bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization of acrylonitrile by catalytic systems consisting of triphenylphosphine and a lewis acid
Authors: Kuran Witold , Borycki Jerzy 
Published: April 2003

AbstractPolymerization of acrylonitrile in the presence of systems that consisted of triphenylphosphine (PPh3) and a Lewis acid RmMXn (ZnCl2, Me3Al, Et3Al, Et2AlCl, EtAlCl2, AlCl3) was studied. The systems that contained Me3Al and Et3Al (i.e., Lewis acid of moderate acidity) were the most efficient catalysts. Conductometric measurements carried out in the polymerization systems showed the presence of ions. The presence of phosphonium cation in the polyacrylonitrile chain formed by the PPh3–RmMXn catalytic systems was determined by IR, 1H‐NMR, and 31P‐NMR spectroscopy. The average molecular weight measurements and kinetic chain lengths of polyacrylonitrile formed within the reaction time in the presence of PPh3–Et3Al showed that transfer reactions occur. According to the results obtained, the polymerization reaction of acrylonitrile by PPh3–RmMXn involved a zwitterion formed by the attack of PPh3 on acrylonitrile complexed by Lewis acid [Ph3P⊕CH2C⊖HCN → MRmXn] and the anion [CH2C⊖CN] formed by the proton abstraction from the monomer.
Polymerization behavior of bistrimethylsilyloxycycloalkenes
Authors: Kondo Akihiro , Nakashima Masataka , Iwatsuki Shouji 
Published: April 2003

AbstractThe radical copolymerizations of bistrimethylsilyloxycycloalkenes, such as 1,2‐bistrimethylsilyloxycyclobutene (I), 1,2‐bistrimethylsilyloxycyclopentene (II), and 1,2‐bistrimethylsilyloxycyclohexene (III), were carried out with acceptor monomers, such as maleic anhydride, N‐phenylmaleimide, and methyl methacrylate. I and II gave alternating copolymers with maleic anhydride and random copolymers with N‐phenylmaleimide but no copolymer with methyl methacrylate. III gave no copolymer with the acceptor monomers. These polymerization behaviors of bistrimethylsilyloxycycloalkenes were explained primarily in terms of the electron donor–acceptor interaction between both monomers.
The identification of peroxy‐features at polymer surfaces by ESCA
Authors: Dilks A. 
Published: April 2003

AbstractA preliminary investigation of the identification of peroxy‐features at polymer surfaces by ESCA is described. Oxidation of a hydrocarbon polymer in the effluent of a singlet molecular oxygen generator, based on a microwave discharge in oxygen, produces surfaces rich in peroxy‐features. By comparison with experimental and theoretical studies of model systems these features can be identified in ESCA spectra by their characteristic O1s binding energies. The oxygen atoms in the peroxy‐linkage have essentially the same binding energy, which is within a narrow range of 534.0 eV for simple peroxides and hydroperoxides and a narrow range of 535.2 eV for peroxy‐features in more highly oxygenated environments; for example, peracids and peresters. Peroxy‐linkages decompose rather rapidly under the typical x‐ray flux used in the ESCA experiment.
Anionic polymerization to high vinyl polybutadiene
Authors: Halasa Adel F. , Lohr D. F. , Hall J. E. 
Published: April 2003

Abstract1,3‐Butadiene was polymerized anionically to polybutadiene which contained up to 100% 1,2‐addition product. The atactic 100% 1,2‐polybutadiene was prepared with n‐butyllithium modified with bis piperidino ethane. The polymerization was done in hexane solvent at −5 to +20°C polymerization temperature.
Reactions of poly(phenylene oxide)s with quinones. I. The quinone‐coupling reaction between low‐molecular‐weight poly(2,6‐dimethyl‐1,4‐phenylene oxide) and 3,3′,5,5′‐tetramethyl‐4,4′‐diphenoquinone
Authors: White Dwain M. 
Published: April 2003

AbstractA bifunctional polymer is formed when low‐molecular‐weight poly(2,6‐dimethyl‐1,4‐phenylene oxide) (I) reacts with 3,3′,5,5′‐tetramethyl‐4,4′‐diphenoquinone (II). Infrared (IR), nuclear magnetic resonance (NMR), and gel permeation chromotography (GPC) measurements indicate that the quinone is bound covalently to the polymer chain as a biphenyl moiety which can be located at a terminal position (III, a = 0) or an internal position (III, a > 0):
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Acetylation of III produces a diacetate ester characterized by field desorption mass spectrometry to confirm the bifunctional nature of III. The reaction of I with II proceeds at 25°C but is faster at elevated temperatures or with amine catalysis. Oxidation of III with oxygen and a copper/amine catalyst of the type used initially to prepare I regenerates II from the biphenyl moiety in III in high yield and converts the remaining oxyphenylene units to high‐molecular‐weight polymer.
Preparation and properties of novel polyhydrazides
Authors: Mahadevan V. , Padma S. , Srinivasan M. 
Published: April 2003

AbstractA new class of polyhydrazides having aromatic as well as aliphatic units has been synthesized by low‐temperature solution polycondensation from equimolar amounts of diacid chloride and dihydrazides in HMPT as solvent. These polyhydrazides have poor solubilities and their intrisnsic viscosities ranged from 0.2 to 0.6 dl/g. X‐ray diffractograms of these polyhydrazides show that the polymers having terephthalic acid dihydrazide unit were more crystalline and all the polymers have densities in the range of 1.2‐1.8 g/cm3. Thermogravimetric analysis of these polyhydrazides showed initial weight losses commencing at 220–300°C in both air and nitrogen.
A novel method for the synthesis of liquid crystalline polymers. Preparation by the interaction of poly(acryloyl chloride) with mesogenic compounds
Authors: Paleos C. M. , Filippakis S. E. , Margomenou‐Leonidopoulou G. 
Published: April 2003

AbstractA new method for the synthesis of thermotropic liquid crystalline polymers, which is comprised of the interaction of reactive polymers with mesogenic compounds, was investigated. This method is illustrated by the interaction of poly(acryloyl chloride) withp‐hydroxybenzylidene‐p‐butylaniline orp‐aminobiphenyl on the preparation of poly(p‐acryloyloxybenzylidene‐p‐butylaniline and poly(N‐p‐biphenylacrylamide)), respectively. These polymers were subjected to characterization studies which included optical microscopy, x‐ray diffraction analysis, and differential scanning calorimetry. It was established that both polymers in the melt exhibit smectic mesomorphism.
Solvation of polymeric organolithium compounds. Stoichiometry and heats of interaction of N,N,N′,N′‐tetramethylethylenediamine (TMEDA) with poly(styryl)lithium and poly(isoprenyl)lithium
Authors: Quirk Roderic P. , McFay Dennis 
Published: April 2003

AbstractThe enthalpies of interaction of N,N,N′,N′‐tetramethylethylenediamine (TMEDA) with poly‐(isoprenyl)lithium and poly(styryl)lithium were measured as a function of R ([base]/[Li]) by using high‐dilution solution calorimetry at 25°C. Both polymeric organolithiums exhibit initial exothermic enthalpies of interaction with TMEDA (R ≃ 0.1) of ca. −13 kcal/mole. The concentration dependencies show a break (decrease) in the plot of ΔH vs. R at ca. R = 0.5 for poly(isoprenyl)lithium and at ca. R = 1.0 for poly(styryl)lithium.
Aqueous polymerization of methacrylamide
Authors: Shukla J. S. , Tiwari R. K. 
Published: April 2003

AbstractThe aqueous polymerization of methacrylamide (I) initiated by KBrO3–thioglycolic acid (TGA) has been studied at 30 ± 0.2°C in nitrogen. The rate is given by K[M]1.19 [thioglycolic acid]1 [KBrO3]0.53 for 10–15% conversion. Activation energy was found to be 53.96 kJ/mole (12.92 kcal/mole) in the investigated range of temperature 30–45°C. The role of addition of a series of aliphatic alcohols and some salts was also determined. The kinetics of polymerization was followed iodometrically.
γ Radiolysis of polyethylene grafted with styrene
Authors: Mitsui Hiroshi , Shimizu Yuichi 
Published: April 2003

Abstractγ Radiolysis of polyethylene grafted with styrene of 0–76 wt % was carried out at 30–100°C in vacuo with a dose rate of 6.35 × 105 rad/hr. The formation of hydrogen and trans‐vinylene unsaturation decreased as the content of styrene unit in polymer increased and the rate of formation was described by zero‐order formation kinetics with respect to each concentration combined with first‐order disappearance. The gel fraction changed with the content of styrene unit according to irradiation time and temperature. The gel data were evaluated by using the Charlesby–Pinner equation. Kinetic analysis showed that in γ radiolysis of polyethylene grafted with styrene the formation of hydrogen is somewhat retarded, the crosslinking and main chain scission are accelerated, and the disappearance of hydrogen and formation and disappearance of trans‐vinylene unsaturation are almost entirely unaffected. On the basis of these results the reactions induced by γ rays in graft polymer were discussed in connection with the reaction mechanisms of the γ radiolyses of polyethylene and polystyrene.
Reactions of hydroxymethylated 2‐methoxy‐ and 2‐methyl‐4,6‐diamino‐s‐triazines with urea
Authors: Tashiro Tatsuo 
Published: April 2003

AbstractThe reactions of hydroxymethylated 2‐methyoxy‐ (MMT) and 2‐methyl‐4,6‐diamino‐s‐triazines (MAG) which had an average degree of formaldehyde (F) substitution (n) = 2, with urea were studied in acidic aqueous solution in the pH 5‐1.6 region. The observed facts were in fairly good agreement with the rate equations. The reaction rate constants of MMT with urea were greater than those of MAG with urea, but their activation energy was almost equal: MMT, 20.3; MAG, 20.2 kcal/mole. For reference summaries of earlier studies were provided.
Copolymerization of butadiene with vinyl chloride by radiation
Authors: Hayashi Kanae , Tachibana Michinori , Tanaka Yoshinori , Okamura Seizo 
Published: April 2003

AbstractThe copolymerization of butadiene with vinyl chloride was demonstrated in homogeneous phase by radiation. The reactivity parameters were r1 = 10 and r2 = 0.02 (M1 = butadiene) in bulk at −10°C. The average molecular weight of the product was about 1000–2500, depending reaction conditions.
Polyetherimides via nitro‐displacement polymerization: Monomer synthesis and 13C‐NMR analysis of monomers and polymers
Authors: White D. M. , Takekoshi T. , Williams F. J. , Relles H. M. , Donahue P. E. , Klopfer H. J. , Loucks G. R. , Manello J. S. , Matthews R. O. , Schluenz R. W. 
Published: April 2003

AbstractThe synthetic route to polyetherimides by displacement of nitro‐groups from disubstituted bis‐imides by the dianion of bisphenols are described. The prepration of bis‐imides and bisphenol dianions, their polymerization, and some of the properties of the polymers are presented in detail. The 13C‐NMR spectra of intermediates and products were used to establish compositions and determine molecular weights.
Gamma radiation‐initiated polymerization of styrene at high pressure. I. Kinetic parameters with intermittent irradiation
Authors: Moore P. W. , Clouston J. G. , Chaplin R. P. 
Published: April 2003

AbstractBy adapting the rotating sector technique to provide an intermittent source of cobalt‐60 radiation the activation volumes for all reaction steps of the bulk polymerization of styrene have been shown to be independent of pressure up to 208 MPa. The activation volumes determined for polymerization, initiation, propagation and termination were, respectively, ΔV≠pol = −20.5 ± 0.22, ΔV≠i = +2.0 ± 0.18, ΔV≠p = −18.6 ± 0.44, and ΔV≠t = +5.8 ± 0.55 cm3 mol−. The values for the effect of pressure on the degree of polymerization ΔDP and the radical lifetime Δτ were, respectively, −22.6 ± 0.16 and −3.9 ± 0.29. The average radical lifetime increased from 4.5 s at atmospheric pressure to 6.3 s at 208 MPa. Because ΔV≠t is less than ΔV≠t and both are positive, the molecular weight increased with pressure at a faster rate than the polymerization rate. Although fewer radical chains were initiated per second under pressure the macroradical concentration increased with pressure because of the longer average lifetime of the radicals.
ESR study of the effects of water, methanol, and ethanol on gamma‐irradiation of starch
Authors: Henderson Alex M. , Rudin Alfred 
Published: April 2003

AbstractThis investigation deals with the nature and relative abundance of stable radicals formed by gamma‐irradiation of wheat starch at room temperature. Additions of equal weights of water, methanol, and ethanol were equally effective in reducing the content of stable radicals in starch which contained about 12% water before the additions. When, however, the starting material was dried starch with 2.9% initial water content additional water and methanol were better radical scavengers than ethanol. This difference is attributed to the superior ability of water and methanol to permeate the starch structure. Superficially different ESR spectra were obtained in products made by irradiating starch and starch that contained added water or methanol. Computer simulation of these spectra showed that they could be matched by superposition of the spectra of the same four component radicals, with some adjustments of relative intensities and peak widths. The structures of these radicals have been dedueed from the spectral assignments and relative effects of the three solvents used on the intensities of the respective ESR spectra.
Solvolysis of 4‐acyloxy‐3‐nitrobenzoic acid substrates catalyzed by polyethylenimine derivatives
Authors: Pavlisko J. A. , Overberger C. G. 
Published: April 2003

AbstractThe solvolytic reactions of anionic activated esters (Sn−) catalyzed by dodecane‐block‐poly[ethylenimine‐graft‐4(5)‐methylimidazole] and related model compounds were investigated. Hydrolysis of 4‐acetyl‐3‐nitrobenzoic acid (S2−) as a function of pH suggested that electrostatic interactions are operative only in the higher molecular weight polymers. Apolar interactions were evident from the greater catalytic rates observed for the hydrolysis of a series of 4‐acetoxy‐3‐nitrobenzoic acid substrates (Sn−). The largest rate enhancements were reflected by catalysts that make effective use of the electrostatic interaction and also provide an apolar binding site. Dodecane‐block‐poly[ethylenimine‐graft‐4(5)‐methylimidazole], with a DP = 85, catalyzed hydrolysis of Sn−(n = 2, 4, and 7), in excess substrate, exhibited saturation kinetics and followed a simple Michaelis‐Menten‐type mechanism. Inhibition of the catalyst in the hydrolysis of S12− was observed and can be rationalized by analogy to certain multisite enzymatic reactions.
Preparation, characterization, and porperties of optically active poly(α‐methyl‐α‐ethyl‐β‐propiolactones)
Authors: Grenier Daniel , Prud'Homme Robert E. , Leborgne Alain , Spassky Nicolas 
Published: April 2003

AbstractS(−) and R(+) enantiomers of α‐methyl‐α‐ethyl‐β‐propiolactone (MEEPL) were prepared in an eight‐step synthesis with respective optical purities of 99 and 97% determined by 1H‐NMR (250 MHz) spectroscopy. Polymers (PMEPL) of different enatiomeric compositions were prepared with an anionic‐type initiator. Substantial differences in physical properties were observed between the racemic and optically pure polymers; for example, the melting point of the latter is 42°C higher than that of the former. Chiroptical properties of PMEPLs are reported. The 13C‐NMR (100.62 MHz) spectra of the polymers indicated that the distribution of configurational units in the macromolecular chain is random.
Studies of inorganic precipitate membrane. Part XXX. Membrane selectivity from electrical potential and conductivity measurements
Authors: Beg M. Nasim , Shyam R. , Beg M. Mohtashim 
Published: April 2003

AbstractBi‐ionic and multi‐ionic potentials across parchment‐supported mercuric sulfide membrane with various combinations of 1:1 electrlytes at different concentrations were measured. Membrane conductivity in contact with a single electrolyte was experimentally determined to evaluate selectivity of the membrane with the predetermined values of intramembrane mobility ratio. The selectivity sequence of the membrane was K+>Na+>Li+, which on the basis of the Eisenman–Sherry model of membrane selectivity, points toward the weak field strength of the charge groups attached to the membrane matrix. The permeability ratio of ions within the membrane was also evaluated by use of the equation based on the macroscopic linear laws of nonequilibrium thermodynamics derived by Sandblom and Eisenman. Three different methods of various integrated forms of the Nernst‐Plank flux equation were used to derive the potentiometric selectivity constant Kijpot of the membrane. These values were close to one another.
Excluded volume effects on polymer reaction rates
Authors: Black P. E. , Worsfold D. J. 
Published: April 2003

AbstractThe rates of reaction of acid chloride groups with nitrophenol groups were measured with the groups attached to polymer chains. The average degree of substitution was kept low, near to one or less groups per chain. It was found that the interpolymer reaction rates decreased several fold in dilute solution for high polymers compared with the rates in more concentrated solutions or with those for low‐molecular‐weight polymers. The results were compared with the models proposed by Morawetz and the effect was of the predicted magnitude. The results also confirmed Morawetz' prediction that smaller effects could be expected for terminally substituted than for randomly substituted polymers.
Reaction of poly(vinyl alcohol) with superoxide anion
Authors: Osawa Zenjiro , Moriyama Chiharu , Nakano Hiroko 
Published: April 2003

AbstractReaction of pol(vinyl alcohol) (PVA) with superoxide anion was carried out in a dimethyl sulfoxide solution at 40°C under nitrogen and changes in the yield of recovered polymer, molecular weight, and chemical structure were examined. Appreciable decreases in the yield of recovered polymer and molecular weight were observed during the reaction, which indicated that a main chain scission of the polymer had occurred. Residual acetyl groups identified by the absorption peaks at ca. 1720 and 1250 cm−1 in infrared (IR) spectra were removed rapidly and β‐diketone groups identified by the peaks at ca. 1640 and 1560 cm−1 in IR spectra and at ca. 255 nm in ultraviolet (UV) spectra were formed during the reaction. Formation of carboxylate groups was also assumed. The reaction mechanism was discussed on the basis of the results obtained.
Liquid crystal polymers. IV. Thermotropic polyesters with flexible spacers in the main chain
Authors: Antoun S. , Lenz R. W. , Jin J.‐I. 
Published: April 2003

AbstractTwo closely related series of polyesters that contain mesogenic units interconnected by flexible spacers along the main chain were prepared and characterized for their liquid crystal properties. All of these polymers showed theotropic behavior, which was examined by DSC, hot‐stage microscopy on a polarizing microscope, small‐angle light and wide‐angle x‐ray scattering methods, and visual observation of stir‐opalescence of the polymer melts. The effect of the length of the flexible spacer and the nature of the substituent, which is on the central aromatic ring of the mesogenic unit, on the stability and molecular order of the mesophase for each of the polymers was investigated and the results are discussed on the basis of the thermodynamic data obtained.
Neighboring effect of thiol group in acyl transfer reaction on a polymer with a lipoic acid structure
Authors: Nambu Yoko , Endo Takeshi , Okawara Makoto 
Published: April 2003

AbstractReductive S‐monoacylation of lipoamide with some carboxylic acids and tri‐n‐butylphosphine was carried out in acetonitrile to obtain the corresponding S‐monoacylated compounds in excellent yield. This method was applied to the preparation of S‐monoacylated dihydrolipoyl polymer with a neighboring thiol group. The acyl transfer from the polymer to cyclohexylamine was enhanced as much as 64 times by adding silver perchlorate.
Combined environment aging effects: Radiation‐thermal degradation of polyvinylchloride and polyethylene
Authors: Clough Roger L. , Gillen Kenneth T. 
Published: April 2003

AbstractResults are presented for a case of polymer aging in which powerful synergisms are found between radiation and temperature. This effect was observed with formulations of polyvinylchloride and polyethylene and occurred insimultaneousandSequentialradiation‐thermal experiments. Dose rate dependencies, which appear to be mechanistically related to the synergism, were also found. The evidence indicates that these aging effects are mediated by a thermally induced breakdown of peroxides initially formed by the radiation. Similar effects could be important to material degradation in a variety of other types of combined‐stress environment. A new technique, which uses PH3treatment of intact polymer specimens to test for the importance of peroxide is the pathway that leads to changes in macroscopic tensile properties, is described.
Degradation of lignin by ozone. II. Molecular weights and molecular weight distributions of the alkali‐soluble degradation products
Authors: Mbachu R. A. D. , Manley R. St. John 
Published: April 2003

AbstractThe molecular weights and molecular weight distributions of the alkali‐soluble degradation products from the ozonolysis of spruce periodate and cuoxam lignins and spruce protolignin have been studied by gel permeation chromatography and ultracentrifugation. The bimodal distribution previously reported for soluble lignins was found to be an artifact; the correct distribution has one broad lowmolecular‐weight maximum, with a long tail extending toward the high‐molecular‐weight end of the distribution. Weight‐average molecuar weights of the alkali‐soluble degradation products, obtained by sedimentation equilibrium measurements, increased with time of ozonization up to about 15 min. Beyond this time fragmentation of the partly degraded products results in a decrease in molecular weight. Lignin degradation followed the pattern expected of a three‐dimensional, infinite‐network polymer gel undergoing breakdown. Based on the molecular weights and the molecular weight distributions, a random stepwise mechanism is suggested as the mode of lignin degradation by ozone.
Preparation and properties of some cardopolyamides
Authors: Srinivasan P. R. , Mahadevan V. , Srinivasan M. 
Published: April 2003

AbstractSeveral polyamides that contained cardo units were prepared. Thus 9,9‐bis(4‐aminophenyl)fluorene and 9,9‐bis(4‐aminophenyl)anthrone were condensed with 2,5‐dimethyl‐1,4‐benzenediacetyl chloride, 2,4‐dimethyl‐1,4‐benzendiacetyl chloride, and 2,5‐dimethoxy‐1,4‐benzediacetyl chloride. Lowtemperature solution polycondensation in dimethyl acetamide (DMAc) was used throughout. The polymers were obtained in 80–90% yield and possessed intrinisic viscosities in the range of 0.6–1.2. The polymers were characterized by infrared (IR) spectra and elemental analysis. The solubility, crystallinity, and thermal stability of the polyamides were also determined.
Solutions of nylon‐6 in antimony trichloride
Authors: Aharoni S. M. , Walsh E. K. , Cilurso F. G. 
Published: April 2003

AbstractDilute solution viscosity measurements of nylon‐6 in molten SbCl3 reveal a polyelectrolyte effect that becomes more pronounced with increased molecular weight of the polymer sample. Intrinisic viscosities result in a relationship of [η] = 2.35 × 10−6M1.45w for nylon‐6 in SbCl3 at 100°C, which indicates a high polymeric chain extension in molten SbCl3 in the limit of zero concentration. Infrared (IR) and nuclear magnetic resonance (NMR) spectra indicate that a substantial fraction of the amide groups in each polymer chain remains unaffected, whereas the rest is interacted, probably, with SbCl4‐ions originating from the self‐ionization of SbCl3.