bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cyclic dicarbonates as new monomers for the synthesis of poly(hydroxy ether)s
Authors: Rokicki Gabriel 
Published: April 2003

AbstractNew 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

AbstractHighly 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

AbstractThe 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

AbstractThe 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

AbstractThree 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

AbstractThe 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

AbstractRaman 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

AbstractA 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

AbstractThree 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

AbstractDialkyldiallylammonium 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

AbstractNumerous 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

AbstractFour 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.
Phase distribution chromatography (PDC) as a method for the investigation of polymers in solution, 4. Deformation concept
Authors: Greschner Georg S. 
Published: April 2003

AbstractIn a previous paper of the author the assumption was stated that the separation mechanism of phase distribution chromatography (PDC), based on a flow equilibrium (steady state) of the transported polymer between the mobile and the stationary phase of the polystyrene/cyclohexane PDC column, can be explained by means of a deformation of the sorbed polystyrene coils by the velocity gradient along the surface of the stationary phase of the column. In this paper this assumption is tested by means of the theory of rubber elasticity applied to the polystyrene coils sorbed on the surface of the polystyrene gel. The velocity gradient near the surface of the gel is estimated by means of the equations of Hagen‐Poiseuille and the deformation of the coil caused by this gradient is calculated from experimental data. The results show that the deformation concept can explain the PDC separation mechanism found from the measurements and published previously.
Phase behaviour and structure of polymer surfactants in aqueous solution. The occurrence of lyotropic nematic phases
Authors: Lühmann Bernd , Finkelmann Heino , Rehage Günther 
Published: April 2003

AbstractThe binary phase diagrams are analyzed in aqueous solutions of monomeric, non‐ionic surfactants and the corresponding polysiloxanes having attached the surfactants as side chains via the hydrophobic parts of the amphiphiles. In contrast to common surfactants these hydrophobic parts additionally contain a rigid, mesogenic biphenyl moiety. While the polymeric surfactants exhibit hexagonal and lamellar lyotropic liquid crystalline phases, similarly to the low‐molar‐mass surfactants, two important results have to be emphasized: (i) The liquid crystalline phase regions are markedly extended with respect to concentration and temperature compared with the corresponding monomers, as shown in a similar way for thermotropic polymer liquid crystals. (ii) The phase sequence of the polymorphic liquid crystalline phases can be changed by polymerization. While for the systems under investigation the monomeric surfactant exhibits a cubic phase, the polymeric surfactant shows no cubic but a nematic phase in front of the hexagonal phase at low surfactant concentration. The nematic phase of the polymeric surfactant is the first example for a nematic phase, which is formed for binary mixtures of non‐ionic surfactants and water.
Photo‐oxydation de polyéther‐block‐polyamides
Authors: Gauvin Pascal , Philippart Jean‐Louis , Lemaire Jacques , Sallet Daniel 
Published: April 2003

AbstractAnalytical and kinetic aspects of the photooxidation in the solid state of two polyether‐block‐polyamides 1a and 1b are described. The block copolymers studied contain different fractions of polyether segments. Nevertheless, their photooxidation presents the same features and concerns mainly the ether groups. In both thermoplastic elastomers, 1a and 1b very high stationary concentrations of hydroperoxy groups CH(OOH)OCH2 are observed (0,3 to 0,7 mol · kg−1). These hydroperoxides are, however, photounstable and thermounstable above 60°C. They are converted into hemiacetals OCH(OH)OCH2, saturated esters and formates. The hemiacetal groups are thermounstable, too, and decompose into alcohol and aldehyde groups, the latter being photoxidized in the matrix. The oxygen consumption rate, the primary hydroperoxidation rate, and the rate of accumulation of final products were determined. A mechanism including the photolysis and the thermolysis of the hydroperoxides can account for the formation of the final photoproducts (hemiacetals, esters, formates and acids).
Systèmes réactifs polyuréthannes bloqués, 3. Etude du blocage des fonctions isocyanate par le butanone‐2 oxime et de leur déblocage par 1H NMR à 350 MHz
Authors: Phai Lê Thi , Camberlin Yves , Pascault Jean‐Pierre , Pham Quang Tho 
Published: April 2003

AbstractThe structures of the adducts of 2‐butanone oxime (1) to different diisocyanates were determined by 1H NMR spectroscopy. The reaction of diisocyanate blocking is quantitative. The different adducts of 1 to 4,4′‐methylenediphenyl isocyanate (2), 2‐methyl‐1,4‐phenylene and 2‐methyl‐1,3‐phenylene diisocyanates (8 and 10) and to the isocyanate resulting from α‐hydro‐ω‐hydroxypoly(oxytetramethylene) and an excess of 2, dissociate upon heating to reform the starting materials. The residual water in the NMR solvent reacts partially with the regenerated diisocyanates to give primary amines and then ureas.
Synthesis of polysiloxane graft copolymers by hydrosilylation reactions
Authors: Chujo Yoshiki , Murai Kazuko , Yamashita Yuya , Okumura Yoshio 
Published: April 2003

AbstractPolysiloxane‐poly(methyl methacrylate) and polysiloxane‐polystyrene graft copolymers of well‐defined structure and composition were synthesized by hydrosilylation. Polysiloxanes with SiH bonds were prepared by equilibrium ring‐opening polymerization of cyclic siloxane oligomers catalyzed by trifluoroacetic acid. Molecular weight and SiH group content were controlled by the feed ratio. Allyl‐terminated poly(methyl methacrylate) and polystyrene were prepared by the reaction of carboxyl‐terminated prepolymers with allyl glycidyl ether. The hydrosilylation reactions of SiH containing polysiloxanes with these allyl‐terminated polymers produced tailor‐made graft copolymers, which were characterized by their 1H NMR and IR spectra.
Studies on chitosan‐induced metachromasy, 2. The reversal of metachromasy by co‐solutes
Authors: Gummow Beryl D. , Roberts George A. F. 
Published: April 2003

AbstractThe influence of co‐solutes on the chitosan‐induced changes in the visible spectrum of the anionic dye C.I. Acid Orange 7 is studied. Addition of neutral electrolytes brings about reversal of the spectral changes, as does the addition of alcohols, urea or excess chitosan. The ease of reversal by electrolyte varies with variation in either the anion or the cation but there are no readily explained trends. The effectiveness of alcohols increases with increasing hydrophobic character, the order being methanol < ethanol < 1‐propanol, whilst the effect of urea is comparable to that of ethanol. Chitosan‐induced metachromasy is also reversed by raising the solution temperature, the spectrum reverting to that of the metachromatic state on cooling down to room temperature. These results confirm that the metachromasy induced in the visible spectra of solutions of some anionic dyes by addition of chitosan is the same as that induced by anionic polyelectrolytes in the spectra of a number of cationic dyes.
Polymerization of styrene and methyl methacrylate by 2,5‐dimethyl‐2,5‐dihydroperoxyhexane, 1. Bulk polymerization
Authors: Baysal Bahattin M. , Bayramli Erdal , Yürük Hüseyin , Hazer Baki 
Published: April 2003

AbstractA new polymerization initiator 2,5‐dimethyl‐2,5‐dihydroperoxyhexane is used as an initiator for the polymerization of styrene and methyl methacrylate at 80°C. It is found that the rates of initiation for this initiator lie in‐between those of di‐tert‐butyl peroxide and benzoyl peroxide for both monomers. The kinetic results show good agreement between dilatometric and gravimetric measurements for the polymerization of styrene. However, mostly oligomers were obtained at high initiator concentrations with methyl methacrylate. A narrow molecular weight distribution is observed from stress‐relaxation measurements for the polystyrene samples obtained at high conversions.
Emulsion copolymerization of acrylonitrile and butyl acrylate, 2. Effect of a radical scavenger on the rate of copolymerization and the copolymer composition
Authors: Capek Ignác , Bartoň Jaroslav 
Published: April 2003

AbstractRandom copolymers of acrylonitrile and butyl acrylate, covering two sets of compositions, are synthetized by emulsion copolymerization conducted to both low and high conversions. The copolymer formed at low conversion is enriched with acrylonitrile. Addition of a small amount of hydroquinone, however, suppresses the formation of copolymer enriched with acrylonitrile, i.e., the formation of copolymer more homogeneous in composition is favoured. Moreover, the effect of a radical scavenger on the kinetic parameters of the emulsion copolymerization is analyzed. In the presence of a small amount of hydroquinone the molecular weight of copolymer is somewhat increased when compared with that prepared without hydroquinone. In addition, the rate of copolymerization unexpectedly decreases with increasing emulsifier concentration. It is supposed that the recipe ingredients themselves and their reaction products or/and intermediates participate in termination reactions within the monomer swollen polymer particles and probably within the emulsified monomer droplets. The initiation of the emulsion copolymerization of acrylonitrile and butyl acrylate is a two‐step process. The first step starts in the aqueous phase by the primary radicals from the water‐soluble initiator and acrylonitrile. The second step occurs in the monomer‐swollen emulsifier micelles by water‐soluble and ‐insoluble radicals (primary and macroradicals) and by radicals derived from the recipe ingredients.
Characterization of butadiene‐acrylonitrile‐methacrylic acid terpolymer by 13C and 1H NMR
Authors: Kanakavel Meenakshisundaram , Sebastian Thazhathuvettoor V. 
Published: April 2003

AbstractThe proton noise‐decoupled 13C NMR spectra were used to characterize the terpolymer of butadiene (BD), acrylonitrile (AN), and methacrylic acid (MMA) prepared by emulsion polymerisation. Assignments for the various triads of butadiene units adjacent to acrylonitrile in the terpolymer were made by comparing the olefinic and aliphatic carbon resonances of a butadiene (B)‐acrylonitrile (A) copolymer. Measurement of intensities of olefinic resonances in the nitrile environment for the terpolymer gives information about the BBB, BBA, ABB and ABA triads distribution, BBA and ABA being predominant. The intensities of methylene carbon resonances of the various triads for BD units connected to AN show a similar trend. The relative populations of various triads calculated from the peak intensities show that the terpolymer has a random structure. The assignments pertaining to BD units were made by comparison with 13C resonances of polybutadiene. The distribution of trans‐1,4‐, cis‐1,4‐ and 1,2‐units in the terpolymer indicates that the terpolymer has a random structure.