bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies in ring‐opening polymerization. IV. Thermal polymerization of phenyl‐substituted 1,3‐dioxolan‐2,4‐diones
Authors: Smith I. J. , Tighe B. J. 
Published: April 2003

AbstractThe effect of C‐5 phenyl substituents on the thermal decomposition of the 1,3‐dioxolan‐2,4‐dione ring has been examined. Unlike the dimethyl‐substituted ring, 5‐methyl‐5‐phenyl‐1,3‐dioxolan‐2,4‐dione decomposes smoothly in dry nonhydroxylic solvents to yield polymer and carbon dioxide. The introduction of a second C‐5 phenyl substituent produces a similar but more rapid decomposition, with the added complication of a competing ring fragmentation leading to ketone formation. An analogy is drawn between the observed behavior of the phenyl‐substituted 1,3‐dioxolan‐2,4‐diones and that of the previously studied 1,3,2‐dioxanthiolan‐4‐one 2‐oxides. These monomers therefore provide another example of the thermal polymerisation mechanism first observed with 5,5‐dimethyl‐1,3,2‐dioxathiolan‐4‐one 2‐oxides. In these reactions the rate‐determining step is the first‐order ring‐scission process leading to the formation of an α‐lactone intermediate. This intermediate then takes part in a very rapid chain‐growth process which governs the characteristics of the polymer formed.
Effect of structure on properties of aromatic‐aliphatic polybenzimidazoles
Authors: Varma I. K. , Veena  
Published: April 2003

AbstractHomopolymers and copolymers containing the polybenzimidazoles ring were prepared from terephthalic acid (T), fumaric acid (F), and 3,3′‐diaminobenzidine tetrachloride (DAB) in polyphosphoric acid. The polymers were characterized by viscometry, infrared spectroscopy, and nitrogen analyses. The effect of copolymer composition on the ultraviolet and visible spectra, solubility in various solvents, and density was also investigated. The relative thermal stability of the various polybenzimidazoles was investigated by using dynamic thermogravimetry in air. Polybenzimidazole derived from terephthalic acid was most stable, and the introduction of aliphatic residues resulted in a decrease in thermal stability. However, the homopolymer of fumaric acid was more stable than the copolymers of fumaric acid and terephthalic acid.
Radiation‐induced polymerization of vinyl monomers adsorbed on inorganic substances. VI. Temperature dependence and effects of additives on methyl methacrylate–silica gel system
Authors: Fukano Kazuyuki , Kageyama Eiichi 
Published: April 2003

AbstractTo elucidate the reaction mechanism of radiation‐induced polymerization of methyl methacrylate adsorbed on silica gel, the temperature dependence and effects of acetone and pyridine were investigated. It was found that even at −78°C the polymerization rate was quite fast. The amounts of high molecular weight GPC peaks of both graft polymers and homopolymers increased with increasing irradiation temperature. The activation energy of the adsorbed state polymerization was low compared with that of bulk polymerization. The low molecular weight peaks of homopolymers decreased with acetone addition but were almost unaffected by pyridine. The low molecular weight peaks of homopolymers were thus polymerized by an anionic mechanism. In the methyl methacrylate–silica gel system both radical and anionic polymerization take place at the same time in formation of graft polymers and homopolymers. A reaction mechanism for the methyl methacrylate–silica gel system was proposed based on the results obtained to date.
Ionic species in γ‐irradiated poly(methyl methacrylate) at 77°K
Authors: Torikai Ayako , Kato Hiroshi , Kuri Zen‐Ichiro 
Published: April 2003

AbstractIonic species in poly(methyl methacrylate) (PMMA) have been studied by optical absorption and ESR spectrometry. γ‐Irradiation of PMMA containing aromatic solutes gave rise to the absorption spectra of corresponding cation radicals. The G value for the formation of cation radicals was determined to be 1.5. Anionic radicals of the solutes were not detected for the aromatic solutes studied. Anionic species of pure PMMA were identified by both absorption spectra and ESR spectra. It has an absorption maximum at 440 nm. A sharp singlet with a line width of about 5 G which was found by ESR spectrometry was tentatively assigned to the trapped electron of PMMA. The results show that a large number of electron traps in PMMA may exist on the ester side chain themselves.
Electropolymerization of aminophthalic acids. I. Polymerization of 4‐aminophthalic acid
Authors: Phillips D. Colin , Spewock Sandra , Alvino William M. 
Published: April 2003

Abstract4‐Aminophthalic acid has been polymerized in almost quantitative yield to low molecular weight polymer by electrochemical initiation at a platinum anode. Systems involving the acid, amine salt, and the ammonium salt have been explored; the acid and/or the amine salt of the acid provides the best means of obtaining polymer. Maximum molecular weight is attained in a very short time at low current densities (∼2 hr at 50 mA). Thermogravimetric data indicate a temperature stability comparable to polyamide‐imide polymers (400°C). Long reaction times and high current densities decrease molecular weight and polymer yield.
Effect of comonomer sorption on radiation‐induced copolymer grafting onto polyethylene and EVA films in the vapor phase
Authors: Yamakita Hiromi , Hayakawa Kiyoshi 
Published: April 2003

AbstractRadiation‐induced copolymer grafting of acenaphthylene and maleic anhydride onto polyethylene or EVA film in the vapor phase was carried out and the effect of comonomer sorption on the grafting was studied. When polyethylene film was used as a backbone polymer, the sorption of the binary monomers during the grafting increased linearly as the grafting reaction proceeded. The marked increase was probably caused by the formation of a grafted layer. Particularly, the sorption of maleic anhydride was brought about by the existence of a grafted layer. In grafting onto EVA film, the content of maleic anhddride in the grafted copolymer increased with the increasing content of vinyl acetate in EVA. Continuous measurements of sorption of the comonomers onto EVA and grafted EVA films were carried out by use of an electrobalance. The distinctive feature of the sorption was that the equilibrium sorption of acenaphthylene or maleic anhydride onto the grafted EVA film increased and the diffusion constants for both comonomers decreased markedly with increasing percentage of graft. The copolymer grafting was explained from these results by assuming that the monomer molecules are supplied to the propagating chain ends mostly through a sorbed state on the polymer film.
Preparation of copolymer of acetylene and butadiene
Authors: Furukawa Junji , Kawagoe Takahiro , Kobayashi Eiichi 
Published: April 2003

AbstractConditions for preparation of acetylene–butadiene random copolymers were investigated. Only a combination of organonickel compound and dialkylaluminum halide was able to copolymerize acetylene and butadiene to give soluble, linear, random copolymers in high yield. Toluene and xylene were the preferred solvents for the copolymerization. The catalyst activity and copolymer composition were influenced by the Al/Ni molar ratio, polymerization temperature, polymerization time, and conditions of preparation of catalyst.
Acceleration effect of poly(vinylpyrrolidone) on williamson reaction. II. Studies on the dissociation of sodium phenoxide in the presence of poly(vinylpyrrolidone)
Authors: Yamazaki Noboru , Hirao Akira , Nakahama Seiichi 
Published: April 2003

AbstractIn connection with the accelerating effect of poly(N‐vinylpyrrolidone) (PVP) on a Williamson reaction, PhONa + NC4H9Br → PhO‐(n‐C4H9) + NaBr, the ionic dissociation of sodium phenoxide (PhONa) was studied by means of conductance measurements and ultraviolet spectroscopy. Results suggest that the degree of dissociation of PhONa increased with the amount of PVP as well as N‐methylpyrrolidone (NMP), the monomeric analog, the effect of PVP being much larger than that of NMP at the same concentration. It is assumed that free phenolate anion produced by solvation of sodium cation with NMP or the pyrrolidone residues of PVP plays an important role in the acceleration of the reaction and that the higher reaction rates in PVP solution are due to the greater dissociation of PhONa.
Chemical behavior of optically active poly[thio 1‐(N,N‐disubstituted aminomethyl) ethylenes] in CuCl2‐methanol mixtures: Induced optical activity of bound Cu(II)
Authors: Huguet Jovanka , Vert Michel 
Published: April 2003

Abstract(+)‐Poly[thio 1‐(N‐sec‐butyl‐N‐methylaminomethyl) ethylene] (I) and (‐)‐poly[thio 1‐(N‐methyl‐N‐(1‐phenylethyl)aminomethyl) ethylene] (II) are soluble in methanol or in a 10/90 dioxane‐methanol mixture in the presence of CuCl2. This salting‐in effect results from interactions between macromolecules and this salt. With a large excess of salt (molar ratio > 8) a precipitate is obtained whose composition is close to a CuCl2:monomer unit ratio of unity. Ultraviolet, optical rotatory dispersion (ORD) and circular dichroism (CD) spectra in solution are described. The three extrinsic Cotton effects observed between 300 and 800 nm are assigned to charge transfer and d‐d electronic transitions of Cu(II) complexed with the macromolecules. In the same solvent system, Cu(II) shows similar induced optical activity in the presence of a nonaminated homolog, (+)‐poly(propylene sulfide) taken as a model of the chains of I and II. No extrinsic Cotton effects are observed in the presence of an optically active tertiary amine without the thioether sulfur atom, (+)‐N‐sec‐butyl‐N‐methyl‐N‐(oxirane‐2‐ylmethyl)amine. It is concluded that Cu(II) gives rise to charge‐transfer complexes with sulfur atoms, while tertiary amine groups are probably protonated in this particular medium.
Radiation‐induced polymerization of acrylic acid in aqueous solution
Authors: Huglin M. B. , Johnson B. L. , Richards R. W. 
Published: April 2003

AbstractAqueous acrylic acid in the presence of cupric chloride has been subjected to γ‐irradiation under various reaction conditions and the molecular weights of the resultant poly(acrylic acid) measured. The results, taken in conjunction with previous findings on the dependence of the rate of polymerization on intensity, monomer concentration, and cupric chloride concentration, indicate chain termination solely by cupric ion (rate constant ktCu) and chain transfer to polymer (rate constant kf). Values have been obtained for ktCu/kp, kf/kp and G(radical) of acrylic acid. On the basis of these data a theoretical chain‐length distribution has been derived which agrees well with distribution measured by gel‐permeation chromatography.
Effect of valence state of vanadium on stereoblock polymerization of methyl methacrylate with VOCl3–AlEt2Br catalyst system
Authors: Gandhi V. G. , Deshpande A. B. , Kapur S. L. 
Published: April 2003

AbstractThe polymerization of methyl methacrylate with the VOCL3–ALEt2Br catalyst system in n‐hexane has been studied. The first‐order dependence of rate of polymerization on catalyst and monomer concentrations, activation energy of 6.67 kcal/mole, and NMR spectra of polymer lend support to a coordinate anionic mechanism of polymerization. It has been shown that the vanadium in V+2 oxidation state is less active than V+3 oxidation state of active complex.
Stereoregularity of poly(2‐vinylpyridine) determined by 1H‐NMR and 13C‐NMR spectroscopy
Authors: Matsuzaki Kei , Kanai Taiichi , Matsubara Tetsuyuki , Matsumoto Susumu 
Published: April 2003

AbstractIn order to determine the stereoregularity of poly(2‐vinylpyridine), 2‐vinylpyridine‐β,β‐d2 was synthesized. The 1H‐NMR spectra of the deuterated polymer in D2SO4 and o‐dichlorobenzene solutions showed three peaks, which were assigned to triad tacticities. Since the absorptions of heterotactic and syndiotactic triads of methine protons overlap those of methylene protons in nondeuterated polymers, only isotactic triad intensities can be obtained from the 1H‐NMR spectra of nondeuterated poly(2‐vinylpyridine). The 13C‐NMR spectra of poly(2‐vinylpyridine) were obtained in methanol and sulfuric acid solutions. In methanol solution the absorption was split into three groups, which cannot be explained by triads, and in sulfuric acid solution several peaks were observed. These splittings may be due to pentad tacticity. The results show that poly(2‐vinylpyridine) obtained by radical polymerization is an atactic polymer.
Determination of the heat of fusion of isotactic poly(methyl methacrylate)
Authors: Kusy R. P. 
Published: April 2003

AbstractThe heat of fusion (ΔHu) of isotactic poly(methyl methacrylate) (PMMA) was determined from the combined linear regression analysis of x‐ray diffraction data and differential scanning calorimetry. By means of two sample preparation techniques to reduce crystallinity, a thermal pretreatment in which a partial melt and quench cycle was utilized, and a mechanical mixture in which a semicrystalline and amorphous material were blended, a value for ΔHu = 1200 ± 80 cal/mole (100 g) was found. The present result represents the first measurement of ΔHu for an acrylic polymer and yields G(‐units) = 12 from cryoscopic measurements for the chemical changes caused by high energy irradiation.
Applications of ESCA to polymer chemistry. XI. Core and valence energy levels of a series of polymethacrylates
Authors: Clark D. T. , Thomas H. R. 
Published: April 2003

AbstractThe core and valence energy levels of a series of poly(alkyl methacrylates) have been studied by ESCA. Surface compositions have been determined both from a comparison of area ratios for the O1s and C1s core levels and from the relative areas for the individual component peaks for these levels. The evidence presented suggests that on the ESCA depth‐profiling scale the technique statistically samples the repeat unit with little or no evidence for preferential orientation of the alkyl side chain at the surface. Little evidence was found for either surface oxidation or hydrocarbon contamination at the surface of the samples studied. The valence energy levels are shown to be characteristic of the polymer system.
Relationship between kinetic chain length and radical polymerization rate
Authors: Ito Katsukiyo 
Published: April 2003

AbstractIn the copolymerization of monomers M1 and M2 which form polymer radicals of chain length n of N1n with electron on a M1 type and N2n with one on a M2 type, it is assumed that the specific rates of termination between N1n and N1n and N1s, N1n and N2s, and N2n and N2s are kα(ns)−a, kβ(ns)−a, and kγ(ns)−a, respectively, where kα, kβ, and kγ are the rate constants of reaction between segment radicals in the respective termination, and a is constant. The relation between kinetic chain length n̄ and polymerization rate Rp is derived as: 1/n̄ = 1/n̄0 + const. (Rp)A(a), where n̄0 is the kinetic chain length of the polymer formed by transfer and A (a) is unity (predominance of transfer) and 1/(1–2a) (no transfer). In the copolymerization between methyl methacrylate (M1) and styrene (M2) at 60°C, when Rp → 0, kr12/k12 + kr21/k21 = 5.9× 10−5 is obtained, where kr12 and kr21 are the rate constants of transfer of N1 to M2 and N2 to M1, and k12 and k21 are the rate constants of propagation of N1 to M2 and N2 to M1. In the absence of transfer, the a value is found to be 0.065 ± 0.008, from the relation between n̄ and Rp, regardless of the monomer composition. Such a value is also estimated by setting b = 0.72 in a = 0.153 (2b–1), where b is the constant in the Mark‐Houwink equation. Further, the value of kβ is found to be 1.18 × 109l./mole‐sec, which is comparable with the diffusion‐controlled rate of reaction between small molecules. The rate of reaction between segment radicals is fivefold larger than the polymer‐polymer termination when transfer predominates.
Bonding between Cu(II) complexes with celluloses and related carbohydrates
Authors: Elsabee Maher Zaki , Mattar Saba Mitri , Habashy Gabriel Mikhail 
Published: April 2003

AbstractThe electron paramagnetic resonance spectra of cupriethylenediamine dihydroxide and cupriammonium hydroxide when complexed with cellulose, hydrocellulose, maltose, and dextrose at −160°C and at room temperature are reported. The spectra of the complexes formed indicate that the interaction is not physical but a chemical one, and the covalent character of the copper ligand has become comparatively weaker. The possibility of weak axial interaction for these complexes is shown to be unlikely, and it is proved that the nature of the interaction is a strong chemical bond between the copper and the 2,3‐hydroxyl groups of the pyranoside ring of the ligand.
Structure of poly(maleic anhydride)
Authors: Bacskai R. 
Published: April 2003

AbstractThe bulk polymerization of maleic anhydride initiated with acylperoxides, di‐tert‐butyl peroxide, AIBN, or pyridine proceeds with evolution of CO2. The amount of CO2 generated depends on the nature and the concentration of the initiator. With peroxide initiators, less than 5% of the polymerized maleic anhydride is decarboxylated. 1H‐NMR spectra, obtained on the benzoyl peroxide‐initiated polymer and its methyl ester, are consistent with the unrearranged poly(maleic anhydride) structure and rule out the polycyclopentanone structure proposed by Braun and co‐workers. Base‐initiated polymaleic anhydride is substantially decarboxylated, and the resulting polymer has anhydride and carboxyl groups. Elemental analyses and 1H‐NMR spectra obtained on the pyridine‐initiated polymer and its methyl ester refute both the cis‐poly(vinylene ketoanhydride) structure suggested by Schopov and the polycylopentanone structure proposed by Braun and co‐workers.
Degradation of polymer mixtures. VIII. Blends of poly(vinyl acetate) with poly(methyl methacrylate)
Authors: Jamieson A. , McNeill I. C. 
Published: April 2003

AbstractThe degradation of blends of PVA and PMMA in the form of films cast from a common solution of the polymers has been studied by TVA, TG, and EGA (evolved gas analysis) for acetic acid. Volatile degradation products have been characterized by spectroscopic and GLC techniques. Molecular weight, spectral and thermal stability changes in PMMA extracted from partially degraded blends have been examined. These blends behave in a closely analogous manner to PVC‐PMMA blends already investigated. The results suggest that the PMMA component of the heterogeneous blends is modified in two ways: (1) in a destabilization reaction series initiated by attack of acetate radicals generated in the PVA phase which migrate into the PMMA phase, and (2) in a stabilization reaction involving conversion of ester side groups to acid and subsequently to anhydride ring structures which act as blocking points for depolymerization. The rate of acetic acid production in the blend is less than in PVA degraded alone. The mechanism of degradation of PVA is reconsidered in the light of these results.
Synthesis of block copolymers by sequential carbenium ion polymerization
Authors: Rooney J. M. , Squire D. R. , Stannett V. T. 
Published: April 2003

AbstractThe sequential carbenium ion block copolymerization of ethyl vinyl ether (EVE) and isobutyl vinyl ether (IBVE) with N‐vinylcarbazole (NVC) is described. Requisite conditions for the successful application of the sequential synthesis technique to these systems were established: (1) the use of stable carbocation initiator salts (e.g., Ph3CSbCl6) which lead to essentially terminationless polymerizations; (2) low solvent‐to‐monomer ratios in order to suppress any possible chain transfer to methylene dichloride molecules; (3) high ratios of initiator to monomer which create a pseudo‐“living” system. The block products (PEVE‐b‐PNVC and PIBVE‐b‐PNVC) were isolated by precipitation and extraction. The intrinsic viscosities of these products displayed minima at 30°C.
Significance of oligomerization reactions in the transesterification of dimethyl terephthalate with ethylene glycol
Authors: Yamanis John , Adelman Maurice 
Published: April 2003

AbstractExperimental investigations dealing with and mathematical models proposed for the kinetics of the transesterification of dimethyl terephthalate with ethylene glycol were critically reviewed. The models were found to be inadequate, while the investigations were found to be entirely lacking in information about the significance of oligomerization reactions. The significance of these reactions was deduced to be negligible by carrying out an analysis of the kinetics of possible ester interchange and transesterification reactions by use of data on methanol reported in the reviewed literature. This analysis was made possible by the application of numerical quadrature routines in testing the assumed models by the integral method.
Two models for the kinetics of the transesterification of dimethyl terephthalate with ethylene glycol
Authors: Yamanis John , Adelman Maurice 
Published: April 2003

AbstractThe present work shows that two models assumed for the kinetics of the transesterification of dimethyl terephthalate (DMT) with ethylene glycol adequately describe the kinetics of this system. The models were derived by considering only monomer ester intercharge reactions and were tested using methanol data from the literature. One model was obtained from a series‐parallel reaction system while the other from an assumed reaction between a methyl ester group with ethyiene glycol. The two models are equally good up to 88% conversion of methyl ester groups but the first is more comprehensive and perhaps more realistic than the second.
Polymerization of coordinated monomers. XIII. Binding in the ternary molecular complex composed of γ‐crotonolactone, styrene, and stannic chloride
Authors: Kcmiyama Makoto , Hirai Hidefumi 
Published: April 2003

AbstractThe time‐averaged orientation of the styrene molecule in the ternary molecular complex composed of stannic chloride, γ‐crotonolactone, and styrene is determined by use of 1H‐chemical shifts of the nonequivalent protons of the γ‐crotonolactone. The chemical shift change for each of the various protons of the γ‐crotonolactone on the ternary molecular complex formation can be represented by the anisotropic shielding effect of the benzene ring of one oriented styrene molecule. This fact indicates that the ternary molecular complex has a definite time‐averaged conformation, though the “complexing” styrene molecule exchanges between in the oriented state and in the free state more rapidly than the time scale of the 1H‐NMR spectrometry. The magnitudes of the Coulomb, induction, dispersion, charge‐transfer, and exchange‐repulsion energies between the γ‐crotonolactone and the styrene in the ternary molecular complex are estimated by use of the result of the extended Hückel calculation and that of absorption spectrometry. The Coulomb and dispersion forces between the carboryl group of the coordinated γ‐crotonolactone and the benzene ring of the styrene function mainly in the ternary molecular complex formation. Both the induction force and the charge‐transfer force make a small contribution to the ternary molecular complex formation.