bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization initiation by in situ initiator formation. II. in situ formation of several peroxydicarbonates and diisobutyryl peroxide
Authors: Ravey M. 
Published: April 2003

AbstractThe rate of formation of a number of dialkyl peroxydicarbonates and one acylperoxide under in situ conditions were followed by using a simulated suspension polymerization system. Results confirm previous findings based on polymer conversions and indicate that for dialkyl peroxydicarbonates, the in situ mode is suitable only for the lower alkyl derivatives.
The flammability properties of copolyesters and copolycarbonates containing acetylenes
Authors: Quinn C. B. 
Published: April 2003

AbstractThe flammability properties of copolyesters and copolycarbonates containing varying percentages of 2‐butyne‐1,4‐diol and 2,4‐hexadiyne‐1,6‐diol were studied by use of oxygen index and dynamic thermogravimetry. The char formation was found to increase with increasing polymer unsaturation. For nonconjugated acetylenes there is an increase in the oxygen index with increasing unsaturation in a polymer. In contrast, conjugated acetylenes dramatically decrease the oxygen index of a polymer system.
Henry's law and diffusion constants of vinyl chloride in poly(vinyl chloride) at high temperature
Authors: Brown Daniel W. , Lowry Robert E. 
Published: April 2003

AbstractThe Henry's law and diffusion constants of vinyl chloride in poly(vinyl chloride) were determined at temperatures of 24, 90, 120, 150, and 170°C for weight fractions of vinyl chloride between 0.2 × 10−3 and 0.8 × 10−3. Above 90°C, Henry's law applies; values of the constant increase with temperature from 1.8 × 102 to 5.5 × 102 atm per unit weight fraction of dissolved vinyl chloride. The heat of desorption is about 15 kJ/mole. At 24°C, the nominal Henry's law constant was smaller than would have been obtained by extrapolating the values found at higher temperature. The diffusion constants increase with temperature from about 2 × 10−13 to 3 × 10−7 cm2/sec. The activation energy for diffusion is about 110 kJ/mole between 90 and 170°C. Although all values were determined in the absence of air, it is likely that they apply to polymer in air. They may, therefore, be used to calculate the vinyl chloride content in the gas above poly(vinyl chloride) under specific processing conditions.
Stereochemistry in cationic polymerization of alkenyl ethers. I. 1H‐ and 13C‐NMR spectra of poly(propenyl ethers)
Authors: Higashimura Toshinobu , Hoshino Mitsuru , Hirokawa Yoshitsugu , Matsuzaki Kei , Uryu Toshiyuki 
Published: April 2003

AbstractBenzyl, ethyl, and deuterated ethyl propenyl ethers (BzPE, EPE, and EPE‐d5, respectively) with different cis/trans isomer ratios were polymerized by BF3O(C2H5)2 at −78°C in toluene, methylene chloride, and nitroethane solvents. Poly(propenyl alcohol) [poly(PA)] was also prepared by treating poly(BzPE) with HBr gas. The steric structure of these polymers was studied by 1H‐ and 13C‐NMR spectroscopy. The poly(EPE‐d5) obtained from a trans‐rich monomer mixture was crystalline, while one from a cis‐rich monomer mixture was amorphous. Poly(BzPE) was always amorphous. Poly(BzPE), poly(PA), and poly(EPE‐d5) gave 1H‐NMR spectra with two β‐methine peaks, relative intensities of which depended on the geometric structure of the monomers. Their spectra of β‐methyl protons decoupled from β‐methine proton were also split into two peaks, relative intensities of which corresponded to those of the two α‐methine peaks. 13C‐NMR spectra of α‐OCH2 and β‐CH3 of poly(EPE), respectively, consisted of two peaks. These observations show that the poly(propenyl ethers) examined, whether crystalline or amorphous, have only two dyad structures (probably threo or erythro‐meso and racemic), and that their α‐ and β‐carbons have the same dyad structure, irrespective of the kind of the alkoxyl groups.
Copolymerisation radicalaire du méthacrylate de méthyle et du chlorure de vinylidène avec ou sans dérive de composition
Authors: Chiang Ta Chi , Graillat Ch. , Guillot J. , Pham Q. T. , Guyot A. 
Published: April 2003

AbstractTwo sets of methylmethacrylate‐vinylidene chloride copolymers were prepared via radical copolymerization in dimethylformamide. The first set is carried out in batches. Gas‐chromatographic analysis of samples allows a kinetic study from which the reactivity ratios rM ‐ 2.73 and rC ‐ 0.24 are derived. For the second set a new apparatus, briefly described, has been used. It permits to keep constant the composition of the monomer mixture, through addition of methyl methacrylate, monitored by a chromatographic analysis. The two sets of copolymers are analyzed using nuclear magnetic resonance (60 MHz) leading to the triad distribution, from which the reactivity ratios are derived. Owing to the composition drift, the method cannot be applied to the first set of copolymers; but in that case, it is possible to calculate the triad distribution, the knowledge of the reactivity ratios, and the calculation fits quite well the experimental results.
Thermal properties and solubility of ordered aromatic polyamides containing a methyl‐substituted phenylene linkage
Authors: Takatsuka Ryoza , Uno Keikichi , Toda Fujio , Iwakura Yoshio 
Published: April 2003

AbstractOrdered aromatic polyamides and copolyamides were prepared by the polycondensation of terephthaloyl and isophthaloyl dichlorides with symmetrical diamines containing preformed amide linkages derived from unsymmetrical methyl—substituted aromatic diamines at low temperature. Thermal properties and solubilities of the ordered polyamides were compared with those of the corresponding random polyamides. There was little difference between thermal stabilities of the ordered polyamide and the corresponding random one, while the former was less soluble in organic solvents than the latter, depending on the extent of hydrogen bonding of the amide groups. The thermal stability of the alternating copolyamides containing both terephthaloyl and isophthaloyl groups as acid components was less than that of the corresponding homopolymers having either a terephthaloyl or an isophthaloyl group, and the solubility of the former resembled that of the corresponding ordered homopolysiophthalamides in accord with the extent of hydrogen bonding of the amide groups in both polymers.
Syntheses of polystyrene–covalently bonded metalloporphyrin complexes and their reaction with molecular oxygen
Authors: Hasegawa Etsuo , Kanayama Tatsuya , Tsuchida Eishun 
Published: April 2003

AbstractThe copolymer of styrene with protoporphyrin IX styrylamide, prepared by the reaction between the porphyrin di(acid chloride) and p‐aminostyrene, was synthesized by radical copolymerization and characterized. The metal complexes of the copolymer were prepared by incorporating corresponding metal ions. It was found by electron spin resonance measurements that the cobalt(II) complex is able to absorb molecular oxygen reversibly in toluene at low temperature.
Dilute solution properties of poly(1,4‐phenylene terephthalamide) in sulfuric acid
Authors: Baird D. G. , Smith J. K. 
Published: April 2003

AbstractThe intrinsic viscosity [η] of dilute solutions of poly(1,4‐phenylene terephthalamide) (PPPT) is found to depend strongly on sulfuric acid strength, exhibiting a maximum at about 100% H2SO4. This behavior instigated measurements of [η] and light scattering from dilute solutions of unfractionated PPPT in concentrated (≈96%) and 100% H2SO4. From [η] and weight‐average molecular weight Mw relationships, Mark‐Houwink exponents a were determined to be 1.36 in 96.6% and 1.62 in 100.2 ± 0.2% H2SO4, indicating that the PPPT molecule can undergo considerable expansion in 100% H2SO4. For the case of 100% H2SO4, a noticeable polyelectrolyte effect is observed in the reduced viscosity versus concentration curves. This result suggests that the repulsive charges generated along the PPPT backbone may be responsible for the change in configuration of PPPT upon increasing the acid strength from 96.6% to 100% H2SO4. It is pointed out that there is considerable experimental difficulty in measuring consistent values of Mw, and this may be the reason for the variation among published data.
Synthesis and properties of alkylene‐linked aromatic polyimides
Authors: Charbonneau L. F. 
Published: April 2003

AbstractAlkylene‐linked aromatic polyimides were prepared from a family of new dianhydride monomers and aromatic diamines. The dianhydrides were synthesized by Friedel‐Crafts catalysis of the condensation of ditertiary alcohols with o‐xylene, subsequent oxidation of the aryl methyl groups to carboxy, and finally, dehydration of the ortho‐carboxy substituents to anhydride groups. Alkylene‐linked aromatic polyimides, with up to 8 methylene groups in the polymer chain, are stable to 400°C in air and can be extruded or compression‐molded at 300°C. In addition, these polymers are soluble in solvents within the solubility parameter range of 10.4 ± 1.2.
Polymerization of α,α‐disubstituted β‐propiolactones and lactams. VII. Stereoregular polymers from optically active lactones
Authors: D'Hondt Christian G. , Lenz Robert W. 
Published: April 2003

AbstractOptically active α‐phenyl‐ααethyl‐β‐propiolactone of high optical purity was prepared and polymerized by homogeneous anionic initiation to the isotactic polyester. The racemic and isotactic polymers had apparently different crystalline properties suggesting that the former may be syndiotactic or may crystallize with unit cells containing both R and S blocks. Similar attempts to prepare α‐methyl‐α‐isopropyl‐β‐propiolactone of high optical purity were unsuccessful although a partially crystalline polymer was obtained from the racemic monomer.
Formation of the radical‐cation of monomer in the photoinduced polymerization of isobutylene in the presence of SnCl4
Authors: Toman L. , Pilař J. , Marek M. 
Published: April 2003

AbstractSpectra of isobutylene with SnCl4 were studied at the temperature of 113°K in the dark and under illumination. Radical‐cations of isobutylene are formed by irradiation of the isobutylene–SnCl4 mixture in n‐heptane substantially more slowly than in the isobutylene–TiCl4 mixture. Polymerization of isobutylene occurs after increasing the temperature up to the melting point of this mixture. The yield of polymer depends on the duration of preirradiation, while the molecular weight of polyisobutylene (Mη) does not depend on the preirradiation of reaction mixture.
Preparation of triblock styrene–tert‐butylstyrene–styrene copolymers by living radical polymerization with a heterogeneous polymeric initiator
Authors: Bigdeli Ebrahim , Lenz Robert W. , Oster Bernd , Lundberg Robert D. 
Published: April 2003

AbstractTriblock copolymers containing the sequence styrene, p‐tert‐butylstyrene, styrene were prepared in an emulsion system by using isotactic polypropylene hydroperoxide as the initiator together with triethylenetetramine as an activator, according to the method of Mikulasova and co‐workers. Polymerization of styrene continued after removal of the initiator from the emulsion by filtration and eventually reached 100% conversion after 4 hr at 35°C. tert‐Butylstyrene at 80°C and styrene at 35°C were added successively to the system, with each polymerization reaction carried to 100% conversion before the next monomer was added. Thin‐layer chromatography was used to separate the homopolymers and block copolymers in order to determine the purity of the product. Monomer compositions of the block copolymers was verified by infrared analysis. The existence of two separate phases in the extracted block copolymer was indicated by the observation of two distinct glass transition temperatures.
Synthesis of polyamides from active 2‐benzothiazolyl dithiolesters and diamines under mild conditions
Authors: Ueda Mitsuru , Sato Akira , Imai Yoshio 
Published: April 2003

AbstractNovel examples were presented of the use in polyamide synthesis of active 2‐benzothiazolyl dithiolesters for which aminolysis is assisted by a neighboring group. Solution polycondensation of new dithiolesters, 2,2′‐(adipoyldithio)bisbenzothiazole and 2,2′‐(isophtahloyldithio)bisbenzothiazole, with both aliphatic and aromatic diamines in polar aprotic solvents (N‐methyl‐2‐pyrrolidone and hexamethylphosphoramide) took place rapidly at room temperature yielding polyamides with high molecular weight. The interfacial polycondensation in a chloroform–water system was also successful for polyamide formation. S,S′‐Di‐p‐nitrophenyl dithioisophthalate reacted much more slowly toward diamines than the 2‐benzothiazolyl dithiolesters. Prior to polymer synthesis, the aminolysis of active monothiolesters was carried out as a model compound study.
Polycycloalkylene‐siloxane polymers: Synthesis and thermal study
Authors: Kim Yung K. , Bourrie Daniel B. , Pierce Ogden R. 
Published: April 2003

AbstractBased on dicyclopentadiene and silacyclopentene, two linear polycycloalkylene‐siloxane polymer systems have been synthesized and the thermal stability of the raw polymers evaluated by differential scanning calorimetry and thermal gravimetric analysis. The DSC data in nitrogen indicate that both polymer systems have excellent thermal stability. In air, these polymers begin to oxidize at approximately 150°C, with catastrophic oxidation occurring at about 400°C.
A theoretical approach to the kinetics of polymer degradation in solution
Authors: Ito Katsukiyo 
Published: April 2003

AbstractAfter main‐chain scission in a polymer, the frequency of encounter between segments in the different fragments is related to the separating process between the fragments. The relationship obtained shows that the separating time is proportional to M½, where M is the molecular weight, when the excluded volume disappears. When good solvent is used, the half‐time for the separation is obtained as τ½ = const. M0.16–0.22, which is approximated to the experimental data obtained previously (τ½ = const. M0.34 and τ½ = const. M0.22) for the degradations of polyisobutene and poly(phenyl vinyl ketone), respectively. The increase of the half‐time with increasing coil density can be explained by the excluded volume. The inverse proportionality of the diffusion of segments to solvent viscosity explains the proportionality of the half‐time to microviscosity. The above separating process reverses the reaction between polymer radicals. From their dependence on the chain length, τ½/kD = const. M½ (where kD is the specific rate for the reaction), is estimated. Such an approximation holds, regardless of the type of solvent.
Improved synthesis of 5(6)‐vinylbenzimidazole: Some polymerization studies
Authors: Overberger C. G. , Mathias L. J. 
Published: April 2003

AbstractA general one‐step reduction ring closure of o‐nitroacetanalides is applied to the synthesis of 5(6)‐acetylbenzimidazole and 5(6)‐acetyl‐2‐methylbenzimidazole in good yield. The former is readily converted to the vinyl monomer by reduction and dehydration. Polymerization of this monomer with free‐radical initiation under a variety of conditions gives polymers with essentially identical nuclear magnetic resonance (NMR) spectra, implying no basic change in polymer structure.
Polyaddition of bisketenimines. II. Synthesis of poly(N‐acylamides) from bisketenimines and dicarboxylic acids
Authors: Kurita Keisuke , Sakata Hikaru , Iwakura Yoshio , Koyanagi Mutsuo 
Published: April 2003

AbstractPoly(N‐acylamides) were synthesized by polyaddition of bisketenimines with dicarboxylic acids. Yields and inherent viscosities of these polymers were low, presumably because of side reactions. The thermal stability and solubility of the polymers were studied.
Alternating copolymerizations of styrene and acrylic monomers initiated with carbanions in the presence of ZnCl2
Authors: Yamazaki Noboru , Nakahama Seiichi , Noda Masami , Nishiwaki Isao 
Published: April 2003

AbstractOn electrochemical initiation of alternating copolymerizations of styrene–acrylonitrile (AN) and styrene–diethyl fumarate (DEF) in the presence of ZnCl2, radical anions of AN–ZnCl2 and DEF–ZnCl2 complexes produced at the cathode were assumed to initiate copolymerization. In analogy with the cathode‐initiated copolymerization, the radical anions of AN–ZnCl2 and DEF–ZnCl2, generated with the carbanions such as sodium naphthalene, disodium α‐methylstyrene tetramer dianion, and butyllithium, were also found to produce alternating copolymers of styrene–AN and styrene–DEF. On the contrary, no polymers were obtained from methyl methacrylate (MMA)–styrene and methacrylonitrile (MAN)–styrene in the presence of ZnCl2 either with carbanions or by electrochemical reduction. Styrene–MAN–ZnCl2 yielded an alternating copolymer with carbanions upon introduction of oxygen.
Pulse radiolysis study on the initial processes of radiation‐induced cationic polymerization of styrene and α‐methylstyrene
Authors: Egusa S. , Tabata Y. , Arai S. , Kira A. , Imamura M. 
Published: April 2003

AbstractInitial processes of radiation‐induced cationic polymerization of styrene and α‐methylstyrene have been studied by means of microsecond pulse radiolysis. For styrene, absorption bands caused by the monomer cation radical St+• appear at 630 and 350 nm in a mixture of isopentane and n‐butyl chloride at about −165°C. In parallel with the decay of St+•, three absorption bands appear in the near‐infrared (IR) region, and at 600 and 450 nm. The IR and 600 nm bands are assigned to the associated dimer cation radical St2+•, and the 450 nm band to the bonded dimer cation radical St‐St+•. The kinetic behavior of these species shows that reaction of St+• with styrene monomer forms both St2+• and St‐St+•. With the decay of St‐St+•, another absorption band appears at 340 nm, and the lifetime of this band is relatively long. The 340 nm band may be due to carbonium ions of the growing polystyrene. For α‐methylstyrene, the monomer cation radical (at 690 and 350 nm), the associated dimer cation radical (in the near‐IR region and at 620 nm) and the bonded dimer cation radical (at 480 nm) behave in a manner similar to that of the corresponding styrene species. The absorption band caused by carbonium ions of growing poly(α‐methylstyrene) appears at 340 nm.
Polyimides derived from bismethylolimides. I. Polyamide–imides from bismethylolimides and dinitriles
Authors: Kurita Keisuke , Itoh Hiroshi , Iwakura Yoshio 
Published: April 2003

AbstractNew polyamide–imides were synthesized from bismethylolimides and dinitriles. The bismethylolimides, N,N′‐bismethylolpyromellitdiimide and N,N′‐bismethylolbenzophenonete‐tracarboxylic diimide, were prepared by the hydroxymethylation of the corresponding diimides with formaldehyde. The polymerization reaction was carried out in either concentrated sulfuric acid or poly(phosphoric acid), and the former was found to be superior to the latter. The polyamide–imides had inherent viscosities in the 0.08–0.41 dl/g range. Most of these polymers were soluble in m‐cresol and dichloroacetic acid. The thermal stability of the polymers was examined by thermogravimetric analysis, and they were found to start to decompose at 275–350°C in air.
Organometallic compounds as catalysts in the alternating copolymerization of acrylonitirle with butadiene
Authors: Kuran Witold , Florjańczyk Zbigniew 
Published: April 2003

AbstractThe catalytic activity of various organometallic compounds of the Lewis acid type RmMXn(M = Zn, Cd, B, Al; R = CH3,C2H5, i‐C4H9, C6H5CH2, C6H5C2H4; X = Cl, OCH3) in the alternating copolymerization of acrylonitrile with butadiene in bulk and in toluene solution has been studied. The activity of the catalyst was found to depend on its acidity, the strength of its MR bond, and on the type of substituent R. The results obtained have been discussed in terms of the copolymerizability of the acrylonitrile complexed by RmMXn and in terms of the effect of the RmMXn structure on the initiation rate of the copolymerization.
Anionic‐initiated polymerization of β‐nitrostyrenes
Authors: Carter Mary E. , Nash James L. , Drueke Joseph W. , Schwietert James W. , Butler George B. 
Published: April 2003

Abstractβ‐Nitrostyrene and many of its derivatives have been shown to yield high polymers via anionic initiation with alkoxide ions in protic solvents, e.g., alcohols. A study was conducted to determine the effect of certain substituents on the polymerization characteristics of representative monomers of this series and the properties of their polymers. A kinetic study was conducted and the relative rates of propagation were unexpectedly found to correlate well with brown's σ+ values. The rates of initiation of two representative monomers, β‐nitrostyrene and p‐methoxy‐β‐nitrostyrene, with sodium ethoxide were found to be 3.51 and 2.86 liter/mole sec, respectively. The rate of chain transfer in ethanol was studied qualitatively by using gel‐permeation chromatography (GPC) to obtain molecular weight distribution (MWD) curves. The low values of the Mw/Mn ratios indicated little chain transfer in the protic solvent.
Application of mass spectrometry to copolymers of ethylene and propylene oxides. II. Kinetic analysis
Authors: Lee A. K. , Sedgwick R. D. 
Published: April 2003

AbstractMolecular‐weight distributions derived from mass spectrometric studies of some alkylene oxide copolymers have been used to calculate rate constant ratios for the first eight steps in the polymerization process. Results suggest that there is a significant reduction in reactivity of the growing chains during this initial period.
Copolymérisations radicalaires sous haute pression. Influence de la pression sur les rapports de réactivité
Authors: Jenner Gérard , Aieche Salah 
Published: April 2003

AbstractThe pressure effect upon the reactivity of the radicals in copolymerizations can be important. The present work reports the pressure dependence of the reactivity ratios for some radical copolymerizations involving monomers of various polarities and proposes an interpretation concerning their variations with pressure based upon the Q—e scheme (or Alfrey–Price scheme). The direction as well as the magnitude of the pressure effect can thus be predicted.
Kinetic analysis of photopolymerization reaction of lauryl acrylate with a photoinduced chemical reaction calorimeter
Authors: Ikeda Mitsuru , Teramoto Yoshihiko , Yasutake Masatoshi 
Published: April 2003

AbstractCalorimetric studies on kinetics of photopolymerization reactions made previously have been limited by the structures of the calorimeters. This report suggests a thermal‐leak type of calorimeter for carrying out kinetic analysis of the photopolymerization reaction. The method was applied to the photopolymerization system consisting of lauryl acrylate and benzoin methyl ether. The results obtained illustrate the utility of this apparatus.
Synthesis of block copolymers containing poly(ferrocenylmethyl methacrylate) units
Authors: Pittman Charles U. , Hirao A. 
Published: April 2003

AbstractFerrocenylmethyl methacrylate (FMMA) has been polymerized by using LiAlH4–tetramethyl‐ethylenediamine initiation to form living polymers in high vacuum systems. The addition of methyl methacrylate or acrylonitrile to these living systems gave the block copolymers FMMA‐block MMA and FMMA‐block AN. The anions were not nucleophilic enough to initiate styrene polymerization. Therefore, living polystyrene was prepared (sodium naphthalide initiation in THF at −78°C) and upon FMMA addition, styrene‐block FMMA copolymers were formed. Extraction, precipitation, and gel‐permeation chromatography studies were performed to examine the purity of the block copolymers.