bluuebunny/crossref_metadata_2025 huggingface dataset:
Cyclic diamides. II. Syntheses and polymerizations of perhydro‐1,5‐diazocine‐2,4‐dione and its derivatives
Authors: Iwakura Yoshio , Uno Keikichi , Haga Kazuo , Nakamura Koutarou
Published: April 2003

One isomer, perhydro‐1,5‐diazocine‐2,4‐dione, was obtained exclusively by the double Beckmann‐rearrangement reactions of cyclohexane‐1,3‐dione dioxime. It is suggested that the other possible isomer was decomposed by a transannular reaction. Perhydro‐1,5‐diazocine‐2,4‐dione was polymerized in the solid state in the presence of water vapor and produced polytrimethylenemalonamide. Further, this monomer was polymerized in the molten state without water. 7‐Methyl‐ and 7,7‐dimethyl‐perhydro‐1,5‐diazocine‐2,4‐dione were prepared, and the latter was polymerized in molten state. Differential thermal analyses of the monomer and x‐ray diffraction measurements of the polymers were carried out.
Applications of ESCA to polymer chemistry. III. Structures and bonding in homopolymers of ethylene and the fluoroethylenes and determination of the compositions of fluoro copolymers
Authors: Clark D. T. , Feast W. J. , Kilcast D. , Musgrave W. K. R.
Published: April 2003

Molecular core binding energies have been measured by ESCA for the homopolymers of ethylene and the fluoroethylenes. The data are interpreted in terms of semiempirical all‐valence electron SCF MO calculations in the CNDO/2 formalism, in conjunction with the charge potential model. The results are used as a basis for interpreting the measured core binding energies of some Viton and Kel F type polymers. The routine application of ESCA to the determination of copolymer compositions is described.
Chromocene‐based catalysts for ethylene polymerization: Kinetic parameters
Authors: Karol Frederick J. , Brown Gary L. , Davison James M.
Published: April 2003

The chromocene catalyst for ethylene polymerization shows a high response to hydrogen which leads directly to highly saturated polyethylenes containing methyl groups as the major terminal functionality in the polymers. At a polymerization temperature of 90°C the ratio of termination rate constants for hydrogen (kH) and ethylene (kM) is kH/kM = 3.60 × 103. The ratio of kH to the chain propagation constant (kp) is kH/kp = 4.65 × 10−1 A simple relation that can be derived from polymerization kinetics and the Quackenbos equation exists between melt index and hydrogen–ethylene ratio. A deuterium isotope effect (kH/kD) = 1.2 was calculated for the termination reaction. The overall polymerization process has an apparent activation energy of 10.1 kcal/mole. Oxygen addition studies show catalyst activity is proportional to initial divalent chromium content.
Block copolymerization. VIII. Anionic polymerization of α‐pyrrolidone by polystyrene initiator
Authors: Yamashita Yuya , Murase Yasuo , Ito Koichi
Published: April 2003

Polystyrene with N‐acyl pyrrolidone groups at both ends was prepared by radical polymerization with 4,4′‐azobis(pyrrolidone 4‐cyanovalerate). With this polystyrene as the initiator, the anionic polymerization of α‐pyrrolidone was carried out, to give the well‐defined ABA‐type block copolymers of α‐pyrrolidone and styrene. The obtained copolymers were characterized by their composition, reduced viscosity, and initiation efficiency. Initiation efficiency was sufficiently high, and the stepwise propagation process was verified so far as the polymerization time was not so long. The results of the polymerization in a high‐vacuum system were compared with those in a low‐vacuum system, and some differences were observed owing to the effect of water.
Polymerization of mixtures of alkyl methacrylates or alkyl acrylates with 4‐methyl‐1‐pentene by Ziegler‐Natta catalyst
Authors: Chiellini Emo , Nocci Roberto
Published: April 2003

Mixtures of methyl methacrylate (MMA) and 4‐methyl‐1‐pentene (4MP)(molar ratio MMA/4MP = 3–0.1) have been subjected to polymerization by VOCl3/Al(C2H5)3. The amorphous polymeric products, extractable with boiling methanol up to 75%, consist mainly of MMA monomeric units (∼80%). The composition of the product was almost independent of the starting MMA/4MP ratio. Comparison of these results with thoseof homopolymerization experiments shows that the presence of MMA drastically reduces the polymerization rate of 4MP. Moreover, 4MP is polymerized with rather low stereospecificity in the presence of MMA. Fractionation by solvent extraction of the unchanged polymeric products as well as of hydrolyzed samples seems to exclude the formation of random copolymers, suggesting to us that the polymerization of the two monomers takes place by different mechanisms. On taking into account these data and analogous data obtained with 4MP and alkyl acrylates or tert‐butyl methacrylate, is it suggested that, contrary to what has previously been proposed, the MMA polymerization by Ziegler‐Natta catalysts does not take place at the same centers which polymerize 4MP; moreover a coordinated anionic mechanism for MMA polymerization does not seem to be very probable.
Nitrogen‐containing organozinc and organoaluminum as catalyst for stereospecific polymerization of propylene oxide
Authors: Oguni Nobuki , Tani Hisaya
Published: April 2003

Catalytic activities of the reaction products of diethylzinc or triethylaluminum with primary amines in the polymerization of propylene oxide were studied. Generally, organozinc compounds give higher ratio of the crystalline to the amorphous polymer than the organoaluminums. In the reactions of organometallic compounds with primary amines, Et2AlNPhAlEt2, Et2AlN‐t‐BuAlEt2, EtZnNH‐t‐Bu, and EtZn‐t‐BuZnEt were isolated in crystalline state. EtZnN‐t‐BuZnEt proved to be an excellent catalyst for the stereospecific polymerization of propylene oxide and forms coordination complexes with some electron donors such as dioxane, pyridine, epichlorohydrin and propylene oxide. The propylene oxide complex is unstable in solution and decomposes at temperatures above room temperature to give poly(propylene oxide), while the pyridine complex has no catalytic activity. Therefore, it is concluded that the polymerization of propylene oxide with this catalyst proceeds through the coordination of propylene oxide to the zinc atom of the catalyst.
Fortran IV programs for the penultimate copolymerization model
Authors: Pittman Charles U. , Rounsefell Thane D.
Published: April 2003

Three programs have been written for calculations involving use of the penultimate copolymerization model. The first computes the penultimate reactivity ratios from composition‐conversion data, without constraints, at any conversion. A nonlinear leastsquares technique using Marquardt's algorithm is employed. The second program computes the four optimum starting monomer feed ratios,M10/M20which should be used by the experimenter from the penultimate reactivity ratios. These optimum feed ratios are obtained by choosing the conditions necessary to minimize the determinant of the variance‐covariance matrix. The input for the first program includes estimates of known values of the penultimate reactivity ratios. By using these two programs sequentially the experimenter has an optimized experimental approach toward evaluating penultimate reactivity ratios at any conversion. Finally, a program has been provided to calculate composition–conversion data, given penultimate reactivity ratios.
Thermal degradation of polybenzyl
Authors: Ellis Bryan , White P. G.
Published: April 2003

Polybenzyl has been synthesized from the benzyl compounds, chloride, methyl ether, and isopropyl ether by using stannic chloride as the Friedel‐Crafts catalyst. The detailed structures of these polybenzyls have been determined by use of methods including elemental analysis, molecular weight determination, and infrared, ultraviolet/visible, and NMR spectra. The structure of these polybenzyls is globular with a high degree of branching. Thermal degradation was studied by using DTA and stepwise and isothermal degradation with analysis of both the volatile fraction and the residue. The activation energy for scissions was determined from changes in the molecular weight of the sample with time at a range of degradation temperatures of 340–440°C. The composition of the volatile fraction changed with both temperature and time of degradation. Thermal scission is directed to internal units and depends on the presence of weak links such as substituted anthracene units.
Peroxidation of caprolactam and its effect on equilibrium polymerization
Authors: Dege G. J. , Reimschuessel H. K.
Published: April 2003

The peroxidation of caprolactam has been studied at 84°C, 100°C and 120°C. The decomposition of the initially formed ε‐caprolactam hydroperoxide was found to be catalyzed by adipic acid monoamide which is formed by hydrolysis of adipimide. This imide results from the decomposition of the hydroperoxide and was found to act as oxidation inhibitor. The molecular weights of the polyamides obtained by polymerizing the peroxidized caprolactam were found to decrease as the extent of peroxidation and thus the concentration of adipic acid monoamide and other decomposition products increased. In all of these polyamides the concentration of acidic functions was appreciably higher than that of the titratable amino endgroups.
Formation and cure of novolacs: NMR study of transient molecules
Authors: Kopf P. W. , Wagner E. R.
Published: April 2003

High‐resolution magnetic resonance spectroscopy has been used to investigate three areas of novolac resin chemistry: first, the lifetimes of glycol species in formalin under acid and base conditions and the reactivity of methylene glycol towards alcohols; second, the in situ identification of novolac resin intermediates; third, the novolac–hexamethylenetetramine cure mechanisms. It is shown that the mean lifetime of a given glycol species is an order of magnitude shorter under basic conditions than under an acid of equal normality. The ratio of the equilibrium constants for the addition of methylene glycol to methanol, benzyl alcohol, and phenol was measured as 70:20:1. New reactive intermediates were discovered while monitoring the reaction of phenol and formalin. The reactions of various phenols with hexamethylenetetramine were studied, and short‐lived benzoxazines were detected at 100–120°C whenever ortho hydrogen was available on the phenolic nucleus. The NMR peak assignments in the reaction sequence: benzoxazine, dibenzylamine, tribenzylamine, diphenylmethane are presented. Spectra of the very elusive p‐benzylamines of 2,6‐xylenol were recorded at 100–155°C. At 170°C, the lifetimes of these p‐benzylamines are too short to afford proton resonance spectra. No evidence of hexahydrotriazine or (CH2 = N‐CH2)3N type structures was found in 100 MHz NMR spectra of reaction mixtures of a phenol and hexamethylene‐tetramine.
13C nuclear magnetic resonance spectra of polyacrylates and their model compounds
Authors: Matsuzaki Kei , Kanai Taiichi , Kawamura Tokiji , Matsumoto Susumu , Uryu Toshiyuki
Published: April 2003

13C nuclear magnetic resonance spectra (13C‐NMR) of poly(methyl acrylates) and poly(isopropyl acrylates) of various tacticities were measured at 25.1 MHz and analyzed. 13C‐NMR spectra of model compounds for poly(methyl acrylate), poly(acrylic acid), and poly(sodium acrylate) were also determined. The spectra of the polymers were generally complicated owing to the splittings corresponding to triad, tetrad, or pentad placements, and the assignment for each peak was difficult. Groups of peaks were analyzed by triad or tetrad placements by assuming Bernoullian or first‐order Markovian statistics.
Viscosity studies of polyethylene in a cosolvent mixture composed of two nonsolvents
Authors: Das Nita , Palit S. R.
Published: April 2003

Polyethylene, normally soluble at an elevated temperature in some single solvents, is found to be soluble in the following binary mixtures of nonsolvents at a much lower temperature, (often in the vicinity of room temperature): xylene–carbon disulfide, cyclohexane–carbon disulfide, cyclohexane–trichloroethylene, and cyclohexane–cyclohexanone. The fractionated polymer samples show a maximum in [η] values at the optimum solvent compositions corresponding to a minimum in cloud temperature Te. The results are discussed with respect to the current theories on solubility. The optimum solvent composition agrees with the prediction of a newly developed theoretical equation in two of the above four mixtures.
Poly‐α‐ester degradation studies. II. Thermal degradation of poly(isopropylidene carboxylate)
Authors: Sutton G. J. , Tighe B. J. , Roberts M.
Published: April 2003

The thermal degradation of poly(isopropylidene carboxylate) has been studied over the temperature range 200–800°C by using the kinetic and analytical techniques described in Part I of this series. Over a wide range of temperature, tetramethyl glycollide, acetone, carbon monoxide, and, to a lesser extent, methacrylic acid are observed when the products are rapidly swept away from the reaction zone. As decomposition temperature is increased, tetramethyl glycollide takes on the role of an intermediate, the more stable products carbon monoxide and acetone being formed from it. At the highest temperature examined, carbon monoxide begins to predominate, and its formation is accompanied by formation of small amounts of a carbonaceous residue. When the reaction products are allowed to remain in the reaction zone, which is possible at the lower end of the temperature range, methacrylic acid becomes the major product. This is interpreted as a dual decomposition route, involving the tetramethyl glycollide intermediate. Kinetic studies have shown that the decomposition is a first‐order process and that the first‐order rate constant k is related to temperature (T) by the expression:

The results are interpreted in terms of an intramolecular ester interchange process involving tetramethyl glycollide as the primary decomposition product.
Synthetic thermally reversible gel systems. VIII. Poly(vinyl chloride)–dioxane
Authors: Haas Howard C. , MacDonald Ruby L.
Published: April 2003

When interpreted by network theory, equilibrium swelling measurements on poly‐(vinyl chloride) (PVC) film in dioxane and moduli measurements on the equilibrium swelled films yield values for the approximate molecular weight between thermally reversible crosslinks and for the number of these crosslinks per polymer chain. These values are in reasonable agreement with the thermodynamic analysis of PVC–dioxane gels by Takahashi, Nakamura, and Kagawa and with the premise that three‐dimensional network formation in these gels occurs by crystallization of a very limited number of syndiotactic sequences per chain having a sequence length of between 8 and 10. Failure to observe fusion endotherms by DTA on PVC–dibutyl phthalate gels supports the view that PVC gels have a low crystalline crosslink density and a low heat of crosslinking. The heat of crosslinking obtained by the method of Eldridge and Ferry shows only moderate agreement with expectations based on the heat of fusion of PVC and the number of repeating units per PVC chain passing through a crystalline crosslink in a PVC–dioxane gel.
Effect of interchange reactions on nonequilibrium distributions of condensation polymers and their associated molecular weight averages
Authors: Kotliar A. M.
Published: April 2003

Theory is developed to determine the effect of interchange reactions on nonequilibrium distributions of condensation polymers and their associated molecular weight averages. The analysis offers a method for determining the interchange rates of condensation polymers.
Synthesis of poly‐α,α‐diphenylglycine. I. Thermal polymerization of 4,4‐diphenyl‐Δ2‐1,2,3‐triazolin‐5‐one
Authors: Ikeda K. , L'abbé G. , Smets G. , Delvaux M. C.
Published: April 2003

The thermal decomposition of 4,4‐diphenyl‐Δ2‐1,2,3‐triazolin‐5‐one (I) was reinvestigated and shown to yield poly‐α,α‐diphenylglycine (III) instead of the previously reported 3,3,6,6‐tetraphenylpiperazine‐2,5‐dione (II). Differentiation between the two structures was made by molecular weight determinations and spectroscopic analyses. The infrared spectra were studied in detail and compared with model compounds. They showed that the absorption peak at 1470 cm−1 must be attributed to the trans‐amide II absorption of the polymer. Furthermore, the polymers were found to contain terminal CONH2 as well as triazolinone or ether functions (from alcohol). Fractionation was performed in three solvents based on solubility differences: dichloroethane (or chloroform), methanol, and n‐hexane. All the fractions were characterized by physical methods. A mechanistic investigation revealed that the polymerization process cannot be rationalized by a radical or cationic mechanism, but is compatible with a molecular mechanism involving triazolinone functions at the growing chain ends.
Organometallic polymers. XXV. Preparation of polyvinylferrocene
Authors: Sasaki Y. , Walker L. L. , Hurst E. L. , Pittman C. U.
Published: April 2003

The synthetic details of solution polymerization in benzene and bulk polymerization of vinylferrocene are reported. In benzene solutions, with azobisisobutyronitrile (AIBN) as the initiator, small yields of low‐polydispersity low molecular weight (M̄n ≃ 5000) polyvinylferrocene is obtained. However, high yields can be obtained by continuous or multiple AIBN addition. Higher molecular weight polymers and binodal polymers can be obtained as the monomer concentration is increased. In bulk polymerizations, yields of 80% can be obtained. The molecular weight increases as temperature decreases from 80 to 60°C in bulk polymerizations, and an increasing amount of insoluble polymer results. The soluble portion is often binodal, the higher molecular weight node consisting of an increasingly branched structure. Lower molecular weight polymer was readily fractionated into narrow fractions from benzene–methanol systems, but higher molecular weight polymer proved impossible to fractionate into narrow fractions due to branching.
Semiconducting polymers based on charge‐transfer complexes. III. Complexing and chemical stability of charge‐transfer complexes in solution
Authors: Litt Morton H. , Summers James W.
Published: April 2003

10‐Methylphenothiazine and p‐(methylthio)anisole were compared to polymers which contained these donor molecules on the side chains of N‐acyl‐substituted polyethylenimines. Charge‐transfer absorption spectra were compared for these donors with the acceptors: dichlorodicyanobenzoquinone, tetracyanoquinodimethane, tetracyanoethylene, and 2,4,5,7‐tetranitrofluorenone. Benesi‐Hildebrand plots show that the formation of the polymer complexes have 3 to 50 times higher equilibrium constants than those of the corresponding model complexes. This can be explained by complexing parallel to the polymer backbone. The polymer has the proper geometry for complexing (6.4 Å, repeat distance in the polymer backbone), and an acceptor molecule can therefore be inserted between two adjacent donor molecules for increased stability. Shifts of the absorption maxima to longer wavelength for some of the polymer complexes can be rationalized by the probability that in the polymer, an acceptor is sandwiched between two donors and thus forms 2:1 complexes; the extra resonance energy may shift the absorption maximum to longer wavelength. A second possible explanation is based on solvation of the complex which reduces the energy of the excited state. Polymers absorb mainly in the complex form. Model compounds absorb mainly by contact charge transfer, which is nonsolvated and thus occurs at higher energy or shorter wavelength. Extinction coefficients are higher for the model complexes than for the polymer complexes. Contact charge transfer, which can contribute in greater proportion to the model than to the polymer complexes, explains this. The amount of contact charge transfer can be calculated simply from the probability of a donor being in the solvent shell of an acceptor. Complex decomposition rates were determined based on measuring changes in the intensities of the charge‐transfer absorption spectra. Dichlorodicyanoquinone complexes were unstable, while the other complexes were stable.
Semiconducting polymers based on charge‐transfer complexes. IV. Electrical properties and structure of polymeric charge‐transfer complexes
Authors: Summers James W. , Litt Morton H.
Published: April 2003

Model electron donor molecules, 10‐methylphenothiazine and 4‐(methylthio)anisole, and polymeric electron donors which contained these molecules on the side chains of N‐acyl‐substituted polyethylenimines, were complexed with the electron acceptors, dichlorodicyanoquinone (DDQ), tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE), and tetranitrofluorenone (TNF). The model donors formed 1:1 complexes with all the acceptors except TCNE. The polymeric donors formed amorphous complexes with DDQ, TCNQ, and TCNE. Crystalline complexes were formed with TNF which had low melting points (lower than the model complexes and the pure polymer). This is apparently due to poor lateral packing of the polymer chains. Electrical resistivities were lower for all the polymer complexes than for the corresponding model complexes. Electrical resistivity also decreased with increase in complex crystallinity. In the best case the polymer complex was two hundred times as conducting as the model. The concentration of unpaired electrons measured by EPR was nearly independent of temperature. Most of the electrons seen are trapped and do not participate in conduction. Thermal activation energies for conduction were in the range of 0.5–1.8 eV and were nearly equal for the model and corresponding polymeric complexes. Elongation of polymer complex with TCNQ by rolling produces a decrease in resistivity in the roll direction, although the complex is amorphous. This reinforces the hypothesis that conduction is parallel to the polymer backbone. A polymer–tetranitrofluorenone complex was photoconducting, though the photoconductivity was smaller than the dark conductivity at the level of illumination used. Dember and Seebeck effects indicated that the major carrier in the complex was holes.
Oxidative thermal degradation of polytetrafluoroethylene
Authors: Paciorek K. L. , Kratzer R. H. , Kaufman J.
Published: April 2003

Oxidative thermal degradation studies were performed on polytetrafluoroethylene in air and oxygen by using a stagnation burner arrangement. The autoignition behavior as a function of temperature and oxidizing medium and the nature and relative proportion of the volatiles produced prior to ignition, on ignition, and during combustion were determined. In oxygen only COF2, CO2, and CF4 were formed; in air C2F4 was observed, together with a spectrum of rearrangement derived fluorocarbons in addition to the expected oxidation products. The autoignition temperature in air was found to be considerably higher than in oxygen (575°C compared to 512°C).
Polymerizability and related problems in the anionic polymerization of lactams
Authors: Sekiguchi Hikaru , Coutin Bernard
Published: April 2003

The anionic polymerization of lactams at low temperatures is not governed by thermodynamic equilibrium between the cyclic monomer and the linear polymer. On the basis of our reaction mechanism we propose therefore a new criterion (in contrast to the thermodynamic one) for estimating the chemical polymerizability of lactam: kendo/klactam, where klactam is the rate constant of alkaline hydrolysis of the lactam and kendo that of the endocyclic imide bond in the corresponding N‐acyl lactam. The value thus found for α‐piperidone and giving the theoretical polymerizability of this lactam accounts, however, only partially for its low polymerizability. Finally, the behavior of α‐piperidone derivatives in α‐pyrrolidone polymerization, as well as that of α‐pyrrolidone and α‐piperidone in polymerization in the presence of inorganic salts such as LiCl and LiSCN, shows that the unusually low ability of this lactam to polymerize could be explained in terms of the hydrogen‐bond‐rich structure of the resulting polymer appearing at a lower stage of conversion than that of other lactams and which might encage the active site situated at the end of the growing chain and thus hinder the access of lactam anion.
Effect of chemical structure in photochromic polymers of the mercury thiocarbazonate series
Authors: Kamogawa Hiroyoshi , Watanabe Hideo
Published: April 2003

The effects of the chemical structure of the functional portion as well as the comonomer composition on the photochromic behavior of vinyl polymers containing mercury thiocarbazonate functional groups in the side chains were investigated. It was found that, for p‐acrylamidophenyl mercuric thiocarbazonate polymers, the uses of β‐naphthyl and strongly electron‐releasing p‐methoxyphenyl groups for the thiocarbazone residue provide absorption maxima shifted somewhat to longer wavelengths as compared with the use of unsubstituted phenyl groups, whereas the electron‐withdrawing o‐trifluoromethylphenyl group brings about much larger shifts towards shorter wavelengths, the o‐trifluoromethylphenyl group and those groups capable of exerting steric hindrances such as β‐naphthyl and o‐methylphenyl groups causing slower light and dark reactions too. The increase of free volumes in the polymers by regulating the comonomer composition, i.e., the lowering of Tg, was found to improve photochromic responses strikingly.
Hydrolysis of linear polyurethanes and model monocarbamates
Authors: Matuszak Michael L. , Frisch K. C. , Reegen S. L.
Published: April 2003

Alkaline hydrolysis of model carbamates, polyurethanes, and poly(urethane‐ureas) has been investigated. The model carbamates were based upon phenyl, benzyl, and cyclohexyl isocyanates. The polyurethanes and poly(urethane‐ureas) were prepared from tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), and 4,4′‐dicyclohexylmethane diisocyanate (H12MDI) and a poly(oxyethylene)glycol of 6000 molecular weight. Pseudo‐first‐order rate constants of hydrolysis were obtained in aqueous pyridine solution at 110°C, and second‐order rate constants were obtained in aqueous KOH solution for the model biscarbamates. Pseudo‐first‐order rate constants of hydrolysis were obtained in alcoholic KOH solution for the polyurethanes and poly(urethane‐ureas). The hydrolysis of the model carbamates showed that the stability increased in the following manner: phenyl < benzyl < cyclohexyl. The pseudo‐first‐order rate constants were dependent upon the pKb of the corresponding amines. The hydrolysis of the polyurethanes and poly(urethane‐ureas) showed that the stability increased in the following manner: aromatic < aralkyl < cycloaliphatic. It was shown that polyurethanes are more susceptible to alkaline hydrolysis than to acidic hydrolysis.
Properties of isocyanurate‐type crosslinked polyurethanes
Authors: Sasaki Nobuyoshi , Yokoyama Tetsuo , Tanaka Takehide
Published: April 2003

Polyurethane elastomers containing isocyanurate rings as crosslinking structure were prepared by crosslinking the prepolymers in N,N‐dimethylformamide solution with sodium cyanide catalyst. Physical properties such as gel fraction, swelling ratio, density, glass transition temperature, Young's modulus, tensile strength, and elongation at break were measured. The effects of diisocyanate structure, the degree of crosslinking, and the crosslinking structure on the properties of polyurethanes were studied. The stress–strain curves of isocyanurate‐type crosslinked polyurethanes prepared from poly(oxytetramethylene)glycol rose at lower extensions and gave higher tensile properties than those of triol‐cured and diamine‐cured polyurethanes. The observed high tensile properties were attributed to the rigid crosslinking structure of isocyanurate ring.
Radiation‐induced polymerization of glass forming systems. VI. Polymerization rate at higher conversion in binary systems
Authors: Kaetsu Isao , Ito Akihiko , Hayashi Koichiro
Published: April 2003

The effect of temperature and composition on the inflection point in the time–conversion curve and the saturated conversion was investigated in the radiation‐induced radical polymerization of binary systems consisting of a glass‐forming monomer and a solvent. In the polymerization of completely homogeneous systems such as glycidyl methacrylate (GMA)–triacetin and hydroxyethyl methacrylate (HEMA)–propylene glycol systems, the time–conversion curve has an inflection point at polymerization temperatures between Tvm (Tv of monomer system) and Tvp (Tv of polymer system). Such conversions at the inflection point changed monotonically between 0 and 100% in this temperature range. Tv was found to be 30–50°C higher than Tg (glass transition temperature) and a monotonic function of composition (monomer–polymer–solvent). The acceleration effect continued to 100% conversion above Tvp, and no acceleration effect was observed below Tvm. The saturated conversion in homogeneous systems changed monotonically between 0 and 100% for polymerization temperatures between Tgm (Tg of monomer system) and Tgp (Tg of polymer system). Tg was also a monotonic function of composition. No saturation in conversion was observed above Tgp, and no polymerization occurred below Tgm. In the polymerization of completely heterogeneous systems such as HEMA–dioctyl phthalate, no acceleration effect was observed at any temperature and composition. The saturated conversion was 100% above Tg of pure HEMA, and no polymerization occurred below this temperature in this system.
Photoinduced ionic polymerization. V. Coexistence of cationic and anionic polymerizations
Authors: Irie Masahiro , Tomimoto Setsuko , Hayashi Koichiro
Published: April 2003

Photopolymerization of a mixture of cyclohexene oxide and nitroethylene was carried out with the purpose of carrying out cationic and anionic polymerizations simultaneously in the same system. The excitation of the charge transfer band by light of wavelength longer than 390 nm gives rise to the polymerization of both monomers. No polymer was obtained in the dark. Additives affect the composition of the polymer, the rates of polymerization, and the molecular weight distributions. These data show that cationic polymerization of cyclohexene oxide and anionic polymerization of nitroethylene occurs simultaneously in this system.
ESR studies of methallyl monomers with redox systems
Authors: Izumi Zenzi , Rånby Bengt
Published: April 2003

The effects of three types of free radical initiators (HO·, H2N·, and H3C·) from redox systems, have been studied for four types of methallyl monomers, by use of ESR with a flow system. The structure, the relative concentrations, and the steric conformations of the monomer radical intermediates have been derived from the ESR spectra. In the case of H2N · and HO · addition to methallyl alcohol (MAA), methallyl amine (MAAm), and sodium methallyl sulfonate (SMAS), the ESR spectra of the reacting species are interpreted as monomer head radicals only (H2N · and HO · are added to the monomer tail). Methallyl acetate (MAAc) with HO ·, is an exception, giving hydrogen abstraction to form an allyl type radical. This reaction may influence the polymerization behavior of MAAc. The methallyl monomers behave differently from the allyl monomers, where appreciable amounts of monomer tail radicals were found in addition to the head radicals which were the main species. For methallyl monomers, this may be due to steric hindrance caused by the two substituents on the α carbon. The CH3 radicals add only to positively polarized reactive double bonds, i.e., in SMAS in this study, and allyl alcohol in a previous study. The coupling constants of β CH2 protons vary considerably with the substituents. For β1 protons, the coupling constants decrease in the order OH > CH3 > NH2. For β2 protons (allyl hydrogen), the coupling constants decrease in the order CH2OH > CH2NH2 > CH2OCOCH3Na, i.e., the constants decrease in the order of increased bulkiness of the groups. Some exceptions are interpreted as due to complex formation with Ti4+. The effects of pH of the reaction medium are largely those expected.
Effect of solvent on the reactivity of functional groups in polycondensation reactions
Authors: Ogata Naoya , Ikari Tokuo
Published: April 2003

The effect of solvent on solution or interfacial polycondensations was investigated in terms of selectivity and control of functional groups such as amine or hydroxyl groups toward polycondensation reactions. Solution polycondensation of a mixture of resorcinol (RL) and m‐xylyenediamine (m‐XD) with isophthaloyl chloride was affected by solvents to such extent as to change the course of the polycondensation reaction, and hexamethylenephosphoramide (HMPA) caused the formation of amide‐rich polymer, while tetrahydrofuran (THF) was a solvent favoring formation of a polyamide ester with a regular structure. Polycondensation of 3,3′‐dihydroxybenzidine (DHB) with isophthaloyl chloride yielded exclusively a linear polyamide in HMPA solution, while with aldehyde as a solvent polyester was obtained owing to the preservation of the amine group. Thus, it was found that the course of polycondensation reactions of monomers having different functional groups could be controlled by selection of a suitable solvent.
Formation and homolytic cleavage of the Ni(II)–styryl σ‐bond
Authors: Henrichi‐Olivé G. , Olivé S.
Published: April 2003

A Ni–carbon σ‐bond is formed from biscyclooctadienenickel(0) and styrene in the presence of organic acids. Homolytic cleavage of this bond gives free radicals. The mechanism of formation and disappearance of the radical‐supplying species is deduced from kinetic and other data. A competing coordinated ligand insertion reaction is discussed.
Radiation‐induced polymerization at high pressure of cis‐ and trans‐1,3,3,3‐tetrafluoropropene in bulk and with tetrafluoroethylene
Authors: Brown Daniel W. , Lowry Robert E. , Wall Leo A.
Published: April 2003

The radiation‐induced polymerization of cis‐ and trans‐1,3,3,3‐tetrafluoropropene in bulk and with tetrafluoroethylene was studied at pressures between 5000 and 15000 atm and temperatures between 21 and 100°C. At 103 rad/hr the homopolymerization rates range from about 10−4 to 1%/hr. The activation enthalpy and volume are about 8 kcal/mole (33 kJ/mole) and −10 cm3/mole, respectively, for both isomers. The cis isomer polymerizes about twice as rapidly as the trans isomer. The latter freezes in the experimental range of temperature and pressure; the polymerization rate is very low in solid phase. Polymer intrinsic viscosities increase with polymerization pressure and decrease with polymerization temperature; the largest value obtained was 0.23 dl/g. In the copolymerizations all reactivity ratios favor incorporation of tetrafluoroethylene by factors of 6–16. The preference is stronger when the trans isomer is used.
Fracture process and molecular kinetics of PMMA
Authors: Johnson F. A. , Radon J. C.
Published: April 2003

The critical value of the stress intensity factor,K1c, (fracture toughness) has been measured for poly(methyl methacrylate) (PMMA) over a wide range of testing speed (K≃ 4 toK̇≃ 50 × 106lb/in3/2‐sec) and temperature (from −197°C to +21°C) in air and inert gas, by use of single‐edge notch, double cantilever beam (normal and compact types) and instrumented impact tests. Some features of the toughness curves were found to be subject to time–temperature shifts and were explained in terms of relaxation motions of parts of the polymer molecule, (second‐order thermodynamic transitions). Correlation with published data on mechanical energy losses in vibration experiments, dielectric losses and NMR results provided an identification of the operative relaxations. The coincidence of the fracture mode transition in the glassy state with the peak of the β relaxation was observed and the trend ofK1cvalues in a transition region was attributed to the close relationship ofK1cto the complex modulus for the hard glassy state. Impact and propagating crack values ofK1chave been discussed in general terms, and the limitations of fracture mechanics in studying a time‐dependent material property have been considered in the light of recent rheological studies on the fracture of polymers.
Polymerization of styrene with chromium acetylacetonate–triisobutylaluminum catalyst system
Authors: Deshpande A. B. , Kale S. M. , Kapur S. L.
Published: April 2003

Styrene is polymerized with chromium acetylacetonate–triisobutylaluminum catalyst at 40°C in a benzene medium. At the stoichiometric ratio of Al/Cr of 4, the activity for polymerization was found to be maximum. Further, the kinetic studies were carried out at this ratio of Al/Cr of maximum activity. The kinetics of polymerization and the total activation energy around 10.00 kcal/mole suggest a coordinate anionic mechanism.
Phenylated polyimides: Diels‐Alder reaction of biscyclopentadienones with dimaleimides
Authors: Harris Frank W. , Norris Steve O.
Published: April 2003

A series of phenylated polydihydrophthalimides has been synthesized by the Diels‐Alder reactions of 3,3′‐(oxydi‐p‐phenylene)bis(2,4,5‐triphenylcyclopentadienone) and 3,3′‐(p‐phenylene)bis(2,4,5‐triphenylcyclopentadienone) with N,N′‐o‐, ‐m‐, and ‐p‐phenylenedimaleimide. The polydihydrophthalimides were soluble in dimethylformamide (DMF) and had intrinsic viscosities that ranged from 0.33 to 1.01, the polymers were dehydrogenated thermally and chemically to afford the corresponding phenylated polyphthalimides. The totally aromatic polyimides were also soluble in DMF but had intrinsic viscosities only as high as 0.41. The thermogravimetric analyses of the polyphthalimides showed breaks near 530°C in air and in nitrogen atmospheres.
Effect of oxygen on the polymerization of vinyl chloride. I. Kinetic features
Authors: Garton A. , George M. H.
Published: April 2003

The effect of oxygen on the liquid‐phase polymerization of vinyl chloride at 55°C in the presence of an added initiator, bis(4‐tert‐butylcyclohexyl) peroxydicarbonate (Perkadox 16), has been studied by the technique of tumbled dilatometry. With this method, at constant initiator concentration, the induction period showed a half‐order dependence on the initial oxygen concentration. At a constant initial oxygen concentration, the induction period varied inversely as the square root of the initiator concentration. Under the experimental conditions empolyed, the polyperoxy radicals with chloroalkyl (∼CH2ĊHCl) endgroups were not wholly scavenged by molecular oxygen but could undergo various decomposition reactions. The degree of conversion of the initial oxygen to peroxidic compounds did not exceed 30% by weight and was dependent on the shape of the reaction vessel empolyed. The existence of other oxidation products has been demonstrated. At 55°C, the average velocity constant for decomposition of the peroxide products from vinyl chloride, measured in dichloromethane solution, was found to be 8 × 10−5 sec−1. A kinetic scheme involving a predominant cross‐termination reaction is proposed to explain the experimental results.
Copolymerization of epichlorhydrin with maleic anhydride catalyzed by Zn(acac)2
Authors: Akimoto Akira
Published: April 2003

Copolymerization of epichlorhydrin (ECH) with maleic anhydride (MA) was investigated under several conditions. Zinc acetylacetonate [Zn(acac)2] was found to catalyze the alternate copolymerization of ECH with MA at a mild temperature, resulting in the formation of polyester, the structure of which was confirmed with the aid of infrared, NMR, and elemental analysis. From kinetic studies of copolymerization an apparent first order of reaction with respect to catalyst concentration and to monomer concentration with 1:1 mole mixture was established.

A possible initiation mechanism was discussed, and Zn(acac)2–MA complex was suggested to be an initiating species.
Friedel‐Crafts acylation reactions in copolymers of methyl methacrylate and styrene and in mixtures of the homopolymers
Authors: Grassie N. , Gilks J. , Moodie T. , Quietsch P. , Riordan P.
Published: April 2003

In the presence of SnCl4 in 1,2‐dichloroethane solution, copolymers of styrene and methyl methacrylate undergo a Friedel‐Crafts acylation reaction between the ester groups and the ortho position of adjacent styrene units to form a partial ladder polymer. This has been confirmed by infrared and ultraviolet spectral analysis and by observing the influence of substituted styrenes on the rate of the reaction. A similar reaction can be induced to occur between polystyrene and poly(methyl methacrylate). Thermal analysis measurements demonstrate that the degradation properties of copolymers of styrene and methyl methacrylate are profoundly changed by this treatment.
Four‐center type photopolymerization in the crystalline state. VI. Kinetic and structural study of the polymerization ofp‐phenylenediacrylic acid diethyl ester
Authors: Nakanishi Hachiro , Nakanishi Fusae , Suzuki Yasuzo , Hasegawa Masaki
Published: April 2003

The effect of temperature on the four‐center type photopolymerization has been investigated forp‐phenylenediacrylic acid diethyl ester over a wide temperature range including crystal transition point (56°C) and melting point (96°C) of monomer. With the elevation of temperature between −50 and 15°C, the polymerization rate in the initial stage increased and the degree of polymerization decreased monotonously, while the rate in the later stage decreased above −25°C. With irradiation at above 25°C, the monomer crystals became sticky, and the polymerization was suppressed at the stage of oligomerization with low conversion. This tendency was enhanced above the crystal transition point, giving mainly dimer in low yield. Above the melting point, only radical polymerization occurred with the aid of oxygen. The steric configuration of the products in the crystalline state was 1,3‐transwith respect to the cyclobutane ring. Peaks in NMR spectra of all products were assigned to the protons involved in four compounds up to tetramer. Various results obtained have been interpreted in terms of the change, as a function of temperature, from a topochemical polymerization which proceeds under a control of the monomer lattice to a photoinitiated vinyl‐type polymerization in the disordered state. It is concluded that a rigid crystal lattice is indispensable for the four‐center type photopolymerization to proceed smoothly.
Preparation and properties of poly(imide‐oxoisoindolobenzothiadiazine dioxides)
Authors: Imai Yoshio , Koga Hiroshi
Published: April 2003

New thermally stable poly(imide‐oxoisoindolobenzothiadiazine dioxides) (PIOD) have been prepared by the three‐step cyclopolycondensation reaction of diaminobenzenesulfonamides with aromatic tetracarboxylic dianhydrides. The polymerization proceeded through the formation of poly(amic acid‐sulfonamides) (PAAS), followed by cyclodehydration to yield polyimide‐sulfonamides (PIS), which were subsequently converted to PIOD at 300°C. PAAS having inherent viscosities in the range of 0.1–0.5 in N‐methyl‐2‐pyrrolidone (NMP) were obtained in approximately quantitative yield. PIOD were insoluble in most organic solvents, whereas PAAS and PIS were soluble in NMP and dimethyl sulfoxide. Differential thermal analysis and thermogravimetric analysis indicated that PIOD began to decompose at 460°C in air. The cyclodehydration of the model compounds was also investigated.
Polymerization mechanism of vinyl chloride with titanium tetrabutoxide–ethylaluminum sesquichloride catalyst and some physical properties of poly(vinyl chloride) prepared at low temperature
Authors: Mitani Katsuo , Ogata Takayuki , Awaya Hiroshi
Published: April 2003

The mechanism of vinyl chloride polymerization by titanium tetrabutoxide–ethylaluminum sesquichloride catalyst system was investigated from the view of the stereoregularity of poly(vinyl chloride). The samples were prepared at a selected temperature in the range from 23 to −78°C. The tactic triads, obtained from 220‐MHz NMR spectra, show clearly the adequacy of Bernoullian statistics in describing the mechanism for stereochemical propagation. The chain propagation proceeds according to Bernoullian statistics with syndiotactic placements favored by 550 cal/mole. These results suggest that vinyl chloride polymerizes by a free‐radical mechanism under the action of the present catalyst system.
Development of free radicals in sulfonated polystyrene ion‐exchange resins upon drying
Authors: Von Goldammer E. , Conway B. E. , Paskovich D. H. , Reddoch A. H.
Published: April 2003

On exhaustive drying of sulfonated polystyrene‐based ion‐exchange resins, it is shown that free‐radical centers develop. These have been examined by electron‐spin resonance spectroscopy. The formation of the free radicals is largely reversible with respect to desorption and sorption of water which was measured by means of a quartz spiral microbalance. The spin‐concentration isotherm as a function of sorbed water concentration is obtained. The presence of free radicals, dependent on water content in the resins, interferes with proton magnetic relaxation studies of hydration of ionized resins by providing a faster electron‐spin coupled nuclear magnetic relaxation mechanism.
Aging and degradation of polyolefins. I. Peroxide‐initiated oxidations of atactic polypropylene
Authors: Niki Etsuo , Decker Christian , Mayo Frank R.
Published: April 2003

Efficiencies of polymer radical production by thermal decomposition of di‐tert‐butylperoxy oxalate (DBPO) have been measured in bulk atactic polypropylene (PP) at 25–55°C; they range from 1 to 26%, depending on [DBPO], temperature, and presence of oxygen. Most of the polymer radicals thus produced disproportionate in the absence of oxygen but form peroxy radicals in its presence. Most of the pairs of peroxy radicals interact by a first‐order reaction in the polymer cage. The fraction that escapes gives hydroperoxide in a reaction that is half order in rate of initiation. In interactions of polymer peroxy radicals, in or out of the cage, about one‐third give dialkyl peroxides and immediate chain termination, two‐thirds give alkoxy radicals. About one‐third of the later cleave at 45°C; the rest abstract hydrogen to give hydroxy groups and new polymer and polymer peroxy radicals. The primary peroxy radicals from cleavage account for the rest of the chain termination. Cleavage of alkoxy radicals and crosslinking of PP through dialkyl peroxides nearly compensate. Up to 70% of the oxygen absorbed has been found in hydroperoxides. The formation of these can be completely inhibited, but cage reactions are unaffected by inhibitors. Concentrations of free polymer peroxy radicals have been measured by electron spin resonance and found to be very high, about 10−3M at 58–63°C. Comparison with results on 2,4‐dimethylpentane indicate that rate constants for both chain propagation and termination in the polymer are much smaller than those for the model hydrocarbon but that the ratio, kp/(2kt)½, is about the same.
Aging and degradation of polyolefins. IV. Thermal and photodecompositions of model peroxides
Authors: Mill Theodore , Richardson Harold , Mayo Frank R.
Published: April 2003

There appear to be no unusual effects of phase change or near‐ultraviolet radiation on the reactions of alkoxy radical models for atactic polypropylene. The oxidation of purified atactic polypropylene by singlet oxygen is not an important process at 50°. Photochemical and thermal cleavages of tert‐amyloxy radicals, a model for polypropylene oxy radicals, give nearly the same ratio of ka/kd at 50°C. Photochemical cleavage of the model compound 1,1‐dinonylethyl hydroperoxide (10‐methyl‐10‐nonadecyl hydropenoxide) gives exclusive cleavage of a nonyl group both in solution and in polypropylene film at 50°C.