bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of the state of titanium ions and the composition of the active component in titanium‐magnesium catalysts for ethylene polymerization
Authors: Zakharov Vladimir A. , Makhtarulin Sergei I. , Poluboyarov Vladimir A. , Anufrienko Vladimir F.
Published: April 2003

The state of Ti3+ ions formed at various steps of preparation and activation of highly active titanium‐magnesium catalysts of various composition (dry milling of TiCl3 with MgCl2; reduction of TiCl4 by nonsolvated magnesium dialkyl; interaction of the TiCl4/MgCl2 system with an organoaluminium compound) was studied by the ESR method. It was found that in all systems studied the same three types of Ti3+ ions in the chlorine environment are formed, differing in coordination and localization sites in MgCl2. The content of these ions depends on the composition and preparation conditions of the catalysts, and does not exceed 20% of the total content of titanium. Most of the Ti3+ ions formed in all systems enter the composition of particles or surface aggregates of TiCl3 and appear in the ESR spectra only after dissolution of the sample in pyridine. The active centers of titanium‐magnesium catalysts are supposed to be constituents of these particles or of surface aggregates.
Reaction of tert‐butoxyl radicals with electron‐rich α‐methylvinyl monomers
Authors: Grant Richard D. , Rizzardo Ezio , Solomon David H.
Published: April 2003

The reactions of tert‐butoxyl radicals with α‐methylstyrene and with isopropenyl acetate were examined. Allylic hydrogen abstraction was shown to compete with addition to the double bond at the CH2 group. The proportion of abstraction relative to addition increases with increasing solvent polarity, however, this effect is more pronounced in the reactions of isopropenyl acetate than in those of α‐methylstyrene.
Stereochemistry in “living” coordination polymerization of propene initiated by vanadium‐based catalytic systems
Authors: Doi Yoshiharu , Koyama Tetsuya , Soga Kazuo , Asakura Tetsuo
Published: April 2003

Soluble catalysts of V(acac)3 and AIR2X (R = C2H5, n‐C3H7, i‐C4H9; X = Cl, Br) initiate a living polymerization of propene at −78°C to afford monodisperse polymers of syndiotactic structure. The stereochemistry of the living polymerization was investigated by examining the structures of monomdisperse polypropylenes and of propylene‐ethylene block copolymers by means of 13C NMR spectroscopy. It was found that syndiotactic‐ and regio‐specificities of the soluble vanadium‐based catalysts are not influenced by the sequence length of the living polymer chain.
Vinyl polymerization, 425. Radical polymerizations of vinyl monomers initiated with diphenyl disulfied and urea
Authors: Ouchi Tatsuro , Beika Nobuaki , Imoto Minoru
Published: April 2003

Polymerizations of vinyl monomers initiated with diphenyl disulfide (1) and urea were carried out in 1,4‐dioxane/water (vol. ratio 7:3). Methyl methacrylate (MMA) and methacrylic acid were found to be easily polymerized with this system, whereas the polymerization of styrene and acrylonitrile is not initiated. The polymerization was found to proceed by a radical mechanism. The polymerization of MMA was kinetically investigated.
Influence of annealing on the formation of long polyenes during PVC degradation
Authors: Gerrard Donald L. , Maddams William F. , Shapiro Jacob S.
Published: April 2003

Mass polymerised poly(vinyl chloride) (PVC), subjected to annealing treatment between 85–140°C under air, nitrogen, vacuum, and hydrogen chloride environment, was found to undergo very slight decomposition in which long polyenes (with more than ten conjugated carbon‐carbon double bonds) were produced. Despite the presence of these polyenes the thermal stability of the resin at 190°C remained unaltered. Resin stability was also unaffected by the atmosphere in which the resin was annealed. By contrast, urea clathrate PVC, known to be highly crystalline, decomposed 300% faster than mass PVC and generated very long polyene sequences (n ≥ 42) at 190°C. The results are discussed in terms of two possible morphological populations of polymer.
Darstellung und polymerisation von diestern aus 2,2′‐methylendiphenolen und acryl‐, methacryl‐ bzw. Crotonsäure
Authors: Böhmer Volker , Funk Rüdiger , Kiełkiewicz Jedrzęj , Vogt Walter
Published: April 2003

Several mono‐ and diesters of four selected 2,2′‐methylenediphenols with acrylic, methacrylic, and crotonic acid were synthesized for the first time. Special emphasis was paid to the preparation of diesters with two different acyl groups which could be obtained via the corresponding monoesters. The radical polymerization of these esters with AIBN (mainly in benzene) gave insoluble (crosslinked) products from dimethacrylates and soluble (linear) polymers from mixed diesters with methacrylic and crotonic acid, while the dicrotonates are not reactive.
Random coil configurations of poly(diethylene glycol isophthalate). Capability of model network formation
Authors: Riande Evaristo , Guzmán Julio , de Abajo Javier
Published: April 2003

Values of the mean‐square dipole moment 〈μ2〉 of poly(diethylene glycol isophthalate) were determined as a function of temperature by means of dielectric experiments carried out on solutions of the polymer in benzene. The value of the dipole moment ratio 〈μ2〉/(nm2), where nm2 is the mean‐square dipole moment of the chains in the idealization that all of the skeletal bonds are freely jointed, is 0,697 at 30°C. Trifunctional model networks were prepared by endlinking hydroxyl‐terminated chains with an aromatic triisocyanate. From thermoleastic experiments performed on the networks over the temperature range 20–80°C, it was found that the value of the temperature coefficient of the unperturbed dimensions 103 d In 〈r2〉0/dT amounts to 1,05 ± 0,17 K−1. The dipole moments and the temperature coefficients of both the dipole moments and the unperturbed dimensions were critically interpreted in terms of the Ratational Isomeric State (RIS) model. Stress‐strain experiments were also performed at 70°C on swollen and unswollen networks. The analysis of the isotherms suggests that the chemical crosslinks are not sufficient to account for the high modulus exhibited by the networks.
Untersuchungen zu Modifikationen von Polyamid‐6 und Polyamid‐4 mit eingelagerten Alkalihalogeniden
Authors: Votteler Christine , Hoffmann Volker , Trafara Gundolf
Published: April 2003

Polyamide‐6 (PA‐6) and polyamide‐4 (PA‐4) doped with alkali halides were investigated by X‐ray diffraction, thermal analysis, infrared and far infrared spectroscopy at various temperatures (10 K – 300 K). The solubility of the alkali halides in PA‐4 is better than in PA‐6. Small ions are molecularly dispersed in PA‐6 and PA‐4. Alkali ions are coordinated to the oxygen, halide ions to the nitrogen of the amide group. The degree of crystallinity of the polyamides depends on the concentration of the alkali halides and the ion radii. Alkali halides stabilize modifications of the polyamides with not fully extended chains. In polyamides crystallized from the melt some alkali halides stabilized the γ‐modification or similar structures. The modification is nearly independent of the alkali halide concentration and will not be destroyed by washing out the alkali halides. If the polyamides are crystallized from formic acid, alkali halides promote a pleated sheet structure with antiparallel chains. The factor group of the layer is D2, indicated by a low temperature splitting of the B2 vibration modes.
The phase behaviour of a poly(ether sulfone) with poly(ethylene oxide)
Authors: Walsh David J. , Singh Vir Bhanu
Published: April 2003

Blends of poly(ethylene oxide) with a poly(ether sulfone) were prepared by casting from a common solvent and were found to be miscible and show a single, composition dependent, glass transition temperature. Mixtures in both cyclohexanone and N,N‐dimethylformamide phase, separated on heating and thus conditions need to be carefully chosen to obtain homogeneous blends. At higher PEO contents, PEO crystallised from the blends at lower temperatures. The melting point depression, as determined by trubidity measurements, was used to calculate an interaction parameter which was negative, as expected for miscible polymers. The blends also phase separated on heating, and the cloud point curve could be measured by turbidity measurements and confirmed by both visible and electron microscopy. The cloud point curve was very skew with a minimum at around 10 wt.‐% PES content. This was not a strong function of the molecular weight and the skew nature was thus presumably due to differences in the state parameters of the pure components. The blends showed a very high mobility with sharp and reproducible could points which might make them ideal for future miscibility studies.
Crystal and molecular structure of S,S‐[sulfonylbis(1,4‐phenylene)] di(thiobenzoate) as a model compound for the respective polymers
Authors: Garbarczyk Józef
Published: April 2003

The molecular and crystal structure of S,S‐[sulfonylbis(1,4‐phenylene)] di(thiobenzoate) (1) was determined from X‐ray diffractometer data. The crystals are monoclinic, P21/a, with Z = 4 in the unit cell of the dimensions: a = 14,050 Å, b = 10,404 Å, c = 16,734 Å and β = 110,57°. The structure was resolved by direct methods and refined by least‐squares techniques up to R = 0,049 for 2466 independent reflections. The molecules of 1 are asymmetric: the thiobenzoate substituents are syn and anti with relation to the central sulfonyl groups and the thiocarbonyl groups do not lie in the planes of the phenylene rings. Three aromatic rings are nearly perpendicular. From energetic calculations the possibility for a rotation around the S1 – C8 bond was evidenced. The results allow to explain the low crystallinity of the polymer consisting of 1 segments.
Asymmetric induction copolymerization of isobutyl vinyl ether with indene by (−)‐menthoxyaluminium dichloride and (−)‐menthoxytitanium trichloride
Authors: Yamaguchi Hidemasa , Doiuchi Tohru , Kawamoto Kohzoh , Yasuzawa Takashi
Published: April 2003

The copolymerization of isobutyl vinyl ether with indene was carried out with (−)‐menthoxyaluminium dichloride (1) and (−)‐menthoxytitanium trichloride (2) as initiators. Although optically active copolymers were obtained in the copolymerization in non‐polar solvents, the copolymers prepared in a polar solvent was optically inactive. From the linear relationship between the optical rotation and the diad probability P2 (m1 m2) of the copolymers, it was found that asymmetric carbon atoms were introduced in vinyl ether monomeric units but not in indene ones.
Synthesis of macromolecular antioxidants by reaction of aromatic amines with epoxidized polyisoprene, 3. Reaction of 4‐anilinoaniline with epoxidized 1,4‐polyisoprene
Authors: Jayawardena Shanthilal , Reyx Danièle , Durand Dominique , Pinazzi Christian Pierre
Published: April 2003

4‐Anilinoaniline (6) reacts with expoxidized 1,4‐polyisoprene in toluene under phenol catalysis. Secondary cyclization reactions are detected at longer reaction times (≧ 18 h). However, the kinetic results, obtained at the beginning of the reaction and for limited phenol concentrations, agree with a mechanism involving a trimolecular transition state and a concerted transfer.
Polymer‐supported bases, 2. Polystyrene‐supported 1,8‐diazabicyclo[5.4.0]undec‐7‐ene as reagent in organic syntheses
Authors: Tomoi Masao , Kato Youichi , Kakiuchi Hiroshi
Published: April 2003

Polystyrene‐supported 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (PDBU) was prepared by the reaction of lithiated 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) with chloromethylated or ω‐bromoalkylated polystyrene resins. PDBU is effective as reagent for dehydrobromination and esterification. The reactivity of PDBU in dehydrobromination is lower than that of DBU. In the case of esterification, PDBU with 19% ring substitution exhibits almost the same reactivity as DBU. PDBU, regenerated from the hydrobromide salt, can be re‐used without decrease in reactivity.
Sequence distribution and glass transition of vinyl alcohol/n‐alkyl vinyl carbonate copolymers
Authors: Arranz Félix , Sánchez‐Chaves Manuel , Molinero Ana
Published: April 2003

13C NMR spectroscopy was used for the determination of the sequence distribution in vinyl alcohol‐ethyl vinyl carbonate copolymers prepared by reaction of poly(vinyl alcohol) with ethyl chloroformate. The 13C NMR spectra of the methylene carbons in the main chain show three split peaks whose intensities change with copolymer composition. These peaks can be assigned to the three dyad sequences. The obtained results show that ethyl vinyl carbonate units have an alternating tendency in the copolymer chain. The Tg values of the vinyl alcohol‐ethyl vinyl carbonate and vinyl alcohol‐butyl vinyl carbonate copolymers are influenced by both the overall copolymer composition and the monomer sequence distribution.
Concentration dependence of the Flory‐Huggins parameter at different thermodynamic conditions
Authors: Schotsch Kurt , Wolf B. A. , Jeberien Hans‐Edwin , Klein Joachim
Published: April 2003

By means of data from critical demixing and vapour pressure measurements and by inverse gas chromatography, including the results of published light scattering measurments, a consistent picture is obtained for the entire dependence of the Flory‐Huggins parameter χ on the weight fraction w2 of the polymer and on the temperature T for the system tert‐butyl acetate/polystyrene. Within the entire T‐range (ca. 0°C – 140°C), χ increases stronger than exponentially with w2, the rise being the larger the larger χH (the enthalpy contribution to χ) becomes in the limit of infinite dilution. At sufficiently high temperatures (≳ 50°C), χH changes its sign from negative to positive as w2 is raised. This behaviour, as well as the general shape of χ(w2) is in qualitative accord with the results of the corresponding‐states theory as developed by Flory et al.
Elastic and quasielastic light scattering studies on the branching characteristics of dextrans
Authors: Fahner Eva M. , Großmann Georg H. , Ebert Klaus H.
Published: April 2003

The influence of branching on the radius of gyration and the hydrodynamic radius of dextran macromolecules was studied by elastic and quasielastic light scattering (ELS and QELS). The hydrodynamic radius is more sensitive to low levels of branching than the radius of gyration. At higher branching levels a saturation of the hydrodynamic radius rh is observed, while the radius of gyration rG still changes distinctly. The ratio rG/rh proves to be a measure of the flexibility of the macromolecules; the latter is increasing with molecular weight for short linear chains and is decreasing with increasing degree of branching. Measurements were carried out in water (thermodynamically good solvent) and in ethylene glycol (under theta conditions) on four series of dextran fractions having rather narrow molecular weight distributions.
Kinetics of polymerization of styrene with butoxy titanium trichloride and diethylaluminium chloride
Authors: Sehra Jagdish C. , Gundiah Subbaraya
Published: April 2003

The kinetics of the polymerization of styrene, using H3C(CH2)3OTiCl3/Al(C2H5)2Cl as catalyst, was examined in a vacuum dilatometer. The polymerization rate was found to decrease continuously with time and the initial and overall rates vary linearly with the catalyst concentration, exhibiting a nearly second‐order and first‐order dependence, respectively, with regard to the monomer. The decrease of the rate with time is attributed to the chemical deactivation of the sites.
The stereoregularity of poly(methyl methacrylate)s formed in the presence of highly syndiotactic poly(methyl methacrylate)s
Authors: Matsuzaki Kei , Kanai Taiichi , Ichijo Chikara , Yuzawa Makoto
Published: April 2003

Methyl methacrylate (MMA) was radically polymerized in the presence of highly syndiotactic deuterated or undeuterated poly(methyl methacrylate)s. In contrast to observations found in the literature no increase in isotacticity was observed. The stereoregularity of the polymers formed in the presence of an undeuterated PMMA as matrix was found by 1H NMR spectroscopy to be about the same as that in polymers prepared without any matrix, except the polymers formed in the early stage of polymerization which show a little lower syndiotacticity. Determinations of triad tacticities of polymers formed in the presence of deuterated PMMA, gave values of syndiotacticity a little higher than in the case of undeuterated matrixes. The polymer formed in the graft copolymerization of MMA onto pre‐irradiated syndiotactic PMMA was fractionated by GPC. The high molecular weight fraction showed a lower syndiotacticity than that of lower molecular weight.
Anionic polymerization of exo‐3,4,5‐trithiatetracyclo[5.5.1.O2,6.O8,12]tridec‐10‐ene (dicyclopentadiene trisulfide)
Authors: Baran Teresa , Duda Andrzej , Penczek Stanistaw
Published: April 2003

The anionic polymerization of exo‐3,4,5‐trithiatetracyclo[5.5.1.O2,6.O8,12]tridec‐10‐ene (1) in bulk and/or in aromatic solvents (benzene, toluene) was studied. The polymerization was initiated with sodium benzenethiolate (sodium cation complexed with dibenzo‐18‐crown‐6). Polymers with high‐molecular weights were obtained (Mn ≈ 105, osmometrically). The polymerization was found to be living and reversible; the equilibrium monomer concentration increases with the temperature. The ceilling temperature was estimated as 167°C. The thermodynamic data of the polymerization in toluene was determined and compared with those of the polymerization of exo‐3,4,5‐trithiatricyclo[5.2.O2,6]decane. The standard enthalpy ΔH = −(6,6 ± 0,6)kJ · mol 1 and entropy ΔS = −(29,3 ± 2,1)J · mol 1 · K 1 of the polymerization of 1 were evaluated from the temperature dependence of the equilibrium monomer concentration, determined dilatometrically.
Rapid succinoylation of cellulose in methanesulfonic acid
Authors: Hirabayashi Yasuhiko , Allan G. Graham
Published: April 2003

The reaction of cellulose with succinic anhydride in nonaqueous methanesulfonic acid under hetero‐or homo‐geneous conditions at 25°C was studied. Homogeneous reaction conditions minimized the formation of crosslinking diester linkages, but during the initial period of heterogeneous succinoylation, topochemically restricted reactions generated crosslinked cellulose derivatives which were not soluble in dilute alkali.
Ethylene‐propene copolymerization in the presence of a 13C enriched catalyst: End group analysis and monomer reactivities in the first insertion steps
Authors: Ammendola Paolo , Vitagliano Aldo , Oliva Leone , Zambelli Adolfo
Published: April 2003

Ethylene and propene were copolymerized in the presence of an isotactic specific 13C enriched catalyst. The 13C enriched end groups in the copolymers were detected by 13C NMR analysis. The resonances of the enriched carbons of the end groups could be assigned and the relative reactivities of the monomers in the insertion steps occurring at the beginning of the copolymerization were determined.
Ziegler‐Natta polymerization of 1‐alkenes: relative reactivities of some monomers toward insertion into metal‐methyl bonds
Authors: Ammendola Paolo , Zambelli Adolfo
Published: April 2003

The relative reactivities of ethylene, 1‐butene and 3‐methyl‐1‐butene in the insertion reaction into the metal‐methyl bond of the active site of the catalytic system δ‐TiCl3/Al(13CH3)3/Zn(13CH3)2 are determined by 13C NMR end groups analysis. The relative reactivities of propene, 3‐methyl‐1‐pentene and 3‐ethyl‐1‐pentene are also calculated from previous data. Some correlations between relative reactivities and reaction mechanism are proposed.
The sedimentation behaviour of polystyrene in various solvents in semidilute solutions
Authors: Huang Tianbao , Meyerhoff Günther
Published: April 2003

Sedimentation coefficients of S of polystyrene covering a broad range of molecular weights M, are measured in toluene and 2‐butanone in the semidilute regime. The results are compared with literature data using a plot of S · NA · η/(1 − νρ) = M · η/f versus concentration c, allowing experiments in different solvents of different density ρ and viscosity η to be compared (ν: partial specific volume of polymer; f: friction coefficient; NA: Avogadro number). According to scaling theory for concentrations higher than a critical concentration c, linear plots are to be expected. This is true for the theta‐solvent cyclohexane, but for the theta‐solvent cyclopentane as well as for the thermodynamically semi‐good and good solvents bent curves are obtained, the slopes of which turn toward a limiting value for high M and low c. The theoretical values of the slope for theta‐solvents (−1) is well represented by both theta‐solvents. For the semi‐good and good solvents the experimental limiting slopes are (slightly) lower than the predicted ones. With samples of still higher M becoming available this difference might become more pronounced.
Crystallinity of methylene‐oxyethylene‐methylene triblock oligomers. A study of the C21, C26 and C30 di‐n‐alkyl ethers of pentadecaethylene glycol
Authors: Yeates Stephen G. , Teo Hoon Hong , Booth Colin
Published: April 2003

Block oligomers of general formula H(CH2)nO(CH2CH2O)15(CH2)nH, where n = 21, 26 and 30, were prepared. Both the oxyethylene and the alkyl blocks are homogeneous. Examination of their crystalline structure (by X‐ray scattering, Raman and IR spectroscopy and differential scanning calorimetry) reveals two characteristic forms: type II formed on slow crystallisation of oligomers with n = 21 or 26, and type III b formed on rapid crystallisation of oligomers with n = 26 or 30. Structure II has unfolded chains in a completely crystalline layer structure, with helical oxyethylene blocks and planar zig‐zag alkyl blocks. Structure III b has once‐folded chains in a partly crystalline layer structure, with non‐crystalline planar zig‐zag oxyethylene blocks and crystalline planar zig‐zag alkyl blocks.
13C NMR characterization of branched structures in polyesters resulting from the reaction of maleic and phthalic anhydride with 1,2‐propanediol
Authors: Judas Didier , Fradet Alain , Maréchal Ernest
Published: April 2003

Several model compounds were synthesized in order to study the side reactions taking place during the synthesis of polyesters, especially chain branching due to the addition of hydroxyl groups to maleate or fumarate double bonds. Diesters or polyesters from 1,2‐propanediol with fumaric acid and various dialkyl alkoxysuccinates were used as models. Their synthesis and characterization are described. The interpretation of their 13C NMR spectra is reported. These spectra are compared with those of the diesters and polyesters of phthalic acid previously described and with the spectrum of a commercial unsaturated polyester. It was possible to identify and to assign the various end groups and the structures resulting from chain branching.
The effects of various catalysts in the in‐situ precipitation of reinforcing silica in polydimethylsiloxane networks
Authors: Jiang C.‐Y. , Mark J. E.
Published: April 2003

A variety of inorganic and organic acids, bases, and salts were studied as catalysts for the hydrolysis of tetraethyl orthosilicate, the reaction previously employed for the precipitation of silica within already‐cured elastomeric networks of polydimethylsiloxane. These substances were compared with regard to the amount of silica precipitated at room temperature, and the extent of reinforcement as judged by the upturns in the stress‐strain isotherms at high elongations. On this basis, the acids were the least effective and the salts the most effective.
Dimethylsiloxane‐ethylene oxide block copolymers, 1. Microphase separation of low segment mass copolymers and their compatibility with water and oil
Authors: Haesslin Hans W. , Eicke Hans F. , Riess Gerard
Published: April 2003

Ternary phase diagrams of linear tri‐block and multi‐block copolymers consisting of poly(dimethylsiloxane) with a constant segment mass of M̄n = 103 and varying poly(oxyethylene) segment masses in the range 100 ≤ M̄n ≤ 2000 with water and oil (cyclohexane) are reported. Also binary mixtures of the same copolymers with water and oil are investigated by differential scanning calorimetry (DSC). Microphase separation of the copolymers and different states of water are detected as a function of composition and structure of the copolymers as well as oil and water content, respectively. The results are discussed in terms of a model having an interphasial zone where intermixing of the dissimilar segments occurs.
Structures of liquid crystalline side group polymers oriented by drawing
Authors: Zentel Rudolf , Strobl Gert R.
Published: April 2003

The fiber patterns of a series of liquid crystalline polymers were analysed. For polymers with smectic phases and for polymers with long spacers and nematic phases, the mesogenic groups orient perpendicularly to the polymer main chains which are parallel to the fiber axis. The fiber pattern indicate a short range order of the mesogenic groups analogous to that in low‐molecular weight liquid crystals. For polymers with short spacer groups and nematic phases qualitatively different fiber patterns are found. These fiber patterns are indicative for a special nematic phase formed by ribbon‐like molecules.
Interaction of poly(diallyldimethylammonium chloride) with ferro‐ and ferricyanide anions
Authors: Bekturov Esen A. , Kudaibergenov Sarkyt E. , Ushanov Valeri Zh. , Saltybaeva Saule S.
Published: April 2003

The interaction of poly(1,1‐dimethylpyrrolidinium‐3,4‐diylethylene chloride) [poly(diallyldimethylammonium chloride)] (1) with ferro‐ and ferricyanide anions was investigated by conductometric titration, viscometry, IR and Raman spectroscopy. It could be shown that the binding of ferro‐ and ferricyanide anions with 1 proceeds by means of an ionic mechanism and is accompanied by a spectral shift of the cyanide bands.
Kinetic investigation of the free radical crosslinking copolymerization in the pre‐gel state, 1. Styrene/m‐ and p‐divinylbenzene systems
Authors: Hild Gérard , Okasha Rouzi
Published: April 2003

The kinetic investigation of the free radical crosslinking copolymerization of styrene with m‐or p‐divinylbenzene was performed at 60°C in benzene solution with 2,&2prime;‐azoisobutyronitrile as initiator. The mole ratio of divinylbenzene to styrene was steadily kept small. At various stages of the process the concentrations of the remaining monomers were measured by vapor phase chromatography which allowed to calculate both the conversion degrees and the instantaneous composition of the copolymers formed. The radical reactivity ratio of styrene, determined kinetically, was found to be in good agreement with the value obtained by the Kelen‐Tüdös linearization method. The branched polymers formed prior to gelation were studied by light scattering and by size exclusion chromatography. The number of pendant double bonds was determined by analytical titration. From all these results, conclusions were drawn concerning the mechanism of network formation, and more specifically on the reactivity of the pendant double bonds that are formed whenever a divinylbenzene unit is incorporated. This latter factor determines the rate of the formation of the branch points and crosslinks.
Conformational transition in poly(methacrylic acid)
Authors: Chidambaram Subbarao , Gundiah Subbaraya
Published: April 2003

The potentiometric behaviour of poly(methacrylic acid) was examined in water/1,4‐dioxane mixtures at 25°C. Conformational transitions were observed in about the same range of apparent ionization in the 1,4‐dioxane concentration range 0 to 15 vol.‐%. Transitions were not observed in the 1,4‐dioxane concentration range 20 to 35% and the corresponding Henderson‐Hasselbalch plots were found to be linear. Phase separations were observed to occur beyond 40 vol.‐% 1,4‐dioxane. The free energy of the conformational transition decreased very rapidly with the initial incorporation of 1,4‐dioxane but slowly at higher concentrations. Van der Waals methyl‐methyl interactions as the cause of the compact form has been inferred. The large increase in intrinsic viscosity observed for the unneutralized poly(methacrylic acid) in a relatively narrow range of composition of the 1,4‐dioxane/water mixtures has been ascribed to a solvent induced conformational transition.
Copolymerization of styrene with Zn(II), Co(II), Ni(II) and Cu(II) acrylates
Authors: Wojtczak Zbigniew , Gronowski Adam
Published: April 2003

The radical copolymerization of styrene with Zn(II), Co(II), Ni(II) and Cu(II) acrylates in methanol at 60°C was studied and that of styrene with Cu(II) acrylate also in acetonitrile at 80°C. In a given period of time an increase of conversion was observed with increasing concentration of the first three metal acrylates in mixtures with styrene. With Cu(II) acrylate, however, a decrease of conversion was found. The monomer reactivity ratios were determined as follows: rSt = 1,10, r = 0,90; rSt = 1,74, r = 0,56; rSt = 1,83, r = 0,53; rSt = 5,94, r = 0,12 (in acetonitrile). The products of the reactivity ratios, almost equal to one, reflect an “ideal” copolymerization and therefore a very little alternating tendency in propagation reactions. The Alfrey‐Price Q‐e parameters for the metal acrylates were calculated and discussed.
The thermodynamics of polyether sulfone‐poly(ethylene oxide) mixtures
Authors: Walsh David J. , Rostami Shamsedin , Singh Vir Bhanu
Published: April 2003

Mixtures of poly(ethylene oxide) and polyether sulfone have previously been shown to be miscible and undergo phase separation on heating, the minimum in the cloud point occurring at about 80°C and at 10:90 w/w PES:PEO composition. This paper describes an attempt to understand the thermodynamics of this system and to simulate the spinodal curves of the phase diagram using a modified form of the equation‐of‐state theory of Flory et al. Two methods were used to gain information about the interactional energy of the polymers. Heat of mixing measurements at 90°C on low molecular weight analogues were used to obtain a value of X12 of −40 J. cm−3. A modified form of the equations for the melting point depression of PEO in the blend was used to obtain values of X̄12 in the range of −35 to −50 J. cm−3 at 52°C, the melting point of PEO. In order to adjust the location of the simulated spinodal, using a value of X12 = −40 J. cm−3, it was necessary to assume an unfavourable non‐combinatorial entropy contribution of Q12 = −0,048 J. cm−3 · K−1. If the spinodals were simulated assuming Q12 = 0 and hence X12 ≡ X̄12 then a value of X12 = −18 J · cm−3 must be used. This is not inconsistent with the melting point depression result considering the large uncertainties in this method and the fact that the results are obtained at a lower temperature. The simulated spinodals are not very molar mass dependent which corresponds to the similar findings of the cloud point. The shape of the spinodal is dominated by the value of the surface area to unit volume ratio S2/S1 through its effect on the interactional terms in the spinodal equation.
α,ω‐dichloropoly(2‐methylpropene) as an inifer: A modification to the Kennedy‐Smith mechanism
Authors: Nuyken Oskar , Pask Stephen D. , Vischer Axel , Walter Michael
Published: April 2003

Experimental details are given of attempts to enumerate the binary ionogenic equilibria (B.I.E.) of 1‐chloro‐1‐methylethylbenzene (1)/BCl3, 1,4‐bis(1‐chloro‐1‐methylethyl)benzene (2)/BCl3 and 1,3,5‐tris(1‐chloro‐1‐methylethyl)benzene (3)/BCl3 in CH2Cl2. Due to chemical reaction (dimerisation or polymerisation) no experimental values for the B.I.E. constants could be obtained. A Born‐Haber cycle is constructed to estimate the relative sequence of the overall B.I.E. constants. A similar treatment for 2‐chloro‐2methylpropane as a thermodynamic model for α,ω‐dichloropoly(2‐methylpropene) (4) suggests that the overall B.I.E. constant for these polymers is somewhat smaller than those for 1 and 2 but greater than that for 3. Using 2/BCl3 as initiator for the polymerisation of 2‐methylpropene (IB) it is shown, that the degree of polymerisation of 4 can be controlled within the limits 10 < DP < 100. It is shown that 4 can also act as an initiator for the polymerisation of IB, that these polymerisations involve only free ion propagation and, from a kinetic analysis of these polymerisations, that: (k)2/k = 12 1 · mol−1 · s−1, k = 1,2 · 10−3 l · mol−1 · s−1, k [P] = 1,7 · 10−3 s−1, and k/(k K) = 102. The same analysis demonstrates that the self‐ionisation of BCl3 can be neglected in terms of any influence on the molar mass of the products. Experiments are also described which show that 2‐chloro‐2‐methylpropane is not suitable as a substitute initiator for IB, but that 2‐chloro‐2,4,4‐trimethylpentane is a useful model for 4 as an initiator for the polymerisation of IB.
Synthèse et copolymérisation avec l'acrylamide de macromonomères d'acrylate de dodécyle
Authors: Bonardi Christian , Boutevin Bernard , Piétrasanta Yves , Taha Mohammed
Published: April 2003

Graft copolymers of well‐defined structure and composition were prepared by radical copolymerization of acrylamide and poly(dodecyl acrylate) macromonomers. The macromonomers were prepared by telomerization of dodecyl acrylate in the presence of 2‐mercaptoethanol as a transfer agent, followed by reaction with acryloyl chloride. Poly(dodecyl acrylate) macromonomers with Mn = 1100, 1100, 2200 and 4600 were synthesized. The kinetics of the radical telomerization of dodecyl acrylate with 2‐mercaptoethanol and AIBN was studied at 66°C in THF. Under these conditions we obtained the transfer constant CT = 0,9. The graft copolymerization of acrylamide with the poly(dodecyl acrylate) macromonomer was carried out in the presence of the transfer agent C6F13C2H4SH. If C0 = [AIBN]/[Acrylamide] = 0,01 and R0 = [C6F13C2H4SH]/[Acrylamide] = 0,01, for acrylamide a DPn = 160 was obtained in all cases, for the macromonomer of Mn = 1100 a DPn = 2,5, and for the macromonomer of Mn > 1100 a DPn = 1.
Cyclic dicarbonates as new monomers for the synthesis of poly(hydroxy ether)s
Authors: Rokicki Gabriel
Published: April 2003

New cyclic dicarbonate monomers 3 were synthesized from bis(2,3‐epoxypropyl) ethers of diphenols with carbon dioxide in the presence of the KI 18‐crown‐6 as catalyst and used for polycondensation reactions with diphenols 4, catalyzed by potassium carbonate and leading to poly(hydroxy ether)s 5 with carbon dioxide elimination. The reaction of phenoxymethylethylene carbonate (1) with phenol (including kinetic measurements) was also studied as a model reaction for the formation of the oxy‐2‐hydroxytrimethyleneoxy group in 1,3‐diphenoxy‐2‐propanol (2).
The extraction of cadmium from waste waters using poly(iminoethylene) containing N‐dithiocarboxylato groups
Authors: Hudson Michael James , Tiravanti Giovanni , Ellis Arthur Franklyn
Published: April 2003

Highly branched poly(iminoethylene) containing N‐dithiocarboxylato groups (polymer 1) has been used to extract cadmium from simulated waste waters. Two conditional stability constants (logK1 = 11, logK2 = 4 to 5) have been related to binding by NHCS2⊖ and nitrogen‐containing groups. Polymer 1 is selective for cadmium over zinc in a solution containing Cd (11,2 mg · dm−3) and Zn (13 mg · dm−3) at pH = 2(H2SO4). The time for half of the available sites to be used by bonding to cadmium (t1/2) is in the order of 20 s. The total NHCS groups on polymer 1 is ca. 3,5 · 10−3 mol · g−1 (22,3% S) and the mole ratio of S: Cd has a limiting value of 3,7.
Spherulitic growth rates of poly(3,3‐dimethyloxetane)
Authors: Pérez Ernesto , Bello Antonio , Fatou José G.
Published: April 2003

The morphology and growth rates of crystallized fractions of poly(3,3‐dimethyloxetane) covering the range Mn = 18500 to Mn = 130000 were studied by polarized light microscopy at crystallization temperatures from 24 to 44°C. It was found that the growth rate is linear and only spherulites are formed in the temperature range examined. The growth rate‐temperature coefficient was analyzed by using nucleation theory. The usual plots are linear in the whole range of crystallization temperatures, and the comparison between dilatometric and growth data revealed that the overall rate‐ and growth rate‐temperature coefficients are approximately the same.
Synthesis of poly[bis(benzimidazobenzisoquinolinones)] in various reaction media
Authors: Jedliński Zbigniew , Kowalski Bogdan , Gaik Urszula
Published: April 2003

The influence of various reaction media, monomer concentration, temperature and reaction time on reduced viscosities ηred of semiladder poly[bis(benzimidazobenzisoquinolinones)] was studied using the 4,4′‐[isopropylidenebis(1,4‐phenyleneoxy)]di‐1,8‐naphthalenedicarboxylic anhydride/3,3′‐diaminobenzidine condensation reaction as a model. m‐Cresol/P2O5, m‐cresol/benzoic acid, m‐cresol/polyphosphoric acid, m‐cresol/di‐m‐cresyl phosphate, phenol/P2O5, and p‐chlorophenol/P2O5 were used as reaction media and it was found that the m‐cresol/P2O5 system was the best one. The use of the m‐cresol/P2O5 medium for the synthesis of poly[bis‐(benzimidazobenzisoquinolinones)] based on other dinaphthalene derived dianhydrides confirmed the universal applicability of this system. All the polymers obtained in the m‐hcresol/P2O5 medium showed high reduced viscosities and were film‐ and fibre‐generating.
Equilibrium copolymerization, 1. Random model
Authors: Cai Gang‐Feng , Yan De‐yue
Published: April 2003

Three cases of equilibrium copolymerization are re‐treated theoretically. The expression of the molecular weight distribution of the copolymer is a two‐dimensional distribution function with two random variables m and n, where m and n are the numbers of two different monomeric units, respectively. The molecular parameters of the copolymer, such as the number‐ and weight‐average molecular weights, number‐average degree of polymerization, copolymer composition and equilibrium conversions of comonomers, are derived. The relation between the parametric variables in the formulae and the equilibrium copolymerization conditions are determined from two binary cubic equations.
Crystallization behaviour of poly(ethylene terephthalate) and poly(tetramethylene terephthalate) blends
Authors: Mishra Siba P. , Deopura Basanti L.
Published: April 2003

The isothermal and non‐isothermal crystallization behaviour of blends of poly(ethylene terephthalate) (PET) and poly(tetramethylene terephthalate) (PBT) is investigated at low percentage of the second component. The melting behaviour of the isothermally crystallized sample shows that the crystallization behaviour in the blend is governed by the mobility of PBT. Below 200°C the crystallization process is hindered, whereas above 200°C the PET crystals are larger in case of added PBT. The non‐isothermal crystallization behaviour shows that the crystallization process is hindered when the PBT content in the blend is less or higher than 6 wt.‐%.
Formation of conjugated polyenes by chemical and thermal degradation of vinyl chloride copolymers and other vinyl polymers
Authors: Bowley Heather J. , Gerrard Donald L. , Maddams William F.
Published: April 2003

Raman and infrared spectroscopic studies on the chemical degradation products of two vinyl chloride/vinyl acetate copolymers and a vinyl chloride/vinyl acetate/vinyl alcohol terpolymer, obtained with the system potassium tert‐butoxide/N,N‐dimethylformamide, show that substantially complete dehydrochlorination occurs. Although the vinyl acetate groups are hydrolysed to the corresponding alcohol these latter largely remain intact and block the extension of the polyene sequences, whose lengths, measured by Raman spectroscopy, are in agreement with values calculated from the initial polymer composition. No degradation other than hydrolysis occurs with vinyl acetate and vinyl alcohol homopolymers or a vinyl alcohol/vinyl acetate copolymer. The thermal degradation of the copolymers containing vinyl chloride, and of two vinyl chloride homopolymers of differing syndiotacticity, at 153°C in N,N‐dimethylformamide, gives both dehydrochlorination and elimination of the comonomer units, the latter reaction occurring at least as rapidly as the former. A crosslinked structure, in which there is some steric stabilisation and, hence, conjugated polyene sequence lengths up to about 40, is formed. A maximum sequence length of 8 is found in thermally degraded poly(vinyl acetate), but the conjugated polyenes are too short to be detected in degraded poly(vinyl alcohol) and the vinyl alcohol/vinyl acetate copolymer.
Continuous fractionation and solution properties of PVC, 1. Continuous fractionation, characterisation
Authors: Geerissen Heinz , Roos Jürgen , Wolf B. A.
Published: April 2003

A new Continuous Polymer Fractionation method, called CPF, is described. The polymer to be fractionated is dissolved in a solvent/non‐solvent mixture, and this solution (feed) is extracted continuously by a second liquid (extracting agent), which contains the same solvent components as the feed. In the case of PVC, the fractionation was carried out with a pulsed counter current extraction apparatus and THF/water was used as solvent/non‐solvent mixture. Fractionation is achieved by the fact that the molecules are distributed over the counter current phases according to their chain length; the feed leaves the column as gel and the extracting agent as sol. First some explorative experiments were made in order to determine suitable working parameters, like frequency and amplitude of pulsation, compositions of feed and extracting agent and the ratio of flow. With the so obtained parameters, preparative experiments were carried out, yielding five PVC‐fractions with molecular weights ranging from 20 000 to 100 000 (GPC, LS) and non‐uniformities, U = (Mw/Mn) −1, of about 0,2 (GPC) using a starting material with Mw = 67 000 and U = 0,95.
Cinétique de télomérisation, 3. Détermination des constantes de tranfert en catalyse rédox
Authors: Boutevin Bernard , Piétrasanta Yves
Published: April 2003

Three methods were used for the determination of transfer constants to the metallic complex in the telomerization reaction with redox catalysis. The first one consists in the determination of DPn as a function of the mole ratio of telogen to monomer at the beginning of the reaction. The second one is based on the variation of the conversion degree of telogen to monomer. The last one requires the knowledge of the cumulated DPn and the conversion degree of monomer samples during the reaction. The proposed laws were checked following the methyl acrylate telomerisation with CCl4 as a telogen and CuCl2 as a catalyst at 120°C. The transfer constant to CuCl2 was found to be about 600 according to the three methods.
Syntheses and polymerizations of dialkyldiallylammonium bromides as vesicles in solution
Authors: Iino Yasuhiro , Ogata Yoshitaka , Shigehara Kiyotaka , Tsuchida Eishun
Published: April 2003

Dialkyldiallylammonium salts 1a–c were prepared by quaternization of diallylamine with alkyl bromides and their polymerizability as oriented molecular assemblies in aqueous solution is discussed. Thin films of those ammonium salts on the glass wall were incubated by adding a phosphate buffer solution to yield giant spherical vesicles with diameters ranging from 10 to 100 μm. When large amounts of the ammonium salt were applied, it was necessary to add more than 5 mol‐% of cholesterol in order to stabilize the resulting giant vesicles. By ultrasonication of the film‐aqueous solution system, much smaller vesicles with diameters ranging from 0,03 to 0,2 μm were obtained. The stabilizing effect of cholesterol addition to the system of the small vesicles is similar to that observed for the giant vesicles. Under an inert atmosphere, the vesicles in aqueous solution were polymerized by ultraviolet irradiation. From the results of TEM and NMR spectroscopy, it was concluded that the molecules were polymerized in the vesicles without changing the profile of molecular assembly during an irradiation of 6 h. However, when the ammonium salts were dissolved homogeneously in degassed benzene, the ultraviolet irradiation polymerization did not proceed beyond a conversion of 5% under the same conditions.
Polylactones, 2 Copolymerization of glycolide with β‐propiolactone, γ‐butyrolactone or δ‐valerolactone
Authors: Kricheldorf Hans R. , Mang Thomas , Jonté J. Michael
Published: April 2003

Numerous copolymerizations of glycolide with β‐propiolactone, γ‐butyrolactone or δ‐valerolactone were conducted either in bulk or in nitrobenzene solution at temperatures in the range of 20 to 150°C. Three classes of catalysts were used, namely acidic catalysts initiating cationic polymerizations, complexing catalysts initiating insertion mechanisms, and anionic catalysts. The molar composition of the copolyesters was determined from 1H NMR spectra and the sequence distribution of the comonomers from 13C NMR spectra. No reasonable copolymerization of glycolide and βhyphen;propiolactone was obtained at 20°C in nitrobenzene, whereas all catalysts yielded copolyesters at 100°C. In the case of glycolide/γ‐butyrolactone only bulk copolymerizations at 60°C with acidic initiators were successful. Under other conditions only homopolymerization of glycolide was observed. Copolymerizations of glycolide and γ‐valerolactone were performed in bulk and in nitrobenzene with both acidic and complexing initiators, whereas anionic initiators only caused homopolymerization of glycolide. Acidic initiators favored the incorporation of δ‐valerolactone, whereas the complexing initiators favored the incorporation of glycolide. The crystallinity of the glycolide/δ‐valerolactone copolymers was characterized by means of differential scanning calorimetry, and a good agreement with the expectations from both molar composition and sequence distribution was found.
Liquid crystalline poly(β‐aminoester)s containing different mesogenic groups
Authors: Angeloni Annino Sante , Laus Michele , Castellari Corrado , Galli Giancarlo , Ferruti Paolo , Chiellini Emo
Published: April 2003

Four series of new poly(β‐aminoester)s based on different mesogenic units and amino spacers were prepared and their properties examined. The polymers were obtained by a Michael‐type polyaddition reaction of the diamines piperazine (5a), 2‐methylpiperazine (5b), N,N′‐dimethylhexamethylenediamine (5c), and 4,4′‐trimethylenedipiperidine (5d) to diacrylates containing the anisotropic group, trans‐4,4′‐vinylenedi‐p‐phenylene diacrylate (1), 4‐(4‐acryloyloxybenzylideneamino)phenyl acrylate (2), 4,4′‐diphenylylene diacrylate (3), and 4,4′‐azoxydi‐p‐phenylene diacrylate (4). The mesophase behaviour of the resulting polymers 6–9 was strongly influenced by the nature of both the anisotropic and spacer groups. The 4,4′‐azoxydi‐p‐phenylene unit appeared to be the most efficient in promoting liquid crystal properties, whereas no mesophases could be observed in polymers incorporating the 4,4′‐biphenylylene unit. Doping of poly(β‐aminoester)s, based on 4,4′‐azoxydi‐p‐phenylene units, with a low‐molar‐mass cholesterogen allowed to obtain cholesteric structures extending over wide ranges of temperature. The molecular weight of the polymers was found to play a role in determining thermotropic mesomorphism by affecting the melting temperature of the polymer. In this context, some non‐macromolecular model compounds were analyzed in respect of their thermal behaviour.