synthèse de poly(oxyéthylène)s rendus biospécifiques par fixation de stéroïdes en extrémités de chaînes. Utilisation d'un poly(oxyéthylène) substitué par des groupes estradiol pour extraire l'isomérase Δ5→4 oxo‐3 stéroïde, par partage d'affinité
Authors: Chaabouni Abdelaziz , Hubert Patrick , Dellacherie Edith , Neel Jean
Published: April 2003

In three consecutive steps involving halogenation, amination, and condensation with a convenient acyl derivative (1 or 2), α‐hydro‐ω‐hydroxypoly(oxyethylene) (3) was transformed into poly(oxyethylene)s 7 containing 0,6 to 1,3 mol of 3‐[3,17β‐dihydroxy‐1,3,5(10)‐estratrien‐7α‐yl]butyroyl end groups or 0,7 mol of 3‐oxo‐4‐androsten‐17β‐ylcarboxyl end groups per mol of polymer. Applying the method of affinity partitioning, the former poly(oxyethylene) derivative 7 was used to purify successfully Δ5→4 3‐oxosteriod isomerase contained in a crude extract from Pseudomonas Testosteroni.
13C NMR sequence analysis, 15. Copolymerization of alanine‐NCA with other α‐amino acid NCAs
Authors: Kricheldorf Hans R. , Schilling Gerhard
Published: April 2003

Alanine‐N‐carboxylic acid anhydride (Ala‐NCA) was copolymerized with glycine‐NCA, phenylalanine‐NCA, valine‐NCA, leucine‐NCA, and sarcosine‐NCA in various solvents and with various catalysts; 22,6 MHz 13C NMR spectra and 90 MHz 1H NMR spectra of the resulting copolypeptides were measured in trifluoroacetic acid and from the signal intensities the rate of incorporation was estimated. The copolypeptides poly(Ala/Gly) and poly(Ala/Phe) contained both monomeric units in an almost equal concentration, while the low reactivity of Val‐NCA and Leu‐NCA resulted in a lower concentration of these residues compared with Ala in poly(Ala/Val) and poly(Ala/Leu). The 13C NMR spectra of poly(Ala/Gly) exhibit four CO‐signals which could be assigned by comparison with the corresponding homopolypeptides and with the sequence polypeptides (Ala‐Ala‐Gly‐Gly)n, and (Ala‐Gly‐Gly)n. From the intensities of these CO‐signals the average length of the homogeneous blocks was calculated. Both block lengths and rate of incorporation proved to be almost independent of solvent, catalyst, and reaction temperature. Poly(Ala/Phe) and poly(Ala/Sar) show also four CO‐signals, but poly(Ala/Val) only two and poly(Ala/Leu) one. The number and shape of the CO‐signals allow one to decide whether random copolypeptides were obtained or not.
Vernetzung von amylose mit Epichlorhydrin, 2. Untersuchung der Vernetzungsprodukte nach dem Gelpunkt
Authors: Pfannemüller Beate , Sperlich Marianne
Published: April 2003

A series of amylose gels prepared by reaction of amylose solutions in 1 M aqueous NaOH with 1‐chloro‐2,3‐epoxypropane (epichlorohydrin) at different concentrations were characterized by several methods: (a) The density of cross‐links was estimated by equilibrium swelling of the gels in water at room temperature. The molecular weight of the segments between the cross‐links (Mc) derived from the Flory equation decreased exponentially with the epichlorohydrin concentration used for gelation. The results obtained for weakly cross‐linked gels are in the same order as the values determined previously by analytical methods. (b) Further differentiation of the gels and the corresponding sol fractions was achieved by enzymes specific for amylose. The size of the fragments resistent to α‐amylase was found to increase linearly with epichlorohydrin concentration. Only minor attack by the exo‐enzyme β‐amylase was found, indicating lack of longer unsubstituted pendant branches. The presence of some short branches is deduced from their priming activity in phosphorolytic synthesis. The grafted amylose chains are located solely at the surface of the gels. The weakly cross‐linked gels give characteristic colours with iodine indicating slightly longer free amylose segments in the gel than in the corresponding sol. The nature of iodine binding by cross‐linked amylose chains is discussed.
Borverbindungen, 9. Metathetische Ring‐Ring‐Gleichgewichte bei Dioxaboracycloalkanen
Authors: Gerwarth Ulrich W.
Published: April 2003

Aryldihydroxyboranes (2,10) condense with α,ω‐alkanediols HO(CH2)xOH (6), which leads to an equilibrium of oligomeric rings (7) of different size due to a ligand exchange at the boron atom. With low diols (6, x = 2,3) the rate of establishing the equilibrium of the exchange reaction is slow enough for isolating the five‐ and six‐membered heterocycles (7, n = 1). Diols with x≥5, however, lead to the equilibrium mixture of oligomeric heterocycles in a somewhat analogous way to olefin metathesis.