bluuebunny/crossref_metadata_2025 huggingface dataset:
Photodehydrochlorination of carbon monoxide–vinyl chloride copolymer
Authors: Kawai Wasaburo , Ichihashi Taichi
Published: April 2003

In order to examine effect of the carbonyl group in carbon monoxide–vinyl chloride copolymer, poly(CO–VC), photoirradiation with a high‐pressure mercury lamp on the copolymer was carried out. Poly(CO–VC) had a rate of dehydrochlorination three times that of PVC, and the reaction involved a decrease in chlorine content. Also there was a marked change in the ultraviolet spectra of the photoirradiated films. However, no pronounced change of molecular weight was observed, but a change in Rf in TLC was observed clearly. These facts confirmed that photoirradiation of poly(CO–VC) produced a structural change by dehydrochlorination without serious decrease of molecular weight. In addition, photodehydrochlorination of the copolymer or PVC film was followed kinetically, and after ozonolysis of the dehydrochlorinated polymers, the number‐average molecular weights were measured. From the results of degree of dehydrochlorination and molecular weight, the number average of conjugated double bonds or carbonyl groups was estimated. A mechanism for dehydrochlorination process by photo‐irradiation is suggested.
Copolymers of conjugated dienes with maleic acid monoesters. IV. Reactivity ratios in copolymerization of isoprene with maleic acid monoesters
Authors: Nanu Ioan , Andrei Constantin
Published: April 2003

Research was carried out on copolymerization of isoprene with maleic acid monoesters in the presence of free radicals (AIBN). The aim of the study was to observe the effect of the different monoesters obtained with normal alcohols of the aliphatic series: monoethyl maleate, monopropyl maleate, monobutyl maleate, monoheptyl maleate, monolauryl maleate, and monocetyl maleate. On the basis of reactivity ratios determined by the Fineman‐Ross method and compared with the Mayo‐Lewis method, all the systems studied are typical cases of heterocopolymerization. The parameter r1 is constant for this homologous series with the exception of the low terms. The experimental results agree with the ultimate model equation (with deviation at very high values of [M10]/[M20]), but not with the copolymer composition equation which considers the effect of the penultimate unity (penultimate model). Characterization of the sequential distribution is also presented (considering the effect of the terminal group only), and deviations of the experimental results are also discussed.
Gel‐permeation chromatography. IX. Instrumental design and computer interfacing of a GPC molecular weight detector system
Authors: Ouano Augustus C. , Horne Donald L. , Gregges Annie R.
Published: April 2003

The detailed design and computer interfacing of a GPC molecular weight detector based on a real time viscometer are described. The working drawings presented will permit one to fabricate and duplicate the viscometer and the complete GPC molecular weight detector system. The uses and advantages of a laboratory automation system in analyzing GPC results are also described.
Degradation of polymer mixtures. IV. Blends of poly(vinyl acetate) with poly(vinyl chloride) and other chlorine‐containing polymers
Authors: Jamieson A. , McNeill I. C.
Published: April 2003

The degradation of the binary polymer blends, poly(vinyl acetate)/poly(vinyl chloride), poly(vinyl acetate)/poly(vinylidene chloride) and poly(vinyl acetate)/polychloroprene has been studied by using thermal volatilization analysis, thermogravimetry, evolved gas analysis for hydrogen chloride and acetic acid, and spectroscopic methods. For the first two systems named, strong interaction occurs in the degrading blend, but the polychloroprene blends showed no indication of interaction. In the PVA/PVC and PVA/PVDC blends, hydrogen chloride from the chlorinated polymer causes substantial acceleration in the deacetylation of PVA. Acetic acid from PVA destabilizes PVC but has little effect in the case of PVDC because of the widely differing degradation temperatures of PVA and PVDC. The presence of hydrogen chloride during the degradation of PVA results in the formation of longer conjugated sequences, and the regression in sequence length at high extents of deacetylation found for PVA degraded alone is not observed.
Optically active diamide as a model for studying interactions between mineral salts and nylon type polyamides in methanol solutions
Authors: Hamoud Muhie Rasoul , Vert Michel , Selegny Eric
Published: April 2003

N,N′‐Dicaproyl (–)1,2‐diaminopropane (I) was used as a convenient model for the study of the optical activity of a nylon type polyamide: polysebacamide (–)1,2‐diaminopropane (II). ORD of I was measured in different solvents. A peculiar behavior is observed in methanol in the presence of mineral salts. The influence of 0.1M potassium salts (Cl−, Br−, SCN−, NO3−, SO4−2) and 0.1M alkaline chlorides and alkaline earth chloride hexahydrates on the optical activity of I in methanol are described. Alkaline salts and MgCl2 give approximately the same effect: there is a decrease of the rotations without change of sign. SrCl2 and CaCl2 shift ORD curves towards the negative rotations, the last one giving complete inversion. This inversion is directly related to the CaCl2 concentration and is attributed to adduct formation between amide groups and salt. Assuming that the different species are at equilibrium, an apparent equilibrium constant is obtained from the optical rotations for a complex of one mole of CaCl2 with one mole of I. Results are used to discuss the complex ORD of poly(−) 1,2‐diaminopropane sebacamide in methanol saturated with CaCl2.
Free‐radical grafting of monomers to polydienes. II. Kinetics and mechanism of styrene grafting to polybutadiene
Authors: Brydon A. , Burnett G. M. , Cameron G. G.
Published: April 2003

A kinetic analysis of the grafting reaction has shown that, provided rubber radicals are not involved in termination reactions, the observed normal kinetics of styrene polymerization are to be expected. An expression relating the graft fraction with the rubber and monomer concentrations has been derived and its validity verified from the results reported in Part I. The observation that the molecular weight of the ungrafted PBD falls during the reaction has been explained on a theoretical basis.
Crystallite structure of cellulose
Authors: Chang Martin M. Y.
Published: April 2003

The crystallite structure of cellulose has been elucidated through analyses of the degradations of model compounds by gel‐permeation chromatography. These compounds include single crystals of cellulose triacetate, regenerated cellulose from single crystals, precipitated celluloses from solutions, and commercial regenerated cellulose. The corresponding distribution profiles are found to follow the Keller transformation, which is a characteristic behavior of the folded crystals of synthetic polymers. It is also found that the leveling‐off DP of cellulose is a first‐order approximation of the corresponding fold length. A detailed folding chain model for the regenerated cellulose was constructed, and the various aspects of the structure are discussed. The kinetic data and the degradation products of native celluloses were also analyzed and found to obey the ruling of the chain fold model but not the conventional fringe‐micellar model. In addition, an iodine‐staining experiment pinpoints a minimum of 1.5% of true amorphous material; this is in quantitative agreement with the conformation analysis for the six‐fold helical β‐loop bonds. It is therefore suggested that the same chain‐fold conformation is applicable to the native polymer. The hydrolysis of cellulose is found to be composed of a triple mode of degradation, i.e., a first‐order random scission at the folds, a zero‐order peeling reaction at the ends of the crystallites, and a first‐order random scission on the lateral surfaces of the cellulose.
Investigation of physical state and phase behavior of polyester‐imides
Authors: Sidorovich A. V. , Koton M. M. , Kuvshinsky E. V. , Nikitin V. N. , Adrova N. A. , Baklagina Yu. G. , Mikhailova N. V.
Published: April 2003

Changes in properties of linear aromatic heterocyclic polymers of the polyimide class after introduction of ester linkages into their dianhydride component and of the oxygen and sulfur atoms into their diamine component have been studied. Thermomechanical, dilatometric, thermographic characteristics and x‐ray diffraction patterns of poly(ester amic acids) and polyester‐imides have been investigated. On heating, poly(ester amic acids) and amorphous polyesterimides exhibited a peculiar effect of self‐orientation of macromolecules. The x‐ray diffraction patterns of unoriented films indicate that they exhibit axial‐planar texture with the c axis of macromolecules in the film plane. The formation of the texture is preceded by mutual arrangement of macromolecules, i.e., by a precrystallization process beginning in the amorphous state. Because of this, on heating at temperatures ranging from 200 to 380°C, polyester‐imides yield highly crystalline products. Crystallographic parameters of the polymer lattices on x‐ray diffraction patterns and dichroism of absorption bands in polarized infrared spectra, the most probable conformations of macromolecules of some polyesterimides are proposed.
Radiation‐induced homogeneous polymerization of ethylene in cyclohexane
Authors: Watanabe Terutaka , Wada Takeshi , Takehisa Masaaki , Machi Sueo
Published: April 2003

The radiation‐induced polymerization of ethylene in cyclohexane was carried out in a reactor of 100 ml capacity under a range of temperature of 25–150°C, dose rate of 4.1 × 104–2.9 × 105 rad/hr, pressure of 200 kg/cm2, and amount of cyclohexane of 20–90 ml. The polymerization was found to proceed at a steady state from the beginning. The polymerization rate is maximum at ca. 50 ml of cyclohexane. The dose rate exponent of the polymerization rate was 0.6 at every temperature from 25 to 150°C. The polymer molecular weight is in the range of 103–104, independent of dose rate, and decreases with increasing amount of cyclohexane. The molecular weight distribution is unimodal and narrow. Kinetic analysis of these results indicates that the polymerization proceeds via a simple scheme of homogeneous polymerization and the polymer molecular weight was determined by the chain transfer reaction which takes place mostly with cyclohexane. The unimodal and narrow molecular weight distribution is also consistent with the homogeneous polymerization scheme.
Effect of ultraviolet irradiation on terpolymerization of sulfur dioxide with two unsaturated compounds
Authors: Furukawa Junji , Kobayashi Eiichi , Nakamura Morio
Published: April 2003

The terpolymerization of sulfur dioxide, butene‐1 and acrylonitrile affords terpolymers containing equimolar amounts of sulfur dioxide and butene‐1 with various acrylonitrile contents. Ultraviolet irradiation was found to accelerate the polymerization and decrease the acrylonitrile content in the polymer. This fact is interpreted by a mechanism through a copolymerization of sulfur dioxide–butene‐1 complex and acrylonitrile, whereby the polymerizability of sulfur dioxide–butene‐1 complexed monomer may be accelerated by ultraviolet light. In fact, a binary system of sulfur dioxide and butene‐1 was found to be accelerated by ultraviolet irradiation, and it affords a maximum rate at a 1:1 composition of feed monomer. Ultraviolet light of 250–300 mμ wavelength is effective for the initiation and the propagation. This may be ascribed to the ultraviolet absorption of the sulfur dioxide–butene‐1 complex. The temperature coefficient was measured in both dark and ultraviolet irradiation reactions. The ultraviolet irradiation enhances the reactivity of sulfur dioxide–butene‐1 complexed monomer at low temperature. In the terpolymerization with sulfur dioxide, isoprene, and butadiene, the ratio of isoprene and butadiene in the terpolymer was not altered by ultraviolet irradiation because both monomers from complexes with sulfur dioxide, perhaps having the same temperature coefficient for the polymerization.
Photostabilization of polypropylene. II. Stabilizers and hydroperoxides
Authors: Carlsson D. J. , Wiles D. M.
Published: April 2003

The effects of various polyolefin photostabilizers on the thermal and photodecomposition of model and polymeric hydroperoxides have been investigated, both in the liquid and solid phases. Several extremely effective ultraviolet stabilizers belonging to the metal chelate class can cause the rapid thermal decomposition of model and polymeric hydroperoxides. Although stabilizers did not reduce the quantum yield for polypropylene hydroperoxide photolysis, several additives can scavenge hydroxyl and macroalkoxy radical products which result from hydroperoxide photolytic cleavage. Ultraviolet stabilizers which were found to trap radicals were able to prevent the photodegradation of polypropylene which already contained a significant concentration of hydroperoxide groups. Highly effective polypropylene ultraviolet stabilizers probably operate by a range of mechanisms including hydroperoxide decomposition, radical scavenging and singlet oxygen quenching.
ESR and chemical study of p‐polyphenylene formed by using an AlCl3–CuCl2 catalyst
Authors: Lerner N. R.
Published: April 2003

The free radicals in p‐polyphenylene and the formation of free radicals in this polymer upon pyrolysis in vacuum have been studied by means of electron spin resonance. For an unpyrolyzed series of polymer samples, a linear relationship was observed between free radical concentration and increasing carbon content. The free radicals observed in the unpyrolyzed samples did not react with NO. When samples of polyphenylene were pyrolyzed, additional free radicals were produced which did react with NO. The growth of free radical concentration upon pyrolysis was observed to be closely related to the production of volatile products from the polymer. In the temperature range 250–600°C, HCl was the principal volatile species produced. Two mechanisms were involved in HCl production: a process with an activation energy of 7.1 kcal/mole which led to the production of stable free radicals; and a process involving 75 kcal/mole which was unconnected with the production of free radicals. From 600 to 700°C, H2 was the principal volatile degradation product. The rate at which H2 was evolved showed a second‐order dependence on phenyl units bearing two or three substituents; this process had an activation energy of 79 kcal/mole. Electron spin resonance spectra indicated that this process led to the production of free radicals, and infrared spectra showed that a highly crosslinked product resulted.
Polymerization of σ‐bonded organo‐transition metal derivatives of styrene
Authors: Fujita N. , Sonogashira K.
Published: April 2003

Five new monomers of transition metal complexes containing a styryl group, trans‐\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm Pd}({\rm PBu}_{\rm 3})_2 \rlap{--} ({\rm C}_6 {\rm H}_4 {\rm CH} \hbox{=\hskip-2pt=} {\rm CH}_2 ){\rm X\ X \hbox{=\hskip-2pt=} Cl(Ia),\ X \hbox{=\hskip-2pt=} Br(Ib)},\ {\rm X \hbox{=\hskip-2pt=} CN(Ic),\ X \hbox{=\hskip-2pt=} Ph(Id)} $\end{document} and trans‐\documentclass{article}\pagestyle{empty}\begin{document}${\rm Pt(PBu}_{\rm 3} {\rm )}_{\rm 2} \rlap{--} ({\rm C}_{\rm 6} {\rm H}_{\rm 4} {\rm CH} \hbox{=\hskip-2pt=} {\rm CH}_2 ){\rm Cl}({\rm II})$\end{document}, were synthesized. The monomers were readily homopolymerized in benzene with the use of AIBN or BBu3–oxygen as the initiator. Copolymerization of Ia with styrene was carried out by using AIBN. From the Cl content of the copolymers by analysis, monomer reactivity ratios and Q–e values were obtained as follows: r1 = 1.49, r2 = 0.45; Q2 = 0.41, e2 = −1.4 (M1 = styrene, M2 = Ia). Based on the above data, the σ‐bonded palladium moiety at para position of styrene acts as a strongly electron‐donating group to the phenyl ring. This is also supported by the olefinic β‐carbon chemical shift of 13C NMR for Ia.
Thermal stability of graft modifications of PVC and related materials
Authors: Abbås K. B. , Thame N. G.
Published: April 2003

The grafting of polyisobutylene and polybutadiene onto PVC by use of alkylaluminum compounds gives graft copolymers which are superior in thermal stability to unmodified PVC as determined by dehydrochlorination measurements at a low degree of decomposition. The alkylation of toluene with PVC also exhibits high heat stability. The improved thermal stability observed for the modified samples is ascribed to the existence of an induction period and/or lower dehydrochlorination rates. PVC grafted with polybutadiene in the absence of cobalt cocatalyst exhibits autocatalytic behavior and is less stable than the unmodified PVC.
Initiation and propagation steps in the equibinary polymerization of butadiene by bis(h3‐allylnickel trifluoroacetate)
Authors: Thomassin J. M. , Walckiers E. , Warin R. , Teyssié Ph.
Published: April 2003

Polymerization of butadiene by bis(h3‐allylnickel trifluoroacetate) in benzene and o‐dichlorobenzene solvents yields an equibinary 1,4‐polybutadiene, containing equal amounts of cis and trans isomers. Initiation proceeds by addition of the allylic moiety of the initiator to a butadiene molecule. The rate of initiation is high enough to ensure complete consumption of the catalyst for a monomer/catalyst molar ratio of about 10 at 5°C. The propagation exhibits the characteristics of a “living” polymerization: the molecular weight is proportional to the conversion, and at the end of the reaction, the average degree of polymerization is equal to the monomer/catalyst molar ratio. Living polybutadienyl‐nickel trifluoroacetate is able to reinitiate not only butadiene polymerization but also allene polymerization. However, for high [monomer]/[catalyst] ratios, conversion‐dependent transfer reactions limit the molecular weight to 7000 in benzene and to 70,000 in bulk polymerization in the presence of small amounts of o‐dichlorobenzene.
Starch xanthate–polyethylenimine reaction mechanisms
Authors: Carr M. E. , Hofreiter B. T. , Russell C. R.
Published: April 2003

The chemical nature of starch xanthate (SX)–polyethylenimine (PEI) reaction products has been studied because of their effectiveness as wet‐end additives for improving strength properties of paper. Model compounds, in conjunction with ultraviolet, infrared, and chemical analyses, served to elucidate SX–PEI reaction mechanisms. Aqueous solutions of SX (degrees of substitution 0.1–0.5) were titrated with PEI at pH 5–7 (25–30°C) to form SX–PEI flocculent precipitates that were determined to be polyelectrolyte complexes. However, when solutions of SX–PEI were kept at pH 10–12, products were formed that included dithiocarbamic acid salts in major quantities, PEI thioureas, and minor quantities of O‐starch PEI thinocarbamate. Acid precipitation of these SX–PEI polymeric reaction products from their alkaline solutions, which contained residual xanthate and PEI, also yielded polyelectrolyte complexes. Model systems suggest that PEI thiuram disulfide and starch xanthide, possible products of air oxidation, could be present in minor amounts and would react rapidly with PEI to yield thioureas and thioncarbamates, respectively. Apparently, mixtures of xanthate and amine gave (1) dithiocarbamic acid salts from both xanthate groups and CS2 (decomposition from xanthate), (2) thioureas from both dithiocarbamic acid salts and thiuram disulfide, and (3) thioncarbamates, principally from xanthate as opposed to xanthide.
Poly(alkyl α‐chloroacrylates). IV. Tacticity analysis from 300 MHz proton magnetic resonance spectra
Authors: Dever G. R. , Karasz F. E. , Macknight W. J. , Lenz R. W.
Published: April 2003

300 MHz proton magnetic resonance spectroscopy was applied to the determination of triad structures of three poly(alkyl α‐chloroacrylates) of widely varying stereoregularities. Assignments and quantitative analyses were made for all of the tetrad peaks in the backbone methylene resonance of poly(methyl α‐chloroacrylate), poly(ethyl α‐chloroacrylate), and poly(isopropyl α‐chloroacrylate). In addition the methyl singlet peaks of poly(methyl α‐chloroacrylate), the methyl triplet peaks of poly(ethyl α‐chloroacrylate) which had not been amenable previously to resolution at 220 MHz, and the methyl doublet peaks of poly(isopropyl α‐chloroacrylate) were resolved, and the triad values which were obtained from these pendant ester group resonances compared favorably with triad values calculated from experimental tetrad values. As a demonstration of the internal agreement of the triad and tetrad peaks assignments, statistical calculations of the stereochemical structures of the actic and syndiotactic polymers were generally described well or to a first approximation by random selection statistics (Bernoullian) while the stereochemical statistics of the moderately to highly isotactic polymers were consistent with a nonrandom statistical process (first‐order Markovian), as expected.
Polymérisation anionique de l'isoprène: Nature de la paire d'ions et stéréospécificité. II. Influence de la nature du solvant
Authors: Essel Alain , Salle Robert , Golé Jean , Pham Quang‐Tho
Published: April 2003

The present work reports some new results on the dependence between the stereospecificity of the anionic propagation of isoprene and the nature of the active centers. The stereospecificity of the propagation of macroheterobicylce separated ion pairs does not depend on the nature of the alkali counterions, and the microstructure of the polyisoprenes obtained does not differ from that of those produced by free ions. Variations in the microstructure were observed in the propagation of contact ion pairs, depending on the nature of the cation and the solvent used. These variations are likely to be related to the degree of intimacy of the contact ion pairs. There are two main factors which affect the stereospecificity of the propagations in different ways: the size of the cation and the donating power of the solvent. Finally, the external solvation of the propagation ions pairs was confirmed by the microstructure of polyisoprenes synthesized in mixed (inert + donor) solvents.
ESCA studies of polymers. VII. Shake‐up phenomena in some alkane–styrene copolymers
Authors: Clark D. T. , Dilks A.
Published: April 2003

Shake‐up satellites corresponding to π* → π transitions accompanying C1s core ionizations have been studied for polystyrene and a series of alkane–styrene copolymers. It is shown that the shake‐up intensities are additive in nature and give a direct measure of copolymer compositions.
Studies on the photooxidation mechanism of polymers. IV. Effect of ultraviolet light (2537 Å) on solid PVC particles suspended in different liquids
Authors: Rabek Jan F. , Canbäck Göran , Lucky Julia , Rånby Bengt
Published: April 2003

The photolysis of virgin PVC powder suspended in water, methanol, n‐hexane, aqueous NH4OH (30 wt‐%), and 0.1 wt‐% iodine in methanol and also as dry powder was studied. The mechanism of photolysis of PVC powder has been investigated by using ESR spectroscopy, conductivity titration, gel‐permeation chromatography (GPC), and absorption spectroscopy. Photolysis of PVC has been found to occur by a free‐radical mechanism. ESR spectroscopy permits a partial identification of several different types of free radicals in PVC such as alkyl, polyenyl, and peroxy radicals. An interpretation is proposed of the mechanism of formation of conjugated polyene structures, and also a new explanation of the crosslinking mechanism, in which transfer of unpaired electrons to double bonds occurs, is suggested. It has also been found that conjugated double bonds can photosensitize free‐radical formation as a result of increased ultraviolet absorption due to polyene structures.
Effect of surface swelling on diffusion in polymers. I. Infrared spectroscopy
Authors: Sefton M. V. , Merrill E. W.
Published: April 2003

The effect of stress transfer‐limited swelling in the surface region on the hydroxylation of styrene–butadiene–styrene block copolymers in the bulk state was investigated. Films of the copolymer were allowed to react with peracetic acid to effect epoxidation and simultaneously with acetic acid and water to cleave the epoxy rings. By infrared spectroscopy it was observed that the hydroxyl content of the films decreased with increasing film thickness and the epoxy content increased commensurately. This was attributed to the presence of a lag between the advancing diffusion fronts for the epoxide groups and for the cleavage agents. This lag increases with increasing thickness due to the presence of stress‐transfer mechanisms which act to reduce the degree of swelling in the surface region and which are more effective in thicker films. The hydroxyl content increased exponentially with time, giving rise to the observation of significant induction time before there was any infrared evidence of hydroxyl formation. This resulted from the relief of part of the compressive stress in the surface region by the reaction process, which in turn increased the permeation rate of peracid.
Synthesis of polyesters by using divalent metal salts of monohydroxyethyl phthalate: Metal‐containing polyesters from such metal salts, anhydride, and epoxide
Authors: Matsuda Hideaki
Published: April 2003

Synthesis of metal‐containing polyesters by reactions of the divalent metal salts of monohydroxyethyl phthalate with phthalic anhydride and epoxide were investigated. It was found that the metal carboxylate groups of these metal salts catalyze the above reactions. These reactions were further studied in model reactions with the use of the Ca salt of monoethyl phthalate. Products obtained were linear metal‐containing polyesters containing ionic links in the main chain; they were yellow or slightly yellow glassy materials; yields were generally high. Molecular weights obtained by the end‐group analyses were generally low; with increase in content of the metal salts in the feed the molecular weight of the polyesters decreased. Inherent viscosities (in DMF at 30°C) of the metal‐containing polyesters were low, ranging from 0.033 to 0.052. Elemental analyses are generally in good agreement with the calculated values. Thermogravimetric analyses of the polyesters were also discussed.
Physicomechanical properties of grafted polymers obtained by radiation‐induced polymerization by radical and ionic mechanisms
Authors: Kabanov V. Ya. , Aliev R. E. , Sidorova L. P.
Published: April 2003

The radiation‐induced grafting of acrylonitrile, 4‐vinylpyridine, and styrene was carried out by both radical and ionic mechanisms. Grafted polymers with equal percentages of graft were obtained by the radical and ionic propagation of the grafted chains. The molecular weight of homopolymers has been determined. The thermomechanical properties of the graft polymers were investigated. The yield temperatures for the graft polymers obtained by ionic propagation of the grafted chains is higher than that of graft polymers obtained by a radical mechanism. This is attributed to the higher molecular weight of the grafted chains obtained by the radiation‐induced grafting by the ionic mechanism. The radiation‐induced grafting of polyacrylonitrile increases significantly the thermal stability of polyethylene. The differential thermal analysis shows no marked differences in properties of the polymers.
Supported catalysts for stereospecific polymerization of propylene
Authors: Chien James C. W. , Hsieh J. T. T.
Published: April 2003

Tetrabenzyltitanium (B4Ti), tribenzyltitanium chloride (B3TiCl), tetra(p‐methylbenzyl)titanium (R4Ti) and tri(p‐methylbenzyl)titanium chloride (R3TiCl) have been used as catalysts for ethylene and propylene polymerization activated by AlEt2Cl. B4Ti‐AIEt2Cl in solution polymerizes ethylene readily but its activity decays rapidly. B4Ti was also supported on Cab‐O‐Sil, Alon C, and Mg(OH)Cl. The last support was found to give catalyst with longest lifetime with a rate of polymerization, Rp = 7.0 g/hr‐mmole Ti‐atm ethylene. 14CO counting techniques gave 1.13 × 10−3 mole of propagating center per mole of B4Ti; the rate constant of propagation, kp = 540 l./mole‐sec. None of the tetravalent titanium compounds polymerize propylene in solution. However, when supported on Mg(OH)Cl, Cab‐O‐Sil, Alon C, Cab‐O‐Ti, and charcoal, they all polymerize propylene. In this work the supports were characterized by various techniques, including the paramagnetic probe method, to determine the concentration and nature of surface hydroxyls. Those factors controlling the rate and stereospecificity of propylene polymerization were investigated. The system B3TiCl–Mg(OH)Cl–AlEt2Cl is the most active with Rp = 2.89 g/hr‐mmole Ti‐atm propylene. The concentration of propagation center is 0.9 × 10−3 mole per mole of B3TiCl; kp = 32 l./mole‐sec. This catalyst gave only about 70% stereoregular polymer. Diethyl ether is found to raise stereospecificity to 100%, but there is a concommittent tenfold decrease of activity. Other interesting catalyst systems are: (π‐C5H5)TiMe3–Mg(OH)Cl–AlEt2Cl (1.56, 89.5); (π‐C5H5)TiMe2–Mg(OH)Cl–AlEt2Cl (0.075, 94.5); and (π‐C5H5)TiMe3–Alon C–Al‐Et2Cl (0.08,97.2), where the first number in the parenthesis is Rp in g/mmole Ti‐hr‐atm and the second entry corresponds to percentage yield of stereoregular polypropylene. Hafnocene and titanocene supported on Mg(OH)Cl produce only oligomers of propylene.
Quantitative estimation of trans‐1,4 and cis‐1,4 isomers in polychloroprene by high‐resolution NMR
Authors: Okada Tadashi , Ikushige Testuo
Published: April 2003

In the 1H‐NMR spectrum of polychloroprene dissolved in C6D6, the CH proton signal was separated into two triplet peaks. These triplet signals were assigned to the CH proton in the trans‐1,4 and cis‐1,4 isomers by measurement of 1H‐NMR spectra of 3‐chloro‐1‐butene and a mixture of trans‐ and cis‐2‐chloro‐2‐butene as model compounds for the 1,2, trans‐1,4 and cis‐1,4 isomers. In 1H‐NMR spectra (220 Mcps) of polychloroprene dissolved in C6D6, two triplet signals were separated completely from which the relative concentrations of trans‐1,4 and cis‐1,4 isomers could be obtained quantitatively.
Reaction of poly(vinyl alcohol) with pentavalent vanadium ion
Authors: Ikada Yoshito , Nishizaki Yasuko , Uyama Yoshikimi , Kawahara Tomoe , Sakurada Ichiro
Published: April 2003

The reaction of poly(vinyl alcohol) (PVAL) with V(V), i.e., pentavalent vanadium ion, was studied in aqueous H2SO4 medium. The viscosity change of reaction mixture with time showed a peculiar feature owing to formation of labile complex between V(V) and PVAL and the subsequent decomposition of the complex. On the other hand, the change of viscosity disappeared when NaOH was added during the reaction to neutralize H2SO4 in the reaction mixture. Under a suitable condition, the reaction mixture set to a gel as a result of complex formation. It appeared that reactive sites in PVAL responsive to complexing with V(V) were 1,2‐glycol unit and 1,2‐ketoalcohol unit resulting from the oxidation of 1,2‐glycol by V(V). The rate of oxidation was increased with increasing H2SO4 concentration. The main‐chain scission of PVAL took place to an insignificant extent, unless the reaction condition was severe. Based on the results obtained a reaction mechanism has been proposed.
Studies of the polymerization of diallyl compounds. XXIV. Effect of temperature on the polymerization of diallyl phthalate
Authors: Matsumoto Akira , Inoue Isao , Oiwa Masayoshi
Published: April 2003

The effect of temperature on the polymerization of diallyl phthalate was investigated in the temperature range of 80–150°C. The degree of polymerization increased slightly with temperature up to 100°C and then decreased; together with the results of primary chain length and the dependence of Rp on initiator concentration, these findings were interpreted in terms of the enhancement of the reinitiation ability of the allylic radical produced by the intramolecular chain‐transfer reaction and of the reactivity of the cyclized radical at elevated temperature. The tendency for cyclization became more marked with increasing temperature. The gel point was almost unaffected.
Formation of free radicals in photoirradiated cellulose and related compounds
Authors: Hon Nyok‐Sai
Published: April 2003

Free‐radical formation in various modifications of celluloses, namely, wood cellulose I, II, III, and IV, rayon cellulose, amorphous cellulose, cotton linters, and absorbent cotton, irradiated with ultraviolet light, has been studied by means of ESR spectroscopy at 77°K. Various types of free radicals were generated from these samples. The line shapes and the signal intensities of the ESR spectra depended greatly upon the degree of crystallinity, the lattice type, and the arrangement of molecules in cellulose. The effect of degree of crystallinity and the amount of sensitizer (Fe3+) absorbed revealed that photochemical reactions in cellulose occurred exclusively in the amorphous regions of the polymer. Free radicals formed in these samples behaved distinctively upon a warm‐up process. Phenomena of radical migration and formation of new radicals were observed from the sensitized samples of rayon cellulose and amorphous cellulose.
Dimethylaniline (DMA)–Cu2+ ion system‐induced graft polymerization of methyl methacrylate on viscose
Authors: El‐Rafie M. H. , Waly A. I. , Hebeish A.
Published: April 2003

Graft polymerization of methyl methacrylate on viscose fibers induced by the DMA–Cu2+ ion system was investigated under different conditions. Variables studied include concentration of DMA, Cu2+ ion, and MMA, reaction time, and temperature. There are optimal concentrations of DMA and Cu2+; below or above these concentrations lower grafting occured. Within 4 hr reaction time, the grafting reaction showed an initial fast rate followed by a slower one at 80°C. At 70°C, on the other hand, the graft yield increased in proportion to the increase in reaction time. Increasing the monomer concentration did not have a significant effect on the graft yield during the first 45 min of reaction. Beyond this, the effect of monomer concentration was marked.
Syntheses of functional condensation polymer. I. Polyesters having pendant functional groups such as hydroxyl, formyl, aldoxime, aminomethyl and hydroxymethyl
Authors: Ogata Naoya , Sanui Kohei , Shimozato Yasuyuki , Munemura Sho
Published: April 2003

Unsaturated polyesters having pendant functional groups such as hydroxyl, formyl, aldoxime, aminomethyl and hydroxymethyl, have been prepared and characterized, and some of their properties were investigated. Reaction conditions for the epoxidation of unsaturated polyesters and hydrolysis of the epoxy groups in the polyesters were established to control the amount of pendant diol groups. It was possible to incorporate up to 90 mole‐% of formyl side groups into the unsaturated polyester by the hydroformylation with the rhodium catalyst. In addition, the formyl side groups of the modified polyester were converted into hydroxymethyl or aldoxime groups and were then converted to amino groups. The melting points of the modified polyesters decreased with increasing the pendant group content of the polyesters, as expected. Aliphatic polyesters having pendant hydroxyl or amino groups had a high affinity for moisture, which might be ascribed to the participation of the hydrophilic pendant groups in the modified polyesters.
Synthesis and characterization of polyaryloxyphosphazene copolymers
Authors: Dieck Ronald L. , Goldfarb Louis
Published: April 2003

A series of polyaryloxyphosphazene copolymers with the general formulas [NP(OC6H5)(OR)]n and [NP(OC6H4–4–OCH3)(OR)]n, where R = C6H4–4–CH3, C6H4–4–C2H5, C6H4–4–isoC3H7, C6H4–4–sec‐C4H9, C6H4–4–tert–C4H9, C6H4–4–OCH3 or C6H4–4–OC4H9, have been prepared under anhydrous conditions. Copolymers as well as selected homopolymers were prepared by the reaction of polydichlorophosphazene with appropriate sodium aryloxides. Each of the polymers was characterized by elemental analysis, infrared spectroscopy, gel–permeation chromatography, and differential scanning calorimetry. Elemental analysis established the empirical formula for the polymers and showed that there were no residual PCl bonds left on the polymer backbone. Infrared spectroscopy indicated the presence of a phosphorus–nitrogen backbone with two aryloxy groups bonded to each phosphorus atom. The copolymers examined exhibited molecular weights of above 1 × 106. Polyaryloxyphosphazene copolymers were examined by differential scanning calorimetry and compared to several of the corresponding homopolymers. Glass transition temperatures ranged between −34 and +44°C for the polymers. The Kelley‐Bueche equation was used to predict the glass transition temperatures of the copolymers. Close agreement was found between calculated and experimental values for most of the systems examined.
Study of the degradation of polyurethanes. III. Mechanism of the photodegradation of polyurethane
Authors: Osawa Zenjiro , Cheu Eng‐Liang , Nagashima Kosaku
Published: April 2003

The effect of triplet sensitizers, benzophenone and anthraquinone and metal acetylacetonates [Co(II, III), Cu, Sn, and Ni] on the photodegradation of polyurethane was examined. Ultravioletvisible (UV‐V) absorption spectra, gel formation, and luminescence emission of the polymer before and after irradiation were measured. Changes in UV‐V absorption of the polymer and the formation of an insoluble fraction in the polymer were accelerated in the presence of the triplet sensitizers, and (Co(II, III)), Cu, and Sn acetylacetonates. Unirradiated polyurethane was excited by irradiation at 290 and 346 nm, and emitted light at 310 and 420 nm. After 1/2 hr irradiation emission of luminescence was observed at 430 nm, excitation at 290 and 346 nm; after 2hr irradiation at 530 nm, excitation at 420 nm was observed. The results suggest that photodegradation of the polyurethane proceeds via excited triplet states forming excimer between the polymers at the initial stage and exciplexes between the polymer and degradation products or intermediates after a certain irradiation.
Synthesis of polyarylamines by vinylogous nucleophilic substitution polymerization of bis(4‐chloro‐3‐nitrophenyl) sulfone with diamines
Authors: Imai Yoshio , Ueda Mitsuru , Otaira Kouetsu
Published: April 2003

A series of new polyarylamines was prepared by the vinylogous nuclephilic substitution polymerization of bis(4‐chloro‐3‐nitrophenyl) sulfone with both aromatic and aliphatic diamines. The synthesis involves the solution polycondensation in a polar aprotic solvent at elevated temperatures, a tertiary amine being used as an acid acceptor. Of these solvents, dimethyl sulfoxide and N‐methyl‐2‐pyrrolidone were the most effective for the preparation of high molecular weight polymers. The polyarylamines having inherent viscosities in the range of 0.1–0.5 were all amorphous and highly soluble in polar aprotic solvents. Thermogravimetric analysis under both air and nitrogen atmospheres indicated that rapid decomposition began above 300°C for the polyarylamines from aromatic diamines.
Photodegradation of carbon monoxide–styrene copolymer in benzene and formation of block copolymer with methyl methacrylate
Authors: Kawai Wasaburo
Published: April 2003

Photodegradation of carbon monoxide–styrene copolymer in benzene was investigated. In relation to the average number of main‐chain scissions per macromolecule versus photoirradiation time, the straight line did not pass through the origin. This phenomenon was attributed to the presence of a labile bond from the carbonyl group in the main chain, in accordance with the results of Cameron and Lawrence which were found in the study of photodegradation of thermally polymerized polystyrene. In utilization of photodegradative behavior in carbon monoxide–styrene copolymer, a block copolymer of styrene with methyl methacrylate was prepared and was ascertained by precipitated fractionation, elementary analysis, and turbidimetry.
Stereoregularity of poly(2‐vinylpyridine) and poly‐(4‐vinylpyridine)
Authors: Matsuzaki Kei , Matsubara Tetsuyuki , Kanai Taiichi
Published: April 2003

In order to determine the stereoregularity of poly(4‐vinylpyridine), 4‐vinylpyridine‐β,β‐d2 was synthesized from 4‐acetylpyridine. The 1H‐NMR spectra of the deuterated and nondeuterated polymers were measured and analyzed. From the 1H‐NMR spectra of poly(4‐vinylpyridine‐β,β‐d2), triad tacticity can be obtained, while the 1H‐NMR spectra of nondeuterated poly(4‐vinylpyridine) give the fraction of isotactic triad. The 13C‐NMR spectra of poly(4‐vinylpyridine) were also observed, and the spectra of C4 carbon of polymers were assigned by the pentad tacticities. The fraction of isotactic triad of poly(2‐vinylpyridine) and poly(4‐vinylpyridine) obtained under various polymerization conditions were determined. The radical polymerization and anionic polymerizations with phenylmagnesium bromide and n‐butyllithium as catalysts of 4‐vinylpyridine gave atactic polymers.
Kinetics of polymerization rate based on the dependence of termination rate on chain length
Authors: Ito Katsukiyo
Published: April 2003

When the structure of a primary radical resembles that of the chain end of the polymer radical, the rate of the primary radical termination is approximately the same as the termination rate between the oligomer radical and the polymer radical. The rate constant of termination between polymer radicals of chain length n and s, which involve the primary radicals, is kt,ns = const.(ns)−a. In the polymerization of methacrylonitrile initiated by 2,2′‐azobisisobutyronitrile in dimethylformamide at 60.0°C, the value of a is found to be 0.091. From data obtained previously in the bulk polymerization of styrene initiated by 1‐azobis‐2‐phenylethane at 60.0°C, the value of a is found to be 0.167. Because such a values are so large that they are not estimated by the excluded volume, the termination rates are discussed by adding the dependence of the diffusion of the segments to that for chain length.
Hydroperoxide‐initiated copolymerization of sulfur dioxide and cyclohexene. I. Characterization of charge‐transfer complex and initiation
Authors: Oster Bernd , Lenz Robert W.
Published: April 2003

The copolymerization of cyclohexene and sulfur dioxide to form an alternating copolymer was initiated by tert‐butyl hydroperoxide. The enthalpies and entropies of formation of the cyclohexene‐sulfur dioxide charge‐transfer complex, which is present during the copolymerization, were determined in two solvents by means of ultraviolet spectroscopy. The reduction of ultraviolet absorption during copolymerization afforded a convenient means of investigating reaction kinetics. No evidence of the direct involvement of the complex in polymerization initiation was found. The observation that the use of unpurified cyclohexene led to spontaneous initiation appears to point to adventitiously formed hydroperoxide rather than the charge‐transfer complex as providing initiating radicals which are produced by the redox reaction of the hydroperoxide with sulfur dioxide. A competing heterolytic scission reaction was found to result in the formation of tert‐butyl peroxide and sulfuric acid. This reaction caused the polymerization reaction to stop after a short period of time due to a time‐dependent decrease in initiator concentration.
Structure of chlorinated poly(vinyl chloride). IV. Chlorination of β,β‐d2‐poly(vinyl chloride) as model for determination of the mechanism of chlorination
Authors: Lukáš R. , Kolínský M. , Doskočilová D.
Published: April 2003

Chlorinated β,β‐dideuterated poly(vinyl chloride) (β,β‐d2‐CPVC) was prepared by photochemical suspension chlorination in concentrated hydrochloric acid with chloroform as swelling agent, and thermally in tetrachloroethane solution. 1H‐NMR (nuclear magnetic resonance) spectra of β,β‐d2‐CPVC were recorded. The content of deuterium was determined in combustion products of β,β‐d2‐CPVC as the D2O:(H1D)2O ratio by means of mass spectroscopy. Both in the photochemical suspension chlorination and in the thermal solution chlorination of β,β‐d2‐PVC, a decrease of the concentration of CHCl groups was observed. The differences in structure of the suspension chlorinated and solution chlorinated β,β‐d2‐PVC were confirmed.
Kinetics and mechanism of the emulsion polymerization of styrene in the aqueous media at 50°C and at low monomer concentration initiated by persulfate. I. Initiation
Authors: Chatterjee S. P. , Banerjee Monoranjan , Konar R. S.
Published: April 2003

The mechanism of the water‐soluble persulfate‐initiated emulsion polymerization of styrene in the aqueous media at 50°C has been investigated kinetically by the conventional dilatometric and gravimetric methods at low concentration of the monomer (5% v/v). It has been found that the initial rate of polymerization Vp is approximately proportional to initiator concentration [I] to the 0.50 power, i.e., Vp ∝ [I]0.50, and the viscosity‐average molecular weight Mv is approximately inversely proportional to the 0.50 power of the initiator concentration, i.e., Mv ∝ [I]−0.50. With the progress of the reaction, the initiator exponent of the reaction rate equation decreases gradually from 0.50 to 0.25, but that of the molecular weight (1) equation remains constant up to 20% conversion and thereafter begins to decrease. Since the kinetic data at zero conversion satisfy the steady‐state kinetics of the free‐radical‐initiated homogeneous vinyl polymerization, it is suggested that the initiation of emulsion polymerization of styrene is a two‐step process. It starts in the aqueous phase by the primary free radicals from the water‐soluble initiator or secondary free radicals derived from the soap molecules. The second step occurs in the monomer‐leaded micelles by the water‐soluble or water‐insoluble macroradicals or by radicals derived from the soap molecules. The latter are likely to be produced in the aqueous phase by the oxidation of soap with S2O82−ions or SO4− radicals. It has been noted that the rate of thermal decomposition of persulfate increases by a factor of 6–8 times under different experimental conditions in the presence of soap.
Bisorthoesters as polymer intermediates. II. A facile method for the preparation of polybenzimidazoles
Authors: Dudgeon C. D. , Vogl O.
Published: April 2003

Aromatic bisorthoesters were found to be good polymer intermediates and could be condensed with aromatic tetramines under mild conditions, in DMSO at 100°C in a relatively short reaction time to give polybenzimidazoles. The hexapropyl orthoesters of terephthalic and isophthalic acid were the preferred aromatic orthoesters because they were relatively easily purified by vacuum distillation to polymer grade intermediates, since they are liquids. Higher orthoesters distill even under good vacuum near or above the decomposition temperature of the orthoester group. Hexaethyl orthooxalate was also used and is a very useful and stable derivative of oxalic acid, which can be used for condensation reactions. These three orthoesters were used for condensations with 3,3′,4,4′‐tetraaminobiphenyl, 1,2,3,4‐tetraaminobenzene, 3,3′,4,4′‐tetraaminobiphenyl ether, and 3,3′,4,4′‐tetraaminobenzophenone. All polybenzimidazoles were obtained in high to quantitative yields and with varying molecular weights (ηinh = 0.1−0.8 dl/g), which in some cases were in the fiber forming range.
On the mechanism of the polymerization of poly(vinyl chloride)
Authors: Caraculacu A. , Buruiană E. C. , Robilă Gabriela
Published: April 2003

The polymerization of poly(vinyl chloride) (PVC), head‐to‐head macroradical plays an essential role in the formation of branches and the appearance of interruption processes that lead to labile unsaturated end groups. A reaction mechanism is suggested to explain these processes and the method of formation of internal double bonds as a result of transfer to polymer. The transfer to monomer can occur only by atom acceptance by the macroradical and not by the monomer giving up an atom.