bluuebunny/crossref_metadata_2025 huggingface dataset:
Eine quantitative, UV‐photometrische bestimmung von Endgruppen in polystyrolen
Authors: Kämmerer H. , Sextro G. , Seyed‐Mozaffari Ahmad
Published: April 2003

Styrene was polymerized in bulk for 45 min at 70°C under a nitrogen atmosphere to a conversion of 6.16 weight‐percent with an aliphatic azo compound, which contained four p‐methoxyphenyl groups per molecule. The polystyrene could be purified easily by column chromatography and was then free of initiator and its decomposing products. It was separated into ten fractions by fractional precipitation (toluene/methanol), and the molecular weights of the polystyrenes were determined osmotically. The ultraviolet absorptions of the polystyrene solutions in dioxane were optically constant and followed the Bouguer‐Lambert‐Beer law. This made it possible to determine the number of absorbing groups per polystyrene molecule, which were constant with a value of 2. Polystyrenes with a number average molecular weight to 106 should be determinable in the same way.
Linear polythioesters. I. Products of interfacial polycondensation of 4,4′‐di(mercaptomethyl)benzophenone with terephthaloyl, isophthaloyl, and phthaloyl chlorides
Authors: Podkoscielny Wawrzyniec , Kultys Anna
Published: April 2003

New polythioesters have been obtained in the interfacial polycondensation of 4,4′‐di(mercaptomethyl)benzophenone with terephthaloyl, isophthaloyl and phthaloyl chlorides. The reactions were carried out at room temperature with the use of 10% excess of acid chloride per mole of mercaptan with vigorous stirring (2000 rpm). The organic phase was composed of benzene and hexane in equal volumes and the ratio of this mixture to water also was 1:1. The structure of the polythioesters was determined from elementary analysis and the infrared spectra. The molecular weight was not determined because of the very low solubility of polythioesters. Some thermal, mechanical, and electrical properties of the products have been determined. Products of dimercaptan with the terephthaloyl and isophthaloyl chlorides show the best properties.
Cationic polymerization of vinyl monomers initiated by phosphorus compounds containing halogens
Authors: Taninaka Takumi , Minoura Yuji
Published: April 2003

Polymerization of vinyl monomers having large negative e values in the presence of phosphorus compounds containing halogens was studied in order to examine the cationic initiation ability of phosphorus compounds. N‐Vinylcarbazole was effectively polymerized by phosphorus compounds such as PCI3, PBr3, PCI2C6H5, PCI(C6H5)2, POCI3, and POCI2C6H5 even in benzene. The initiation ability of phosphorus compounds decreased in the order; PCI2 ≃ PBr3 > PCI2C6H5 > PCI(C6H5)2, and also POCI3 > POCI265. On the other hand, PCI3 and PBr3, which were less effective than POCI3, showed initiation ability for the polymerizations of styrene and α‐methylstyrene in nitrobenzene as a solvent. The results of the copolymerization of styrene with methyl methacrylate by PCI3 in nitrobenzene, the result of solvent dielectric constant effect, and the effect of additives such as water, tert‐butyl chloride, triethylamine, and hydroquinone, indicate the polymerization of styrene by PCI3 to proceed by a cationic mechanism.
Studies on the thickening reaction of polyester resins employed in sheet molding compounds
Authors: Gandhi K. S. , Burns R.
Published: April 2003

The mechanism of the thickening reaction between alkaline earth metal oxides and acid group‐terminated polyester resins was studied. The thickening can occur either by the increase in molecular weight of the resin through neutral salt formation or by complex formation between the basic salt and carbonyl oxygens. Simultaneous analysis of reacted resins for moisture content by near infrared spectroscopy and metal content by atomic spectroscopy was carried out to differentiate between the two possibilities. It was established that the amount of basic salt present in the reaction mixtures was small and hence the thickening appears to be due to neutral salt formation. The neutral salt formation reaction, being similar to condensation polymerization, could be modelled to predict the course of the thickening process as a function of time. A model proposed hypothesizes the thickening process to be heterogeneous in nature and to occur in a sequence of three steps: diffusion of metal oxide into the resin, reaction of the dissolved metal oxide with the resin to form the basic salt, and the further reaction of the basic salt with the resin to form the neutral salt. The model predicts all the observed features of the thickening process qualitatively. Further, quantitative agreement was obtained between experimental data and the theoretical predictions of plateau viscosities and in several aspects of the kinetics of the thickening process.
Reaction of poly(vinylbenzyl chloride) with various phenolic derivatives
Authors: Cohen H. L.
Published: April 2003

Poly(vinylbenzyl chloride) reacts with phenolic derivatives in the presence of Lewis acids to give the corresponding polymeric benzylated derivatives.
Spatially intermittent polymerization
Authors: O'Driscoll K. F. , Mahabadi H. K.
Published: April 2003

A novel reactor has been designed which permits the precise determination of absolute rate constants in photoinitiated free‐radical vinyl polymerization. A solution of monomer and initiator flows through a dark tubular reactor past regularly spaced slots through which light shines. The alternating dark and light regions produce spatially intermittent polymerization (SIP) and make the system analogous to the well‐known rotating‐sector technique. However, the SIP reactor has the advantage of producing large volumes of reaction product, at low conversion, suitable for analysis of both conversion and molecular weight. This supplies the necessary data, from a single set of experiments, for the simultaneous determination of the rate constants for propagation and termination. Experimental data are reported at 25°C for methyl methacrylate which indicate that kp = 315 I./mole‐sec, independent of polymer molecular weight, and kt is dependent on molecular weight especially at low molecular weight, approaching a lower value of kt = 30 × 106 I./mole‐sec at a molecular weight of 106. For styrene, measurements being made only at high molecular weight, kp = 74 ± 5 and kt = 37 ± 0.3 × 106 l./mole‐sec at 25°C.
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

The 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

Homopolymers 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

To 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

Ionic 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

4‐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

Radiation‐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

Conditions 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

In 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

(+)‐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

Aqueous 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

The 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

In 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

The 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

The 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

In 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

The 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

The 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

The 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

The 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

Experimental 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

The 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

The 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.
Kinetics of two‐phase bulk polymerization. II. The influence of dissolved polymer
Authors: Ludwico W. A. , Rosen S. L.
Published: April 2003

The effect of dissolved polybutadiene on the initial rate of polymerization of styrene was investigated by using high‐precision dilatometric techniques. The dissolved polymer reduced the rate of polymerization by amounts greater than can be accounted for by a reduction in monomer concentration. Rate reductions increased with the amount of dissolved polybutadiene and with its molecular weight and were greater for benzoyl peroxide initiator than for equal concentrations of azobisisobutyronitrile. Surprisingly, analogous rate reductions were observed when polystyrene were substituted for the polybutadienes, except that at high polystyrene concentrations, the expected autoacceleration was observed. These rate reductions showed no correlation with the viscosity of the reaction mass, nor did the dissolved polymer affect initiator efficiency. At a given level of a particular dissolved polybutadiene, rate reductions were diminished by increasing levels of each initiator, and by adding a chain‐transfer agent. Good quantitative agreement was obtained with the number‐average length of the growing polymer chains, whether varied by using different initiators, changing initiator level, or adding chain‐transfer agent. These results are inconsistent with a chemical mechanism, but they are explained by a proposal originated by North and Reed whereby the dissolved polymer makes the reaction mass a “poorer” solvent for the growing polymer chains, reducing their overall coil dimensions and enhancing their rate of diffusion together for termination.
Acidic dehydration as an analytical method for evaluating ethylene oxide–propylene oxide copolymers
Authors: Cervenka A. , Merrall G. T.
Published: April 2003

Acidic dehydration by p‐toluenesulfonic acid at 250°C converts poly(alkylene oxides) into dioxane derivatives which can be separated by gas–liquid chromatography. This procedure has been developed as an analytical technique for characterizing some aspects of the molecular structure of polymers of ethylene and propylene oxides. Experimental data on homopolymers, their blends, and some model copolymers have shown that the method is capable of distinguishing between copolymers of different structures, giving correct overall comonomer contents and also ranking copolymers according to their degrees of blockiness.
Cationic polymerization of p‐substituted α‐methylstyrenes. III. Effect of polymerization conditions on tacticity and molecular weight for p‐chloro‐α‐methylstyrene
Authors: Lenz Robert W. , Westfelt Lars C.
Published: April 2003

The cationic polymerization of p‐chloro‐α‐methylstyrene was investigated for the effect of initiator and solvent on polymer tacticity, molecular weight, and molecular weight distribution. The products were generally crystalline polymers of 80–90% syndiotactic content with fairly high molecular weights and broad molecular weight distributions. Tacticities and molecular weight distributions followed similar patterns suggesting that the effect of reaction conditions on ionpair end‐group structures was the dominant factor.
Mechanism of thermal decomposition of peroxide radicals formed in polytetrafluoroethylene by γ‐ray irradiation
Authors: Hagiwara Miyuki , Tagawa Toru , Amemiya Hideo , Araki Kunio , Shinohara Isao , Kagiya Tsutomu
Published: April 2003

Thermal decomposition of polymer peroxide radicals formed in γ‐irradiated polytetrafluoroethylene, ∼CF2CF(OO·)CF2∼ (radical I) and ∼CF2CF2(OO∼) (radical II), was studied by mass spectral analysis of the gas evolved in comparison with their photolysis with ultraviolet light. In the thermal decomposition of radicals I and II, CO2 was the most abundant component, with smaller amount of CO, CF2O, and gases present. In the photolysis, CO instead of CO2 was the most abundant in the case of radical I, while in the case of radical II, CO2 was again the main product. When a labeled polymer peroxide radical, ∼CF2CF(18O‐18O·)CF2∼, was treated with heat or ultraviolet light, C18O16O was detected as a main component. In the treatment with ultraviolet light, a large amount of C18O comparable to that of C18O16O was also obtained. The mechanism of main‐chain scission of radicals I and II is discussed.
Effects of the acid chain length and copolymer crosslinking on the acylation of N‐hydroxysuccinimide copolymers with carbobenzoxyoligo‐ϵ‐aminocaproic acids
Authors: Akiyama M. , Narita M. , Seida K. , Osawa T.
Published: April 2003

N‐Hydroxysuccinimide‐type soluble copolymer with styrene and three similar divinylbenzene (3–4 mole‐%) crosslinked copolymers with styrene, N‐vinylpyrrolidone, and N,N‐dimethylacrylamide were prepared from their precursor copolymers of N‐acetoxymaleimide. Acylation of these N‐hydroxyl polymers with carbobenzoxyoligo‐ϵ‐aminocaproic acids was conducted in dimethylformamide at room temperature by using dicyclohexylcarbodiimide as condensing agent. The soluble styrene copolymer was acylated in good conversions (76–89%) in every case (n = 1–3), whereas the acylation of the crosslinked copolymers decreased slightly from n = 1 to n = 2, and dropped suddenly to only small conversions (4.7–7.4%) with n = 3, showing a marked inhibitory effect of crosslinking when the acids became longer. The effect of the microenvironment of the polymer did not appear significant. All the acyl polymers, including the precursor polymers, yielded the corresponding cyclohexylamides when treated with cyclohexylamine.
Synthesis and structure of the p‐hydroxybenzoic acid polymer
Authors: Economy James , Storm R. S. , Matkovich V. I. , Cottis S. G. , Nowak B. E.
Published: April 2003

The synthesis and structure of the p‐hydroxybenzoic acid polymer is described. The polymer was successfully prepared from either the phenyl ester of p‐hydroxybenzoic acid or from p‐acetoxybenzoic acid. With highly purified acetoxybenzoic acid, single crystals of the polymer could be prepared. The structure of the polymer was determined and shown to consist of a double helix where the two chains are in a reversed head‐to‐tail order. The unit cell dimensions are: a = 17.8 Å and c = 18.4 Å, where c corresponds to the chain length with a repeat distance of three units. The mechanism of polymerization and formation of the single crystal is discussed. The polymer displays a reversible high‐temperature crystalline transition at 325–360°C (not a melting point). The transition was characterized by differential thermal analysis, differential calorimetry, thermal expansion coefficient measurements, high‐temperature x‐ray scans, and dielectric constant determinations. Orientation of the polymer chains during fabrication and changes in the mechanism of oxidative degradation above the crystal transition are described.
Glass transition temperature of low molecular weight styrene–isoprene block copolymers
Authors: Toporowski P. M. , Roovers J. E. L.
Published: April 2003

Different series of poly(styrene–isoprene) diblock and poly(styrene–isoprene–styrene) triblock copolymers were prepared. In each series, the low molecular weight polystyrene block was kept constant, and the molecular weight of the polyisoprene block varied. The glass transition behavior of these polymers was studied and their glass transition temperatures compared with those of the random copolymers of styrene and isoprene. It is concluded that some low molecular weight styrene‐isoprene block copolymers form a single phase. Krause's thermodynamic treatment of phase separation in block copolymers was applied to the data. One arrives at a polystyrene–polyisoprene interaction parameter χ1,2 ≈ 0.1. The experimental and theoretical limitations of this result are discussed.
Studies of methyl methacrylate–glycidyl methacrylate copolymers: Copolymerization to low molecular weights and modification by ring‐opening reaction of epoxy side groups
Authors: Paul Swaraj , Rånby Bengt
Published: April 2003

The copolymerization of methyl methacrylate (MMA) with glycidyl methacrylate (GMA) at 60°C with 2,2′‐azobisisobutyronitrile (AIBN) as radical initiator and in the presence of thiophenol (TP) as chain‐transfer agent has been investigated. Monomer reactivity ratios for MMA and GMA are found to be r1 (MMA) = 0.80 ± 0.015 and r2 (GMA) = 0.70 ± 0.015, from which Q and e values are calculated to be 0.68 and −0.36 for GMA. The initial rate of copolymerization Rp at 60°C with AIBN (0.02 mole/l.) and TP (0.1, 0.01 mole/l.) were found to increase nonlinearly with increasing GMA concentration in the monomer feed. Homopolymerizations of MMA and GMA monomers were studied in the presence and in the absence of thiophenol. The values of δ (= kt1/2/kp) for MMA and GMA were determined to be 10.25 and 3.00 (mole‐sec/l.)1/2, respectively. Using the values r1 (MMA), r2 (GMA), δ1 (MMA), δ2 (GMA), and Rp, the cross‐termination constants ϕ for MMA–GMA monomers were determined (average value ϕ = 0.42). The increase in Rp values with increasing GMA content has been attributed to the cross‐termination of MMA–GMA radicals. The transfer constant of TP has also been determined for GMA and found to be 1.00. A MMA–GMA copolymer of low molecular weight, containing 2.01% of oxirane oxygen, was modified by opening of the oxirane ring of GMA by reaction with diethanolamine (DEA). The reaction was carried out at 70 ± 1°C, the copolymer content of epoxy groups and the amine being assumed to be in the molar ratio of 1:4. Addition of a hydrogen‐bond acceptor like nitrobenzene decreases, while addition of a hydrogen‐bond donor like phenol increases the rate of epoxy ring opening with DEA. This indicates that a hydrogen‐bonded intermediate is involved in this reaction and that it weakens the epoxy ring and enhances the rate of its opening with DEA. From the studies of the conversion rates, existence of a “nonspecific” side reaction has been shown which involves the reaction of the terminal epoxy groups of the copolymer and the hydroxyl groups of DEA or formed in the reaction with DEA (involves a chain coupling). DEA can be trifunctional in this reaction. This has been further confirmed from the increase of number‐average molecular weights M̄n of the copolymers resulting from this coupling and the nitrogen content in the copolymers after modification with DEA.
Cyclic acetal‐photosensitized polymerization. II. Photopolymerization of styrene in the presence of various monocyclic acetals
Authors: Ouchi Tatsuro , Hamada Masao
Published: April 2003

The polymerization of styrene (St) in benzene solution in the presence of 1,3‐dioxane (DON), 1,3‐dioxepane (DOP), trioxane (TRON), or tetraoxane (TEON) by means of photoirradiation of the system at 40°C has been studied kinetically from the standpoint of photosensitized polymerization. The rate of photosensitized polymerization Rp increased in the order: DOP < DON < TRON < TEON, as shown by the rate constant of decomposition of cyclic acetals, and then could be expressed by Rp = k[monocyclic acetal]0.5[St]1.0. The polymerization was confirmed to proceed via a radical mechanism.
Preparation of block copolymers from occluded vinyl acetate macroradicals
Authors: Seymour Raymond B. , Stahl G. Allan
Published: April 2003

Stable vinyl acetate macroradicals were produced by polymerization in a nonviscous poor solvent, a viscous good solvent and a viscous poor solvent. These macroradicals were then allowed to react with a second vinyl monomer to produce block copolymers. The formation of block copolymers was monitored for rate and yield data. The block copolymers produced were poly(vinyl acetate‐b‐methyl methacrylate), poly(vinyl acetate‐b‐acrylic acid), poly(vinyl acetate‐b‐vinylpyrrolidone), poly(vinyl acetate‐b‐acrylonitrile), poly(vinyl acetate‐b‐styrene), and poly(vinyl acetate‐b‐methyl acrylate). The block copolymers were characterized by yield, precipitation in selected solvents, pyrolysis gas chromatography, and differential scanning calorimetry.
The nature of active centers of a polymeric catalase analog
Authors: Pshezhetskyǐ V. S. , Ikryannikov S. G. , Kuznetsova T. A. , Kabanov V. A.
Published: April 2003

The decomposition of hydrogen peroxide by a polymer complex of Fe3+ and poly(acrylic acid) partially amidated by diethylenetriamine has been studied. The molecular mechanism of catalysis is discussed. The rate constant of the reaction is k = 6.9 × 107 exp {−2.300/RT}. Decomposition of hydrogen peroxide proceeds via activation by the diethylenetriamine which is a cofactor.
Studies on propagating species in cationic polymerization of styrene derivatives by acetyl perchlorate or iodine. II. Salt effect on the relative reactivity in the cationic copolymerization of styrene derivatives with 2‐chloroethyl vinyl ether initiated by iodine
Authors: Yamamoto Kenji , Higashimura Toshinobu
Published: April 2003

To determine the effect of the dissociation of propagating species on the relative reactivity of monomers, 2‐chloroethyl vinyl ether was copolymerized with p‐methoxystyrene or with p‐methylstyrene by using iodine in various solvents at 0°C. A common‐ion salt (tetra‐n‐butylammonium iodide or tetra‐n‐butylammonium triiodide) was added to these copolymerization systems in a polar solvent to depress the dissociation of the propagating species. The addition of a common‐ion salt increased the vinyl ether content in the copolymer. The more the dissociation of propagating species was depressed, the more the vinyl ether content in the copolymer increased. This effect of common‐ion salt was in agreement with that of decreasing solvent polarity which yielded vinyl ether‐rich copolymer as well. Therefore, the change of the monomer reactivity ratio by the solvent polarity, which used to be explained in terms of a selective solvation, must be reconsidered from the viewpoint of varying degrees of the dissociation of propagating species.
Syntheses and properties of phosphorus‐containing copolyamides
Authors: Shalaby S. W. , Sifniades S. , Sheehan D.
Published: April 2003

Caprolactam was copolymerized with 1,5‐dioxo‐1‐methyl‐4‐azaphosphepane or methylphosphacaprolactam. The molecular weight of the resulting copolymers decreased with increasing concentration of the thermally labile phosphorus moieties. Copolymers based on ≥40% caprolactam were shown to be crystalline by differential scanning calorimetry and x‐ray techniques. As the concentration of the phosphorus structures in the copolymers increased, the glass transition and crystallization temperatures increased while the melting temperatures, crystallinities, and thermal stabilities decreased. Melt blends of nylon 6 and polymethylphosphacaprolactam were shown by differential scanning calorimetry, a selective extraction technique, and elemental analysis to contain appreciable amounts of block copolyamides, and no crystalline random structures were detected. The thermal stabilities of the melt blends were similar to those of random copolymers having comparable concentrations of the phosphorus‐containing sequences.
Solvent effects on the radiation‐induced graft polymerization of styrene onto poly(isobutylene oxide)
Authors: Omichi Hideki , Araki Kunio
Published: April 2003

The graft polymerization of styrene onto preirradiated poly(isobutylene oxide) (PIBO) with methanol and benzene was studied. The order of grafting yield and of the number‐average molecular weight of graft chains decrease in the order; undiluted styrene > styrene–methanol (1:1) solution > styrene–benzene (1:1) solution. A kinetic treatment to calculate rate constants from the rate of grafting and the molecular weight of the graft chain was proposed. The propagation rate constant kp was 0.2–0.3 l./mole‐sec and the termination rate constant kt was 1.0–16.0 l./mole‐sec. The ratio kp/kt in this heterogeneous system was larger than that in homogeneous system by a factor of about 104–105.
Para‐ordered polybenzimidazole
Authors: Kovar Robert F. , Arnold F. E.
Published: April 2003

A series of novel AB monomers such as 2‐[p‐carboxyphenyl]‐5,6‐diaminobenzimidazole hydrochloride have been synthesized. In addition, a new aromatic monomer, 1,3‐diamino‐4,6‐bis(p‐toluenesulfonamido)benzene has been prepared in high purity and substituted for 1,2,4,5‐tetraaminobenzene in a polymerization with terephthalic acid. Homopolymerization of the AB monomers, and polycondensation of monomer with terephthalic acid in polyphosphoric acid, produced the rod‐like para‐oriented polymer, poly[1,7‐dihydrobenzo(1,2‐d: 4,5‐d)diimidazole‐2,6‐diyl‐1,4‐phenylene]. The yellow polymer was completely soluble in methanesulfonic acid (MSA) and PPA, exhibiting intrinsic viscosities as high as 5 dl/g in MSA, and a blue opalescence in solution. Polymerization at temperatures above 225°C caused crystallization and subsequent precipitation to occur. Polymer thus obtained was completely insoluble in MSA and possessed a high degree of crystallinity as demonstrated by x‐ray analysis.
Photodegradation of polyacetaldehyde in solution. I. Direct photolysis
Authors: Marsh Dana G.
Published: April 2003

The quantum yields measured for the random scission of main‐chain bonds of polyacetaldehyde in benzene solution by 254 nm irradiation at 298°K are on the order of 10−3–10−4 scissions per quantum absorbed by the polymer. The quantum yields are unaffected by oxygen but are dependent upon initial polymer concentration and upon the inverse square root of absorbed light intensity. The direct photochemistry involves excitation of carbonyl chromophores in their 1nπ* bands, and a Norrish type I process is believed to be responsible for subsequent free‐radical random‐chain scissions. It has been established that direct photoexcitation processes do not lead to sequential depolymerization of polyacetaldehyde to monomer.
Sulfur‐containing polymers. XVIII. Preparation and properties of thiuram polysulfide polymers
Authors: Kobayashi Norio , Osawa Akiko , Kimoto Hisao , Hayashi Yasuo , Shimizu Kiwako , Fujisawa Tamotsu
Published: April 2003

Thiuram polysulfide polymers have been prepared from alkali metal bisdithiocarbamates either by oxidation with ammonium persulfate or by polycondensation with sulfur chlorides. In some cases, isothiocyanate formation and/or thiourea formation were noticed. The polymer properties were significantly affected by the diamines used. Polymers derived from p‐phenylenediamine decomposed gradually at room temperature with the liberation of elemental sulfur. Polymers based on aliphatic primary diamines were more stable. Piperazine gave the most stable polymer.