bluuebunny/crossref_metadata_2025 huggingface dataset:
Cationic polymerization of N‐ethyl‐3‐vinylcarbazole
Authors: De Mola A. H. , Ledwith A. , Yanus J. F. , Limburg W. W. , Pearson J. M.
Published: April 2003

Highly purified samples of N‐ethyl‐3‐vinylcarbazole are readily polymerized in CH2Cl2 by conventional initiators of cationic polymerization, including boron trifluoride etherate and tropylium hexachloroantimonate. Reaction rates measured calorimetrically yield an estimate for the free‐cation propagation rate coefficient (kp+ = 2 x 10+4 liter/mole‐sec) at 0°C, which is some 20 times smaller than that for the closely related monomer N‐vinylcarbazole. Distinguishing aspects of the cationic polymerization of N‐ethyl‐3‐vinylcarbazole are the very high molecular weights obtained and the linear dependence of M̄n of the monomer/catalyst mole ratio, indicating that transfer and termination are comparatively unimportant. Polymerizations initiated by tropylium hexachloroantimonate exhibit a characteristic absorption band at 468 nm, tentatively assigned to the propagating cation, which undergoes rapid changes after all monomer has been consumed. The stability of the species responsible for the absorption band at 468 nm appears to be least in conditions where ion pairs are important.
Applications of ESCA to polymer chemistry. XVII. Systematic investigation of the core levels of simple homopolymers
Authors: Clark D. T. , Thomas H. R.
Published: April 2003

The core levels of a series of 83 homopolymers have been studied by electron spectroscopy for chemical analysis (ESCA). Comparisons of the experimentally determined core‐level binding energies with theoretical calculations using the ground‐state potential model in the complete neglect of differential overlap (CNDO/2) self‐consistent field molecular orbital (SCF MO) formalism have been made on the C1s and O1s core levels for the oxygen‐containing polymers in the series. A comparison of the ground‐state potential model (GPM) and relaxation potential model (RPM) on a series of six model compounds representative on the series of polymers is given. Compilations are given of binding energies of C1s, O1s, N1s, Cl2p, S2p, Si2p, and Br3d levels for typical structural features of common occurrence in polymer systems. These data, taken in conjunction with that previously published on fluoropolymers, provide a sound basis for the development of ESCA as a fingerprint tool in the elaboration of features of structure and bonding in polymers in general.
Vinylation and polymerization with trivinylaluminum. II. Synthesis of α,ω‐diene‐polyisobutylene
Authors: Mandal Broja M. , Kennedy Joseph P.
Published: April 2003

The polymerization of isobutylene by 3‐chloro‐1‐butene/trivinylaluminum (V3Al) and t‐butyl chloride/V3Al initiator systems with methyl chloride and methylene chloride as solvents has been investigated in the range from −30 to −72−C. The rate of polymerization increases with decreasing temperatures from −30 to −50°C and then decreases when the temperature is further lowered, for example, to −72°C. Mayo plots and a determination of the number of polymer molecules n̄ formed per molecule of initiator employed suggests a transfer‐less, i.e., termination‐dominated system. A critical analysis shows that for systems containing both free ions and ion pairs, the Mayo equation is meaningful only when the degree of dissociation α remains constant over the whole [M] range investigated. This condition is achieved in RCl/V3Al‐initiated systems by using an initiator (t‐BuCl) for which the rate of catalyst destruction is insignificant compared to rate of initiation, Ri, i.e., initiation efficiency, f ≈ 1 and Ri independent of [M]. Polyisobutylene, containing, 1.8 ± 0.1 terminal unsaturation, has been synthesized by the use of 3‐chloro‐1‐butene initiator in conjunction with V3Al coinitiator, and avenues for further efficient synthesis of α,ω‐diene‐polyisobutylenes have been outlined.
Polymerization of vinylene carbonate in dimethyl sulfoxide
Authors: Reimschuessel H. K. , Creasy W. S.
Published: April 2003

Pure vinylene carbonate polymerizes readily in dimethyl sulfoxide solutions upon initiation by azobisisobutyronitrile (AIBN). The monomer conversion is characterized by a limiting value which appears to be a function of the temperature and the initial concentrations of both the initiator and the monomer. Increasing both initiator concentration and temperature results in higher final conversions, whereas a maximum conversion is indicated for initial monomer concentrations in the range of 80% to 90%. Principal kinetic quantities were found to be adequately represented by the equations kd = 24.3 × 105 exp {−11300/RT} and kp(f/kt)1/2 = 46.3 × 105 exp {−8900/RT} for the temperature range of 50–80°C. The average degree of polymerization was found to be affected by chain transfer to the solvent. A value of 5.8 × 10−4 was determined for the corresponding chain transfer constant.
Some aspects of the polymerization of N‐vinylcarbazole by grignard reagents
Authors: Biswas Mukul , John K. J.
Published: April 2003

The polymerization of N‐vinylcarbazole (NVC) initiated by PhMgBr in benzene was studied at 32°C. Rp is second order with respect to PhMgBr concentration but increases with NVC concentration (up to 0.06 M) and falls thereafter. Rp and Pn are depressed by the addition of thiophene and water. Modifiers such as benzaldehyde, butanone, and ethylene glycol practically inhibit the polymerization. Carbon tetrachloride and carbon dioxide, when passed through the NVC solution first, enhance the Rp and Pn increases with increasing PhMgBr and NVC concentrations, respectively. Rp increases with temperature, but Pn shows a maxium at a certain temperature. A cationic mechanism has been proposed where the polymerization is initiated by RMg+ cations produced from the ionization of PhMgBr by the Ashby and Smith mechanism.
Effect of oxygen on the radical polymerization of acrylamide in ethanol and water
Authors: George M. H. , Ghosh A.
Published: April 2003

The polymerization of acrylamide has been studied in ethanol at 80°C with 2,2′‐azobisisobutyronitrile (AIBN) as the initiator, and also in water at 60°C with 4,4′‐azobis‐4‐cyanopentanoic acid (ACV) as the initiator. For the first system, it was found, approximately, that the well defined in duction period showed an inverse dependence on both the initial monomer and initiator concentrations, but was directly proportional to the square root of the initial oxygen concentration. For the second system, the rate of oxygen uptake was approximately directly proportional to the monomer and initiator concentration but independent of the oxygen concentration. The results obtained for these two systems are compared.
Reactivity of polymer substituents. II. Aminolysis of p‐nitrophenyl acrylate copolymers with acrylamide or N,N‐dimethylacrylamide in aqueous solution
Authors: Su Chin‐Pao , Morawetz Herbert
Published: April 2003

Rates of the benzylaminolysis of acrylamide and dimethylacrylamide copolymers with a small amount of p‐nitrophenyl acrylate in water solution were compared with the analogous reaction of p‐nitrophenyl isobutyrate. Rates of the dimethylacrylamide copolymer and analog were also measured in methanol. The copolymer reactions were much slower than those of the analog, in contrast with results obtained in dioxane. It was found that the reaction of the analog is much more sensitive to the medium than the reaction of the polymer, because the “effective solvent medium” in the polymer domain is largely determined by properties of the polymer chain backbone.
Modification of properties of ion‐exchange membranes. IV. Change of transport properties of cation‐exchange membranes by various polyelectrolytes
Authors: Sata Toshikatsu
Published: April 2003

A change in electrodialytic transport properties of various cation exchange membranes was observed after the membranes had been adsorbed or ion‐exchanged with various cationic polyelectrolytes. Transport properties measured in this report were the relative transport number of calcium ion to sodium ion PCaNa, the current efficiency of cations, and the electric resistance of the membrane during the electrodialysis. Weakly basic and strongly basic cationic polyelectrolytes of various molecular weights were used. Though PCaNa of any cation exchange membrane decreased by the adsorption or ion exchange of any cationic polyelectrolyte, the degree of the decrease in PCaNa changed with species and molecular weight of polyelectrolytes and species of cation‐exchange membranes. Weakly basic polyelectrolytes and low molecular weight, strongly basic polyelectrolytes were effective in producing a marked decrease in PNaCa of any cation exchange membrane. The effect of strongly basic polyelectrolytes of high molecular weight on PCaNa was weak in most cases. However, if it was possible to make the polyelectrolyte adhere to the surface of the membrane to form a compact coiled structure, any cationic polyelectrolyte was effective in producing a remarkable decrease in PCaNa of any cation‐exchange membrane.
ESCA applied to polymers. XIX. Investigation of polymer films produced by inductively coupled RF plasmas excited in vinylidene fluoride
Authors: Clark D. T. , Shuttleworth D.
Published: April 2003

Films of known thickness have been prepared in situ by radio frequency (RF) glow discharge techniques with the use of vinylidene fluoride as the monomer. A description of the structure as revealed by ESCA is presented and comparison drawn with related work. Electron mean free paths have been measured as a function of kinetic energy corresponding to photoemission from the C1s (967 eV), F1s (563 eV), and F2s (1220 eV) levels of the plasma‐polymerized material. The results confirm that for a given class of materials such as polymers, escape depths are not strongly dependent on fine details of structure and bonding and moreover that mean free paths are comparable with those measured for typical metals and semiconductors.
Anionic polymerization of p‐diisopropenylbenzene in tetrahydrofuran: Reactivity of pendent double bond
Authors: Okamoto Akio , Mita Itaru
Published: April 2003

Anionic polymerization of p‐diisopropenylbenene was found to be an equilibrium polymerization not only with respect to the monomer but also with respect to the pendent double bond. The polymerization was studied from kinetic as well as from the thermodynamic point of view, especially to ascertain the reactivity of the pendent double bond as compared with the double bond of monomeric analog. It was shown that the crosslinking rate constant of the pendent double bond is lower by about three to four orders than the propagation rate constant of the monomeric analog. The rate of cyclization was also very slow. From the equilibrium, the heat and entropy of polymerization of the monomer were determined as ΔHss = −5.8 kcal/mole and ΔSss = −18.0 cal/deg mole, respectively, and those of the pendent double bond as ΔHss = −6.3 kcal/mole and ΔSss = −27.8 cal/deg mole. When compared with the polymerization of α‐methylstyrene, the low thermodynamic polymerizability of the pendent double bond is attributed to the low heat of polymerization, which may arise from the large steric hindrance of neighboring groups. The effect is much smaller for the equilibrium than for the rate of polymerization, however.
Esterolytic activity of imidazole‐containing polymers. Synthesis and characterization of copoly[1‐alkyl‐4‐ or 5‐vinylimidazole/4(5)‐vinylimidazole] and its catalytic activity in the hydrolysis of p‐nitrophenyl acetate
Authors: Overberger C. G. , Kawakami Y.
Published: April 2003

The water‐soluble monomers, 1‐methyl‐4‐vinylimidazole, 1‐methyl‐5‐vinylimidazole, 1‐ethyl‐5‐vinylimidazole, and 1‐propyl‐5‐vinylimidazole have been synthesized, polymerized, and copolymerized with 4(5)‐vinylimidazole. The copolymers were characterized by 14C‐labeling, NMR, pKa determination and viscosity measurements. The monomer reactivity ratios determined by 14C counting are r1 = 1.04; r2 = 0.94 [M1 = 4(5)‐vinylimidazole, M2 = 1‐methyl‐4‐vinylimidazole] and r1 = 1.01; r2 = 0.86 [M1 = 4(5)‐vinylimidazole, M2 = 1‐methyl‐5‐vinylimidazole]. The esterolytic activity of the copolymers for the hydrolysis of p‐nitrophenyl acetate (PNPA) at pH 7–8 in 28.5% ethanol–water was higher than that of the mixtures of homopolymers. At pH 5–6 the esterolytic activities of the copolymers and the mixtures were similar. The most efficient esterolytic activity for PNPA hydrolysis at pH 7.11 in 28.5% ethanol–water occurred for copolymers containing 75 mole % 4(5)‐vinylimidazole and for copolymers containing 1‐methyl‐4‐vinylimidazole rather than 1‐methyl‐5‐vinylimidazole.
Catalysis by polyethylenimine derivatives with two functional groups
Authors: Nango M. , Klotz I. M.
Published: April 2003

Modified polyethylenimines have been prepared containing imidazole and dimethylamine functionalities for catalytic purposes, as well as apolar groups to increase binding. The cooperative effect of the two functionalities increases the catalytic effectiveness of these polymers some 2–20‐fold, depending on the kinetic parameters being compared.
Polymerization of cyclic esters of phosphoric acid. VI. Poly(alkyl ethylene phosphates). Polymerization of 2‐alkoxy‐2‐oxo‐1,3,2‐dioxaphospholans and structure of polymers
Authors: Libiszowski Jan , Kałużynski Krzysztof , Penczek Stanisław
Published: April 2003

Five‐membered cyclic esters of phosphoric acid of the general formula: CH2CH(R)OP(O)‐(OR′)O polymerize readily to solid, soluble polymers of high molecular weight without any rearrangement known for various tri‐ and pentavalent organophosphorus monomers. 1H‐, 13C‐, and 31P‐NMR spectra of polymers confirmed their linear structure:
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where R is H, with R′ = CH3, C2H5, n‐C3H7, i‐C3H7; n‐C4H9, CCl3CH2, or C6H5, or R is CH2Cl and R′ is C2H5. The use of n‐C4H9Li, (C5H5)2Mg, or (i‐C4H9)3Al as initiators leads to polymers with Mn = 104–105.
Selective initiation of nonconjugated dienes containing electron donor–electron aceptor systems. I. Synthesis of vinyl ether–β‐nitrostyrene monomers
Authors: Nash Jr. James L. , Thompson Ronald E. , Schwietert James W. , Butler George B.
Published: April 2003

The objectives of this work were to synthesize, characterize, and conduct a polymerization study on a set of ideal crosslinking monomers. The monomers studied are the three isomers of (2‐vinyl‐oxyethoxy)‐β‐nitrostyrene. Such monomers contain both the electron‐donating vinyl ether moiety and the electron‐accepting β‐nitrostyrene moiety. A study of the spectral properties of these monomers was carried out in an effort to determine whether there was a contribution to the structure through an intramolecular interaction of the nature of a charge‐transfer complex. Such studies have led to little or no support for such an interaction. As model compounds for comparison of spectral properties, the monomer series, o‐, m‐, and p‐(2‐ethoxyethoxy)‐β‐nitrostyrenes were synthesized and characterized as above. A comparison of the spectral and physical properties of these two series of compounds show that there are significant differences suggestive of the interactions proposed. However, since these discrepancies are small in most cases, it is not possible at present to correlate them specifically with the postulated intramolecular interactions.
Selective initiation of nonconjugated dienes containing electron donor–electron acceptor systems. III. Synthesis of vinyl ether–styrene monomers
Authors: Thompson Ronald E. , Butler George B.
Published: April 2003

In a continuation of our studies on nonconjugated dienes containing electron donor–electron acceptor systems which may function as model crosslinking monomers, we here report the synthesis of the series, 2‐, 3‐, and 4‐(2‐vinyloxyethoxy)styrenes. The dipole moments μ, infrared and ultraviolet absorption properties, refractive indices nD30, molar refractions (MRD), and optical exaltations of the compounds were determined. In order to establish whether any intramolecular electronic interactions, e.g., intramolecular charge‐transfer complexes, contribute to the structure and properties of these compounds, 2‐ and 4‐(2‐ethoxyethoxy)styrenes were also prepared, and their properties compared with those of the vinyloxy series. While there are differences in certain of the properties of these two groups of monomers, these differences are not sufficiently large to permit definite correlations with the proposed interactions.
Selective initiation of nonconjugated dienes containing electron donor–electron acceptor systems. IV. Polymerization of vinyl ether–styrene monomers
Authors: Chu Shaw‐Chang , Butler George B.
Published: April 2003

Three isomeric nonconjugated dienes, o‐, m‐ and p‐(2‐vinyloxyethoxy)styrenes, were selectively polymerized by anionic or radical initiators through the styryl double bond while leaving the vinyl ether moiety intact. The anionic‐initiated polymeric products are of high molecular weight and narrow molecular weight distribution as characterized by membrane osmometry and gel‐permeation chromatography, respectively. These polymers were subsequently crosslinked by cationic initiators via the vinyl ether moiety on the polymer side chains. Acid‐catalyzed hydrolysis of the poly(2‐vinyloxyethoxy)styrenes yielded their respective hydroxy‐containing polymers, polyvinylphenoxyethanols. The latter were physically and spectroscopically identical to authentic samples prepared by radical polymerization of the corresponding vinylphenoxyethanols, which, in turn, were synthesized by hydrolysis of the (2‐vinyloxyethoxy)styrenes. The polyvinylphenoxyethanols were shown to undergo many chemical transformations, such as esterification with 3,5‐dinitrobenzoyl chloride, cyanoethylation, and urethane formation.
Constitution moléculaire d'α,ω‐difluoropolydiméthyl‐N‐méthylsilazanes. Equilibres obtenus par une réaction de redistribution
Authors: Pace Simonne C.
Published: April 2003

Unlike the α,ω‐dihalogenopolydimethylsiloxanes, the α,ω‐dichloropolydimethyl‐N‐methylsilazanes show a net preference for cyclic species with respect to linear structures at equilibrium. The aim of this study is to evaluate the perturbations in the molecular constitution of these α,ω‐dihalogenopolydimethyl‐N‐methylsilazanes resulting from the substitution of the terminal chlorine atoms by fluorine atoms. This polymeric family was prepared by reacting (CH3)2SiF2 with nonamethylsilazane [(CH3)2SiNCH3]3. The redistribution of the fluorine atoms with the bridging methylimino groups reached an equilibrium after about 5 months' heating at 150°C for all the samples prepared. The relative abundance of the various molecular species and fragments at equilibrium was deduced from the quantitative analysis of the proton nuclear magnetic resonance (NMR) spectra. The molecular constitution at equilibrium is described by two constants. The first, K = [neso] [middles in chains]/[terminal moieties]2 = (2.8 ± 0.8) 10−2, shows that the presence of terminal fluorine atoms is unfavorable to the formation of short chains. On the other hand, the trimeric cyclic species [(CH3)2SiNCH3]3 are found to be highly favored (K°3 = 550 ± 100 mole/liter). These observations further confirm that the equilibrium constants which control the noncyclic part of polymeric families depend little on the functionality of the substituents exchanged [for example, on changing from N(CH3)2 to NCH3] when the reorganization heat order is one.
Glass transition in polyesteramides
Authors: Akçatel P. , Jasse B.
Published: April 2003

The glass transition of three different polyesteramides, polyundecanamide‐undecanoates, polyundecanamide‐nonanoates, and polyundecanamide–p‐methylbenzoates has been investigated by differential thermal analyses. As the amino acid content in the polymer increases, the evolution of the glass transition temperature is strongly influenced by the comparative length and the stiffness of the two monomer units. The experimental data are discussed in terms of the disruption of a hydrogen‐bonded network in the amorphous regions of the copolymers.
Polymerization of monoallyl phthalate
Authors: Imai Itsuro , Matsumoto Akira , Oiwa Masayoshi
Published: April 2003

Radical polymerization of monoallyl phthalate (MAP) was conducted at 70, 80, and 90°C, benzoyl peroxide being used as an initiator. It was found that the analytical values of the polymer obtained were always lower than the calculated ones for MAP homopolymer and nearly constant regardless of the polymerization conditions. From the detailed investigation it was concluded that the results are due to the formation of polymer including about 20 mole % of allyl alcohol units; such allyl alcohol units might be incorporated into the polymer through propagation accompanied by partial elimination of phthalic anhydride.
Electron diffraction studies of multilayers of vinyl stearate
Authors: Day David , Lando Jerome B.
Published: April 2003

Multilayers of vinyl stearate monomer were built up using the Blodgett technique. These were observed at low temperatures by electron diffraction and hexagonally twinned diffraction was observed. The reflections were indexed to be the (200) and (112) resulting from the pure vinyl stearate monoclinic cell. Hexagonal twinning was attributed to three preferred growth directions dictated by the original monolayer order–disorder packing.
Effects of phosphorus oxychloride and phenylphosphonic dichloride on the radical polymerization of methyl methacrylate and styrene
Authors: Taninaka Takumi , Uemura Hideaki , Iwamoto Kohji , Minoura Yuji
Published: April 2003

Effects of pentavalent phosphorus compounds on the radical polymerization of methyl methacrylate (MMA) and styrene (St) were studied. Phosphorus oxychloride (Cl3PO) and phenyl‐phosphonic dichloride (C6H5Cl2PO) were used. Polymerization was carried out in benzene at 50°C by the standard solution method, α,α′‐azobisisobutyronitrile (AIBN) being used as the initiator. In the polymerization of MMA, both phosphorus compounds increased the rate of polymerization. NMR spectral data suggested that this increasing effect was due to the complex formation between each phosphorus compound and MMA monomer. In the case of polymerization of St, NMR data also indicated the formation of a complex between the phosphorus compound and St monomer. Both phosphorus compounds showed an increasing effect for the rate of polymerization. Though these increasing effects could be explained by the complex formation, the polymerization of St in the presence of Cl3PO was especially found to be due to the cationic polymerization initiated simultaneously by Cl3PO in addition to the radical polymerization. These phosphorus compounds acted as chain‐transfer agents in both polymerization systems. The parameters (Qtr,etr) which indicate the reactivity of a chain‐transfer agent were calculated from the observed values of chain‐transfer constant for both polymerization systems.
Das Monte Carlo‐studium der binären copolymerisation in der annahme des vorletzten Effektes. I. Theorie, MEMORY 5‐programm, anwendungen
Authors: Motoc I. , Vancea R. , Holban St.
Published: April 2003

This paper presents a mathematical model (using the Monte Carlo technique) for the building of a binary copolymer considering the penultimate effect. One discusses the algorithm and the computer implementation. Finally, two applications are given. The purpose of this series of papers is to provide a Monte Carlo method to compute the sequence distribution for the hypothesis of penultimate effect (program MEMORY 5), ultimate effect (program MEMORY 3), and copolymerization with depolymerization (program MEMORY 6).
Das Monte Carlo‐studium der copolymerisation der ester der benzylidencyanessigsäure mit styrol
Authors: Motoc I. , Vancea R. , Holban St.
Published: April 2003

The Monte Carlo study of copolymerization of styrene with four esters of benzylidenecyanoacetic acid has pointed out that (a) for methyl and hexyl esters one cannot decide among the ultimate and penultimate effect (using copolymer composition and Fischer statistic), and (b) cyclohexyl and benzyl esters copolymerize following the kinetics of penultimate effect. Finally, the most probable sequence distribution in the studied copolymers is presented.
Random copolymerization of acetylenic monomers and 1,3‐dienes
Authors: Furukawa Junji , Kobayashi Eiichi , Kawagoe Takahiro
Published: April 2003

Copolymerization of acetylenic monomers and 1,3‐dienes was carried out by use of nickel naphthenate–diethylaluminum chloride catalyst. The molecular weight of the copolymers is rather low, and the copolymers are suitable as prepared for direct use as coating vehicles. In the system of acetylene and 1,3‐dienes, the order of the copolymerization rate decreases in the following order: butadiene > isoprene > 2,3‐dimethylbutadiene > chloroprene. 1,3‐Dienes substituted at 1‐and/or 4‐position were scarcely copolymerized with acetylene. Methylacetylene and dienes tend to form cyclized copolymers. In the system of phenylacetylene and dienes, polyphenylacetylene was the main product; the copolymer was not obtained. The copolymer composition and the sequence distribution of linear copolymers were evaluated by 1H‐NMR spectra. Comparison of dyad fractions of copolymers evaluated from NMR spectra and those calculated by assuming random polymerization indicated that the copolymers of acetylene and dienes were random, and that the copolymers of methylacetylene and dienes were somewhat blocky. The coordination of monomers on the catalyst may play an important role in controlling the copolymerizability.
Polymerization of propene with organomagnesium–reduced titanium (IV) chloride‐based catalyst
Authors: Gardner Kevin , Parsons Ian W. , Haward Robert N.
Published: April 2003

A kinetic study of the polymerization of propene by use of magnesium–reduced titanium (IV) chloride‐based catalyst systems has been carried out and the tacticities and molecular weights of the polymers formed have been investigated. The rate constant for the formation of isotactic polymer is estimated to be 69 ± 18 dm3/mole sec and that for the atactic polymer to be 12 ± 5 cm3/mole sec. The number of active sites producing atactic polymer has been determined as 3 ± 1% of the Ti atoms present, whereas sites producing isotactic material amount to 0.36 ± 0.13% of the Ti atoms. The overall tacticity of the polymers corresponds to approximately 40% isotactic material. This figure is barely affected by heat treatment of the catalyst.
Reactions of tert‐butoxy radicals with vinyl monomers
Authors: Encina M. V. , Rivera M. , Lissi E. A.
Published: April 2003

Tert‐butoxy radicals generated in the photolysis of di‐tert‐butyl peroxide in benzene at 25°C react with vinyl monomers by double‐bond addition and, in most cases, also by competitive hydrogen abstraction. The rate constant for the double‐bond addition changes by a factor of 17 between isoprene, which shows the highest reactivity, and the methacrylate derivatives, which are the least reactive of the monomers considered. The fraction of tert‐butoxy radicals that react by hydrogen abstraction varies considerably with the monomer structure, ranging from 0.9 (cyclohexyl methacrylate) to less than 0.05 (styrene and conjugated diolefins). In the methacrylate derivatives, most of the hydrogen abstraction takes place, not in the α‐methyl group, but in the alkyl chain.
Structure and extinction of counterflow diffusion flames above condensed fuels: Comparison between poly(methyl methacrylate) and its liquid monomer, both burning in nitrogen–air mixtures
Authors: Seshadri K. , Williams F. A.
Published: April 2003

Since poly(methyl methacrylate) is known to depolymerize largely to its monomer when heated, the chemical kinetics in the gaseous diffusion flame produced by this polymer in a fire may coincide with that of burning liquid methyl methacrylate. To test this hypothesis, flat diffusion flames were probed and extinguished adjacent to surfaces of each of these fuels. Profiles of temperature and of concentrations of stable chemical species are reported, as are gas velocities of approach flow required to produce extinction for various oxygen/nitrogen ratios of the stream. Results revealed structural differences attributable to differing thermal properties of the fuels. Many fuel species were observed in the gas phase, their profiles being partially rationalized on the basis of a suggested decomposition mechanism for gaseous methyl methacrylate. Overall kinetic parameters for gasphase combustion, obtained by use of extinction results in a previously developed theory, are nearly the same for the polymer and monomer but appear to differ by amounts exceeding experimental uncertainties. It is suggested that this may be traced to small differences in fuel species leaving the condensed phase which, for the polymer, is covered by a thin, two‐phase region.
Photolytic and radiolytic polymerization of N‐ethylmaleimide in cyclohexene
Authors: Wipfelder E. , Heusinger H.
Published: April 2003

Irradiation of N‐ethylmaleimide (NEMI) in cyclohexene (CH) with ultraviolet light or γ rays gives rise to polymer formation. Separation of the components by liquid chromatography and determination of their structure of pyrolysis—gas chromatography (GC)–mass spectrometry (MS) coupling, infrared spectroscopy, and 13C‐ and 1H‐resonance spectroscopy show that the polymer produced in photolysis as well as in radiolysis consists of an almost alternating copolymer of NEMI and CH and small amounts of a NEMI homopolymer. Based on the experimental results, we propose a radical mechanism for copolymerization and an anionic mechanism for homopolymerization.
Effect of solvent on radical polymerization of vinyl benzoate
Authors: Kamachi Mikiharu , Satoh Jiro , Nozakura Shun‐Ichi
Published: April 2003

Absolute rate constants of the vinyl benzoate polymerization have been measured by use of the intermittent illumination method in various aromatic solvents and ethyl acetate at 30°C. The determination of absolute rate constants showed that effects of solvent on the polymerization rate of vinyl benzoate were mainly ascribed to the variation of kp values with solvents rather than that of kt values. The kp values for solvents used increased in the order: benzonitrile < ethyl benzoate < anisole < chlorobenzene < benzene < fluorobenzene < ethyl acetate. There was an eightfold difference between the largest and the smallest values The large variation among kp values was explained neither by the copolymerization through solvents nor the chain transfer to solvents, but by a reversible complex formation between the propagating radical and aromatic solvents. This explanation was supported by a correlation between kp values and calculated delocalization stabilizations for the complexes.
Surface grafting of polyethylene by mutual irradiation in methyl acrylate vapor. II. High‐energy electrons irradiation
Authors: Yamamoto Fumio , Yamakawa Shinzo , Kato Yoshinori
Published: April 2003

Vapor‐phase mutual grafting of methyl acrylate (MA) onto polyethylene (PE) at high dose rates from an electron accelerator yields the same surface graft structure as does the grafting at low dose rates from 60Co sources; i.e., a homopolymer layer (consisting of only MA component) is easily formed on the inner graft copolymer layer (consisting of both MA and PE components) as a result of the continuously increasing surface graft composition. To produce the surface layer, 4‐MeV electron irradiation with a linear electron accelerator requires only less than 3 min of irradiation time at dose rates of more than 2 Mrad/min, whereas γ irradiation with a 60Co source requires at least 1 hr at dose rates of less than 2 × 103 rad/min. The rate of monomer consumption (or polymerization) in the surface homopolymer layer shows no dependence of irradiation time and a positive dependence of dose rate. It has been suggested that this kinetic feature at the high dose rates shows some contribution of vapor‐phase homopolymerization and subsequent deposition (onto the grafting surface) followed by recombination with the grafted side chain radicals, although secondary graft copolymerization from the grafted chain radicals is still the principal process for the growth of the surface homopolymer layer.
Modification of poly(vinyl chloride). XXIX. Cross linking of poly(vinyl chloride) with 2‐dibutylamino‐4,6‐dithiol‐s‐triazine and MGO
Authors: Mori Kunio , Nakamura Yoshiro
Published: April 2003

Thermal crosslinking of poly(vinyl chloride) (PVC) with 2‐dibutylamino‐4,6‐dithiol‐s‐triazine (DB) and MgO has been studied to determine the kinetic parameters such as induction period (t0), rate constant (k), and activation energy (E), and to elucidate the structure of crosslink and the crosslinking mechanism. The thermal crosslinking was treated as a pseudo‐first‐order reaction. In the crosslinking, k and t0 were about 0.075 min−1 and 6.8 min at 180°C, respectively, and E was 16.6 and 14.2 kcal/mole for k and 1/t0, respectively. The structure of crosslink was confirmed to be indicated as the following scheme (I) from the results of model reactions and IR spectra of crosslinked products
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The crosslinking reaction was found to proceed through the following three processes: (1) formation of DB‐Mg from DB and MgO; (2) formation of DB‐Mg pendants by the reaction of PVC with DB‐Mg; and (3) formation of crosslink by the reaction of PVC with DB‐Mg pendants.
High‐transition‐temperature polyamides based on 2(2‐aminophenyl)1,1‐dimethylethylamine
Authors: Lee Lester T. C.
Published: April 2003

Novel polyamides have been prepared from the 2(4‐aminophenyl) 1,1‐dimethylethylamine (APDEA) and various diacyl compounds. Unique properties have been found in these polyamides in that they possess a high glass‐transition temperature (Tg), yet have an exceptionally high Tg/Tm ratio. Structure—property relationships in these interesting polyamide and copolyamide systems are investigated. Unsubstituted polyamides and those with saturated rings were synthesized to demonstrate the important role played by the methyl substitution and the rigid ring in affecting the Tg and Tm. It seems reasonable to conclude that the gem‐dimethyl substituents and the stiff phenyl group or the interaction of these two groups with each other and with other adjacent segments in this particular molecular architecture contribute to this desirable transition‐temperature performance.
Degradation of polymer mixtures. IX. Blends of polystyrene with polybutadiene
Authors: McNeill I. C. , Ackerman L. , Gupta S. N.
Published: April 2003

The degradation of cis‐1,4‐polybutadiene, polystyrene, and blends of PB and PS has been studied by thermogravimetry, thermal volatilization analysis, and differential scanning calorimetry. Volatile products have been investigated and separated by subambient TVA and characterized spectroscopically. In the degradation of the blends, there is no change in the nature of the volatile products of degradation, but the rate of degradation of the PS component is markedly reduced. The PB component is the first to break down, and during the initial period of degradation of the PB, the PS degradation is apparently inhibited. It is suggested that some of the volatile products of decomposition of PB, most notably 4‐vinylcyclohexene, may diffuse into the PS phase in the blend and act as radical inhibitors.
Collapsed conformation of poly(methacrylic acid) chain containing nonionic hydrophilic units
Authors: Ponrathnam S. , Rao S. P. , Kapur S. L.
Published: April 2003

Copolymers of methacrylic acid (MAA) and a nonionic hydrophilic monomer N‐vinylpyrrolidone (NVP) were synthesized by polymerization in aqueous solution in the absence of metal ions. The NVP content of the copolymers ranged from 2 to 36 mole % with sequences of MAA interrupted at random by a single unit of NVP at all compositions. The pH‐induced conformational transition of these copolymers was followed by potentiometric titration and viscosity studies and the results were compared with those of pure poly(methacrylic acid) (PMAA). The negative free energy of transition from the un‐ionized compact from to expanded structure showed a gradual decrease with increasing NVP content, and the collapsed conformation observable for PMAA at low degrees of ionization (0 < α < 0.3) disappeared at NVP contents greater than 15 mole%. These findings are supported by viscosity data. The results suggest that long‐range methyl–methyl hydrophobic contacts still possible in higher NVP content copolymers are not sufficient to bring about the collapse of the molecule and a minimum average sequence length of about 20 MAA units is required to compact the molecule. Hydrophilic “shielding” of MAA chains by NVP segments could also partly destabilize the collapsed structure.
13C‐NMR sequence analysis. 11. Anionic copolymerization of lactams
Authors: Kricheldorf Hans R. , Hull William E.
Published: April 2003

Using sodium as the catalyst and benzoylchloride as cocatalyst, copolymerizations of γ‐butyrolactam with ε‐caprolactam and ω‐capryllactam were carried out at 100°C. In a similar manner copolymerizations of ε‐cparolactam, ω‐capryllactam, and ε‐laurinlactam were achieved at 150 and 250°C without a cocatalyst. The 90.5‐MHz 13C‐NMR spectra of all random copolyamides in fluorosulfonic acid show three or more CO signals that allow the ratio of homogeneous (AA and BB) to heterogeneous (AB and BA) amide groups to be determined. These results cleárly demonstrate that despite the reaction temperature or reactivity of the lactams the copolyamides do not contain long homogeneous blocks (An and Bn). The CO signals of the random copolyamides were assigned by comparison with the corresponding homopolyamides and alternating copolyamides. Solutions of the alternating copolyamide (‐β‐Ala‐ε‐Aca‐)n, in fluorosulfonic acid were measured to determine whether the 13C chemical shifts and line widths are dependent on concentration.
Microstructure determination of poly‐(1,3‐pentadiene) by a combination of infrared, 60‐MHz NMR, 300‐MHz NMR, and X‐ray diffraction spectroscopy
Authors: Beebe D. H. , Gordon C. E. , Thudium R. N. , Throckmorton M. C. , Hanlon T. L.
Published: April 2003

A quantitative procedure has been developed for characterizing the complete microstructure of polymers of 1,3‐pentadiene, including the tacticity of any crystalline component. This can be accomplished by a combination of infrared spectroscopy, X‐ray crystallinity, and 300‐MHz NMR spectroscopy. A series of high structural purity polymers were synthesized with a series of previously unreported mixed microstructures. These samples were characterized by using the three techniques mentioned, including the previously unreported 300‐MHz NMR data. With those results a 60‐MHz NMR/IR method of spectroscopy was developed to determine the composition of poly(1,3‐pentadiene)s in terms of percent cis‐1,2‐, cis‐1,4‐, trans‐1,4‐, and 3,4‐pentadiene units.
Synthesis and polymerization of novel formamidinium salts: A new pathway to polyamides derived from aromatic diamines
Authors: Spiewak J. W.
Published: April 2003

A new polycondensation pathway has been developed for the preparation of polyamides at high temperatures. p‐Phenylenediamine was converted to N,N‐p‐phenylene bis(N′,N′‐dimethylformamidine) (I), which formed 1–1 and 2–1 salts with terephthalic and adipic acids, respectively:
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Dicarboxylate salts were polymerizable by heating in bulk or suspension. Low‐molecular‐weight poly(p‐phenyleneterephthalamide) was obtained from N,N‐p‐phenylene bis(N',N'‐dimethylformamidinium) terephthalate above 225°C. The low degree of polymerization was due to terephthalic acid sublimation as well as to the well‐known intractability of poly(p‐phenyleneterephthalamide). High‐viscosity poly(p‐phenyleneadipamide) was obtained from N,N‐p‐phenylene bis(N′,N′‐dimethylformamidinum hydrogen adipate) above 200°C. Both salts liberated dimethylformamide (DMF) during polymerization. The adipate salt also released 1 mole of adipic acid during the high‐temperature vacuum stage of polymerization. A polycondensation mechanism was proposed for each salt, based on thermal gravimetric analysis (TGA‐MS) and infrared (IR) analyses.

The hydrolysis of N,N‐p‐phenylene bis(N',N'‐dimethylformamidine), N,N‐p‐phenylene bis(N',N'‐dimethylformamidinium chloride), and the two dicarboxylate salts of (I) was monitored by nuclear magnetic resonance (NMR) at room temperature. The dihydrochloride salt was most resistant to hydrolysis (kH 6.9 × 10−9 sec−1; relative rate 1.0) followed by (I) 7.1, terephthalate salt, 14.9, and adipate salt, 27.2. Both dicarboxylate salts possessed sufficient hydrolytic stability for use as polycondensation monomers
Effect of hydrogen bonding on the acid character of some synthetic copolymers
Authors: Chatterjee S. K. , Pachauri L. S.
Published: April 2003

A copolymer of p‐hydroxybenzoic acid, formaldehyde, and p‐bromoaniline was prepared in the presence of acid catalyst, and five fractions have been separated from it. Br content of each of the fractions was determined by chemical analysis, and on the basis of mole ratio of repeating units present in the copolymer chain, the total amounts of acidic and basic groups in a given weight of the copolymer were calculated. Nonaqueous titrations of all the fractions have been carried out in acidic and basic medium with suitable titrants. An excellent correlation was observed between the calculated and observed values of functional groups. The features of the titration curves were interpreted in terms of intramolecular hydrogen bonding and homoconjugation.
Alternating copolymerization of propylene oxide and carbon dioxide with an alumina supported diethylzinc catalyst
Authors: Soga Kazuo , Hyakkoku Kyoko , Izumi Katsuyuki , Ikeda Sakuji
Published: April 2003

Diethylzinc was allowed to react with γ‐alumina in n‐heptane at 50°C, and the copolymerization of propylene oxide and carbon dioxide was investigated in some detail at 30–90°C by using the reaction product as a catalyst. From an analysis of the catalyst it was found that diethylzinc reacted with the surface hydroxyl groups of γ‐alumina mainly to give the following A‐type species by evolving ethane:
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The catalyst showed considerably high activity for the copolymerization. The polymer obtained was a white solid with a high molecular weight soluble in benzene, acetone, dioxane, and methylene chloride and insoluble in diethyl ether and water. It was confirmed as an alternate copolymer of propylene oxide and carbon dioxide.

The copolymerization was also conducted with a reaction mixture of the catalyst and catechol in which the molar ratio of catechol to the A‐type species was varied. The copolymerization activity decreased linearly with an increase in the molar ratio and disappeared completely at the molar ratio of unity.

On the basis of these results it has been concluded that the A‐type is the true active species for the copolymerization.
Thermal degradation of ammonium polymethacrylate and polymethacrylamide
Authors: McNeill I. C. , Zulfiqar M.
Published: April 2003

The degradation of ammonium polymethacrylate and polymethacrylamide has been studied by a combination of thermal analysis methods (TVA and TG) and examination of volatile and involatile products by infrared analysis. It is shown that total reaction comprises an initial cyclization and further fragmentation of the modified chain at higher temperatures to yield gaseous volatiles. The partially degraded NH4PMA contains anhydride ring and cyclic imide structures in the chain. Quantitative comparison of yields of isocyanic acid and carbon dioxide has shown that imidization is the major reaction and anhydride formation is of less importance. The mechanisms of the various reactions are discussed.
Structure of chlorinated poly(vinyl chloride). V. Molecular parameters of chlorinated poly(vinyl chloride)
Authors: Lukáš R. , Janča J. , Mrkvičková L. , Pokorný S. , Kolínský M.
Published: April 2003

The molecular parameters of samples of chlorinated poly(vinyl chloride) (CPVC) and chlorinated β,β‐dideuterated poly(vinyl chloride) (β,β‐d2‐CPVC) were determined by gel permeation chromatography (GPC), light scattering, osmometry, and viscometry. Comparison of GPC, light scattering, osmometric, and viscometric data resulted in a discussion of the possibility of degradation and the causes of changes in the solution properties in chlorination of PVC and ββ‐dideuterated poly(vinyl chloride) (ββ‐d2‐PVC). The results obtained are discussed in relation to the mechanism of chlorination of PVC.
Cation‐exchanging macroreticular composites
Authors: Vasudevan Padma , Singh Maninder , Nanda Satish , Sarma N. L. N.
Published: April 2003

Sulfonated phenol formaldehyde resins were prepared under different conditions. Composites of these resins with sulfonated coals were also prepared and their physical properties and structure were studied. It was found that the resins are macroreticular and possess high surface areas.
Thermooxidative degradation of polyethylene. I and II. Structural changes occurring in low‐density polyethylene, high‐density polyethylene, and tetratetracontane heated in air
Authors: Holmström Arne , Sörvik Erling M.
Published: April 2003

Samples of low‐density polyethylene (LDPE), high‐density polyethylene (HDPE), and tetratetracontane (n‐C44H90) free from additives were heated in air at temperatures between 120 and 180°C. As a comparison, “as received” HDPE containing unspecified additives has also been included.

The structural changes have been studied with gel chromatography, viscometry, infrared spectroscopy, differential scanning calorimetry, and gravimetric measurements.

LDPE, HDPE, and n‐C44H90 follow the same course of thermooxidative degradation when they are free from additives and present in the molten state. Both molecular‐diminishing and enlargement reactions occur. At temperatures below 150°C molecular enlargement is not observed until after rather long exposure times, whereas at higher temperatures enlargement occurs immediately. The difference is because “peroxide curing” becomes increasingly important above 150°C, whereas ester formation is operating at all temperature levels. Degradation below Tm is restricted to the amorphous phase that results in a different degradation pattern.

In accelerated testing work extrapolations of the Arrhenius type in the prediction of structural change are thus not justified, even within the actual narrow temperature range. Neither are changes in commonly used standards like carbonyl content justified as a measure of the changes; for example, in mechanical properties.

The stabilizer in the unpurified HDPE not only influences the induction period but also the course of the thermooxidative degradation.
Some perfluorocarbocyclic ethers and polyethers from hexafluorobenzene
Authors: Toy Madeline S. , Stringham Roger S.
Published: April 2003

High‐resolution nuclear magnetic resonance (NMR) spectroscopy was used to determine the microstructures of some perfluorocarbocyclic ethers and polymers from reactions of bis(fluoroxy)‐difluoromethane and hexafluorobenzene. The thermal and photochemical reactions of CF2(OF)2 and excess hexafluorobenzene are described. The structures of several new perfluoro‐1,3‐dioxolanes in which the rings constituted part of a bicyclic system were elucidated by 19F‐NMR, gas chromatograph, gas chromatograph‐infrared, and gas chromatograph‐mass spectra.

The copolymers of molecular weight about 2500 are, with 40% of the difluoromethylenedioxy groups, estimated by 19F‐NMR to be in the polymer chain and the rest as pendant groups to the perfluorocyclohexylene and perfluorocyclohexenylene moieties. The suggested polymer structures are described and the mechanisms discussed.
Alternating copolymers of propylene and alkyl acrylates
Authors: Logothetis A. L. , McKenna J. M.
Published: April 2003

High‐molecular‐weight alternating and acrylate‐rich copolymers of propylene and ethyl acrylate were prepared by using boron trifluoride to complex the acrylate ester. The polymerizations were run at room temperature and autogeneous pressures with free‐radical initiation. The polymers were characterized by their nuclear magnetic resonance (NMR) and infrared (IR) spectra, differential scanning calorimetry, and gel permeation chromatography. The proton and 13C NMR spectra show that the equimolar copolymers are alternating to a high degree.