bluuebunny/crossref_metadata_2025 huggingface dataset:
Photodegradation of polyethylene in the presence of ferric salt: Influence of ferric acetylacetonate on model compounds
Authors: Ogiwara Yoshitaka , Kubota Hitoshi , Kimura Yuji
Published: April 2003

The influence of ferric acetylacetonate [Fe(acac)3] on the photodegradation of model compounds of polyethylene (PE) was examined. By studying electron‐spin‐resonance (ESR) spectra of photoirradiated compounds such as 1‐octene and 1,7‐octadiene, which contain carbon double bonds, Fe(acac)3 was found to accelerate the formation of allyl radical by contact with them. On the other hand, Fe(acac)3 suppressed the radical formation based on Norrish type I reaction in a carbonyl group of compounds such as 2‐octanone and 3‐octanone. Based on the study of ultraviolet (UV) spectra as well as ESR spectra on photoirradiated samples, the influence of Fe(acac)3 on the photodecomposition of model compounds of PE was discussed. Finally, the discussion turned to the mechanism of photodecomposition of PE in the presence of ferric salt.
Alternating copolymerization of benzofuran with crotononitrile and α‐chloroacrylonitrile
Authors: Furukawa Junji , Kobayashi Eiichi , Nagata Shiro
Published: April 2003

The copolymerizations of benzofuran with α,α‐ or α,β‐disubstituted acrylic monomers were studied. The alternating copolymer of benzofuran and crotononitrile was prepared in the presence of an excess amount of crotononitrile with respect to benzofuran, ethylaluminum dichloride, and azobisisobutyronitrile. The intrinsic viscosity of copolymers was 0.1–0.2 dl/g. Crotononitrile is known to possess a polar carbon–carbon double bond from 13C‐NMR spectroscopy but the alternating copolymerizability with benzofuran is low. It was found that the order of alternating copolymerizability of acrylic monomers is as follows:

This fact may be attributed to the steric hindrance of the β‐methyl of crotononitrile. The induced shifts by complexation with ethylaluminum dichloride on 13C‐NMR spectra of the two isomers of crotononitrile are almost same but the copolymerizability of cis isomer is higher than that of trans isomer.

α‐Chloroacrylonitrile shows the highest alternating copolymerizability with benzofuran in the presence of weak Lewis acid such as ethoxyaluminum chloride. Alternating copolymerizability of acrylic monomers seems to be in proportion to their e value. The reactivity of cis‐ and trans‐crotononitrile may depend on the nature of a ternary complex composed of aluminum compound, crotononitrile, and benzofuran.
The cationic dimerization of 1,1‐diphenylethylene. III. Kinetics of initiation by aluminum chloride
Authors: Masure M. , Sauvet G. , Sigwalt P.
Published: April 2003

Kinetics of the reaction of AlCl3 with 1,1‐diphenylethylene (DPE) in CH2Cl2 solution have been investigated at low temperature by ultraviolet (UV) spectrophotometry. Initiation proceeds in three successive stages. The first, very fast and leading to a low and constant concentration of carbocations, is assigned to residual traces of cocatalyst. A second stage, slower but more extensive, yields about one carbocation for two aluminum in a reaction that is first order in AlCl3 and first order in monomer (ki = 2.5 10−2 liter mole−1 sec−1 at −30°; Ei = 10 kcal mole−1). This stage, which takes place after consumption of residual cocatalyst, should be attributed to a direct initiation. In a proposed mechanism the cationic intermediate produced by reaction of DPE with AlCl3 transfers a proton to DPE, thus leading to a stable diphenylethyl cation and to alkenyldichloroaluminum (Al‐Cl2CHCPh2). A third stage develops slowly and the yield in carbocations finally reaches 65–70% with respect to AlCl3. This stage is tentatively assigned to a second direct initiation by the less active organoaluminum compound formed in the preceding stage.
ESR studies of trapped free radicals and polymer deposition in xylene plasmas
Authors: Scott Thomas W. , Chu Keh‐Chang , Venugopalan M.
Published: April 2003

Rates of polymer deposition and radical trapping in xylene plasmas produced in a Siemens tube with 60‐Hz current decreased linearly with increasing flow rate but increased linearly with power and decreased in the order ortho > meta > para at a constant flow rate and pressure. These results indicate that radical recombination and disproportionation are unimportant and that the polymerization rate equation is first order in free radical concentration.
Syntheses of N‐substituted carbazoles involving polymerizable terminal vinyl groups
Authors: Kamogawa Hiroyoshi , Koizumi Hitoshi , Nanasawa Masato
Published: April 2003

Eleven N‐substituted carbazoles (CZ) with terminal vinyl groups were synthesized by five sequences of reaction: N‐(p‐vinylbenzyl)‐ and N‐β‐(vinyloxyethyl)CZ by N‐alkylations of potassium CZ with corresponding chlorides; N‐(β‐acryloyloxyethyl)CZ by the esterification of N‐(β‐hydroxyethyl)CZ with acryloyl chloride; N‐acrylamido‐or methacryl‐amido‐methyl CZ from N‐hydroxymethyl CZ and acryl‐ or methacrylamide; N‐(3‐acryloyl‐ or methacryloyl‐oxy‐2‐hydroxypropyl)CZ and N‐[3‐(p‐ or m‐vinylanilino)‐2‐hydroxypropyl] CZ from N‐(2,3‐epoxypropyl)CZ and acrylic or methacrylic acid and p‐ or m‐vinylaniline, respectively; and 2‐[β‐(N‐carbazyl)propionyloxy]ethyl acrylate or methacrylate by the Michael addition of CZ to 2‐hydroxyethyl acrylate or methacrylate, followed by esterifications. The vinyl polymers with pendant carbazyl groups more or less distant from the polymer backbones, prepared by conventional radical or cationic polymerization procedures, indicated charge‐transfer spectra with 2,4,7‐trinitrofluorenone (TNF) in tetrahydrofuran (THF) solutions that are spread over most of the visible range.
Photooxidative degradation of cellulose: Reactions of the cellulosic free radicals with oxygen
Authors: Hon David N.‐S.
Published: April 2003

Photooxidative degradation of cellulose resulted in decreases of degree of polymerization (DP) and α‐cellulose content, concurrently producing chromophoric groups; namely, carbonyl, carboxyl, and hydroperoxide groups within the polymer. Electron spin resonance (ESR) studies revealed that cellulosic carbon free radicals readily reacted with oxygen molecules at 143–160 K to produce peroxy radicals, whereas cellulosic oxygen free radicals were inert toward oxygen molecules throughout the photooxygenation reactions. At 77 K it is feasible that only photoexcited oxygen molecules reacted with cellulosic carbon free radicals to produce peroxide radicals. These radicals were themselves stabilized at 273 K by abstraction of hydrogen atoms from cellulose to produce polymer hydroperoxides. Simultaneously, new radical sites, which exhibited three‐line ESR spectra, were generated in cellulose.
Polymerization of coordinated monomers. XV. 13C‐NMR study on the alternating copolymers of methyl methacrylate with styrene
Authors: Hirai Hidefumi , Koinuma Hideomi , Tanabe Tsuneaki , Takeuchi Kazuhiko
Published: April 2003

By the use of various metal halides methyl methacrylate and styrene were copolymerized to produce equimolar alternating sequences and different cotacticities. The 13C‐NMR spectra of these copolymers were simple in comparison to those of random copolymers because of the fixed monomer sequence which yielded sharply split triplets for carbonyl, methoxy, and quaternary carbons. The relative intensities in these split peaks varied according to the metal halide used. A comparison of the intensities made it possible to obtain clear‐cut and quantitative information on the methyl methacrylate‐centered triad cotacticity of the copolymers. The spectral assignment with respect to the methoxy carbon was definitely justified by the combined use of partly relaxed Fourier transform and selective decoupling techniques. The spectrum of aromatic C1 carbon in styrene units also split into three main peaks. From their relative intensities the splitting was attributed to styrene‐centered triad cotacticity. The assignment of this carbon was compared with two other assignments made for random copolymers of methyl methacrylate with styrene; they were contradictory, however. Furthermore, an apparent discrepancy was observed between methyl methacrylate‐and styrene‐centered tactic triads of these alternating copolymers. The origin of this discrepancy suggests a close relationship with the copolymerization mechanism.
Polymerization of acrylamide with persulfate–thiomalic acid initiator
Authors: Misra G. S. , Dubey S. L.
Published: April 2003

The redox system of potassium persulfate–thiomalic acid (I1–I2) was used to initiate the polymerization of acrylamide (M) in aqueous medium. For 20–30% conversion the rate equation is

where Rp is the rate of polymerization. Activation energy is 8.34 kcal deg−1 mole−1 in the investigated range of temperature 25–45°C. Mn is directly proportional to [M] and inversely to [I1]. The range of concentrations for which these observations hold at 35°C and pH 4.2 are [I1] = (1.0–3.0) × 10−3, [I2] = (3.0–7.5) × 10−3, and [M] = 5.0 × 10−2–3.0 × 10−1 mole/liter.
Peroxide‐initiated crosslinking of maleic anhydride‐modified low‐molecular‐weight polybutadiene. II. Crosslinking degree and thermal degradation of cured polymers
Authors: Gancarz I. , Łaskawski W.
Published: April 2003

The crosslinking density and thermal properties of peroxide‐crosslinked low‐molecular‐weight polybutadiene and its modification products with maleic anhydride were studied. It was shown that the Flory‐Rehner equation may be used for describing the equilibrium swelling of the studied systems. The molecular weight between crosslinks calculated from this equation has values from 117 to 216. It was found thermogravimetrically that the thermal stability of modified polybutadiene is lower than the unmodified material. The thermal destruction of the polymers studied is a step‐by‐step reaction, the first being of zero order, with activation energy of 76.6–112.6 kJ/mole, the second, a first‐order reaction with an Ea of 286.8–363.4 kJ/mole.
Maleimide‐terminated amide‐imide prepolymers: Synthesis and basic properties
Authors: Kruh Daniel , Jablonski Richard J.
Published: April 2003

Representatives of a family of soluble, imidized maleimide‐terminated amide‐imide precursors for molding and composite applications were prepared and characterized. The key step was the preparation of an amine‐terminated amide‐imide intermediate that was needed in order to introduce the maleimide groups. Trimellitic anhydride (TMA) and its monoacid chloride (TMAC) were each investigated for utility in reaction with molar excesses of methylenedianiline. With TMA the limiting factor was the time‐consuming amidation reaction, which, although catalyzed with triphenyl phosphite, required 24 hr to bring to completion in hot N‐methylpyrrolidone (NMP). The use of TMAC provided a more facile route to the intermediate and, as shown by gel permeation chromatography (GPC), resulted in a narrower molecular weight range than with TMA for the final maleimide‐terminated products. The reactions were followed by carboxyl titration, and the resulting products were characterized by IR, NMR, DTA, GPC, and inherent viscosity. The relative thermal capabilities were compared by isothermal aging as thin films (250°C) and as molded bars (316°C). Physical properties were assessed on glass laminates and molded bars. Although soluble in polar solvents, the products were viscosity unstable at ambient conditions. A solution to this problem was demonstrated by the preparation of the cyclopentadiene adduct, which was viscosity stable.
Radiation‐induced bulk polymerization of vinyl chloride under centrifugation
Authors: Carenza M. , Tavan M. , Palma G.
Published: April 2003

Radiation‐induced bulk polymerization of vinyl chloride has been carried out under centrifugation at 21°C. The polymerization rate and the molecular weight of the polymer produced were found to remain constant in the low‐conversion region and to be equal to the corresponding values that were obtained by extrapolation at zero conversion in normal polymerization. This was at variance with the case of normal polymerization in which both quantities exhibit a continuous increase from the start of the polymerization. Such an increase is to be associated with the presence of large agglomerates, formed through flocculation of initially originated particles, in the liquid monomer phase during the polymerization under quiescent conditions. For the constancy of the kinetic parameters in the polymerization under centrifugation it should be assumed that in the system there remain dispersed only particles not yet flocculated.
Kinetic studies on the formation of cyclic oligomers in poly(ethylene terephthalate)
Authors: Ha Wan Shik , Choun Young Kwan
Published: April 2003

The mechanism of cyclic oligomer formation has been kinetically studied by determining the rate of the formation of cyclic oligomers during melt of poly(ethylene terephthalate) (PET) at several levels of average molecular weight, which were obtained by fractionation and did not initially contain oligomers. The experimental rate equation of cyclic oligomer formation was introduced and then compared with the rate equation derived theoretically. The close agreement between the two equations suggested that the cyclic oligomer formation takes place according to cyclodepolymerization by the action of hydroxyl end groups in PET. The relation is represented as [C] = m·[OH]0·t1–n, where [C] is the concentration of cyclic oligomers, [OH]0 is the initial concentration of hydroxyl end groups, m and n are constants, and t is melting time. A method has also been developed for separating cyclic oligomers from PET using dimethylformamide (DMF) as a solvent.
Cationic polymerization of α‐methylstyrene from polydienes. I. Synthesis and characterization of poly(butadiene‐g‐α‐methylstyrene) copolymers
Authors: Ambrose R. J. , Newell J. J.
Published: April 2003

The preparation of poly(butadiene‐g‐α‐methylstyrene) copolymers was investigated with three different alkylaluminum coinitiators. The alkylaluminum compounds in conjunction with polybutadiene which contained a low concentration of labile chlorine atoms initiated the polymerization of α‐methylstyrene to produce graft copolymers. Trimethylaluminum gave higher grafting efficiencies than diethylaluminum chloride at comparable monomer conversions. Triethylaluminum produced only very low monomer conversions (<5%), even at long reaction times, and for this reason was not studied extensively. The number of grafts per polybutadiene backbone was determined for a number of copolymers and found to increase slightly as the allylic chlorine concentration in the polybutadiene backbone was increased. In all cases, however, only a low percentage of the available labile chlorine sites along the polybutadiene backbone resulted in grafted α‐methylstyrene side chains. The addition of small quantities of water to the polymerization solvent greatly enhanced the grafting rate and ultimate monomer conversion during the synthesis of these poly(butadiene‐g‐α‐methylstyrene) copolymers. The mechanistic role of water during these grafting reactions is unknown at the present time.
Polychlorinated polyamides. II. Synthesis and characterization of polyamides derived from 2, 5‐dichloroterephthaloyl dichloride and perchloroterephthaloyl dichloride
Authors: Díaz F. R. , Gargallo L. , Lizana C. , Gilbert S.
Published: April 2003

New thermally stable polyamides were prepared by interfacial polymerization of the title compounds and various aliphatic and aromatic diamines. The polymers were characterized by infrared spectrometry, elemental analysis, and differential scanning calorimetry. The molecular weights of the polymers were estimated by viscosity measurements. The influence of the halogen content on the thermal properties and degree of polymerization of the polymers was studied. One of the polyamides was fractionated to determine the degree of polydispersity.
New carbazole‐containing monomers and polymers
Authors: Simionescu C. I. , Percec V.
Published: April 2003

Five novel vinyl monomers, all of which contain 3‐substituted carbazolyl groups [i.e., N‐(9‐ethyl‐3‐carbazolyl)‐maleimide, 9‐ethyl‐3‐carbazolyl acrylamide, 9‐ethyl‐3‐carbazolyl methacrylamide, 9‐ethyl‐3‐hydroxymethylcarbazolyl acrylate, and 9‐ethyl‐3‐hydroxymethylcarbazolyl methacrylate], and their corresponding polymers were synthesized. Two methods were used for the synthesis of the last two monomers.
Malonic ester‐blocked aliphatic isocyanates
Authors: Kostyk Barry W. , Wicks Zeno W.
Published: April 2003

Products formed on pyrolysis of malonic ester‐blocked aliphatic isocyanates depend on the enolizability of the blocked isocyanate. Previous work reported that diethyl malonate‐blocked aliphatic isocyanates on pyrolysis yield predominantly “abnormal” products rather than the expected isocyanates. It has now been shown that this behavior results from the reactions of the enol forms. A nonenolizable diethyl methylmalonate‐blocked isocyanate has been synthesized. On pyrolysis essentially quantitative conversion to isocyanate and diethyl methylmalonate occurs. Significant differences in reactivity with amines and alcohols also result from the difference in enolizability.
Synthesis and thermal characterization of some novel phenol carbonates
Authors: Gibson Harry W. , Bailey F. C. , Pochan John M.
Published: April 2003

A total of 16 carbonates, all but one new compounds, have been synthesized. These include bis‐(phenyl carbonate)s of 13 bisphenols and 3 bis(substituted phenyl carbonate)s of 2,2‐bis(p‐hydroxyphenyl) butane. The present report characterizes them in terms of melting points Tm, elemental analyses, glass transition temperatures Tg, and enthalpies and entropies of fusion and relates the thermal properties to structure on a comparative basis. A number of the carbonates have what seem to be two distinct crystal structures as deduced from differential scanning calorimetry and x‐ray patterns. In keeping with data for polycarbonates, these bis(phenyl carbonate)s show abnormally high Tg/Tm relative to most polymers.
Copolymers of vinyl and vinylidene chlorides with alkyl acrylates
Authors: Logothetis A. L.
Published: April 2003

High‐molecular‐weight copolymers of vinyl chloride and ethyl or butyl acrylate were prepared in high conversion and yield in the presence of boron trifluoride as the acrylate ester complexing agent. When the vinyl chloride monomer is in excess of equimolar amounts, the resulting copolymers are alternating; and when the alkyl acrylates are in excess, acrylate‐rich copolymers are obtained. Ethylene–vinyl chloride–ethyl acrylate and propylene–vinyl chloride–ethyl acrylate terpolymers were also obtained with an ethyl acrylate content of 50 mole %. The relative reactivities of propylene, vinyl chloride, and ethylene in these polymerizations were 5.4, 3.8, and 1.0, respectively. Vinylidene chloride–ethyl acrylate copolymers that are nearly alternating and rich in acrylate or in vinylidene chloride have also been prepared. The monomer reactivity ratios for vinylidene chloride and ethyl acrylate in the presence of boron trifluoride are considerably lower than in its absence.
Mechanism of inhibitory action of metal dithiocarbamates. II. Autooxidation of tetralin and cumene and decomposition of tetralin hydroperoxide in the presence of zinc bisisobutyldithiocarbamate
Authors: Kateva J. , Ivanov S. K.
Published: April 2003

In the initial moment of the tetralin oxidation in the presence of tetralin and cumene hydroperoxides (THP, CHP) as well as of zinc diisobutyldithiocarbamate (ZDTC) an intensive absorption of oxygen‐prooxidation effect was observed. A pulsation absorption of oxygen during the oxidation of tetralin with ZDTC and AIBN was established. It has been proved that the stoichiometric coefficient of inhibition (f) is a function of the ZDTC concentration. A probable scheme of the decomposition of the THP with ZDTC which includes the formation of SO2 as possible decomposition agent of ROOH according to the ionic mechanism was suggested.
Biphenylene as a crosslinking unit in polyaromatic ether–ketone and ether–ketone–sulfone resins. XVI
Authors: Swedo Raymond J. , Marvel C. S.
Published: April 2003

Biphenylene units have been incorporated into polyaromatic ether–ketone and polyaromatic ether–ketone–sulfone resins as useful crosslinking sites. Crosslinking is achieved by heating the resins to 300–400°C. The keto polymers are soluble only in sulfuric acid before curing, but the sulfone polymers are soluble also in some aprotic solvents. Molded “I beams” of the cured keto polymer are stronger than those of the sulfone polymer. Both classes of polymer are quite thermally stable. Curing can be hastened by catalyzing with rhodium compounds.
Polymerization of vinyl fluoride initiated by the system silver nitrate–tetraethyl lead
Authors: Raucher Daniel , Demiel Arieh , Levy Moshe , Vofsi David
Published: April 2003

The initiator system AgNO3–tetraethyl lead was used for the polymerization of vinyl fluoride. Dimethyl sulfoxide was found to have a specific effect on the half‐life of the initiating system, which leads to long reaction times and high conversions at ambient temperatures. This effect was explained by the complexing power of DMSO on silver ions, which slows down the rate of formation of AgEt and permits the polymerization to proceed for longer periods than in other solvents. The kinetics of the polymerization agreed with the scheme developed earlier. Tetraethyl lead acts as a powerful chain transfer agent and determines to a large extent the resulting polymers.
A novel metal alkyl‐free catalyst for the ring‐opening polymerization of cycloolefins
Authors: De Figueiredo Cecilia M. C.
Published: April 2003

A new catalytic system based on tungstic acid (H2WO4) and aluminum trichloride (AlCl3) polymerizes cyclopentene and 1,5‐cyclooctadiene through a ring‐opening mechanism in high yields and high molecular weight.
Linear polythioesters. III. Products of interfacial polycondensation of 1,4‐, 1,5‐di(mercaptomethyl)‐naphthalene, and their mixture with adipoyl and sebacoyl chlorides
Authors: Podkościelny Wawrzyniec , Charmas Władysław
Published: April 2003

New polythioesters of naphthalene derivatives by polycondensation of 1,4‐di(mercaptomethyl)‐naphthalene, 1,5‐di(mercaptomethyl)naphthalene, as well as their mixture with adipoyl and sebacoyl chlorides have been obtained. Low‐temperature and high‐temperature solution polycondensation as well as interfacial polycondensation have been used. Interfacial polycondensation proved to be the most useful. To define the optimal conditions of interfacial polycondensation, the following factors influencing the process have been studied: ratio of aqueous to organic phase, concentration of hydrochloride acceptor, temperature of reaction and rate of addition of acid chloride, contribution of emulsifier and catalyst. Yield for all reaction products and reduced viscosity have been found. The structure of polythioesters of high‐value viscosity and good yield was determined from elementary analysis, infrared spectra, x‐ray, and thermogravimetric analysis. Some mechanical and electrical properties of the polythioesters obtained from the mixture of 1,4‐ and 1,5‐di(mercaptomethyl)naphthalene have been studied after pressing in increased temperature. The molecular weight was not determined because of very low solubility.
Alternating copolymerization of 1‐ and 2‐vinylnaphthalene with methyl methacrylate by using diethylaluminum chloride
Authors: Hirabayashi Tadamichi , Nishikawa Yoshikazu , Yokota Kenji
Published: April 2003

The alternating copolymerization of 1‐ and 2‐vinylnaphthalene (1‐VNap and 2‐VNap) with methyl methacrylate (MMA) by using diethylaluminum chloride (Et2AlCl) in toluene at 0°C has been studied. No polymerization could occur without Et2AlCl, and alternating copolymers were obtained only when an equimolar amount of Et2AlCl with MMA was supplied. Through 1H‐NMR analyses on both dyad and triad of alternating deuterated 1‐ and 2‐α‐d‐VNap–MMA copolymers, each configuration could be described successfully by a single parameter, coisotacticity σ, whose value was estimated as 0.41 for the former and 0.56 for the latter copolymer, respectively. A rather low coisotacticity of copoly(1‐VNap–MMA) was explained in the terms of steric effect (peri effect) of 1‐VNap monomer.
The mobility profile around polymer segments as calculated from microviscosity data on polymer solutions and gels
Authors: Elmgren Hans
Published: April 2003

A mobility profile describes the change of the solvent mobility with the distance from the surface of a suspended particle. By means of numerical integration on a computer, a relationship was found between such profiles and the concentration dependence of microviscosity in suspensions of cylinders (models for polymer segments in polymer solutions and gels) and spheres (e.g., protein molecules).

The obtained relationship was used to calculate the mobility profile in aqueous solutions of hydroxyethyl cellulose and ribonuclease A. The influence of the macromolecules on the water mobility was found to change as the inverse distance to the power of 1.6 and 2.2, respectively. At a distance of 40 Å from the cellulose segment, or from the surface of the ribonuclease molecule, the mobility is reduced by 10% from that in bulk solvent.
Thermodynamics of binding methyl orange and its homologs by polyvinylpyrrolidone: The effect of hexamethylenetetramine
Authors: Takagishi Toru , Kuroki Nobuhiko
Published: April 2003

Hexamethylenetetramine (HMT) has been examined for its effect on the binding of methyl orange homologs, methyl orange, ethyl orange, propyl orange, and butyl orange by polyvinylpyrrolidone (PVP). In the presence of HMT the entropy changes associated with the binding tend to become more positive and the absolute magnitude in the enthalpy changes becomes smaller compared with those in the absence of HMT. These tendencies are accounted for in terms of the water‐structure‐promoting effect of HMT, hence the enhancement of hydrophobic interactions in the binding. PVP undergoes changes in conformation on the addition of HMT and its conformation becomes more compact. This also increases the contribution of the hydrophobic interactions to the macromolecule‐small molecule interaction. Some other effects exerted by the added HMT on the binding system are also described.
Plasma polymerization. III. An ESCA investigation of polymers synthesized by excitation of inductively coupled RF plasmas in perfluorocyclohexa‐1,3‐ and 1,4‐dienes, and in perfluorocyclohexene
Authors: Clark D. T. , Shuttleworth D.
Published: April 2003

The plasma polymers prepared from perfluorocyclohexa‐1,3‐diene, perfluorocyclohexa‐1,4‐diene, and perfluorocyclohexene have been investigated by ESCA. The carbon‐to‐fluorine stoichiometries of the diene‐derived polymers are similar and close to that of the starting material. The polymer prepared from perfluorocyclohexene is depleted in fluorine compared to the fluorine content of the “monomer.” The polymers prepared in nonglow regions are also studied and shown to be high in CF2 derived species. The results are compared with those for perfluorobenzene and perfluorocyclohexane, and the polymerization rates are in the order C6F6 > C6F8 1,3 ∼ 1,4 > C6F10 ∼ C6F12. The variations in composition of the plasma polymer as revealed by ESCA as a function of the polymerization conditions are discussed.
Studies of the polymerization of diallyl compounds. XXVI. Enhanced polymerizability by the hydroxyl group in the polymerization of diallyl hydroxydicarboxylates
Authors: Ohata Tetsuji , Matsumoto Akira , Oiwa Masayoshi
Published: April 2003

In order to elucidate the effect of the hydroxyl group on the polymerization of diallyl hydroxydicarboxylates, we investigated in detail the radical polymerizations of diallyl succinate (DASu), diallyl malate (DAMa), and diallyl tartrate (DATa), each of which have similar structure differing only in the number of hydroxyl groups present. The rate of polymerization (Rp) was quite enhanced in the order DASu < DAMa < DATa, in accord with the increase in the number of hydroxyl groups within a monomer unit. The enhanced ability of the allylic monomer radical to reinitiate chain growth was also in the same order, as was clear from the dependence of Rp on the initiator concentration. The dependence of the residual unsaturation of the polymer on the monomer concentration in the polymerizations of DAMa and DATa was abnormal in terms of cyclopolymerization. These results are discussed in connection with the formation of the intermolecular hydrogen bond through the hydroxyl groups.
High‐molecular‐weight polyterephthalamide by direct polycondensation reaction in the presence of poly(ethylene oxide)
Authors: Higashi Fukuji , Nakano Yoshimasa , Goto Mitsuyoshi , Kakinoki Hideo
Published: April 2003

Polyterephthalamides of high molecular weight (ηinh up to 1.9) were obtained by the direct polycondensation reaction of terephthalic acid and aromatic diamines in the presence of poly(ethylene oxide) (PEO) with triphenyl phosphite in a N‐methylpyrrolidone (NMP)–pyridine solution that contained lithium chloride. The molecular weights of the polymers produced varied with the amount and molecular weight of PEO, which showed maximum values when PEO with a molecular weight of 2.0 × 104−5.0 × 105 was used in a concentration of about 0.5 wt % in the solvent. The polycondensation reaction was significantly affected by the level of pyridine in a mixed solvent of NMP and pyridine and by the concentration of the lithium chloride added.
Polymérisation anionique de i'isoprene et du butadiene en presence d'agents complexants
Authors: Alev Samson , Collet André , Viguier Michel , Schué François
Published: April 2003

With the aid of DCHE and [222], solutions of sodium, potassium, rubidium, and cesium have been prepared in tetrahydrofuran (THF) and in benzene. All these new species initiate the polymerization of butadiene and isoprene avoiding the inconvenience of heterogeneous reactions. The presence of free ions and/or complexed ion pairs allows the increase of vinyl structures even in benzene.
Thermostability of polymers containing indanic units in the main chain
Authors: Nishimura J. , Tanaka N. , Yamashita S.
Published: April 2003

The acid‐catalyzed stepwise polymerization of 1,1‐diphenylethylene derivatives, p‐di(1‐phenylvinyl) benzene, bis[p‐(1‐phenylvinyl)phenyl]methane, 1,2‐bis[p‐(1‐phenylvinyl)phenyl]ethane, bis[p‐(1‐phenylvinyl)phenyl]ether, and bis[p‐(1‐phenylvinyl)phenyl]sulfide produced selectively indanic‐unit‐containing polymers in pertinent conditions. Their molecular weights (M̄n) were in the 1600–15, 700 region after the fractionation in hot ethnol. Melting points were in the 214–281°C region. They dissolved fairly well in conventional solvents like benzene, tetrahydrofuran, and carbon tetrachloride. According to TGA they started to decompose at 397–432°C and showed 10% weight loss at 478–502°C in air at a heating rate of 5°C/min. Focusing on the thermostability, we report on their physical properties.
Syntheses of polyethylenimine containing asymmetric nucleic acid base derivatives as grafted pendants
Authors: Overberger C. G. , Morishima Y.
Published: April 2003

Preparations of new model polymers of polynucleotides with linear polyethylenimine (PEI) backbones and optically active nucleic acid base derivatives as pending side chains are described. (±)‐2‐(Thymin‐1‐yl)propionic acid (II) and (±)‐2‐(adenin‐9‐yl)propionic acid (IV) were synthesized. These carboxylic acid derivatives were grafted onto PEI at the imino nitrogen by the p‐nitrophenyl active ester method. The enantiomeric pairs of II were optically resolved with quinine to yield (−) and (+)‐2‐(thymin‐1‐yl)propionic acid (VII and VIII). VII and VIII were grafted onto PEI through amide bond by direct coupling with diethylphosphoryl cyanide to give optically active graft polymers. The related monomer and dimer model compounds were also prepared by the same method from diethylamine and dimethylethylene diamine, respectively.
New processable polyaromatic ether–keto‐sulfones curable by Diels‐Alder cycloaddition
Authors: Sankaran V. , Marvel C. S.
Published: April 2003

New Processable polyaromatic ether‐keto‐sulfones were prepared from the acid chloride of bis‐m‐carboxyphenyl acetylene (XII), isophthaloyl chloride (XX), diphenyl ether (XVIII), and 4,4′‐diphenoxydiphenyl sulfone (XIX) in a Friedel‐Crafts‐type polymerization. These polymers were cured by Diels‐Alder cycloaddition with 1,4‐diphenyl‐1,3‐butadiene. The cured polymers showed an increase in Tg and in thermal and heat stabilities. The polymers form colorless, transparent, brittle films and can be cast into a glass fiber laminate. Both meta‐and para‐substituted acid chlorides of biscarboxyphenyl‐1,3‐butadiene yielded insoluble polymers under the same conditions but form processable polymers where combined with acetylene units in the polymer chain. Polymers that contained both acetylene and butadiene units were prepared but could not be cured by an intramolecular Diels‐Alder cycloaddition reaction.
Heat‐resistant polymers with thianthrene analog units. II . Aromatic polyamides
Authors: Niume K. , Nakamichi K. , Toda F. , Uno K. , Hasegawa M. , Iwakura Y.
Published: April 2003

A series of polyamides which contained thianthrene, phenoxatiin, and dibenzo‐p‐dioxin units was synthesized from tricyclic fused‐ring diamines and aromatic diacid chlorides by solution polycondensations at a low temperature. The amorphous polyisophthalamides were highly soluble in polar organic solvents, whereas some of the polyterephthalamides with a fair degree of crystallinity were insoluble. The solubility of the series of polyamides increased in the order of the dibenzo‐p‐dioxin‐containing polymers < phenoxatiin‐containing polymers < thianthrene‐containing polymers. The thermal stability increased in the reverse order and the dibenzo‐p‐dioxinpolyamides were more thermostable than the corresponding open‐chain polymers with diphenyl ether linkages. The polyamides derived from 2,8‐oriented tricyclic diamines showed somewhat lower glass transition temperatures than those from 2,7‐oriented diamines.
Photochemistry of polymeric systems. II. Photocrosslinking of polymers and copolymers containing various aromatic N‐oxide groups
Authors: Decout Jean‐Luc , Lablache‐Combier Alain , Loucheux Claude
Published: April 2003

2‐Methyl‐5‐vinylpyridine‐N‐oxide, 4‐vinylquinoline‐N‐oxide. 9‐vinylacridine‐N‐oxide, p‐N,N‐dimethylaminostyrene‐N‐oxide units were introduced in polymeric chains as homopolymers or/and as styrene copolymers to study their photocrosslinking. The method used for characterization of photocrosslinked films was a “photoresist test” described in Part I of this series. The photosensitivity of the different chromophores bound to the different polymer has also been studied by UV, IR, and fluorescence spectrophotometries. The use of aromatic amine N‐oxide groups in polymers seems to be a general means to produce their photocrosslinking by radical reactions. Among the different polymeric materials prepared, 4‐vinylpyridine‐N‐oxide and 4‐vinylquinoline‐N‐oxide are the most photosensitive.
Polymerization of cyclic derivatives of uracil and thymine
Authors: Inaki Yoshiaki , Futagawa Hidekazu , Takemoto Kiichi
Published: April 2003

Cyclic derivatives of uracil and thymine were synthesized from their corresponding 1‐(2′‐chloroethyl) derivatives by dehydrochlorination. These compounds were found to undergo a variety of reactions, giving many valuable derivatives of uracil and thymine. The cyclic derivatives, as monomers, were polymerized with a cationic initiator by a unique ring‐opening process. The polymerization proceeded by ring opening with isomerization of the pyrimidine ring to give a polymer in which pyrimidine rings were connected with ethylene between N‐1 and N‐3 or O‐4 in the pyrimidine ring. The structure of these polymers was determined by nuclear magnetic resonance (NMR), ultraviolet (UV), infrared (IR), and mass spectra. The structure was affected by polymerization temperature.
Enantioselective ester synthesis in the presence of optically active polymers
Authors: Kawakami Yuhsuke , Sugiura Tomiya , Mizutani Yutaka , Yamashita Yuya
Published: April 2003

Enantiomer‐differentiating ester syntheses from acid salts, chlorides, and an anhydride were studied in the presence of optically active polyamines. Enantiomer selection occurred in reactions of a racemic salt with an achiral alkyl bromide and vice versa, which is good evidence of the importance of activation of the carboxylate group by complexation of the counterion and activation of alkyl bromide by the formation of a quaternary salt with polyamine under solid–liquid, phase‐transfer reaction conditions. Only small optical activity was observed in the products of acid anhydride or chloride with alcohol.
Kinetics of crosslinking copolymerization of styrene with symmetric divinyl compounds
Authors: Fink Johannes Karl
Published: April 2003

Gel formation usually occurs in crosslinking systems during polymerization. The critical conversion in this process is dependent on the reactivity ratios of the different kinds of double bond in the system and on the tendency to cyclization. In this article a procedure for estimating the gel point for small amounts of a symmetric divinyl compound is shown in measurements of the degree of polymerization at different conversions. A method is also given to relate the reactivity ratio of the pendent double bonds to the amount of cyclization and to the degree of multiple crosslinking. In m‐divinylbenzene/styrene the results indicate that about 10% of the pendent double bonds is consumed by cyclization due to backbiting of the primary chain, whereas an initial effective crosslink results in about seven multiple crosslink bonds.
Condensed phase aromatization during degradation of poly(vinyl chloride)
Authors: Brauman Sharon K. , Chen Ida J.
Published: April 2003

Proton NMR results for partially degraded PVC show that aromatization accompanies dehydrochlorination in the condensed phase; subsequent fragmentation leads to loss of volatile aromatics.
Polytetrafluoroethylene surface modification by impregnation with iron and manganese oxides
Authors: Baumhardt‐Neto Ricardo , Galembeck Sérgio Emanuel , Joekes Inés , Galembeck Fernando
Published: April 2003

Polytetrafluoroethylene (PTFE) surfaces can be modified by impregnation with Fe and Mn oxides by procedures based on Fe(CO)5 sorption in the polymer and followed by oxidation with H2O2 or KMnO4. The effect of some variables (reagent concentrations and temperature) on the amount of oxides deposited was examined. The oxides incorporated in PTFE can be only partly removed by acid cleaning. Water–PTFE contact angles and PTFE surface resistivity are altered. Electron and x‐ray diffractograms of the oxides were obtained but unambiguous identification was not achieved. Transmission electron microscopy examination of surface replicas showed that impregnation with oxides which covered most of the PTFE surface was fairly uniform.
Transfer constants relative to the cationic polymerization of 1‐ and 2‐vinyl naphthalenes and 3‐vinyl phenanthrene
Authors: Blin Philippe , Bunel Claude , Marechal Ernest
Published: April 2003

Transfer and termination constants have been determined for the cationic polymerization of 1‐ and 2‐vinyl naphthalenes and 3‐vinyl phenanthrene. They have been compared with the values obtained for styrene under the same experimental conditions. Experimental values are in good agreement with theoretical determinations.
N‐substituted poly(p‐phenylene terephthalamide)
Authors: Takayanagi Motowo , Katayose Teruo
Published: April 2003

N‐substituted poly(p‐phenylene terephthalamide)s (PPTA), such as N‐alkylated, N‐aralkylated, and N‐carboxymethylated poly(p‐phenylene terephthalamide), were synthesized from PPTA and the corresponding halides by the polymer reaction via the metalation reaction in a solution of sodium methylsulfinylcarbanion in dimethyl sulfoxide at low temperature. The introduction of various substitutional groups into the amide groups of PPTA increased their solubilities, but decreased their thermal stabilities compared with PPTA. The effects of various substitutional groups on the thermal properties and the solubilities are discussed. Liquid crystal formation was noticed for PPTA substituted with bulky groups such as 9‐anthrylmethyl group.
Polymerization of acrylonitrile initiated by the redox system 2,2′‐thiodiethanol/Ce4+ in aqueous sulfuric acid
Authors: Jayakrishnan Athipettah , Haragopal Mahadevan , Mahadevan Venkatanarayana
Published: April 2003

The polymerization of acrylonitrile initiated by the redox system 2,2′‐thiodiethanol/Ce4+ in dilute sulfuric acid was investigated in the temperature range of 15–25°C. Oxidation of the substrate in the absence of the monomer has also been studied. The reaction involves the formation of an intermediate complex between the metal ion and the protonated species of the reductant, whose decomposition gives rise to the initiating free radicals. Multual interaction of the growing macroradicals accounts for the termination of polymerization. A suitable kinetic scheme has been proposed and rate and equilibrium constants evaluated.
Mechanism of smoke suppression by metal oxides in PVC
Authors: Ballistreri A. , Montaudo G. , Puglisi C. , Scamporrino E. , Vitalini D.
Published: April 2003

The amount of smoke suppression induced in PVC by some metal oxides was measured as a function of temperature. The amount of CO2 evolved in the combustion was also measured simultaneously with smoke emission. Our results show that in a smoldering condition smoke occurred almost immediately, whereas CO2 occurred at a later stage. A good correlation was found between smoke density and char yield in nitrogen, and the amount of benzene suppression, induced by metal oxides, also correlated well with the char yield. These facts are taken as evidence that crosslinking catalyzed by metal oxides is the principal mechanism of smoke inhibition and that char oxidation is responsible for the reduction of char yield.
Novel thermostable polymers from bis‐o‐aminophenylbenzimidazoles and aromatic tetracarboxylic dianhydrides
Authors: Niume K. , Toda F. , Uno K. , Hasegawa M. , Iwakura Y.
Published: April 2003

Novel aromatic hetero polymers, polybenzoylenebenzimidazoquinazolines, were prepared. These polymers were synthesized by the polymerization of bis‐o‐aminophenylbenzimidazoles with aromatic tetracarboxylic dianhydrides in organic solvents, followed by cyclocondensation of the polyamic acids in polyphosphoric acid. In the resulting polymers the o‐phenylenediamine component behaved trifuntionally and the connecting groups were tricyclic fused rings that contained seven‐membered rings. These polymers some of which has a ladder‐type structure, exhibited excellent thermal properties.
Compatibility of cross‐linked polymers with plasticizers by glass transition temperature measurement and swelling tests
Authors: Chi Minn‐Shong
Published: April 2003

To elucidate the compatibility of polymer and plasticizer components of binders a study of polymer–plasticizer interactions by differential scanning calorimetry (DSC) and swelling tests was conducted. The glass transition temperatures (Tg's) of mixtures of polymers and plasticizers, both cured and uncured, were determined with a DSC technique. Results with the PEG polymer systems were complicated by the partial crystallization of the polymer from the polymer/plasticizer mixtures. The PGA polymer system did not exhibit this behavior. However, the Tg's of cured PGA with various plasticizer mixtures made complicated departures from linearity (plots of Tg versus weight fraction of plasticizer) that indicated polymer–plasticizer interaction. By using least‐squares analysis of data plotted by the equation

Values of the interaction parameter K were determined for cured PGA in various plasticizer systems. These K values are in good agreement with the molecular flexibility of the plasticizers based on their molecular structure. The results of swelling tests are discussed to elucidate further the nature of the interaction of these polymers with plasticizers. Calculated polymer‐plasticizer interaction values (χ) from the swelling tests correlated with the solubility parameter (δ) for a given class of polymer (polyether, polyester) and plasticizer (nitrate ester, ether‐type). The efficiency of a plasticizer in reducing the Tg of a polymer (below the linearly interpolated value) was found not to be related to the swelling behavior of the polymer in the plasticizer.
Thermal polymerization of acrylamide by differential scanning calorimetry
Authors: Kishore K. , Santhanalakshmi K. N.
Published: April 2003

Thermal polymerization of acrylamide was studied by differential scanning calorimetry. Latent heat of fusion ΔHf and enthalpy of polymerization ΔHp values were found to be 36 and −18.0 kcal mol−1, respectively. The overall activation energy E for the polymerization was calculated to be 19 k cal mol−1 up to 60% conversion. The added free‐radical inhibitor (benzoquinone) was found to desensitize the thermal polymerization of acrylamide suggesting the polymerization to be a free‐radical type. The existing rate equation for the heterogeneous bulk polymerization in the presence of initiators has been modified for the thermally initiated bulk polymerization of acrylamide. The experimental overall E value was found to agree well with the calculated E value when considering only the propagation and termination steps, thereby suggesting the process to be similar to postpolymerization of acrylamide.
Microstructure of vinyl acetate–butyl acrylate copolymers studied by 13C‐NMR spectroscopy: Influence of emulsion polymerization process
Authors: Pichot Christian , Llauro Marie‐France , Pham Quang‐Tho
Published: April 2003

The compositions and sequence distributions of vinyl acetate–butyl acrylate copolymers obtained with batch and semicontinuous emulsion polymerizations have been studied by 1H and 13C NMR. The batch process gives heterogeneous copolymers while with the semicontinuous one the sequence distribution is statistical. These differences in sequence distributions have been related to the physical properties of the copolymers.
A 13C‐NMR investigation of plasma polymerized ethane, ethylene, and acetylene
Authors: Dilks A. , Kaplan S. , Van Laeken A.
Published: April 2003

Solid‐state 13C‐NMR spectra were obtained by cross‐polarization and magic angle spinning of polymers prepared by injecting ethane, ethylene, and acetylene into a radiofrequency plasma. By use of the delayed decoupling technique to suppress protonated carbon peaks and difference spectroscopy five resolved spectral bands can be distinguished. These bands are assigned to (I) unsaturated nonprotonated, (II) unsaturated CH and CH2, (III) quaternary, (IV) methine and methylene, and (V) methyl carbons by comparison with standard 13C shifts compiled for organic materials. The relative amounts of these structural features in the polymers were determined quantitatively and the possible sources of errors considered.
Polymerization of coordinated monomers. XIX. Kinetic study of the alternating copolymerization of methyl methacrylate with styrene by boron trichloride
Authors: Hirai Hidefumi , Takeuchi Kazuhiko , Komiyama Makoto
Published: April 2003

Alternating copolymerizations of methyl methacrylate with styrene in the presence of boron trichloride at 0°C in 1,2‐dichloroethane were carried out by using benzoyl peroxide as an initiator. Conversion increased proportionally with polymerization time, whereas the degree of polymerization was constant irrespective of time. The rate depended linearly on the square root of the concentration of benzoyl peroxide. The equilibrium constants for the formation of the ternary molecular complex composed of methyl methacrylate, styrene, and boron trichloride in 1,2‐dichloroethane at −20, −10, and +4°C were determined by 1H‐NMR spectroscopy. The concentrations of the ternary molecular complex in the polymerization mixtures were evaluated from the equilibrium constant of the formation. The rate of the alternating copolymerization was proportional to the first order of the concentration of the ternary molecular complex. The distribution of methyl methacrylate‐centered triads in the alternating copolymer was different from that of styrene‐centered triads. These results can be explained by a mechanism involving the homopolymerization of a ternary molecular complex.