bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymerization of tetrahydrofuran by AlEt3–H2O promoter system: Rate of propagation reaction
Authors: Saegusa Takeo , Imai Hirosuke , Matsumoto Shu‐Ichi
Published: April 2003

Kinetic studies were carried out on the polymerization of tetrahydrofuran with catalyst systems of aluminum alkyl–epichlorohydrin. As aluminium alkyl species AlEt3, AlEt3–H2O (1:0.1 to 1:1.0), and “oxyaluminum ethyl” were employed. The polymerizations with these catalysts are characterized by a mechanism of stepwise addition without chain transfer or termination, which is expressed by the kinetic relation Rp = Kp[P*] ([M]–[M]e), where [M] and [M]e are the instantaneous and equilibrium concentrations of monomer and [P*] is the concentration of propagating species calculated from the amount and molecular weight of the product polymer. The determination of the rate constant kp for these catalysts has shown that the polymerization rate varied considerably with the change of aluminum alkyl species, i.e., with the water‐to‐aluminum ratio, but the propagation rate constant itself varied very little. The variation of polymerization rate was, therefore, attributed primarily to the differences in concentration of the propagating species, i.e. the efficiency of the catalyst in forming propagating species. The catalyst efficiency was closely related to the acid strength of the aluminum alkyl species, which was estimated from the magnitude of shift of the xanthone carbonyl band in the infrared spectrum of its coordination complex with aluminum alkyl. The maximal catalyst efficiency was attained at about [H2O]/[AlEt3] = 0.75.
Sorption of water vapor by poly(vinyl alcohol): Influence of polymer crystallinity
Authors: Takizawa Akira , Negishi Takao , Ishikawa Kinzo
Published: April 2003

The influence of crystallinity on water sorption behavior by poly(vinyl alcohol) (PVA) was studied by using a PVA of low crystallinity (15% crystalline by x‐ray analysis) and an annealed sample there from (46%) crystalline. With the increase of crystallinity, the sigmoid shape (which is a characteristic for the sorption isotherm of the low crystalline polymer) diminishes. The B.E.T. plots of the isotherms are linear between the relative vapor pressures of 0.1 and 0.4 as usual, and deviate from straight lines in the higher pressure range in the direction of a larger sorbed quantity than that predicted by the B.E.T. theory. This tendency is regarded as a kind of dissolution, and the Flory‐Huggins interaction parameter χ1 was calculated. In both polymers, the χ1 versus pressure relation has a maximum, while overall χ1 values are smaller in the polymer of low crystallinity. The maximum point (which lies in the higher pressure region in case of the less crystalline sample) is considered to be a transition point from a phenomenon controlled mainly by an adsorption mechanism to a phenomenon controlled mainly by a dissolution mechanism. Accordingly, the separation of the isotherm into adsorption and a dissolution components was made, and the polymer fraction which contributes to the dissolution mechanism versus pressure relation was calculated. The result indicates that the crystalline region observed by x‐ray analysis may partly contribute to the dissolution process at room temperature.
Lithiation of diene polymers
Authors: Minoura Yuji , Shiina Kyo , Harada Hiroshi
Published: April 2003

It was found that the metallation of diene polymers with n‐butyllithium in n‐heptane takes place in the presence of a tert amine, i.e. N,N,N′,N′‐tetramethylethylenediamine. Butyllithium was added to the diene polymer in n‐heptane in the presence of an equimolar amount of the amine, and the mixture was allowed to react at 80°C. for 60 min. under nitrogen. As a result, 27% and 9% per monomer unit for polybutadiene and polyisoprene, respectively, were metallated. The effects of the concentrations of the diene polymer, butyllithium, and the amine on the reaction were studied at 80°C., and the reaction mechanism was discussed. The overall rate of metalation was proportional to the diene polymer concentration and to the square root of the butyllithium concentration. The overall activation energies of metalation were 6.6 and 8.4 kcal./mole for polybutadiene and polyisoprene, respectively. Many kinds of polymer derivative were obtained by treating the metalated polymers with various reagents, such as carbon dioxide, Michler's ketone, trimethylchlorosilane, triphenylchlorosilane, benzaldehyde, and pyridine.
Photochemical crosslinking of polypropylene
Authors: Kujirai C. , Hashiya S. , Furuno H. , Terada N.
Published: April 2003

A study was carried to determine experimentally the crosslinking of irradiated polypropylene by ultraviolet rays in vacuo. Three methods of detecting crosslinking were used: measuring the degree of swelling in decalin at room temperature, measuring the gel fraction in a tetrachloroethylene solution of the irradiated sample, and comparing the infrared spectra before and after irradiation. It was found that as the time of irradiation increases, the degree of swelling decreases, whereas the gel fraction in tetrachloroethylene solution increases. This shows that the crosslinking reaction proceeds with time. On the other hand, the infrared spectra of the irradiated sample remained almost unchanged, which shows that different bond species can hardly be formed by irradiation in vacuo. From these facts it may be concluded that the measurements amply confirm the hypothesis. Furthermore, it is demonstrated that ash residue in polypropylene plays an important role in photocrosslinking; that is, the photochemical primary process of the reaction is the absorption of light by the ash residue.
Direct determination of crosslinking and chain scission in polymers
Authors: Kells D. I. C. , Koike M. , Guillet J. E.
Published: April 2003

A direct method has been developed for determining G(crosslinks) for irradiated polymers using the analytical ultracentrifuge. The sedimentation velocity technique is employed to follow changes in the molecular weight of a narrow distribution polystyrene sample irradiated in vacuum with 60Co γ‐rays. It is shown that G(crosslinks) can be determined at low doses before significant structural changes have occurred in the polymer. At about one‐fifth of the gel dose G(crosslinks) was found to be 0.019 compared to a value of 0.040 obtained from gel‐sol fraction measurements. It is concluded that G(crosslinks) may increase with dose due to processes such as the addition of radicals to double bonds formed during the irradiation.
Liquid carbon dioxide as a solvent for the radiation polymerization of ethylene
Authors: Hagiwara Miyuki , Mitsui Hiroshi , Machi Sueo , Kagiya Tsutomu
Published: April 2003

The usefulness of liquid carbon dioxide as a solvent for polymerization of ethylene was studied. The effect of liquid carbon dioxide on the polymerization was investigated under conditions of the pressure of 400 kg./cm.2 over the temperature range 20–45°C. by using γ‐radiation and AIBN as initiators. The infrared spectrum of the polymers showed that carbon dioxide had little effect on the polymer structure. The polymers contained no combined carbon dioxide and only small amounts of vinylidene unsaturation. The methyl content of the polymers was 0.5–4.0 CH3/1000C. The polymer yield and molecular weight were found to be decreased by the addition of carbon dioxide in both polymerization by γ‐radiation and AIBN. The number of polymer molecules formed per unit time increased with the content of carbon dioxide in the γ‐ray polymerization, and was constant in the case of AIBN. The advantages of the use of liquid carbon dioxide as a solvent in this polymerization were also considered from the viewpoints of the continuous process, the separation of polymer, the stability of carbon dioxide to radiation, and commercial applications.
Kinetics of the γ‐radiation‐induced polymerization of ethylene in liquid carbon dioxide
Authors: Hagiwara Miyuki , Mitsui Hiroshi , Machi Sueo , Kagiya Tsutomu
Published: April 2003

The γ‐radiation‐induced polymerization of ethylene with the use of liquid carbon dioxide as a solvent, was studied from the viewpoint of kinetics. The polymerization was carried out at conversions less than 10% under the pressure ranging from 100 to 400 kg./cm.2, dose rates 1.3 × 104−1.6 × 105 rad/hr., and temperatures of 20–90°C. The concentration of carbon dioxide varied up to 84.1 mole‐%. The polymerization rate and the polymer molecular weight were observed to increase with reaction time. This observation, however, becomes less pronounced with increasing concentration of carbon dioxide and with rising temperature. The exponents of the pressure and the dose rate were determined to be 2.3 and 0.85 for the rate, and 2.0 and −0.20 for the molecular weight, respectively. From the kinetic considerations for these results, the effect of carbon dioxide on the initiation and termination reaction in the polymerization was evaluated.
Emulsion polymerization. II. Review of experimental data in the context of the revised Smith‐Ewart theory
Authors: Gardon J. L.
Published: April 2003

Tables are presented for convenient calculation of the basic parameters of the revised Smith‐Ewart theory. For the methyl methacrylate (MMA)/sodium lauryl sulfate (SLS)/K2S2O8, and for the styrene/SLS/K2S2O8 reaction mixtures parameters are presented from which the absolute values of the following quantities can be conveniently calculated for any temperature, soap, and initiator concentration: particle number, particle radius, conversion where particle nucleation stops, rate and molecular weight in interval II, the interval after completion of particle nucleation and before the disappearance of monomer droplets. The theoretical predictions are compared to new experimental data and to those from the literature. The available data confirm the theoretical prediction that particle nucleation stops after a very small amount of polymer is formed, of the order of 0.01 cc. polymer/cc. water in most recipes. The theory and experiments are in good qualitative agreement for the conversion rate prior to completion of particle formation: the conversion rate rises with time and, when particle nucleation stops, it levels off. Excellent quantitative agreement can be obtained between theoretical and experimental particle size values. In the experiments of this laboratory the SLS concentration was varied 60‐fold, the K2S2O8 concentration was varied 140‐fold and the difference between theoretical and experimental poly(MMA) particle radii was always less than about 20%. Similar good agreement was obtained for polystyrene over the temperature range 30–90°C. Some polystyrene data from the literature with carboxylic soaps give just as good fit as the data with SLS of this laboratory. The predicted proportionality between particle number and the product of 0.6 power of soap concentration and of 0.4 power of initiator concentration was observed for several monomers. The theoretical predictions for the rate and molecular weight obtained in interval II are valid only for relatively low initiator and high soap recipes. For recipes for MMA and styrene the rate data are in good agreement with those calculated from the theory. The theory also correctly predicts the order of magnitude of the experimental molecular weights. For several monomers the rate and molecular weight vary with initiator and soap concentrations in a manner close to theoretical predictions.
Cationic polymerization of cyclic dienes. V. Polymerization of the methylcyclopentadiene
Authors: Kohjiya Shinzo , Imanishi Yukio , Okamura Seizo
Published: April 2003

Methylcyclopentadiene (MCPD) has been polymerized with cationic catalysts in toluene solution at −78°C. to a white powdery polymer, whose intrinsic viscosity in benzene solution at 30°C. ranged from 0.1 to 0.5. The comparison of the rate of homopolymerization of MCPD with that of cyclopentadiene (CPD) and the copolymerization of MCPD and CPD indicated that MCPD is much more reactive than CPD. It was suggested that the high stability of cycloalkenyl cation is responsible for the high reactivity of cyclic dienes. Infrared and NMR spectroscopy on polymethylcyclopentadiene showed that almost all of the monomer units in polymethylcyclopentadiene produced under the present conditions have a trisubstituted double bond. The mechanism of the initiation reaction in the polymerization of cyclic dienes is also discussed.
Electron‐transfer polymers. XXX. Preparation of poly(1‐vinyl‐3,4,6‐trimethyl‐2,5‐benzoquinone)
Authors: Nakabayashi Nobuo , Wegner Gerhard , Cassidy Harold G.
Published: April 2003

1‐Vinyl‐3,4,6‐trimethyl‐2‐methoxy‐5‐hydroxy‐benzene (I) was prepared in good yield by the Wittig reaction from the corresponding chloromethyl compound. It could be polymerized cationically to low molecular weight material. The polymer could be oxidized to poly(1‐vinyl‐3,4,6‐trimethyl‐2,5‐benzoquinone) (III) and could be reduced to the corresponding hydroquinone. Compound (I) was acetylated at the phenolic hydroxyl group and polymerized. The acetyl group was quantitatively reduced with lithium aluminum hydride, and the resulting polymer could be oxidized quantitatively to (III). Its molecular weight was a little higher than that prepared directly from (I).
Kinetics of the polymerization of tetrahydrofuran in the presence of water
Authors: Kučera M. , Hladký E. , Majerová K.
Published: April 2003

The polymerization of tetrahydrofuran was studied with regard to the presence of polar and nonpolar compounds, or well‐solvating and poorly solvating compounds, respectively. Tetrahydrofuran is highly nucleophilic, with a high solvation ability. It is capable of activating the native initiator itself and can be polymerized without any added cocatalyst. The addition of water to the tetrahydrofuran–initiator system decreases the polymerization rate. However, the dependence of the polymerization rate on the concentration of water in the dilute tetrahydrofuran runs through a maximum. The reaction rate is a function of the position of an equilibrium established during the solvation of initiator. All components of the system take part in the establishment of equilibrium.
Polymerization of styrene with VCl4–aluminum alkyls
Authors: Anand L. C. , Dixit S. S. , Kapur S. L.
Published: April 2003

Polymerization of styrene has been carried out with VCl4–AlEt3 and VCl4–Al(i‐Bu)3 catalyst systems. These two systems have been found to behave in a similar manner but their behavior is different from those systems where VOCl3 has been used instead of VCl4. Reaction is first order with respect to monomer concentration for both the systems and first order with respect to catalyst in the case of VCl4–AlEt3. In the case of VCl4–Al(i‐Bu)3, the rate of polymerization is independent of catalyst concentration but intrinsic viscosities increase with increasing catalyst concentration. The average valence of vanadium in the catalyst complexes has been discussed in relation to nature of catalyst sites. Activation energy and effect of diethyl zinc support the anionic mechanism for the two systems.
Study of Ziegler‐Natta catalysts. Part I. Valence state and polymerization activity
Authors: Kollár L. , Simon A. , Osváth J.
Published: April 2003

Polymerization at temperatures lower than the temperature of catalyst formation induces no changes in the solid phase of the catalyst formed by Al(C2H5)3 + TiCl4. In polymerizations with catalysts of this class, maximum activity is observed when the titanium component of the catalyst is trivalent. Any different behavior indicates the presence of aluminum alkyl chlorides in the liquid phase of the catalyst.
Solid‐state initiation of polymerization of N‐vinylcarbazole by gases
Authors: Meyers R. A. , Christman E. M.
Published: April 2003

Chlorine gas has been shown by previous investigators to initiate the polymerization of solid N‐vinylcarbazole at room temperature, giving a maximum yield of 66% polymer after 18 hr. This initiation of polymerization of N‐vinylcarbazole without the application of heat, by a gas, is the only solid‐state initiation other than those that are radiation‐induced known to us. This study was undertaken in order to determine both the scope and the mechanism of the room‐temperature solid‐state initiation of vinyl polymerization of N‐vinylcarbazole by gases. The gases (HCl, Cl2, and N2O4) were absorbed by solid N‐vinylcarbazole, giving very rapid exothermic polymerization: HCl, 37% polymer yield, M̄n 2500; Cl2, 50% polymer yield, M̄n 4703; N2O4, 91% polymer yield, M̄n 7073. The gases NOCl, BF3, and HBr were not absorbed by N‐vinylcarbazole and did not initiate polymerization. The N2O4‐initiated polymerization, which gave a high yield of polymer, was complete within 5 min. after introduction of gas. This polymerization method and the resulting polymer compared favorably with conventional peroxide‐initiated melt polymerization and the polymer obtained thereform. The mechanism of gas‐initiated polymerization, which was studied with introduction of inhibitors, appears to be classically cationic in nature.
Dehydrochlorination reactions in polymers. Part III. Vinylidene chloride–styrene copolymers
Authors: Haldon R. A. , Hay J. N.
Published: April 2003

A systematic study of the effect of styrene units on the thermal stability of vinylidene chloride copolymers was made. In general, the copolymers were more easily dehydrochlorinated than the homopolymer. The copolymers eliminate HCl at rates that could only be interpreted in terms of styrene group activation. However, the elimination rate fell too rapidly with reaction extent to be accounted for by concentration changes or weak links and was consistent with retardation by the reaction products. The elimination was a radical process and accompanied by chain scission and crosslinking in competition.
Part II. Pyrolysis of a tetrafluoroethylene–acrylonitrile copolymer
Authors: Fock J.
Published: April 2003

The pyrolysis of copolymers obtained by radiation‐induced grafting of acrylonitrile onto polytetrafluoroethylene has been studied. Infrared spectroscopy shows disappearance of CN and appearance CN absorptions, indicative of the conjugation of the nitrile groups in the polyacrylonitrile segments. Aromatization is suggested by the appearance of aromatic CH absorption and by the disappearance of aliphatic CH absorption in the infrared spectra, as well as by the decrease of the C/H ratio and the constancy of the N content during exposure to 280°C. shown by elementary analysis. Melting and remelting was studied by differential thermal analysis with respect to temperature, extent, and shape of peak area. An increase in the melting temperature proportional to the content of acrylonitrile in the copolymer was explained in terms of entropy effects. The melting peak obtained after grafting appears as a doublet. The latter disappears after annealing for 14 hr. at 300°C. and does not reappear on crystallization or on remelting. In addition, the areas obtained on first and repeated meltings shows a decrease which is proportional to the content of grafted polyacrylonitrile. These results are taken as an indication of an exothermic reaction involving crosslinking. The rate of disappearance of the CN absorption reaches a maximum at the melting temperature. It seems that the exothermic reaction occurring in the crystalline region is identical with “propagation crosslinking” suggested by Grassie and Hay. It is concluded that an interesting new type of polymeric material has been found.
The preparation of polysiloxane–vinyl monomer graft and block copolymers
Authors: Minoura Yuji , Shundo Minoru , Enomoto Yasushi
Published: April 2003

In another paper the radical polymerization of styrene in the presence of various chlorosilanes was investigated, and polystyrenes having chlorosilyl groups as endgroups were obtained. In the present work attempts were made to obtain polysiloxane styrene graft and block copolymers from chlorosilyl polystyrenes. Block copolymers were obtained with dichlorosilane and graft copolymers with tri‐ and tetrachlorosilanes. In the latter case the insoluble fractions increased, if a suitable stopper, such as butanol or trimethylchlorosilane [(CH3)3SiCl], was not used in the condensation reaction. Methyldichlorosilane was used for the preparation of the graft copolymer, because the SiH bond was more effective than the SiCl bond for the chain transfer reaction.
Molecular weight distribution of liquid poly(ethylene glycols): Determination by gas chromatography
Authors: Fletcher J. P. , Persinger H. E.
Published: April 2003

The molecular weight distribution of liquid polyethylene glycols 200, 300, and 400 can be determined by gas chromatography by using trimethylsilyl ether derivatives. The relative response factors for the first five members of the homologous series were determined experimentally. Attempts are made to extrapolate the experimental data to relative response factors for higher members of the homologous series.
Polymerization of isocyanates. III. Chemical behavior and structure of polyisocyanates
Authors: Iwakura Yoshio , Uno Keikichi , Kobayashi Norio
Published: April 2003

The chemical behavior of polyisocyanates was investigated. Dissociation of the polymer to the monomer was observed directly by infrared spectra. Aminolysis of the polymer gave cyclic trimer and asymmetric urea as reaction products, and the formation of the latter was ascribed to the reaction of amine with the monomer dissociated from the polymer. It was concluded that polyisocyanates are composed of disubstituted amide structure only.
Aromatic polydiketopiperazines
Authors: Iwakura Yoshio , Izawa Shin‐Ichi , Hayano Fusakazu
Published: April 2003

Aromatic polydiketopiperazines have been prepared from bis‐2‐chloroacetamides of aromatic diamines in the presence of an epoxide as HCl acceptor and a quaternary ammonium halide catalyst. The structures of the polymers were characterized by infrared and NMR spectra. These polymers were soluble in organic acids such as formic acid, dichloroacetic acid, and trifluoroacetic acid but insoluble in common organic solvents such as dimethylformamide, dimethylacetamide, and dimethyl sulfoxide. Thermogravimetric analysis indicated that these polymers decomposed at 300–340°C.
Infrared studies of stereoregular polymerization of methyl methacrylate and methacrylonitrile by organometallic compounds
Authors: Fujimoto Taketoshi , Kawabata Nariyoshi , Furukawa Junji
Published: April 2003

Infrared spectra of reaction mixtures of methyl methacrylate or methacrylonitrile with an equimolar amount of organometallic compounds were investigated in relation to the stereoregulating ability of the catalysts in polymerization. It was found that the carbonyl or nitrile stretching frequency correlated with the stereoregularity of polymers prepared with the corresponding catalysts; i.e., the higher the frequency, the higher the isotacticity. From these results a mechanism of isotactic polymer formation was proposed, in which catalyst counterion was located near the carbonyl group in polymer terminal and that of monomer to be reacted, and consequently the isotactic polymerization is facilitated.
Contribution to the study of the mechanism of curing of unsaturated polyester resins
Authors: Fijolka Paul , Shahab Yousif
Published: April 2003

The mechanism of copolymerization of monomethyl and dimethyl maleates and fumarates with styrene was studied by analysis of the conformation of the acid units of the resulting copolymers. The absorption bands for CO stretching and OH stretching in the spectra of the copolymers are fully identical. They are quite different from the spectra of the copolymers obtained from maleic anhydride and styrene that are subsequently treated with absolute methanol to give the monoester which is then esterified with diazomethane to give the diester. The acid units of the copolymers derived from maleic anhydride exist in a gauche configuration; copolymers derived from fumaric units exist in a trans conformation. The identity of copolymers derived from maleic units with those derived from fumaric units but not with those derived from maleic anhydride indicates that the first step in the copolymerization of the maleic units is an isomerization to fumaric units, which are actually the genuine comonomers.
Investigation of reactions in carboxyl‐terminated polybutadiene and tris‐[1‐(2‐methyl)aziridinyl] phosphine oxide
Authors: Strecker R. A. , Tompa A. S.
Published: April 2003

The functionalities of a series of carboxyl‐terminated polybutadiene samples (CTPB) were calculated from an infrared spectroscopic study of the samples reacting to the gel point with tris‐[1‐(2‐methyl)aziridinyl] phosphine oxide (MAPO), Epon X801, and glycerol. Identical functionalities were calculated when Epon X801 and glycerol were used as curing agents. Higher functionalities for CTPB with MAPO were due to additional reactions that MAPO underwent with hydroxyl groups and water, present in carboxyl‐terminated polybutadiene, and with itself (homopolymerization). Rate constants were calculated for the homopolymerization of MAPO in Nujol, in nonfunctional polybutadiene, and in CTPB. The homopolymerization resulted in an increase and then a gradual decrease in MAPO functionality, which was in agreement with that predicted from theoretical considerations.
Preparation and copolymerization of vinyl 10,11‐epoxyundecanoate
Authors: Chow Roberta C. L. , Marvel C. S.
Published: April 2003

Vinyl 10,11‐epoxyundecanoate has been copolymerized with vinyl chloride and vinyl acetate to give film‐forming copolymers which are readily converted to insoluble materials.
Monomer reactivity ratios for the copolymerization of styrene with 1,2,4‐trivinyl and p‐divinylbenzenes
Authors: Wiley Richard H. , Ahn Tae‐Oan
Published: April 2003

The copolymerization kinetics of 1,2,4‐trivinylbenzene (TVB) with styrene do not clearly resemble those of o‐, m‐, or p‐divinylbenzene (DVB), structural elements of which are present in TVB. A control determination of the reactivity ratios for the styrene‐p‐DVB pair under different conditions (70°C., pre‐gel point conversion), run for comparison with the TVB data, show values (r1 = 0.77; r2 = 1.46) similar to those previously recorded (r1 = 0.77; r2 = 2.08).
Electron spin resonance study of the radiation‐induced polymerization of N‐vinylcarbazole
Authors: Ayscough P. B. , Roy A. K. , Croce R. G. , Munari S.
Published: April 2003

When crystals of N‐vinylcarbazole are γ‐irradiated at 77°K., the ESR spectrum observed before warming consists of three peaks attributed to a radical–cation with the unpaired spin associated mainly with the nitrogen atom. Above 90°K. polymerization occurs, initiated by the cation, and the spectrum changes to that of an alkyl type of radical, NĊHCH2, trapped in the polymer. Single crystals were used for a detailed analysis of the nuclear hyperfine parameters of the observed radicals.
Polyisonitriles. II. Heterophasic catalytic synthesis of poly(α‐phenylethylisonitrile) and of poly(n‐hexylisonitrile)
Authors: Millich Frank , Sinclair R. G.
Published: April 2003

A three‐component catalytic system has been discovered, which successfully polymerizes α‐phenylethylisonitrile to high polymer (DP = 200–900) and also polymerizes n‐hexylisonitrile. The catalyst components are a strong acid, a free‐radical source, and a heterophase and are all necessary in this system. The use of a liquid medium in which the polymer is insoluble promotes the rate of polymerization and total yield. Poly(α‐phenylethylisonitrile), formed from monomer in a presence of oxygen and finely ground glass coated with sulfuric acid, can itself serve, in the presence of monomer and oxygen, as a catalyst for this polymerization. Preparative details and discussion of these synthesis factors are given.
Linear polyhydrazides
Authors: Takahashi Hiroshi , Hasegawa Masaki
Published: April 2003

Linear polyhydrazides have been obtained successfully by heating diphenyl dicarboxylate with 1,6‐dihydrazino hexane. The structure of the polymers was established by the N‐deuteration method. The resulting polymers have many remarkable characteristics, such as high water‐absorption ratio (20–100%), basic character (pKa = 3.15), the ability to form a metal complex, and the power to initiate vinyl polymerization as a cocatalyst with ferric ion.
The stereoregularity of polyacrylonitrile and its dependence on polymerization temperature
Authors: Matsuzaki Kei , Uryu Toshiyuki , Okada Munehisa , Shiroki Hiroyuki
Published: April 2003

The stereoregularity of polyacrylonitrile was studied by NMR spectroscopy. The methylene protons in isotactic configuration are equivalent in dimethylformamide‐d7 solution and are nonequivalent in dimethylsulfoxide‐d6 solution. In the case of the latter solution the difference in chemical shift between the isotactic methylene protons is 6.6 cps. The stereoregularity of polyacrylonitrile‐α‐d instead of polyacrylonitrile was determined on the dimethylformamide‐d7 solution. In the radical polymerization all the polyacrylonitrile‐α‐d's that polymerized at temperatures between 80 and −78°C. have a configuration consisting of about 50% of isotactic diads and, accordingly, the stereoregularity of polyacrylonitrile does not depend upon the polymerization temperature. Analysis of the NMR spectra of isotactic polyacrylonitrile prepared from acrylonitrile–urea canal complex was also carried out. The NMR spectra of meso‐ and dl‐2,4‐dicyanopentanes, dimer models of isotactic and syndiotactic polyacrylonitriles, respectively, were analyzed by a computer program proposed by Bothner‐By.
Determination of concentration of propagating species in cationic polymerization of tetrahydrofuran
Authors: Saegusa Takeo , Matsumoto Shu‐Ichi
Published: April 2003

A spectroscopic method is described for the determination of the concentration of propagating species, [P*], in the polymerization of tetrahydrofuran catalyzed by a mixture of AlEt3−H2O (1:0.5) and epichlorohydrin. A phenyl ether group was introduced at the polymer chain end by the quantitative reaction of the propagating species with excess sodium phenoxide. From the amount of phenyl ether groups in the polymer and of the remaining sodium phenoxide, [P*] was determined by means of ultraviolet spectroscopy. The [P*] value so determined was found to be in good agreement with that calculated from the amount and molecular weight of polymer based on a stepwise addition mechanism without chain transfer or termination. The present method of [P*] determination was employed to examine the course of polymerization. It has now been found that [P*] increases progressively during an induction period and remains unchanged in the subsequent period of polymerization.
Relaxations of selenium in crystalline and amorphous states
Authors: Nishi Toshio , Wada Yasaku
Published: April 2003

Complex shear modulus at 33 kc./sec. is measured at temperatures of −150–150°C. for amorphous selenium and crystalline selenium with different crystallinities. The dielectric relaxation at 10 kc./sec. to 3 kc./sec. to 3 Mc./sec. is observed at temperatures of −32–25°C. for iodine‐doped crystalline selenium. It is concluded from the results of this study and of others' that selenium exhibits four relaxations, α, β γ, and δ, in order of descending temperature. The β relaxation is observed only in the amorphous sample above the glass temperature and is assigned to the primary relaxation. The α, γ, and δ relaxations are found in the crystalline selenium. The α relaxation, which is prominent in a highly crystalline sample, is assigned to the crystalline relaxation. The γ and δ relaxations increase in peak height with decreasing crystallinity and are attributed to the disordered region in the crystalline selenium. The dispersion map (logarithm of frequency versus reciprocal absolute temperature of loss maximum) of selenium is presented.
Electrical conductivity of N‐substituted polyamides
Authors: Kasica H. , Kryszewski M. , Szymaniski A. , Włodarczyk M.
Published: April 2003

The electrical volume and surface resistivity of some poly(N‐chloroalkoxylmethyl caproamides) were measured as a function of voltage at 39% R. H. and under vacuum. The results were compared with non‐N‐substituted polycaproamide. Polarization and depolarization phenomena were observed. The mechanism of conduction is discussed, and important deviations from Ohm's law, observed in dry samples, suggest that charge carriers are injected from the electrodes and that the current–voltage characteristics may be interpreted on the assumption of space‐charge‐limited current theory.
Reaction between ethanol and silicon–hydrogen of poly(p‐vinylphenyldimethylsilane)
Authors: Iwakura Yoshio , Toda Fujio , Hattori Kenjiro
Published: April 2003

A kinetic approach to the polymer reaction, with KOH as catalyst, between ethanol and poly(p‐vinylphenyldimethylsilane) containing silicon–hydrogen as a functional group on the side chain was carried out. The rate equation was obtained by measuring the initial rate of the model reaction as v = k[KOH] [SiH] [EtOH] in benzene and v = k[KOH] [SiH] in methyl ethyl ketone. It was observed that the rate of reaction was affected by the polarity of the solvents. In the polymer reaction the rate constant decreased markedly with increasing ethanol concentration. A change of viscosity of the polymer in various solvents was observed to have a good correlation with the decrease in reaction rate in corresponding solvents. In mixed solvents, consisting of both good and poor solvents for the polymers, the reaction rate depended upon two factors, the entanglement of the polymer chain and the polarity of the solvents. The equivalent globular model of the polymer chain is suggested for study of the polymer reaction. A schematic local‐distribution curve of the reaction species is proposed.
Solvent effect on NMR spectra of poly(methyl methacrylate)
Authors: Nagai Makoto , Nishioka Atsuo
Published: April 2003

The NMR spectra of stereoblock poly(methyl methacrylate) in several solvents were measured. It is concluded from the following experimental results that the solute–solvent complexes are formed in benzene solution: the chemical shifts measured in C6H6 go to a lower field than do those in CDCl3, except those of the ester methyl group, which splits into three resonances, and the shifts in the aromatic solvents are so different from those in the aliphatic solvents that Buckingham's theory cannot be applied to the results. The analysis of the temperature dependence of the chemical shifts of PMMA in benzene solution gave the heat of formation of the complex: ΔH = 2.8 ± 0.5 kcal./mole.
Study of the substitution pattern of hydroxyethylcellulose and its relationship to enzymic degradation
Authors: Wirick M. G.
Published: April 2003

The concentration of completely unsubstituted anhydroglucose (AHG) units in hydroxyethylcellulose (HEC) at varying average number of moles of substituent (MS) is in accord with a reaction rate ratio of 3:1:10:10 for the etherification of the C2, C3, C6, and side chain hydroxyls. Assuming random substitution along the cellulose chain at these relative reaction rates, the degree of substitution (DS), average poly(ethylene oxide) side‐chain length, and probably frequency of isolated and multiple adjacent unsubstituted AHG units have been projected as functions of MS. Such estimates of DS and side‐chain length compare favorably with actual measurements made on a variety of samples by other investigators below a substitution level of 2.0 MS. Reducing end, intrinsic viscosity, and ultracentrifuge data on enzymically hydrolyzed HEC's varying from 1.9 to 3.7 in MS indicate resistance to chain scission is a function of substitution, best expressed in terms of a proposed substitution index, the percentage of substituted AHG units. The rate of chain scission under carefully controlled conditions is initially rapid, tapering to a very slow, essentially steady level. On relating the frequency of chain breaks to the predicted substitution pattern of these samples, this behavior is interpreted to mean that scission occurs relatively rapidly at multiple contiguous unsubstituted sequences, but much more slowly adjacent to isolated unsubstituted AHG units. A possible mechanism of enzyme attack, correlating molecular chain breaks with glucose released, has been developed.
Thermally stable polymers from 1,4,5,8‐naphthalenetetracarboxylic acid and aromatic tetraamines
Authors: Van Deusen R. L. , Goins O. K. , Sicree A. J.
Published: April 2003

Polycondensations of 1,4,5,8‐naphthalenetetracarboxylic acid (NTCA) with both 3,3′‐diaminobenzidine (DAB) and 1,2,4,5‐tetraaminobenzene tetrahydrochloride (TAB) in polyphosphoric acid (PPA) were found to produce soluble polymers which exhibit excellent thermal stabilities. Polymer structures were deduced from infrared, thermal, and elemental analyses of model compounds and polymers. Polymer derived from TAB had a ladder‐type structure. Polymers with solution viscosities near 1 or above (determined in H2SO4) were obtained from polymerizations near 200°C., and analysis showed these to possess a very high degree of completely cyclized benzimidazobenzophenanthroline structure. Less vigorous reaction conditions gave polymers with lower solution viscosities which appeared to be less highly cyclized. Low‐viscosity polymer was also prepared from DAB and NTCA by solid‐phase polycondensation. Some advancements in the solution viscosities of polymers synthesized from DAB in PPA were caused by second staging in the solid phase.
Retardation of discoloration of poly(vinyl chloride) and decolorization of discolored poly(vinyl chloride) with diimide
Authors: Nakagawa Tsutomu , Okawara Makoto
Published: April 2003

Retardation of discoloration of poly(vinyl chloride) with diimide was studied in dimethylformamide at 130°C. with the use of p‐toluenesulfonylhydrazide (PSH) as a source of diimide. A process was proposed that involved prolonging the induction periods of discoloration by inhibiting the development of conjugated polyene structure. The optimum proportion of PSH was one fourth of the poly(vinyl chloride), the best results. Furthermore, poly(vinyl chloride) discolored by thermal degradation in o‐dichlorobenzene or gamma‐ray irradiation under vacuum was decolorized in solution at 130°C. by addition of PSH. The decolorized poly(vinyl chloride) thus obtained was thermally stable compared with that obtained by oxidative methods.
Effects of metal salts on polymerization. Part V: Polymerization of N‐vinylcarbazole initiated by sodium chloroaurate
Authors: Tazuke Shigeo , Asai Michihiko , Okamura Seizo
Published: April 2003

The polymerization of N‐vinylcarbazole (VCZ) initiated by sodium chloroaurate (NaAuCl4·2H2O) in nitrobenzene was studied at 30°C. The rate of polymerization (Rp) is proportional to [AuIII] [VCZ] after a short induction period. When reducing agents (ascorbic acid, ferrocene, or mercury metal) are added to the system, the rate of polymerization in the dark increases. The Rp is relatively unaffected by addition of water and N‐ethylcarbazole, but the polymerization is completely inhibited in the presence of ammonia. Oxygen and DPPH act as neither inhibitors nor retarders. Kinetic treatments based on the assumption that the active initiating species is AuII produced by reduction of AuIII by VCZ and other reducing agents explain the experimental results very well.
Polymerization and copolymerization of α‐methacrylophenone
Authors: Mulvaney J. E. , Dillon J. G. , Laverty J. L.
Published: April 2003

Under a variety of conditions it has not been possible to induce the free‐radical‐initiated homopolymerization of α‐methacrylophenone (α‐MAP). The only product isolated from such efforts was the Diels‐Alder dimer of the monomer. A Mayo‐Lewis plot of the free‐radical copolymerization of α‐MAP and styrene shows considerable scatter but the copolymer composition indicates that an α‐MAP unit can add to itself. These results have been ascribed to a penultimate effect. α‐MAP is homopolymerized by dimsylsodium or n‐butyllithium. Attempted copolymerization of α‐map and styrene with n‐butyllithium produces >95% α‐MAP. Unexpectedly, α‐MAP does not homopolymerize with lithium dispersion, but does react in the presence of styrene to give product containing a relatively small amount of α‐MAP.
A new transition point of polyacrylonitrile
Authors: Okajima Saburo , Ikeda Morio , Takeuchi Akio
Published: April 2003

A polyacrylonitrile sample of molecular weight 78,000 was dissolved into a 15% solution in 70% aqueous HNO3, spun into an undrawn model filament with diameter 0.3 mm. using a 30% aqueous HNO3 as the coagulation bath. The fresh filament was drawn 4–16× in water at various temperatures (40, 65, and 75°C.) and then steamed at 90–180°C. Dynamic mechanical tests were carried out on these filaments at 138 cps and it was found that the steamed filaments had a new transition at about 160°C. in addition to the two well‐known transitions at 60–70°C. (β) and 110°C. (αa), although the unsteamed samples had only the two absorptions, αa and β. This newly found transition was designated αx. The αx was measured at 3.5, 11, and 110 cps from which the activation energy of this relaxational motion was estimated to be 95 kcal./mole. The αx peak height was lowered by stretching and recovered on resteaming; the change in the peak height was paralleled by the changes in the x‐ray crystallinity produced by the stretching and the resteaming. These phenomena lead us to a conclusion that the region contributing to the αx absorption is of considerably higher order than that of the αa transition with an activation energy about 50 kcal./mole and intimately related to the crystallinity, although it cannot be connected directly to the crystalline region itself because a single crystal mat did not show the αx.
Inorganic esters of novolacs
Authors: Dannels B. F. , Shepard A. F.
Published: April 2003

Reaction of conventional novolacs with polyfunctional materials is known to yield crosslinked infusible products. Surprisingly, high proportions of polyfunctional phosphorus derivatives can be esterfied with o,o′‐linked novolacs without encountering gelation. Soluble, fusible resins of high phosphate content, which possess improved flame retardance, are conveniently obtained. We attribute this result to the formation of cyclic esters in preference to crosslinking, as evidenced by the formation, in good yield, of the eight‐membered heterocyclic compound C27H31O4P from o,o′‐methylenebis(p‐tert‐butylphenol) and phenyl phosphorodichloridate. Relatively large amounts of polyfunctional derivatives of boron and silicon can also be reacted with o,o′‐linked novolacs, presumably in a similar manner. Novolacs partially reacted with phosphorus, boron, or silicon derivatives and retaining some phenolic hydroxyl cure readily with hexamethylenetetramine, yielding products exceptionally low in volatile loss at 400°C.
Determination of theoretical plates in gel permeation chromatography by using polydisperse materials (polymers)
Authors: Bly Donald D.
Published: April 2003

The need for an improved method of expressing performance of GPC columns and operating conditions is discussed. It is shown that theoretical plates can be calculated from chromatograms of high molecular weight materials (polymers) if the curve widths are normalized for polydispersity. The resulting value N, where N = 16d2(v/W)2, is a useful measure of the real plate count afforded by the columns to polymers and is useful for comparison purposes. Since N does not provide absolute data on separation, it is better to use formulas for resolution and fractionation when such data are needed.
Silicon‐containing amide, benzimidazole, hydrazide, and oxadiazole polymers
Authors: Kovacs Hanna Nagy , Delman Alvin D. , Simms Bernard B.
Published: April 2003

This study reports the synthesis of new silicon‐containing amide, benzimidazole hydrazide, and oxadiazole polymers. Procedures are described for the preparation of several intermediate compounds. The silicon‐containing polymers are soluble in organic solvents. Solution‐cast films from the polymers generally are flexible and exhibit good adhesion to glass and metal surfaces. Preliminary examination indicates that the polymers are heat‐stable at elevated temperatures.
Effects of methyl sidegroup on the extent of hydrogen bonding and modulus of polyurethane elastomers
Authors: Tanaka Takehide , Yokoyama Tetsuo , Yamaguchi Yukio
Published: April 2003

The effects of methyl sidegroup on the properties of polyurethane elastomers, mainly hydrogen bonding and elastic properties, were studied. Polyurethanes of almost equal crosslinking density and urethane group concentration, but with different side methyl groups, were prepared by a prepolymer method. The extent of hydrogen bonding was determined by an infrared technique. The density and Young's modulus are decreased by the introduction of methyl sidegroup, swelling ratio and Tg are increased, but the extent of hydrogen bonding is not affected.
Aminimides. V. Preparation and polymerization studies of trimethylamine‐4‐vinylbenzimide
Authors: Culbertson B. M. , Sedor E. A. , Dietz S. , Freis R. E.
Published: April 2003

Trimethylamine‐4‐vinylbenzimide (TAVBI) has been homo‐ and copolymerized with styrene, methyl methacrylate, and hydroxypropyl methacrylate by free‐radical initiators to soluble, low molecular weight polymers containing pendant aminimide groups along the backbone of the polymer molecules. The reactivity ratios in the copolymerization of TAVBI (M1) with styrene (M2) were determined: r1 = 0.63 ± 0.07, r2 = 0.47 ± 0.05. The Alfrey‐Price Q and e values for TAVBI were also calculated: Q = 0.88, e = 0.31. This introductory work indicates that TAVBI has potential for the preparation of a wide variety of reactive polymers.
The emulsion polymerization of vinyl acetate. Factors controlling particle surface area and rate of polymerization
Authors: Gulbekian E. V.
Published: April 2003

An emulsion polymerization system with uniform continuous addition of vinyl acetate monomer, Pluronic F68 surfactant, and persulfate initiator has been examined with variation of the surfactant concentration over a tenfold range. The particle surface area per unit weight of emulsion was found to vary directly as the surfactant/monomer ratio, as also did the emulsion viscosity. At constant polymer/emulsion weight the number of particles per unit emulsion weight varied directly as the cube of the surfactant concentration. It is shown that these relationships apply also to other monomers, such as styrene and methacrylate esters. The solubility of vinyl acetate in a range of Pluronic F68 aqueous solutions was determined, and it was shown that the rate of polymerization is dependent on the solubility of the monomer in the surfactant solution. It is concluded that when a water‐soluble initiator is used, polymerization proceeds in the aqueous phase. The principal factors controlling the rate of polymerization in the emulsion polymerization of vinyl acetate are, consequently, the initiating system and the concentration of monomer in the aqueous phase. Solubilization characteristics indicate that the surfactant concentration will have a much greater effect on the less water‐soluble monomers, such as styrene, than on the more soluble ones, such as vinyl acetate.