bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of amount of medium on the radiation‐induced polymerization of ethylene in tert‐butyl alcohol
Authors: Wada Takeshi , Watanabe Terutaka , Takehisa Masaaki 
Published: April 2003

AbstractThe kinetics of the radiation‐induced polymerization of ethylene in the presence of various amounts of medium (tert‐butyl alcohol containing 5 vol‐% of water) was studied, and the effect of the amount of medium on the polymerization was investigated. The polymerization was carried out by use of a reactor of 100 ml capacity under the following conditions: temperature, 24 ± 3°C; pressure, 200 kg/cm2; dose rate, 2.0 × 104−1.6 × 105 rad/hr. The amount of polymerized monomer and the rate of polymerization were maximum when about 50 ml of the medium was used. Data obtained with the use of 30, 50, and 90 ml of the medium were analyzed kinetically and the rate constants of each elementary reaction were determined by the method based on a reaction mechanism which contains both first‐ and second‐order terminations for the concentration of propagating radical. These results were compared with those obtained with the use of 70 ml of the medium already reported in the previous paper. The dose rate exponents of the rate of polymerization were about 0.7–0.8. It was found that G values for the initiation of ethylene and the medium were 1.5 and 3.8, respectively, and the rate of propagation was proportional to the fugacity of ethylene. It is supposed that the medium plays an important role in the first‐order termination, because the apparent rate constant of the reaction was larger when a larger amount of medium was used.
Water‐soluble cellulose derivatives prepared by the action of solutions of nitrogen dioxide in dimethylformamide
Authors: Clermont L. P. , Bender F. 
Published: April 2003

AbstractCellulose derivatives soluble in water and in dilute alkali were prepared by dissolving a bleached sulfite pulp in solutions of nitrogen dioxide in dimethylformamide (DMF) and heating at 70–90°C for 1–3 hr. No cellulose oxidation was detected. Nitrite esters and apparently also, nitrate esters, were formed with degrees of substitution (DS) ranging from 0.18 to 0.55 and with nitrogen contents ranging from 1.47 to 4.32%. Solution viscosities in water increased with increasing nitrogen content. The degree of polymerization (DP) decreased rapidly in the initial stages of the reaction followed by a slow, gradual decrease with increasing reaction times.
Photopolymerization V. Unsensitized solution photocyclopolymerization of N,N ′‐alkylenebismaleimides
Authors: De Schryver F. C. , Boens N. , Smets G. 
Published: April 2003

AbstractThe term, “photopolymerization,” is defined as a polymerization process in which every chain‐propagating step involves a photo‐chemical reaction. This type of polymerization is exemplified by the unsensitized solution photocyclopolymerization of several N,N ′‐alkylenebismaleimides, substituted at the double bond. N,N ′‐Alkylenebismaleimides substituted with a bromine atom or two methyl groups at their double bond produce high polymeric products upon ultraviolet irradiation in solution. A general reaction scheme for the photopolymerization is proposed. Kinetic measurements show that the solution photopolymerization of substituted bismaleimides is a multistep reaction.
Polymerization of vinyl chloride and copolymerization with carbon monoxide by a new initiator
Authors: Kawai Wassaburo , Ichihashi Taichi 
Published: April 2003

AbstractThe system comprising the ethoxydized product of triethylaluminum, cuprous chloride, and carbon tetrachloride was used as an initiator for polymerization of vinyl chloride, and the polymerization kinetics was studied. From plots of the molar number of number‐average polymer chain Y/P̄ versus yield Y, the two parameters a ( = ∫ Ridt − 1/2 ∫ Rtdt) and b ( = ∫ Rtrdt/∫ Rpdt) were estimated to be 6 × 10−3 mole/l. and 6.6 × 10−4 respectively. Studies of the tacticity of the poly(vinyl chloride) showed isotactic = 49.3% and syndiotactic = 50.7%. The present initiator also permitted copolymerization of vinyl chloride with carbon monoxide; the monomer reactivity ratios were r1 = 0.40 (vinyl chloride) and r2 = 0.01 (carbon monoxide).
Polyester formation by the free‐radical copolymerization of cyclohexene and formic acid
Authors: Gebelein Charles G. 
Published: April 2003

AbstractCyclohexene and formic acid have been copolymerized to an unsaturated polyester by a free‐radical‐initiated, step‐growth polymerization process. The polymerization system contains iodine and a hydroperoxide in addition to the cyclohexene and formic acid. No polymerization occurs if any one of these components is omitted. The polymerization process is rapid, and polymer yields as high as 95% have been obtained in less than 1 hr. The polymer is an unsaturated polyester and appears to be poly(oxy‐2‐cyclohexen‐1,4‐enylcarbonyl). A step‐growth polymerization mechanism involving formic acid radicals, iodine atoms, and cyclohexene allylic hydrogen atom abstraction has been proposed for this reaction.
Inhibited degradation of nylon 66 in presence of nitrogen dioxide, ozone, air, and near—ultraviolet radiation
Authors: Jellinek H. H. G. , Chaudhuri A. K. 
Published: April 2003

AbstractDegradation of nylon 66 films of different morphologies was studied in the presence of nitrogen dioxide, ozone, oxygen, and near‐ultraviolet radiation (λ > 2900 Å). Films cast from formic acid solution showed normal random degradation, whereas films cast from benzyl alcohol solutions and dried at elevated temperatures under nitrogen showed very strongly inhibited random degradation. This inhibition may be due to protection of peptide groups by hydrogen bonding with benzaldehyde or benzoic acid or even to their chemical reactions at elevated temperatures. Oxygen was not rigorously excluded during preparation of the films. Degradation of nylon 66 films cast from formic acid solutions at room temperature containing benzaldehyde or benzoic acid, respectively, is also inhibited. The energy of activation for inhibited degradation in presence of nitrogen dioxide is relatively small, indicating that the process is either controlled by diffusion of polymer radicals from medium cages or by diffusion of gases into the polymer. The degradation kinetics can be expressed by “weak”‐link random degradation. The weak links are in the present case unprotected peptide groups. The functional relationship between chain scission rate constants and NO2 pressure is linear.
Perfluoroalkylene‐linked aromatic polyimides. II. Further property studies
Authors: Critchley J. P. , White Mary A. 
Published: April 2003

AbstractThe synthesis and general physical characteristics of the perfluoroalkylene‐linked aromatic polyimides have been discussed in Part I. In this paper the hydrolytic, oxidative, and thermal stabilities of these polymers are compared with those of certain wholly aromatic polyimides. Comparative studies are also made on the effect of the fluoroalkylene chain on the glass transition temperatures. The polymer from di‐(4‐aminophenyl) ether and 1,3‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride has been studied in most detail and various mechanical and electrical properties of this polymer in film and solid molded form are discussed.
NMR and ESR studies of the solid‐state polymerization of vinyl monomers. II. Acrylic acid
Authors: Forchioni A. , Chachaty C. 
Published: April 2003

AbstractThe post‐polymerization of acrylic acid, γ‐irradiated at 77°K, has been studied by broad‐line NMR and ESR between 240°K and 286°K (mp). The changes in the structure of NMR spectra during the polymerization has been related to the conversion yield checked by gravimetry of the polymer formed. The very fast reaction occurring above ⋍270°K has been followed simultaneously by NMR and thermal analysis. This last method indicates an activation energy of chain propagation of 18.6 ± 2 kcal/mole in satisfactory agreement with the value given by the initial slope of the conversion—time curves. ESR experiments show that, while the average radical concentration decays by a factor of about ten between 77°K and 240°K, the local concentration of radicals persisting after prolonged annealing at T > 240°K, remains the same as at 77°K, i.e., 1.4 × 1019 spins/g. A kinetic scheme, assuming an exponential decay of propagation and termination rate constants with chain length, has been proposed to explain the shape of conversion—time curves as well as the almost constancy of the local concentration of growing polymer chains.
Electron paramagnetic resonance spectroscopy of γ‐irradiated cellulose and related compounds
Authors: Ahmed A. U. , Rapson W. H. 
Published: April 2003

AbstractEPR studies were carried out on different irradiated cellulosic materials. The shape of the EPR spectrum was found to depend upon the fine structure of cellulose. The peak‐to‐peak distances of the large peaks on the differential curves were found to be 23.3 and 24.8 gauss, respectively, for the amorphous and recrystallized cellulose. The number of free radicals present per unit weight in the recrystallized cellulose and in the amorphous cellulose were found to be in the ratio of 2.1:1. The EPR spectrum of a sample of irradiated cotton crystallites which was soaked in acetone before being dried was markedly symmetrical, in contrast to the EPR spectra of samples of cotton linters and of cotton crystallites dried from water, and was considered to be a reflection of the lower intermolecular bonding in the former. For corresponding doses, the free radicals on cotton crystallites have the highest g value, followed by cotton linters, followed by regenerated cellulose I. The g value decreased as the irradiation dose was increased.
1:1 alternating copolymers of 1‐bicyclobutanecarbonitrile with styrene
Authors: Hall H. K. , Rhoades J. W. 
Published: April 2003

AbstractHigh molecular weight, 1:1 alternating copolymers of 1‐bicyclobutanecarbonitrile with styrene were prepared in tetramethylenesulfone solution by complexing the electron‐poor bicyclobutane monomer with zinc chloride. Methyl 1‐bicyclobutanecarboxylate under these conditions gave copolymers containing a slight excess of styrene units (ratio 1:1.3 to 1:1.8). High molecular weight homopolymers of 1‐bicyclobutanecarbonitrile and of methyl 1‐bicyclobutanecarboxylate were prepared similarly. The tendency of the bicyclobutane nitrile to form 1:1 alternating copolymers is as great as that of its vinyl analog, acrylonitrile, and the synthesis of other alternating copolymers from this monomer should be possible.
Studies on substituted lactams. II
Authors: Klein K. P. , Reimschuessel H. K. 
Published: April 2003

AbstractSynthesis and reactions of 4‐carboxy‐6‐alkyl‐2‐piperidones and 4‐carboxyl‐6‐alkyl‐2‐pyrrolidones are described. Upon heating, the substituted 4‐carboxy‐2‐piperidones underwent both polymerization to polysuccinimides and isomerization to pyrrolidone derivatives. No polymerization but isomerization to ethylidene succinimide was observed upon heating the substituted 4‐carboxy‐2‐pyrrolidone. Both polymerization and isomerization can be explained by mechanisms discussed previously.
Gas‐phase copolymerization of sulfur dioxide and butene‐1
Authors: Brown J. R. , O'Donnell J. H. 
Published: April 2003

AbstractMixtures of sulphur dioxide and butene‐1 have been polymerized in the gas phase to the 1:1 alternating copolymer by electron irradiation. The rate of polymerization, measured by the decrease in gas pressure, decreased with increase in temperature over the range −20 to +30°C. The initial G(‐monomer) values decreased from 500 to 50 giving an Arrhenius activation energy of −30 kJ mol−1. These results are consistent with a ceiling temperature‐pressure relationship. The ceiling temperature is about 60°C lower than that observed previously in the liquid phase in accord with thermo‐dynamic prediction.
Stereoregularity of poly(methyl α‐chloroacrylate)
Authors: Uryu Toshiyuki , Ito Katsuhiko , Matsuzaki Kei 
Published: April 2003

AbstractTriad and tetrad tacticities of poly(methyl α‐chloroacrylate) and poly(methyl α‐chloroacrylate‐β‐d1) were determined by nuclear magnetic resonance (NMR) spectroscopy. Methyl α‐chloroacrylate‐β‐d1 and its polymer were first synthesized. Isotactic poly(methyl α‐chloroacrylate) was prepared with ethylmagnesium chloride‐benzal‐acetophenone in combination as catalyst. The syndiotacticity of radically polymerized polymers increased with decreasing polymerization temperature. For radical polymerization, enthalpy and entropy differences between isotactic and syndiotactic additions were calculated to give ΔH − ΔH = 850 cal/mole and ΔS − ΔS = 0.93 eu. The stereoregularity of the polymer prepared with phenylmagnesium bromide catalyst was analyzed in fairly good agreement with first‐order Markov statistics, while polymerization with fluorenyllithium seems predominantly to proceed by a mechanism similar to free‐radical mechanism. Stereoregularity‐controlling power for individual substituents is briefly discussed.
Telechelic diene prepolymers. V. Copolymers with 4‐chlorostyrene
Authors: Reed Samuel F. 
Published: April 2003

AbstractCopolymers of butadiene, isoprene, and chloroprene with 4‐chlorostyrene have been prepared with hydroxyl and carboxyl terminal groups, 4,4′‐azobis(4‐cyano‐n‐pentanol) and 4,4′‐azobis(4‐cyanovaleric acid), respectively, being used as the initiators. The copolymerizations were carried out in dioxane solution to give liquid prepolymers of low molecular weight capable of undergoing conventional chain‐extension reactions and suitable for utilization as encapsulating resins. Preparative and prepolymer characterization properties are described.
A new simple synthesis of soluble high molecular weight polyphenylenes by the cotrimerization of mono‐ and bifunctional terminal acetylenes
Authors: Chalk A. J. , Gilbert A. R. 
Published: April 2003

AbstractThe monofunctional acetylenes, phenylacetylene and m‐ethynyltoluene, were each copolymerized with diethynylbenzene in a 1:1 mole ratio by using TiCl4/3AlEt2Cl as cyclotrimerization catalyst. The aromatic polymers which were produced were polydisperse with a molecular weight of ∼10,000. Variation of catalyst concentration had no effect on the molecular weight profile. An excess of bifunctional acetylene produced some insoluble gel but when some of the monofunctional acetylene was withheld and added only after an initial molecular weight build‐up by the excess bifunctional acetylene, soluble polymers with molecular weights of approximately 50,000 were obtained in high yield, provided the overall ratio of mono‐ to bifunctional acetylene was maintained at 1:1. The resulting polyphenylenes were highly soluble in benzene and chlorinated solvents but gave brittle films. This was attributed to a highly branched structure resulting from a lack of specificity by the catalyst. Thermogravimetric analysis showed the polymers to have high thermal stability.
Strahlenchemische pfropfung aus der monomerdampfphase von polymeren an der oberfläche von füllstoffen als methode ihrer aktivierung
Authors: Taubman A. B. , Yanova L. P. , Blyskosch G. S. , Ryabchikova G. G. , Glasunov P. Y. 
Published: April 2003

AbstractThe vapor‐phase radiation graft polymerization of styrene, methyl methacrylate, and acrylonitrile on surface of dispersed filler (magnesium oxide) was studied. It was established that the polymer graft films are irreversibly chemically bound to the surface, cover it with a discontinuous layer which leaves a part of the surface free from polymer in the form of a mosaic. The grafting modifies the surface and increases the compatibility of filler with the polymer medium.
Preparation of polyimides from pyromellitic dithioanhydride and aromatic diamines
Authors: Imai Yoshio , Kojima Katsunori 
Published: April 2003

AbstractThe reaction of phthalic thioanhydride and aniline yielded N‐phenylphthalimide quite readily. The reaction was strongly dependent on solvent and temperature. Various additives tried as a reaction promoter were almost ineffective. By the extension of the model reaction, polyimides were prepared in a simple one‐step synthesis from pyromellitic dithioanhydride and aromatic diamines in dimethylacetamide or other solvents. Polymers with inherent viscosity up to 0.3 in concentrated sulfuric acid were obtained in approximately quantitative yield.
Kinetics of transesterification in the formation of polyesters
Authors: Utracki L. A. 
Published: April 2003

AbstractThe overall third‐order transesterification reaction, comprising one order each with respect to hydroxyl group, ester group, and catalyst, was considered on assuming a varying reactivity of OH group. The integrated expression for the catalyzed (constant catalyst concentration) reaction predicts an apparent order of reaction n dependent on the extent of reaction p: for p → 0, n = 2; whereas p → 1, n = 5/4. For practical reasons the order of reaction was redefined in terms of (1 − p) ∝ P, (where Pn is the number‐average degree of polycondensation). The integrated expression was compared with published experimental results of diphenyl carbonate transesterification by 4,4,‐isopropylidene diphenol. At T < 200°C, the expression was well obeyed, at 200 < T < 230°C the reaction showed an intermediate behavior, whereas at still higher temperatures the third‐order reaction was found. It is proposed that these changes are due to variations in the chemical nature of the zinc catalyst, resulting in the difference in the transesterification mechanism. A convenient approximate relation for calculating Pn from measured viscosity‐average degree of polymerization Pv is also proposed.
Fluorination of polyhydrofluoroethylenes. I. Direct fluorination of poly(vinyl fluoride) film
Authors: Shinohara H. , Iwasaki M. , Tsujimura S. , Watanabe K. , Okazaki S. 
Published: April 2003

AbstractIt has been demonstrated that the poly(vinyl fluoride) film can be fluorinated by exposing the polymer to an environment of fluorine under atmospheric pressure and at ambient temperature. Fluorine content, infrared spectra, thermal properties, and solubilities in the polar solvents were investigated for the fluorinated products and the following results were obtained. In the case of films less than 10 μ in thickness, the fluorination appeared to proceed homogeneously. Under any fluorinating conditions applied, i.e., fluorine pressure of up to 800 mm Hg and temperatures of up to 90°C, the fluorine content never exceeded 65% which corresponds to a composition of C2F2.5H1.5. The activation energy of the reaction was calculated to be 6.8 kcal/mole. The polymer reacted with a small amount of oxygen contained in the fluorine to form acyl fluoride groups. The fluorinated films became insoluble in boiling N,N‐dimethylformamide, N,N‐dimethylacetamide, and dimethyl sulfoxide, but colored gradually to a dark brown. The occurrence of some crosslinking in the products was revealed.
Alternating copolymer of butadiene and propylene. IV. Studies on the catalysts for alternating copolymerization
Authors: Furukawa Junji , Hirai Ryuichi 
Published: April 2003

AbstractThe catalysts for alternating copolymerization of butadiene and propylene were investigated by means of ESR technique and potentiometric titration. It was found that several kinds of active species for the production of alternating copolymer, 1,2‐polybutadiene, and trans‐1,4‐polybutadiene are formed, depending upon the catalyst composition of VO(acac)2Et3AlEt2AlCl. ESR and potential titration studies suggest that the active species for alternating copolymerization is a divalent vanadium compound existing in an associated form.
Gel‐permeation chromatography. VII. Molecular weight detection of GPC effluents
Authors: Ouano A. C. 
Published: April 2003

AbstractA detector system for GPC has been built consisting of a pressure cell and capillary viscometer, a constant‐flow‐rate pumping system, a concentration detector, and a computer interfacing system. This detector system provides two chromatograms; pressure drop (ΔP) versus retention volume and concentration (C) versus retention volume. Since at constant flow rate ΔP is proportional to the effluent viscosity η, the intrinsic viscosity of any effluent fraction can be computed from the equation,

where subscripts 1 and 0 refer to the solution and solvent, respectively. The precision and accuracy of the above technique were evaluated using well characterized broad and narrow molecular weight distribution polymers. Both the precision and accuracy were found to be comparable to light scattering and other classical molecular weight measurement techniques. In its present form, the molecular weight detector system was found to be very sensitive to polymers with very high molecular weights, as expected, and also useful for molecular weights less than 50,000.
Radiation‐induced polymerization of glass‐forming systems. I. Effect of temperature on the initial polymerization rate
Authors: Kaetsu Isao , Okubo Hiroshi , Ito Akihiko , Hayashi Koichiro 
Published: April 2003

AbstractRadiation‐induced polymerization of hydroxyethyl methacrylate (HEMA) and glycidyl methacrylate (GMA) was investigated. HEMA and GMA formed a stable supercooled or glassy phase by themselves at low temperatures. It was found that the initial polymerization rate was proportional to ca.0.5 power of the dose rate in the region of relatively high temperatures and the dose rate exponent changed sharply to 1.0 at a temperature Tr, at which the viscosity of monomeric systems reached ca. 103 cP as the temperature decreased. Moreover, a maximum in the polymerization rate–temperature curve occurred at Tv. It was deduced that the polymerization mechanism changed from the stationary to the nonstationary at Tv. The temperature at which a minimum of the polymerization rate occurred could be calculated kinetically considering the viscosity dependency of termination rate, and it agreed well with that obtained experimentally. It was deduced that occurrence of the minimum polymerization rate above Tv was attributable mainly to the decrease in termination rate due to diffusion control.
Radiation‐induced polymerization of glass‐forming systems. II. Effect of temperature on the polymerization rate at higher conversion
Authors: Kaetsu Isao , Okubo Hiroshi , Ito Akihiko , Hayashi Koichiro 
Published: April 2003

AbstractThe effect of temperature and conversion on the polymerization rate at higher conversion was investigated with regard to the γ‐ray‐induced polymerization of hydroxyethyl methacrylate (HEMA) and glycidyl methacrylate (GMA) in the supercooled phase. The polymerization rate changed from acceleration to depression at various conversions, depending on the polymerization temperature. It was found that Tv at which the viscosity of the system became ca. 103 cpoise influenced the shape of the polymerization time–conversion curve. The experimentally obtained conversion reflection point in the polymerization time–conversion curve agreed with the conversion where the polymerization temperature is the same as the calculated Tv of the system. When the polymerization temperature was lower than Tv of the monomer, no acceleration of the polymerization occurred. When the polymerization temperature was higher than Tv of the polymer, no depression of the polymerization rate was observed. The effect of temperature on the saturated conversion (final conversion) was also examined in terms of Tg of the polymerization system. The experimentally obtained saturated conversion agreed with the conversion where the polymerization temperature is the same as the calculated Tg of the system.