bluuebunny/crossref_metadata_2025 huggingface dataset:
Dielectric absorption in oriented poly(vinylidene fluoride)
Authors: Kakutani Haruko
Published: April 2003

The dielectric behavior of poly(vinylidene fluoride) is affected by orientation and crystal modification. The loss peak caused by molecular motion of the molecules in crystalline regions appears at about 70°C (110 Hz) (α1 absorption) for the α form, and at about 110°C (110 Hz) (α2 absorption) for the β form. Orientation significantly affects the magnitude of the β absorption which appears at about −40°C. The very high value of the dielectric constant for stretched film is believed to be due to the orientation effect. The γ absorption, which is assumed to be local‐mode absorption, is not so much affected by orientation. An additional loss peak has been found at around 0°C in dynamic mechanical measurements, but the molecular mechanism is unknown.
Rheo‐optical studies of high polymers. XVII. Time‐temperature superposition of time‐dependent birefringence for high‐density polyethylene
Authors: Fukui Y. , Sato T. , Ushirokawa M. , Asada T. , Onogi S.
Published: April 2003

The strain‐optical coefficient and relaxation modulus were simultaneously measured for high‐density polyethylene at various temperatures ranging from 12 to 100°C. Not only horizontal but also vertical shifts were necessary to obtain smooth master curves by the application of time–temperature superposition. However, the relaxation modulus decreases with rising temperature while the strain‐optical coefficient increases. This behavior indicates that the variation of the relaxation modulus and the strain‐optical coefficient with time can not be explained by a decrease in crystallinity with rising temperature since a decrease in crystallinity usually causes a decrease in the strain‐optical coefficient with time can not be explained by a decrease in crystallinity with rising temperature since a decrease in crystallinity usually causes a decrease in the strain‐optical coefficient. It was emphasized that another explanation should be sought for the vertical shift in the time–temperature superposition of the time‐dependence curves of the relaxation modulus and the strain‐optical coefficient at various temperatures. The master curve of the strain‐optical coefficient at various temperatures. The master curve of the strain‐optical coefficient or the optical distribution function of relaxation times determined from it serve to distinguish the type and thermal history of the polyethylene.
ESR studies of the photodegradation of polyethylene containing trapped allylic free radicals
Authors: Shimada S. , Kashiwabara H. , Sohma J.
Published: April 2003

Changes produced in γ‐irradiated polyethylene by subsequent ultraviolet irradiation have been investigated by ESR measurements, ultraviolet spectroscopy, and viscometric determination of average molecular weight. The photoinduced changes depend on the wavelength of irradiation. Upon irradiation at wave length greater than 3900 Å, main‐chain scission occurs by reaction of trapped allylic radicals:
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A reduction in molecular weight sndicated by this reaction was verified by fractionation experiments and molecular weight determinations.
Relationship between self‐seeded and epitaxial crystallization from polymer solutions: A potentially new method for molecular weight separation and a new decoration method for alkali halides
Authors: Carr S. H. , Keller A. , Baer Eric
Published: April 2003

It was established that polyethylene and polyoxymethylene crystallize epitaxially on NaCl cleavage faces over a temperature range in which the usual polymer single crystals dissolve but a crystallization memory remains due to very small quantities of self‐seeding nuclei persisting in the solution. By performing this epitaxial crystallization in the presence of self‐seeding nuclei, it could be established that epitaxial crystallization at these elevated temperatures involves only the very largest molecules in the distribution. Further, the self‐seeding nuclei themselves could be isolated for observation, and these results were found consistent with previous predictions. By utilizing both the adhesion of these nuclei to NaCl and the selective nature of the epitaxial crystallization, the largest molecules could be extracted and reintroduced again to the same or different solutions. This opens up the possibility of a novel kind of chromatography for the separation and characterization of the highest molecular weight end of a distribution to a sensitivity which cannot be approached by other methods. The epitaxy phenomenon itself, under the circumstances involved, provides a new decoration method for the study of the surface topography of alkali halides. The origin of such as epitaxy occurring at low supercoolings and terminating at a limiting thickness raises important questions regarding long‐range forces and some unsettled features in the theory of chain‐folded crystal growth in polymers.
Scattering of light from oriented polymer films. II
Authors: Stein R. S. , Hashimoto T.
Published: April 2003

A statistical theory for the scattering of light from oriented polymer films is developed in terms of angularly dependent generalized correlation functions. Numerical calculations of scattering patterns are carried out for special cases. The scattering depends upon two types of distributions describing (1) the orientation distribution of optical axes of scattering elements and (2) the angular dependence of correlation in orientation between pairs of optic axes. These distributions are expanded in Fourier series (in a two‐dimensional treatment), the coefficients of which are functions of elongation and describe the elongation dependence of the scattering patterns.
Effect of temperature on the dynamic young's and shear moduli of unidirectional carbon fiber‐epoxy composite beams
Authors: Dudek T. J.
Published: April 2003

The resonance frequencies of unidirectional carbon fiber reinforced/epoxy composite beams were studied over the temperature range 24–225°C. Longitudinal Young's moduli E11 and longitudinal‐transverse shear moduli G12 were computed from the experimental data by the use of Timoshenko beam theory. The effects of transverse shear deformation (a function of E11/G12) were found to increase in importance with increasing temperature. Values of G12 were found to be approximately proportional to the shear modulus Gm of matrix material but were about 30% lower than predicted by the theory of Hashin and Rosen. The anisotropy of the carbon filaments and voids in the composite samples were proposed to account for the discrepancy between theory and experiment.
Dilute solution studies of pyrrone prepolymers
Authors: Berry G. C. , Rumon K. A.
Published: April 2003

Data on dilute solutions of a pyrrone “prepolymer” are presented and the tendency of this polymer to aggregate in certain solvents commonly used in dilute solution studies is discussed. It is concluded that reliable molecular weights can be determined if solvents that interact with the prepolymer through hydrogen bonding are used.
Polymeric nature of selenium crystallization. II. Crystallization kinetics and secondary crystallization
Authors: Crystal Richard G.
Published: April 2003

The crystallization of elemental selenium has been studied in light of present concepts of crystallization in organic polymers. Bulk‐crystallization kinetic data as measured by a dynamic density technique and spherulite growth‐rate data as measured by optical microscopy are presented for the temperature range 70°C to 160°C. Plots of extent of isothermal crystallization versus time were sigmoidal in shape. Spherulite growth rates were constant for a given temperature and reached a maximum at approximately 130°C. Evidence is presented for secondary crystallization in selenium, and a model is proposed for destruction of chain folds with interlamellar crystallization during the spherulitic‐to‐“metallic” transformation above 100°C.
Mass spectral characteristics of poly(2,6‐dimethyl‐1,4‐phenylene ether)
Authors: Wiley Richard H.
Published: April 2003

The mass spectral characteristics of poly(2,6‐dimethyl‐1,4‐phenylene ether), its monomer (2,6‐xylenol), and its dimer (3,5‐dimethyl‐4‐hydroxyphenyl 2,6‐xylyl ether) have been determined. The monomer and dimer show peaks for the molecular ions (122; 242 amu) and degradation patterns similar to those of o‐methylaryl ethers. Loss of methyl and cleavage of the ether with transfer of an o‐methyl hydrogen are observed. Metastable transitions are recorded corresponding to a loss of 15 from 122 and 56 from 107 amu (xylenol) and of 151 from 242 and 40 from 104 amu (ether). The polymer volatilizes readily at 380–400°C. (TGA shows rapid weight loss at 400°C) and gives sets of peaks at (N × 120) ± 14 up to 1080 (N = 9). The principal peak is at (N × 120) + 2, calibrated against PFA, and this is attributed to an ion of a volatilized oligomer. The oligomer is either present as such, is formed in a degradation process involving an ether redistribution, or is formed in a hydrogen transfer process in the ether cleavage reaction.
Mechanism of the three‐dimensional polymerization of glycol methacrylates. II. The system glycol monomethacrylate–glycol dimethacrylates–solvents
Authors: Kopec̆ek J. , Lím D.
Published: April 2003

The three‐dimensional polymerization of the system glycol monomethacrylate–glycol dimethacrylates–solvents has been studied. The kinetic dependences thus obtained were interpreted in terms of the dependence of rate constants of the individual reactions on the properties of the medium used. The three‐dimensional polymer formed was characterized in the range from medium to the highest conversions.
Formation of polyimides by COOH and CN reactions
Authors: Čefelín P. , Šebenda J. , Wichterle O.
Published: April 2003

The synthesis of linear polyimides by the addition of dicarboxylic acids to dinitriles has been investigated. Adipic, suberic, m‐ and p‐phenylenediacetic, isophthalic, and p‐cyanobenzoic acids as well as adiponitrile, m‐ and p‐phenylenediacetonitrile, and isophthalonitrile were studied. Fairly favorable results, low molecular weight polymers only, were obtained in the reaction of p‐phenylenediacetic acid with p‐phenylenediacetonitrile. The formation of polyimides seems to be restricted by the solubilities of the reactants and products as well as by the pK values of the starting dicarboxylic acid and of the acid which is formed.
Al(Cap)3 as initiator in the anionic polymerization of ε‐caprolactam at high temperature
Authors: Konomi T. , Tani H.
Published: April 2003

Mechanism for polymerization of ε‐caprolactam in the presence of both sodium and aluminum caprolactamate was investigated at 171°C. The role of Al(Cap)3 as an initiator was revealed. The apparent rate constant of propagation reaction decreased with the increase in the concentration of Al(Cap)3, as the two different metal salts interact even at 171°C. The activation energy of the overall polymerization reaction with this catalyst system was estimated to be 41.18 kcal/mole.
γ‐Radiation‐induced ionic polymerization of pure liquid styrene. III. Effect of temperature
Authors: Potter R. C. , Metz D. J.
Published: April 2003

We have extended our previously reported studies on the radiation‐induced ionic polymerization of styrene to higher dose rates and have covered a temperature range between 0 and 50°C. The data at 0°C are in striking agreement (up to 106 rad/hr) with the mechanism proposed by Williams, Okamura, et al.; on the other hand, styrene of the highest purity exhibits a very complex behavior with temperature variations, which does not agree with this mechanism. These apparent anomalies are presented and discussed. Data are also presented on the effects of adding dry oxygen or degassed water to pure styrene.
Copolymerization of propylene with acrylate by a Ziegler‐Natta type catalyst
Authors: Matsumura Kiichiro , Fukumoto Osamu
Published: April 2003

Propylene was polymerized by using a Ziegler‐Natta type catalyst in the presence of ethylchloroaluminum acrylate, which was formed by the reaction of diethylaluminum chloride with acrylic acid. The polymer obtained contained acrylic units which were proved to be copolymerized with propylene units by solvent extraction, infrared spectrum, and NMR spectrum. The copolymer showed much improved properties compared with the polypropylene homopolymer.
Influence of monomer concentration on the structure of poly(methyl methacrylate) polymerized by butyllithium
Authors: Amerik Y. , Reynolds W. F. , Guillet J. E.
Published: April 2003

The polymerization of methyl methacrylate has been studied in toluene and tetrahydrofuran solution at −78°C using butyllithium as catalyst. The structure of the polymer produced was determined by analysis of the α‐methyl groups using 100 MHz NMR. It is shown that in a noncomplexing solvent such as toluene, the number of isotactic triads increases from 70% to 93% as the monomer concentration during polymerization is reduced from 5 mole/l. to approximately zero. The value of Pss/Pis depends strongly on monomer concentration, and hence any calculations regarding penultimate effects in such systems should be made at close to zero monomer concentration. In the THF solution the penultimate effect is nearly independent of monomer concentration, and both Pii/Psi and Pss/Pis are close to unity. The results may be explained in terms of a mechanism of the polymerization process in which toluene does not complex with the active site, while monomer and THF are weak and strong complexing agents, respectively.
Synthesis and investigation of polybenzimidazoles containing alkyl substituents in aromatic nuclei
Authors: Korshak V. V. , Teplyakov M. M. , Fedorova R. D.
Published: April 2003

Polybenzimidazoles have been synthesized from 3,3′‐diamino‐5,5′‐dimethylbenzidine, 3,3′,4,4′‐tetraamino‐5,5′‐dimethyldiphenylmethane, bis(3‐amino‐4‐methylamino)phenylmethane, bis(3‐amino‐4‐methylamino‐5‐methyl)phenylmethane, and diphenyl esters of adipic, sebacic, isophthalic, and terephthalic acids and 4,4′‐dicarboxydiphenyl oxide by solid‐phase polyheterocyclization. Properties of the polybenzimidazoles have been studied. The polymers have high thermal stability. They are soluble in a number of organic solvents and give strong, elastic films. Solubility and thermal stability of polybenzimidazoles is determined by the methyl group position in the polymeric chain. The influence of other alkyl substituents on properties of polybenzimidazoles have been investigated. The polymer structure has been studied by infrared and PMR spectroscopy and elemental analysis.
Anionic copolymerizations of acrylonitrile with β‐propiolactone
Authors: Katayama Shitomi , Horikawa Hideichi , Masuda Noboru
Published: April 2003

Anionic copolymerizations of acrylonitrile (monomer 1) with β‐propiolactone (monomer 2) and the structures of the resulting copolymers were studied. The copolymerization with sodium cyanide in N,N‐dimethylformamide gave copolymers of the structure I containing acid anhydride linkage in the molecular chains, with the monomer reactivity ratios, r1 = 1.20, r2 = 0.00.
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The copolymerization with potassium hydroxide gave either copolymers of the structure II (r1 = 0.00, r2 = 3.64 at 30°C; r1 = 0.00, r2 = 5.00 at 40°C) in N,N‐dimethylformamide or only β‐propiolactone homopolymer in toluene.
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Anionic copolymerization of p‐anisaldehyde with dimethylketene
Authors: Hashimoto Kazuhiko , Sumitomo Hiroshi
Published: April 2003

Anionic copolymerization of p‐anisaldehyde (ANA) with dimethylketene (DMK) was made with use of benzophenone–dilithium complex as an initiator at −78°C in a high vacuum. In spite of a copolymerization in such a good polar solvent as tetrahydrofuran, the composition of the copolymer was nearly exactly 1 : 1 over a quite wide range of the monomer feed. From the analytical data of the product after the hydrogenolysis of the copolymer with lithium aluminum hydride, the copolymer was found to have a structure resulting from the alternating addition of the CO double bond of ANA to the CC double bond of DMK. No copolymerizations of ANA with phenyl isocyanate and methyl isocyanate take place under the same conditions.
Chain scission of butyl rubber by nitrogen dioxide. II. Photo‐oxidation as function of nitrogen dioxide, oxygen pressure, and temperature
Authors: Jellinek H. H. G. , Hrdlovic P.
Published: April 2003

Studies of chain scission of butyl rubber (1.75% by weight of isoprene) have been extended. Experiments showing chain scission as function of various oxygen and nitrogen pressures, temperatures, and near‐ultraviolet light intensity are presented. The experimental data agree with the mechanisms assumed in previous work or with elaborations of such mechanisms to include additional factors (ultraviolet radiation etc.). NO2 retards chain scission in presence of near‐ultraviolet light. Photo‐oxidation in presence of relatively high and low nitrogen dioxide pressures, respectively, show experimental curves of opposite curvature; these data have also been evaluated in terms of méchanism. Arrhenius equations are presented for experiments related to the different reaction mechanisms.
Degradation of polymers and morphology: Photo‐oxidative degradation of isotactic polystyrene in presence of sulfur dioxide as function of polymer crystallinity
Authors: Hrdlovic P. , Pavlinec J. , Jellinek H. H. G.
Published: April 2003

The photo‐oxidative chain scission of isotactic polystyrene films has been studied as a function of the degree of crystallinity, SO2, and NO2 pressures, and temperature. The rate of chain scission increases in the presence of SO2 with extent of crystallinity. It is assumed to be faster due to strain in and near the folds in the crystalline areas than in the amorphous regions. In the presence of NO2, chain scission increases up to about 8% crystallinity but subsequently becomes constant with further increase in crystallinity. It is suggested that the diffusion rates of oxygen and nitrogen dioxide into the films decrease with increasing crystallinity. These two processes compensate each other.
Polymerization, copolymerization, and terpolymerization of 1‐isopropylidene‐dicyclopentadiene by anionic coordination catalysts
Authors: Cesca S. , Bertolini G. , Santi G. , Duranti P. V.
Published: April 2003

A detailed investigation of the terpolymerization reaction of ethylene and propylene with 1‐isopropylidene‐dicyclopentadiene (II) was carried out by empolying vanadiumbased anionic coordinate catalysts [preferentially V(Acac)3AlEt2Cl]. The influence of some polymerization parameters, i.e., concentration of II, of the catalyst; polymerization time, etc., were particularly examined. The catalysts were found to be active in C2H4II copolymerization also, but neither C3H6II copolymer nor II homopolymer were obtained. By using the 5,6‐dihydro derivative of II as comonomer, it was found through ultraviolet, infrared, and NMR analyses that the incorporation of II in polyethylene or ethylene–propylene chains took place randomly and by selective opening of the norbornene double bond. The quantitative determination of the unsaturation present in C2H4C3H6II terpolymer was studied by means of absorption of iodine halides and through a spectroscopic ultraviolet method. Reference was made to terpolymer samples containing 14C‐labeled II. The content of II was generally less than 35 wt‐% both in copolymer and in terpolymer prepared. The relatively high reactivity of II is discussed in terms of norbornene ring strain and compared with the reactivity of 1‐isopropylidene‐3a,4,7,7a‐tetrahydroindene (I) previously reported.
Assessment of the state of order of hydroxyl groups and of molecular segments in hydrocellulose
Authors: Rowland S. P. , Roberts E. J. , Bose J. L. , Wade C. P.
Published: April 2003

Through a study of the selective distribution of substituents introduced into hydrocellulose from reaction with N,N‐diethylaziridinium chloride, the change in selective availability of hydroxy groups at C‐2, C‐3, and C‐6 has been followed as a function of duration of hydrolysis to form the hydrocellulose. The hydrocellulose formed at a particular duration of hydrolysis showed maximum selective availability of hydroxyl groups; this was found to coincide with minimum moisture regain and minimum breadth at half height for 101, 101, and 002 peaks in x‐ray diffractograms. These points are discussed in terms of the structures of the hydrocelluloses at various stages of hydrolysis and in terms of the sequence of changes which is now associated with the conversion of fibrous cotton to “exemplar hydrocellulose,” i.e., the hydrocellulose having the highest degree of crystalline order, and subsequently, to less highly ordered hydrocelluloses.
Thermal decomposition of poly(vinyl chloride) and chlorinated poly(vinyl chloride). I. ESR and TGA studies
Authors: Liebman S. A. , Reuwer J. F. , Gollatz K. A. , Nauman C. D.
Published: April 2003

Significant effort has been made in the past by many workers to investigate the mechanism of thermal decomposition of poly(vinyl chloride) (PVC). The presence and role of free radicals has been controversial in this regard. Our data on PVC and chlorinated PVC systems demonstrate the existence of macroradicals in the early stage of thermal decomposition under inert and oxidative atmospheres. Data from conventional thermogravimetric experiments are used in conjunction with the electron spin resonance findings.
Radiation‐initiated homogeneous grafting of styrene to benzylcellulose
Authors: Betty R. W. , Rapson W. H.
Published: April 2003

Graft copolymers of benzylcellulose and styrene were prepared by direct irradiation of benzylcellulose–styrene solutions with 60Co γ‐radiation. The solutions remained homogeneous during irradiation. The amount of styrene grafted to benzylcellulose increased in dilute solutions and was dose‐dependent up to 4.0 MR. The graft copolymer consisted of both branched and linear structures with one in every 140–1020 benzylated anhydroglucose units carrying a grafted polystyrene chain. Grafted polystyrene was isolated from the graft copolymer by hydrolysis of the benzylcellulose substrate. The number‐average molecular weight and molecular weight distribution of the grafted polystyrene were the same as those for hompolymer formed in the same solution, indicating that the substrate is fully accessible to the monomer and polymerization conditions are uniform throughout the solution during the grafting procedure. The existence of a true graft copolymer was proved by the solubility behavior, intrinsic viscosity, number‐average molecular weight, and density‐gradient sedimentation of the product of the grafting procedure. Column elution fractionation of the gross products of the grafting procedure failed to isolate the benzylcellulose–styrene copolymer which was eluted with ungrafted benzylcellulose.
Thermal decomposition of poly(vinyl chloride) and chlorinated poly(vinyl chloride). II. Organic analysis
Authors: Liebman S. A. , Ahlstrom D. H. , Quinn E. J. , Geigley A. G. , Meluskey J. T.
Published: April 2003

A concerted study of poly(vinyl chloride), chlorinated poly(vinyl chloride), and poly(vinylidene chloride) polymers by spectroscopy, thermal analysis, and pyrolysis‐gas chromatography resulted in a proposed mechanism for their thermal degradation. Polymer structure with respect to total chlorine content and position was determined, and the influence of these polymer units on certain of the decomposition parameters is presented. Distinguishing differences were obtained for the kinetics of decomposition, reactive macroradical intermediates, and pyrolysis product distributions for these systems. It was determined that chlorinated poly(vinyl chloride) systems with long‐chain CHCI units were more thermally stable than the unchlorinated precursor, exhibited increasing activation energy for the dehydrochlorination, and produced chlorine‐containing macroradical intermediates and chlorinated aromatic pyrolysis products. The poly(vinyl chloride) polymer was relatively less thermally stable, exhibited decreasing activation energy during dehydrochlorination, and produced polyenyl macro‐radical intermediates and aromatic pyrolysis products.
Thermal and photochemical oxidation of 2,6‐dimethylphenyl phenyl ether: A model for poly(2,6‐dimethyl‐1,4‐phenylene oxide)
Authors: Jerussi Robert A.
Published: April 2003

The oxygenation of 2,6‐dimethylphenyl phenyl ether (I) at 260°C has resulted in the formation of 4‐methylxanthone (II), 2‐hydroxy‐3‐methylbenzophenone(III), 2‐phenoxy‐3‐methylbenzaldehyde (IV), 2‐phenoxy‐3‐methylbenzoic acid (V), 2‐phenoxy‐3‐methylbenzyl o‐cresotinate (VI), 2‐phenoxy‐3‐methylbenzyl alcohol (VII), and 2‐phenoxy‐3‐methylbenzyl 2‐phenoxy‐3‐methylbenzoate (VIII), The photochemical oxidation at 75° produced compounds II, III, IV, VII, and VIII. Oxidation of poly(2,6‐dimethyl 1,4‐phenylene oxide) film at 200°C and photochemically at 50°C produced a carbonyl band at ca. 1730 cm−1. The gel content of the photochemically aged film could be significantly reduced and the 1730 cm−1 peak in the thermally aged specimen could be moved to longer wavelength by base treatment. The isolation of compound VIII in both processes with the model compound and the results with the polymer allows us to propose an ester group as a crosslinking unit in thermally and photochemically aged polymer film.
Polymerization of methyl methacrylate under ultrasonic irradiation. Part V. Effect of ultrasonic irradiation on stereoregularity of the polymers and oligomers produced by grignard catalyst in toluene–dioxane mixed solvent
Authors: Osawa Zenjiro , Kimura Takao , Ogiwara Yoshitaka , Matsubayashi Noriyuki
Published: April 2003

Polymerization of methyl methacrylate with Grignard reagent in toluene–dioxane mixed solvent was carried out under ultrasonic irradiation. The effects of ultrasonic irradiation and the order of catalyst addition on Grignard reagent and the microstructure in the reacting sites were examined on the basis of the stereoregularity of polymers and oligomers produced. The formation of oligomers was also discussed on the basis of the consumption of initiator. The stereoregularity of the polymers in series A (no ripening of catalyst with solvent) is higher than that in series B (ripening of catalyst with solvent). The effect of ultrasonic irradiation on the stereoregularity was completely reversed in series A and B; it increased in the former and decreased in the latter with ultrasonic irradiation. Similar results were obtained for the stereoregularity of the oligomers, but the stereoregularity of the oligomers was lower than that of polymers.
Effect of crystallinity on radiation‐induced graft copolymerization on cellulose
Authors: Ahmed A. U. , Rapson W. H.
Published: April 2003

With vinyl monomers, viz., styrene, butyl methacrylate, dimethylaminoethyl methacrylate, and ethyl acrylate, it was noted that higher per cent grafting was obtained with “recrystallized” cellulose than with “amorphous” cellulose. The possibility of the production of a porous structure in cellulose as a result of γ‐irradiation followed by the dissolution of the reactive regions is suggested. DTA and DTG data of irradiated cellulose triacetate (CTA) reveal lowering of the melting point on irradiation, indicating a decrease in crystallinity. Decrease in density of cellulose on irradiation by γ‐rays also indicates loosening of the structure of cellulose. It is postulated that grafting occurs in those regions of cellulose which were crystalline before irradiation, as well as in less crystallinie regions.
Telechelic diene prepolymers. II. Carboxyl‐terminated polydienes
Authors: Reed Samuel F.
Published: April 2003

Butadiene, isoprene, and chloroprene have been polymerized in dioxane under free‐radical initiation to give liquid prepolymers containing terminal carboxyl groups. 4,4′‐Azobis(4‐cyanovaleric acid) was employed as the initiator. The prepolymers were obtained with molecular weights of 12,000 to 2000 and with functionalities usually greater than 2.0. Experimental parameters were studied to determine their effect on prepolymer yields and properties. The general preparative procedure and prepolymer characterization are described.
On the condensation equilibrium in polymerization of caprolactam
Authors: Reimschuessel H. K. , Dege G. J.
Published: April 2003

The investigation of the condensation equilibrium of the hydrolytic polymerization is described for systems obtained by polymerizing caprolactam in the presence of water (or aminocaproic acid) and any of the following additives: mono‐ di‐, and tricarboxylic acids, mono‐ and diamines, and the salts derived from a monoamine and either a mono‐ or dicarboxylic acid. Relationships in terms of the equilibrium constant K2, the equilibrium conversion (K3), and the initial composition were derived for the calculation of the molecular weights of the corresponding equilibrium polymers. Very good agreement between calculated and experimental data was observed. The results show that the thermodynamical quantities derived for the pure caprolactam–water system are also valid for polymerizations that involve the participation of organic acids, amines, and their salts in the initiation and equilibration.
Polymerization of propadiene. I. Comparison of catalytic systems in relation to polymer structure and polymerization by a new Ni‐based catalyst
Authors: Van Den Enk J. E. , Van Der Ploeg H. J.
Published: April 2003

A literature survey is given of the methods of preparation of 1,2‐and 1,2,2,1‐polyallene. The spectroscopic data and other physico‐chemical properties are compiled. Spectral analysis of the products in relation to the catalyst used leads to conclusions with regard to the effect of electron‐donating and electron‐withdrawing ligands to the transition metal of the catalyst on the ratio of 1,2 to 1,2,2,1‐polyallene structural units in the polymer obtained. This hypothesis enabled us to prepare a structurally homogeneous 1,2 polyallene in almost quantitative yield. The catalyst was prepared by adding propadiene to a benzene solution of Ni(II) acetylacetonate followed by addition of triisobutylaluminum. This sequence of addition appeared to be the essential factor for obtaining an active catalyst. A kinetic scheme for the polymerization is put forward.
Radiation‐induced postpolymerization of trioxane in the solid state. III. Effect of oxygen on the postpolymerization of trioxane
Authors: Ishigaki Isao , Ito Akihiko , Iwai Tadashi , Hayashi Koichiro
Published: April 2003

In order to investigate the effects of oxygen on the radiation‐induced postpolymerization of trioxane in the solid state, a kinetic study has been made. Trioxane was purified by sublimation through Ag2O and Na‐K alloy in vacuo and was irradiated and polymerized in the presence of rigorously dry oxygen. It was found that the initial rate of polymerization and the polymer yields are larger than those obtained in vacuo. By using the kinetic scheme proposed previously the results were analyzed kinetically. It was found that the influence of oxygen on the postpolymerization of trioxane is mainly attributable to the increase in the concentration of active species. The results obtained in dry air have been discussed in comparison with those in vacuo reported previously.
Vacuum and oxidative pyrolysis of poly‐p‐xylylene. II. Chromatographic analysis and kinetics of reaction products
Authors: Jelinek H. H. G. , Ronel S. H.
Published: April 2003

Reaction products of vacuum and oxidative degradation of poly‐p‐xylylene have been quantitatively determined by chromatographic analysis as function of time, temperature and oxygen pressure. Respective Arrhenius parameters were also ascertained for some of the reaction products and for the sums of all products. The energies of activation for the sums agree quite satisfactorily with the energies of activation obtained previously by uninterrupted experiments in quartz‐spoon reaction vessels. The results found here can be described in terms of mechanisms previously postulated on the basis of the total loss in weight (or volatile production) data. Scission of “weak” links (due to abnormal structures) takes place followed by formation of various products. The whole process is governed by the initial chain scission reaction; however, the energies of activation for each of the products do not need to be identical with that of the chain scission reaction. Each product is formed by a reaction which has its own characteristic number average kinetic chain lengths; the latter have their specific energy of activation values.

Oxidative degradation produces the same organic compounds as vacuum degradation and in addition CO, CO2, and H2O. Oxidized intermediate compounds are apparently fairly rapidly decarboxylated and decarbonylated. Oxidative chain scission is appreciably faster than that in vacuum. Almost simultaneous “weak” link and “normal” chain scission are taking place initiating the formation of a number of products.
Antioxidative stabilization of poly(vinyl chloride)
Authors: Stapfer Christian H. , Granick Joel D.
Published: April 2003

Halogenated resins such as poly(vinyl)chloride undergo rapid degradation when exposed to heat. Such degradation is significantly increased by oxygen, and it is believed that the induction of the process of decomposition is caused by autoxidation of the polymer, followed by extensive dehydrohalogenation. Sulfur‐containing peroxide decomposers allow primary stabilization of PVC with organic compounds which are not HCl acceptors but prevent free radical cross‐linking of the polymer. This implies a discolored polymer melt (due to loss of HCl and formation of polyenes) which nonetheless exhibits good long term stability (no cross‐linking). The stabilization of labile chlorine atoms results from the oxidation of various chain irregularities, and thus the elimination of the early discoloration can be achieved by the use of small quantities of monohydrocarbyltin co‐stabilizers. The relative performance of various antioxidant systems are reported and possible stabilization mechanisms are discussed.
Formation and reactions of radiation‐induced free radicals in chemically modified cotton celluloses
Authors: Chidambareswaran P. K. , Sundaram V. , Prakash Jai , Verma N. C. , Singh B. B.
Published: April 2003

With a view to assessing the role of chemical substitutions in the modification of radiation effects on cotton fibers, the induction and post‐irradiation behavior of free radicals in γ‐irradiated pure, mercerized, benzoylated, and allylated cottons have been investigated by ESR spectroscopy. While mercerization and allylation were found to influence both the nature and yield of radicals, benzoylation reduced only the yield. These substitutions, which have been found to protect cotton fibers against radiation damage, therefore act differently at the molecular level.
Friedel‐crafts copolymerization of thiophene and p‐di(chloromethyl)benzene. I. Products, kinetics, and mechanism of the early stages of the reaction
Authors: Grassie N. , Colford J. B. , Meldrum I. G.
Published: April 2003

The rate of polymerization of thiophene, at concentrations of catalyst (SnCl4), and thiophene of the same order as was subsequently used in studying the reaction between thiophene and di(chloromethyl)benzene, is of the order of 10‐2%/hr at 30°C. There is no significant self‐condensation of DCMB under the same conditions. Since the reaction between thiophene and DCMB is complete at 30°C in minutes rather than hours, it is assumed that self‐condensation of thiophene or DCMB during the reaction between them will be negligible and should not influence the course of the reaction or the structure of the resulting polymer. Reaction at 30°C is much too fast for convenient study. A temperature of 0°C is more appropriate and was used in subsequent kinetic work. The first two products of the condensation of p‐di(chloromethyl)benzene (DCMB) with thiophene have been identified by a combination of mass, infrared, and nuclear magnetic resonance spectroscopy as thenylchloromethylbenzene (TCMB) and dithenylbenzene (DTB). DCMB, TCMB, and DTB have been estimated quantitatively during the course of the reaction by gas‐liquid chromatography (GLC), and it has been established that the rates of each of the two reaction steps is first‐order with respect to the chloro compound (DCMB and TCMB respectively), thiophene, and SnCl4. Rate constants for these two consecutive reactions were calculated to be k1 = 2.79 × 10‐4l.2/mole2‐sec, k2 = 6.37 × 10‐3l.2/mole2‐sec; the corresponding energies of activation are E1 = 7.93 kcal/mole, E2 = 7°67 kcal/mole. These rate constants are appreciably higher than values previously obtained for the corresponding DCMB–benzene reactions.
Studies with inorganic precipitate membranes. III. Consideration of energetics of electrolyte permeation through membranes
Authors: Siddiqi Fasih A. , Lakshminarayanaiah N. , Beg Mohammad N.
Published: April 2003

The permeability of various electrolytes through parchment‐supported ferrocyanide membranes of manganese, cobalt, silver, and cadmium has been measured at 10, 15, 20, 25, and 30°C. The order of permeability at a given temperature was Cl‐ > NO3‐ > CNS‐ > CH3COO‐ > SO42‐ for both monovalent and divalent cations. For any given anion, the cations followed the sequence NH4+ > Li+ > Ba2+ > Ca2+ > Mg2+ > Al3+. This sequence has been correlated with the size of the hydrated ion. Further, the data have been considered from the standpoint of the theory of rate processes and the values for the entropy of activation (ΔS′) have been derived assuming an equilibrium distance of 3 Å in the membrane. The values of ΔS′ were all negative and decreased with increasing valence of the ions. This was interpreted to mean electrolyte permeation with partial immobilization in the membrane.
Radical copolymerizations of β‐propiolactone with acrylonitrile and with styrene
Authors: Katayama Shitomi , Horikawa Hideichi , Toshima Osamu
Published: April 2003

Radical copolymerizations of β‐propiolactone (denoted 2) with acrylonitrile (denoted 1) and with styrene (also denoted 1) and the structures of the resulting copolymers were studied. The bulk copolymerization with acrylonitrile by α,α′‐azobisisobutyronitrile at 50°C gave polyesteracrylonitriles of high enough molecular weight to form tough and transparent films, with the monomer reactivity ratios, r1 = 0.84, r2 = 0.00, and the structure of the copolymers was
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Radical copolymerization with the same initiator in N,N‐dimethylformamide gave polyesteracrylonitriles of the same structure as that of the bulk polymer, blended with β‐propiolactone homopolymer which was due to the competing anionic homopolymerization of β‐propiolactone. The reactivity ratios on the bulk copolymerization with styrene were r1 = 6.2 and r2 = 0.0 with benzoyl peroxide at 80°C, and r1 ≅ 32, r2 = 0 with α,α′‐azobisisobutyronitrile at 50°C. Polyesterstyrenes of intrinsic viscosity up to 0.83 were obtained.
Synthesis of 1,2‐bis(4‐aminocyclohexyl)ethane and its polyamides
Authors: Komoto Hiroshi , Hayano Fusakazu , Takami Toshio , Yamato Sadao
Published: April 2003

The synthetic route to 1,2‐bis(4‐aminocyclohexyl)ethane from toluene via p‐nitrotoluene and p,p′‐dinitrodibenzyl was established. The distribution of geometric isomers was estimated by NMR and fractional recrystallization. Polyamides were synthesized from 1,2‐bis(4‐aminocyclohexyl)ethane and dodecanedioic or sebacic acid. Polymer melting temperatures were varied with isomer compositions. A high content of the trans conformation causes high melting temperatures. Glass transition temperatures of polyamides were in the range of 105–120°C and were less sensitive to isomer compositions.
Polymers containing anthraquinone units: Polymers from 1,5‐diaminoanthraquinone and aralkyldiketones
Authors: Mortier Roy M. , Dutt P. K. , Hoefnagels J. , Marvel C. S.
Published: April 2003

Schiff's‐base polymers have been formed by the condensation of 1,5‐diaminoanthraquinone with 1,4‐ and 1,3‐diacetylbenzene and 2,6‐diacetylpyridine. These polymers were soluble in methanesulfonic and concentrated sulfuric acids (1,4‐diacetylbenzene polymer) or N,N‐dimethylacetamide. The polymer formed from 1,4‐diacetylbenzene was ring‐closed in polyphosphoric acid to yield a thermally stable polymer soluble in concentrated sulfuric acid which lost only 10% of its weight at 900°C in a TGA test.
Optical rotatory properties of synthetic polymers. I. Optical inversion of poly(propylene oxide)
Authors: Tsunetsugu Toshiyuki , Furukawa Junji , Fueno Takayuki
Published: April 2003

(+)‐1,2‐Diethoxypropane, a model diether for the repeating unit of poly(propylene oxide), was prepared, and its behavior in solutions regarding optical rotatory dispersion and proton magnetic resonance was compared with those of the polymer. It was found that the model compound and the poly(propylene oxide) show essentially the same optical properties in solutions. By using the Brewster model of optical activity, it was concluded that the solvation of the polymer may well modify the polarizability of the optically active species to cause changes in the order of the polarizabilities of four atoms directly attached to the asymmetric carbon atom. The explanation is shown to be applicable also to some of related polymers.
Kinetic aspects of the copolymerization of tetrahydrofuran with alkylene oxides
Authors: Blanchard L.‐P. , Kondo S. , Moinard J. , Pierson J. F. , Tahiani F.
Published: April 2003

Cationic (BF3) copolymerizations and terpolymerizations of 1,2‐butylene oxide (BO), propylene oxide (PO), and tetrahydrofuran (THF), have been carried out at 0°C in ethylene dichloride under dry inert conditions. Reactivity ratios of THF–BO, THF–PO and BO–PO systems have been determined with the use successively of 1,2‐propanediol and 1,2,3‐propanetriol (glycerine) as cocatalysts. Terpolymer compositions established experimentally compare well with those predicted by calculations with the reactivity rations determined in the binary systems. With the triol as cocatalyst, the existence of a ternary azeotrope was confirmed. Its composition is: M1(THF) = 0.125; M2(BO) = 0.205; and M2(PO) = 0.670.
Kinetic aspects of catalyzed reactions in the formation of poly(ethylene terephthalate)
Authors: Hovenkamp S. G.
Published: April 2003

The influence of different types of catalysts on the polycondensation reaction has been studied in a model system. It has been found that two kinds of catalysts are to be distinguished. “Transesterification” catalysts (Mn, Pb, Zn) are very active in media having both a high and a low hydroxyl content. However, they are easily poisoned by very small amounts of carboxylic endgroups. This restricts their activity to the period of transesterification. The “polycondensation” catalyst antimony is insensitive to the presence of acidic endgroups. However, its activity is inversely proportional to the hydroxyl group concentration For this reason antimony is hardly effective during transesterification. During polycondensation it becomes gradually more active.
Piezoelectricity, pyroelectricity, and the electrostriction constant of poly(vinylidene fluoride)
Authors: Nakamura Ken'ichi , Wada Yasaku
Published: April 2003

A new device for measuring the electrostriction constant of polymer films is described. Observed values for various polymers except poly(vinylidene fluoride) and poly(methyl methacrylate) agree well with those calculated from the Clausius‐Mosotti equation. Elongational piezoelectricity, the pyroelectric current, and the electrostriction constant are measured for undrawn and roll‐drawn poly(vinylidene fluoride) films. The piezoelectricity and pyroelectric current are attributed to space charges antisymmetrically distributed along thickness direction of the film for two reasons: (1) the polarity coincides between these two phenomena for all specimens, and (2) the piezoelectricity and the electrostriction constant have the same anisotropy for drawn films. Similarity of signs between piezoelectricity and pyroelectric current is observed also in poly(vinyl chloride) films. The electrical behavior of poly(vinylidene fluoride) is interpreted in terms of the ferroelectric nature of the β‐form crystal.
Oscillatory shear measurements on polystyrene melts in the terminal region
Authors: Mills N. J. , Nevin A.
Published: April 2003

Oscillatory shear measurements have been made on a range of anionic polystyrene melts of molecular weights 1000‐‐500,000. For M < 5000 the polymer chain is too short to act as a Gaussian coil and hence the compliance of the melt is very low. For 10,000 < M < 100,000 the compliance of the melt follows the Rouse model of the elasticity of isolated polymer molecules. It is necessary to use the Ferry, Landel and Williams extension of the Rouse theory for M > 40,000 to allow for the effect of entanglements on the complex modulus. For M > 200,000 the entangelment network dominates the compliance and the Rouse theory is no longer applicable.
Intrinsic viscosity of polyelectrolytes in salt solutions
Authors: Yeh R. , Isihara A.
Published: April 2003

The dependence of the intrinsic viscosity of polyelectrolytes on the concentration of added salt is given satisfactorily by a formula obtained recently. A new viscosity—molecular weight relation gives satisfactory agreement with experiments.
Scattering of light by deformed disordered spherulites
Authors: Stein R. S. , Hashimoto T.
Published: April 2003

The change in the light‐scattering patterns upon deforming two‐dimensional disordered spherulites is shown to arise from four effects occurring upon stretching: (1) the change in shape of the spherulite, (2) the change in average orientation of the optic axes of the scattering volume elements, (3) the change in deviation of the optic axis orientation angle from its average value, and (4) the change in the distance over which this deviation is correlated. The effects of these contributions upon the experimental scattering patterns are analyzed.
Morphology of polyethylene crystallized by solution stirring
Authors: Rijke A. M. , Hunter J. T. , Flanagan R. D.
Published: April 2003

Dilatometric and calorimetric studies have been made of the fusion process of linear polyethylene crystallized by stirring xylene solutions at elevated temperatures. It is shown that the melting point of the crystals increases rapidly from 139.5°C to 145°C in the crystallization temperature range of 100–103°C and levels off to 146 ± 0.5°C, provided that very slow heating rates are employed. Stirrer‐crystallized samples treated with fuming nitric acid show higher crystalline contents. Comparison of their enthalpies of fusion and melting points indicate that higher molecular order along the fiber axis is associated with higher crystallization temperatures. This is in general agreement with corresponding results of other modes of crystallization. The attack of fuming nitric acid on stirrer crystals is characterized by weight‐loss curves similar to those of dilutesolution crystals and bulk polyethylene. The linear molecular weight dependence on time of exposure to nitric acid suggests that the oxidation proceeds mainly from the chain ends at a constant rate for samples stirred in the lower crystallization range, but an increased rate is observed for a sample stirred from xylene at 105°C. It is suggested that the lamellar overgrowths, most evident at low crystallization temperatures, are epitaxially attached to the fiber axis, whereas the smaller crossbandings observed at higher crystallization temperatures are possibly made up of elements of chains that are only partly incorporated in the highly ordered fibrous core.
Ultraviolet photoelectric effects in polyethylene
Authors: Vermeulen L. A. , Wintle H. J. , Nicodemo D. A.
Published: April 2003

Photocurrents developed in polyethylene in the wavelength range 360–180 nm have been measured. The action spectra show features which can be related to the corresponding features in the absorption spectrum, and in addition there is electron injection from the metal electrode at a wavelength determined by the electrode material. The time dependence of the response indicates that a long‐lived space charge is formed in the material.