bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactivity of methacrylates in anionic copolymerization with methyl methacrylate by n‐BuLi
Authors: Yuki Heimei , Okamoto Yoshio , Ohta Koji , Hatada Koichi 
Published: April 2003

AbstractMonomer reactivity ratios, r1 and r2 were determined in the anionic copolymerizations of methyl methacrylate (MMA, M1) with ethyl (EtMA), isopropyl (i‐PrMA), tert‐butyl (t‐BuMA), benzyl (BzMA), α‐methylbenzyl (MBMA), diphenylmethyl (DPMMA), α,α‐dimethylbenzyl (DMBMA), and trityl (TrMA) methacrylates (M2) by use of n‐BuLi as an initiator in toluene and THF at ‐78°C. The order of the reactivity of the monomers towards MMA anion was DPMMA > BzMA > MMA > EtMA > MBMA > i‐PrMA > t‐BuMA > TrMA > DMBMA in toluene and TrMA > BzMA > MMA > DPMMA > EtMA > MBMA > i‐PrMA > DMBMA > t‐BuMA in THF. Except for the extremely low reactivity of TrMA and DPMMA in toluene due to steric hindrance, the order was explained in terms of the polar effect of the ester groups. A linear relationship was found between log (1/r1) and Taft's σ* values of the ester groups, where the ρ* value was 1.1. The plots of log (1/r1) vs. the 1Ha (cis to the carbonyl) and 13Cß chemical shifts of the monomers were also on straight lines. The polymer obtained in the copolymerization of MMA with TrMA in toluene by n‐BuLi at ‐78°C was a mixture of poly‐MMA and a copolymer, suggesting that there exist two kinds of growing centers.
Determination of the elementary rate constants of autoacceleration reactions on polymers
Authors: Stoy V. 
Published: April 2003

AbstractEquations describing the course of an autoacceleration reaction on a polymer in the low conversion region were derived and used to obtain relationships between the curvature of the conversion curve at the beginning and the elementary rate constants k1 and k′2. Calculations carried out by using our relationships are compared with the procedure suggested by Kawabe and Yanagita, and the applicability of the individual methods for the determination of the elementary rate constants is discussed.
Estimation of molecular weight distribution based on chain length dependence of termination rate
Authors: Ito Katsukiyo 
Published: April 2003

AbstractWhen a chain length dependence of polymer‐polymer termination is given by kt,ns = const. (n−2a + s−2a) where n and s are the chain lengths for the polymer radicals and a is parameter, an instantaneous weight fraction of the non‐reacting polymers is derived as:

where h and k̄ are the kinetic parameters, p is a parameter depending on a, and pn is instantaneous number‐average chain length. Such a weight fraction corresponds to the experimental one over a wide range of conversion in the polymerization of styrene. On the scope of this correspondence, the polymer‐polymer termination rate is estimated as: k̄t = 8πR0D1/100 ( = 4πRsDs) where R0 is reaction radius between monomer radicals and D1 is the diffusion coefficient of the monomer; Rs is reaction radius between segment radicals with n ≅ 100 and Ds is the diffusion coefficient of the segment. The Fujita‐Doolittle theory applies to such a rate. Further, the rate also yields 1.5 × 1071./mole‐sec, which is the observable extent at conversions less than 0.2.
Gel‐permeation chromatography: A procedure that corrects for imperfect resolution
Authors: Timm D. C. , Rachow J. W. 
Published: April 2003

AbstractGel‐permeation chromatography is an excellent tool for obtaining polymer fractionation data. Inasmuch as chromatograms are functions of instrument operating conditions, an interpretation procedure must be employed to yield correct molecular distributions of macromolecular materials. A procedure is described that corrects for imperfect resolution. Extensive experimental testing of polymeric materials with kinetically known molecular distributions demonstrates its validity in regions where poor resolution is experienced.Applications will allow one to utilize equipment with inherently poor resolution or to operate instruments with high resolution in regions of poor resolution (e.g., rapid analysis).
Effects of acids on vinyl polymerization initiated by chromous acetate‐alkyl halide
Authors: Lee Munam , Minoura Yuji 
Published: April 2003

AbstractEffects of various acids, i.e., acetic, chloroacetic, hydrochloric, and sulfuric acids on the polymerization of styrene initiated by Cr2+–CHCl3 in DMF was studied. These acids reduced the rates of polymerization by Cr2+–CHCl3 initiator systems. This phenomenon could be explained by a decrease of the reducing power of Cr2+ for alkyl halide. On the other hand, chloroacetic acids could initiate the polymerization of styrene without CHCl3 because these acids have active chlorine in the molecule for Cr2+. It was found that the polymer obtained by this initiator system had an endgroup containing chromium carboxylate, therefore this polymer was green in color and insoluble in benzene.
Interpolymer complex between poly(ethylene oxide) and poly(carboxylic acid)
Authors: Ikawa Takeo , Abe Koji , Honda Kenji , Tsuchida Eishun 
Published: April 2003

AbstractAn interpolymer complex was prepared by mixing aqueous solutions of poly(ethylene oxide) (PEO) and of a poly(carboxylic acid), i.e., poly(acrylic acid)(PAA), poly(methacrylic acid)(PMAA), or styrene‐maleic acid copolymer(PSMA). The complexation mechanism was discussed on the basis of results of such experimental methods as viscosity, potentiometric titration, and turbidimetry. The hydrogen bond is primarily involved in these complexations, but the influence of hydrophobic interaction on complexation can not be ignored. If the degree of dissociation α of carboxylic acid or the degree of polymerization Pn of PEO was perceptibly changed, a stable complex was obtained at about α 0.1 or Pn(PEO) = 40 for PMAA, 200 for PAA. This fact indicates that more than a definite number of binding sites are necessary for a stable interpolymer complex to be formed and that cooperative interaction among active sites plays an important role in complex formation.
Radiation‐induced polymerization of tetrafluoroethylene and 1,2,3,4,5‐pentafluorostyrene at high pressure
Authors: Brown Daniel W. , Lowry Robert E. 
Published: April 2003

AbstractTetrafluoroethylene (A) and 1,2,3,4,5‐pentafluorostyrene (B) were irradiated at 15°C at autogenous pressure by use of 30–92 mole‐% A and at 5000 atm by use of 42–99.9 mole‐% A. The high‐pressure results indicate that the reactivity ratio rA for monomer addition to A‐ended radicals is 0.005; the other reactivity ratio rB appears to vary from 15 to 60 generally increasing with the A content of the charge. At autogenous pressure rA is small, but a precise determination is not possible because of the very low polymerization rate when the A content of the charge is high. However, if rA is less than 0.01, then values of rB vary from 15 to 50, again generally increasing with the A content of the charge. Mixtures of A and B exhibit positive deviations from Raoult's Law. Activity coefficients were measured at autogeneous pressure and used in an attempt to correct rB for the nonideality of solution. The range of rB was reduced only slightly to 8–27, and charges with high A contents now generally gave low values of rB; consequently, this approach was not regarded as a success. Another attempt was made to account for the apparent variation in rB by ascribing influence to the penultimate units of the radicals. Improved agreement between theoretical and observed compositions resulted, but significant discrepancies remained unexplained. Rate data agreed well with those calculated from a theoretical copolymer rate equation using values of rA and rB of 0.0045 and 40, respectively. The equation predicts an almost proportional decrease in rate with increasing proportions of A in the charge from 0 to 99 mole‐% A.
Copolymerization of fluorinated acrylic monomers with p‐vinylphenol and hydroxyethyl methacrylate
Authors: Overberger C. G. , Sincich Eugene 
Published: April 2003

AbstractCopolymers of p‐vinylphenol were prepared in bulk with heptafluorobutyl and pentadecafluorooctyl acrylates and trifluoroethyl, hexafluoroisopropyl, heptafluorobutyl, octafluoropentyl and pentadecafluorooctyl methacrylates using azobisisobutyronitrile as the initiator in sealed tubes. Intrinsic viscosities of the copolymers ranged from 0.44 to 1.85. Monomer reactivity ratios for copolymers of trifluoroethyl methacrylate (M1) were: with hydroxyethyl methacrylate (M2), r1 = 0.47, r2 = 1.0; with methyl methacrylate (M2), r1 = 0.82, r2 = 0.50; with styrene (M2), r1 = 0.29, r2, = 0.20; and with p‐vinylphenol (M2), r1 = 0.096, r2 = 1.5. Q and e values of trifluoroethyl methacrylate were 1.30 and 0.92, respectively. Monomer reactivity ratios of octafluoropentyl methacrylate (M1) were: with styrene (M2), r1 = 0.26, r2 = 0.20; and with p‐vinylphenol, r1 = 0.21, r2 = 1.5. Q and e values for octafluoropentyl methacrylate were 1.27 and 0.92, respectively. Critical surface tensions of the homopolymers ranged from 17.9 to 14.8 dyn/cm. A copolymer of hexafluoro‐i‐propyl methacrylate and p‐vinylphenol exhibited a critical surface tension of 16.5 dyn/cm.
Synthesis of hydrophilic polyamide from L‐tartarate and diamines by active polycondensation
Authors: Ogata N. , Hosoda Y. 
Published: April 2003

AbstractDimethyl L‐tartarate underwent polycondensation reaction with hexamethylenediamine in solutions at 30°C to form polyamide having pendent hydroxyl groups. Solvents had a great influence on polymer yields and diglyme, tetrahydrofuran (THF) or dimethylsulfoxide (DMSO) were favorable in respect of polymer yields. Solution viscosities of resulting polyamide were as low as 0.1 to 0.2. However, post‐polycondensation of the precursor polyamide at solid phase yielded hydrophilic polyamide having film‐forming ability. The polyamide decomposed at 210°C by heating.
Polyimidothioether–polysulfide block polymers
Authors: Crivello James V. , Juliano Peter C. 
Published: April 2003

AbstractThe synthesis of a new class of block polymers that contain alternating polyimidothioether “hard” blocks and polysulfide elastomer “soft” blocks is described. Compositions with 70% and greater polysulfide component are solvent‐resistant, thermoplastic elastomers exhibiting room temperature tensile strengths of up to 1500 psi and ultimate elongations of nearly 800%. The physical properties are a strong function of test temperature due to relatively short polyimidothioether blocks, 850 ≤ M̄n≤ 3500 g/mole. These short polyimidothioether blocks were necessary to minimize degradation of the polysulfide elastomer blocks during thermal processing at temperatures ∼100°C above the “hard” block domainTg.
Radiation copolymerization of vinyl acetate with the diethyl esters of maleic and fumaric acids
Authors: Du Plessis T. A. , Schnautz N. G. , Lustig A. 
Published: April 2003

AbstractThe radiation‐induced copolymerization of vinyl acetate with diethyl maleate and with diethyl fumarate was investigated in the temperature range from −40 to 90°C over a wide range of comonomer compositions. Both the rates of copolymerization and the molecular weights of the resulting copolymers were found to depend strongly on the initial comonomer compositions. The apparent activation energy was found to change at 13°C with an increase in temperature from a value of 1.76 kcal/mole to a value of 4.31 kcal/mole in the copolymerization with diethyl maleate, while in the case of the copolymerization with diethyl fumarate the apparent activation energy changed at 21°C from a value of 1.76 kcal/mole to a value of 5.98 kcal/mole. Scavenger studies indicate that a free‐radical mechanism prevails over the entire temperature range investigated in the case of both copolymerizations.
Thermal cis–trans isomerization and decomposition of polyacetylene
Authors: Ito Takeo , Shirakawa Hideki , Ikeda Sakuji 
Published: April 2003

AbstractThermal cis‐trans isomerization and decomposition of polyacetylene film prepared with a Ti(OC4H9)4–Al(C2H5)3 (Al/Ti = 4) system were investigated under inert gas or in vacuum by means of thermal analysis and infrared spectroscopy. Thermograms of differential thermal analysis of cis‐polyacetylene revealed the existence of two exothermic peaks at 145 and 325°C and one endothermic peak at 420°C which were assigned to cis‐trans isomerization, hydrogen migration accompanied with crosslinking reaction, and thermal decomposition, respectively. The isomerization was followed by infrared spectroscopy over the temperature range 75–115°C. The reaction did not obey simple kinetics. The apparent activation energy for the cis‐trans isomerization was 17.0 kcal/mole for the polymer containing 88% cis configuration and increased with increasing trans content up to 38.8 kcal/mole for 80% trans content.
Hydroxamic acid polymers
Authors: Winston Anthony , Mazza Edward T. 
Published: April 2003

AbstractA polymer bearing hydroxamic acid groups and having a high affinity for iron(III) was prepared through the following procedure. Acryloylalanine (III), prepared by the reaction of acryloyl chloride with alanine, was treated with N‐hydroxysuccinimide in the presence of dicyclohexylcarbodiimide to give the N‐hydroxysuccinimide ester (IV). The ester IV was polymerized by using AIBN in dioxane to give polymer V. Treatment of polymer V with methylhydroxylamine in DMF gave the hydroxamic acid polymer II. The water‐soluble polymer II was purified by dialysis or by gel‐permeation chromatography (GPC) on Sephadex G‐25. Analytical GPC on Sephadex G‐200 and Sepharose 4B indicate that the average molecular weight of the polymer is in the range of 5 × 105 to 1 × 106. The presence of hydroxamic acid groups is confirmed by the intense red‐brown color produced by the addition of iron(III) to a 50% aqueous DMF solution of the polymer under acidic conditions. In pure water the polymer‐iron complex precipitates as a tan solid. Iron‐binding studies of the polymer reveal that the iron(III) trihydroxamic acid complex FeA3 forms at low concentrations of iron. At higher iron levels a lower order of stability is apparent, which can be accounted for by the conversion of FeA3 to FeA2+. In contrast, the FeA3 complex of the trihydroxamic acid deferoxamine‐B is stable at all iron levels. These results are consistent with the polymer structure, which for steric reasons would favor a stable complex, FeA2+, between iron and two adjacent hydroxamic acid groups. An FeA3 complex would be expected to have a lower stability as a result of either bond angle strain and atomic compression, or a lower probability in bringing a third hydroxamic acid into position to form the octahedral complex.
N‐Aryltetramethylguanidines, living catalysts for polyurethane foams
Authors: Ulrich Henri , Reymore Harold E. , Sayigh A. A. R. 
Published: April 2003

AbstractN‐Aryltetramethylguanidines catalyze the formation of polyurethane foams by a novel exchange reaction involving CN double bond of the guanidines and the isocyanate groups of the polyisocyanates. The catalyst sites are transferred to the growing polymer network, achieving a rapid catalytic build‐up of the foam.
Stereoregulation in the polymerization of methyl α‐ethylacrylate by n‐BuLi in toluene
Authors: Hatada Koichi , Kokan Susumu , Niinomi Toshikazu , Miyaji Koh , Yuki Heimei 
Published: April 2003

AbstractThe polymerization of methyl α‐ethylacrylate was carried out in toluene by n‐BuLi at various temperatures. The yield of the polymer decreased with increase in the polymerization temperature and at 30°C and above no polymer was obtained, indicating that the ceiling temperature of this monomer lay between 0 and 30°C. The isotacticity increased with an increase in the polymerization temperature and at 0°C a highly isotactic polymer was obtained. The fractionation of the polymer obtained at −78°C showed that the polymer was a mixture of isotactic and syndiotactic ones. Upon the addition of a small amount of methanol or water in the polymerization mixture the isotacticity of the polymer increased while the yield decreased. Syndiotactic polymer was obtained in the polymerization by n‐BuLi in tetrahydrofuran as well as by diisobutyl aluminum diphenylamide in toluene.
Analysis of the linear methods for determining copolymerization reactivity ratios. II. A critical reexamination of cationic monomer reactivity ratios
Authors: Kennedy Joseph P. , Kelen Tibor , Tüdös Ferenc 
Published: April 2003

AbstractA thorough examination of some cationic copolymerization systems by a new method has shown that many published r values have to be corrected significantly and that some are erroneous and meaningless, because for these systems the conventional copolymer compositions equation does not hold. Available information in regard of cationic copolymerizations has been treated in terms of three classes: (a) Systems in which the conventional copolymer composition equation adequately describes the copolymerization mechanism and previous authors justifiably used the two parameter model to calculate reactivity ratios. Our results show that the discrepancy between published r values and the more precise values obtained in this work is about ±23%. (b) Systems in which the approximations implicit in the conventional copolymer composition equation do not hold and the calculated r values are erroneous and misleading. Monomer pairs comprising monomers of significantly different reactivities belong to this class indicating that in copolymerizations in general and in cationic copolymerizations in particular a strong cast system exists, i.e., copolymerization can readily occur within the cast (between monomers of similar reactivities); however, only with difficulty if at all between casts (between monomers of differing reactivities). (c) Systems in which the use of the copolymer composition equation is completely unjustified, the calculated r values are meaningless and in some cases the existence of true copolymers is questioned.
Kinetic study of radical polymerization of acrylonitrile in the presence of triphenyl phosphite
Authors: Taninaka Takumi , Minoura Yuji 
Published: April 2003

AbstractIn the presence of triphenyl phosphite (TPP), the radical polymerization of acrylonitrile (AN) with α,α′‐azobisisobutyronitrile (AIBN) as the initiator was carried out at 50°C, and the effects of TPP on the polymerization were kinetically investigated. The rate of polymerization was found to be proportional to the first order of the AIBN concentration and the AN concentration, respectively, at all concentrations of TPP. However, the rate of polymerization was proportional to the reciprocal of the TPP concentration at low concentrations, but to the first order of the TPP concentration at high concentrations. On assuming two termination reactions, i.e., the usual unimolecular termination by occlusion of the polymer radical and a bimolecular termination between the propagating radical and TPP, and the formation of the weak n‐π complex between AN and TPP which accelerates propagation step, the rate of polymerization and the degree of polymerization were kinetically discussed. The equations derived were in good agreement with the experimental results.
Low‐angle x‐ray fine structure investigation of tussah protein fiber
Authors: Ratho T. , Patel A. 
Published: April 2003

AbstractLow‐angle x‐ray methods have been used to evaluate some macromolecular parameters of the scattering particles in tussah, a silk fiber. A low‐angle Kratky camera of recent design has been used for the experimental measurements of the scattering intensities. The sample under investigation is taken as a densely packed colloidal system belonging to general micelle system and the well known theories of Kratky and Kratky and Porod have been utilized. The parameters determined are specific inner surface of the dispersed phase (O/V), transverse lengths like the length of inhomogeneity (lr) and the length of coherence (lc), and the air fraction of the scattering particles in tussah fiber; these were found to be 7.084 × 10−6Å−1, 100.6 Å, 367.7 Å, and 0.02%, respectively.
Formation of free radicals in photoirradiated cellulose. V. Effect of temperature
Authors: Hon Nyok‐Sai 
Published: April 2003

AbstractESR spectra of purified and ferric ion‐sensitized celluloses irradiated with ultraviolet light in vacuo at 45, 20, −80, and −196°C were recoreded and compared. Generally, several kinds of spectra, viz., singlet, three‐line, five‐line, and seven‐line spectra, were observed. At higher temperatures, only singlet and three‐line spectra of stable free‐radical species were detected, whereas at lower temperatures such as at −196°C, two doubled spectra of formyl radicals and hydrogen atoms were also detected in addition to cellulose radicals. It is believed that the intricate spectra observed at low temperatures are superimposed upon spectra generated by free radicals which may or may not be stable at high temperatures. During reirradiation at −196°C with an alternative light sources, i.e., λ > 2537 Å and λ > 3400 Å, of samples which were irradiated at 20°C or at −196°C, phenomena indicative of radical transformation and formation of new radicals or of decay of radicals in terms of ultraviolet bleaching were observed on studying the changes of line‐shapes and relative signal intensities of the spectra.
Chemical reactions in monomolecular layers solid‐state polycondensation of octadecyl urea formaldehyde
Authors: Rosilio C. , Ruaudel‐Teixier A. 
Published: April 2003

AbstractEvidence is given for solid‐state polycondensation reactions in octadecyl urea multilayers, built up by the Langmuir‐Blodgett method. The disappearance and infrared frequency modifications of characteristic functional groups are followed by spectroscopy in transmitted and reflected light and in ATR. The crosslinked polymer thus obtained on a solid substrate is compared with the polymer obtained at the liquid‐air interface. The chemical reactions are accompanied by molecular reorientation phenomena in multilayers.
Synthesis and radical ring‐opening polymerization of spiro o‐carbonates
Authors: Endo Takeshi , Bailey William J. 
Published: April 2003

AbstractSyntheses and radical ring‐opening polymerization of spiro o‐carbonates(I‐IV) were investigated.
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These polymers were yellow powders and soluble in common organic solvents. The infrared and NMR spectra indicated that the polymers were alternate copolymers of either and carbonate containing double bonds. The polymerization mechanism is discussed.
Structure and reactivities of alkyl vinyl ketones in their radical copolymerizations with styrene
Authors: Otsu Takayuki , Tanaka Hitoshi 
Published: April 2003

AbstractTo clarify the effect of the alkyl substituents in alkyl vinyl ketones (RVK) on their radical copolymerizations, the copolymerizations of six such alkyl vinyl ketones with styrene were investigated. From the results obtained, the relative reactivities of RVK toward the polystyryl radical were correlated with the Taft equation: log (1/r1) = ρ*σ* + δEs, in which σ* and Es are polar and steric substituent constants, respectively, and ρ* and δ are reaction constants. The values of ρ* and δ obtained were 0.40 ± 0.05 and 0, respectively. It was observed that the Q and e values obtained for RVK increased with increasing of σ* values, and that both relative reactivities and Q,e values of methyl vinyl ketone also increased with increasing of the ET values of the solvents used. From the spectral determination of the RVK monomers, it was also found that their n–π interactions were related to the copolymerization reactivities. Furthermore, the radical polymerization of tert‐butyl vinyl ketone (t‐BVK) with azobisisobutyronitrile (AIBN) was investigated, and its rate Rp was found to be expressed by the following rate equation: Rp = k [AIBN]0.5[t‐BVK]1.0.