bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies of the polymerization of diallyl compounds. XXVII. Copolymerization of diallyl tartrate with several vinyl monomers
Authors: Ohata Tetsuji , Fukumori Etsuro , Matsumoto Akira , Oiwa Masayoshi 
Published: April 2003

AbstractThe radical copolymerization of diallyl tartrate (DATa) (M1) with diallyl succinate (DASu), diallyl phthalate (DAP), allyl benzoate (ABz), vinyl acetate (VAc), or styrene (St) was investigated in order to disclose in more detail the characteristic hydroxyl group's effect observed in the homopolymerization of DATa. In the copolymerization with DASu or DAP as a typical diallyldicarboxylate, the dependence of the rate of copolymerization on monomer composition was different for different copolymerization systems and unusual values larger than unity for the product of monomer reactivity ratios, r1r2, were obtained. In the copolymerization with ABz or VAc (M2), the r1 and r2 values were estimated to be 1.50 and 0.64 for the DATa/ABz system and 0.76 and 2.34 for the DATa/VAc system, respectively; the product r1r2 for the latter copolymerization system was found again to be larger than unity. In the copolymerization with St, the largest effect due to DATa monomer of high polarity was observed. Solvent effects were tentatively examined to improve the copolymerizability of DATa. These results are discussed in terms of hydrogen‐bonding ability of DATa.
Temperature drop turbidity. IV. Polystyrene
Authors: Hay James N. , Fitzgerald Pauline A. 
Published: April 2003

AbstractThe molecular weight distribution of fractionated and unfractionated polystyrene samples has been determined by temperature drop turbidimetry, in which polymer is precipitated from dilute solutions in cyclohexanol by progressively cooling from 388 to 310 K. Estimates of the molecular weight averages and the polydispersities, obtained by calibration of the temperature of initial onset of precipitation, Ti, and the weight‐average molecular weight were low, but could be substantially improved by correcting for concentration changes during precipitation. An empirical procedure correlating the breadth of turbidity‐temperature curves to the logarithm of the polydispersity, as measured by gel permeation chromatography, appeared to be a simpler method of characterizing the polymer samples and as accurate as the computational methods above.
Effects of electron beam preirradiation on the γ radiolysis of polyethylene
Authors: Mitsui Hiroshi , Shimizu Yuichi 
Published: April 2003

AbstractThe γ radiolysis of polyethylene preirradiated with electron beams to 3 Mrad was carried out at 30–100°C in vacuo with a dose rate of 6.35 × 105 rad/hr. The hydrogen formation in the γ radiolysis was little affected by the preirradiation of electron beams, whereas the formation of trans‐vinylene unsaturation and gel was somewhat retarded. The rates of the formation of hydrogen and trans‐vinylene unsaturation were described by the zero‐order formation kinetics with respect to each concentration combined with the first‐order disappearance. The apparent rate constants and activation energies for the formation and disappearance of hydrogen and trans‐vinylene unsaturation were almost independent of the preirradiation. The gel fraction was analyzed by using the Charlesby–Pinner equation. The G values of crosslinking and main chain scission were increased by the preirradiation, whereas their activation energies remained unaltered. On the basis of these results the effects of preirradiation on the reactions induced by γ rays in polyethylene were discussed.
Synthesis and optical properties of polyethylenimine containing L‐proline and optically active thymine derivatives
Authors: Overberger C. G. , Morishima Yotaro 
Published: April 2003

AbstractPreparation and optical properties of linear polyethylenimine (PEI) containing L‐(−)‐N‐[(−)‐2‐(thymin‐1‐yl) propionyl] prolyl group as grafting pendant, [P‐(−)Pro‐(−)T], and its related monomer and dimer model compounds are described. Hypochromic effects and circular dichroism of these compounds were compared with those of PEI containing (−)‐2‐(thymin‐1‐yl) propionyl group as grafting pendant, [P‐(−)T], which has no L‐proline ring as a spacing group. P‐(−)Pro‐(−)T showed no exciton coupling of B2u π‐π* transition although it showed large hypochromicity in neutral aqueous solution, implying that the stacking of the bases has no screw sense.
Electrochemical and chemical polymerization of acrylamide
Authors: Bhadani Suraj N. , Prasad Yugal K. , Kundu Swapna 
Published: April 2003

AbstractThe electrochemical and chemical polymerization of acrylamide (AA) has been studied. The electrolysis of the monomer in N,N‐dimethylformamide (DMF) containing (C4H9)4NClO4 as the supporting electrolyte leads to polymer formation in both anode and cathode compartments. The cathodic polymer dissolves in the reaction mixture and the anodic polymer precipitates during the course of polymerization. A plausible mechanism for the anodic and cathodic initiation reaction has been given. The chemical polymerization of acrylamide that has been initiated by HClO4 is analogous to its anodic polymerization. The polymer yield increases with an increase in concentration of the monomer and HClO4. Raising the reaction temperature also enhances the polymerization rate. The overall apparent activation energy of the polymerization was determined to be ca. 19 kcal/mole. The copolymerization of acrylamide was carried out with methyl methacrylate (MMA) in a solution of HClO4 in DMF. The reactivity ratios are r1 (AA) = 0.25 and r2 = 2.50. The polymerization with HClO4 appears to be by a free radical mechanism. When the polymerization of acrylamide is carried out with HClO4 in H2O, a crosslinked water‐insoluble gel formation takes place.
Evolution of HCN by thermal oxidative degradation from nylon 66 at high temperatures including burning
Authors: Jellinek H. H. G. , Dunkle S. 
Published: April 2003

AbstractWork on the evolution of HCN from nylon 66 was extended to temperatures from ca. 300 to 695°C. Below ca. 300°C the evolution of HCN is governed by chemical decomposition, and above 300°C the evolution is controlled by diffusion. Above 530°C oxidation of HCN becomes noticeable and ignition occurs at 590°C. The rate constants for all of the temperature ranges and for the oxidation of HCN are given in terms of Arrhenius equations. The activation energy for the oxidation of HCN before ignition (590°C) is reached is 47 kcal/mole, and beyond this point, the oxidation is controlled by diffusion. The rate constants increase linearly with oxygen concentration as long as HCN oxidation is negligible; however, they pass through maxima if HCN oxidation is appreciable (some HCN is evolved even in the absence of oxygen). A new flash degradation apparatus has been constructed for these high‐temperature ranges and a degradation mechanism has been proposed which is in satisfactory agreement with the experimental results.
New telechelic polymers and sequential copolymers by polyfunctional initiator‐transfer agents (inifers). II. Synthesis and characterization of α,ω‐di(tert‐chloro)polyisobutylenes
Authors: Kennedy Joseph P. , Smith Robert Alan 
Published: April 2003

AbstractDetailed understanding of the mechanism of initiation and chain transfer in BCl3‐coinitiated isobutylene polymerization led to the efficient synthesis of symmetric telechelic polyisobutylenes carrying ∼CH2C(CH3)2Cl groups at either end of the molecule Cl‐PIB‐Cl. The synthesis is based on the use of inifers, i.e., bifunctional initiator‐transfer agents that effect controlled initiation and propagation in the absence of chain transfer to a monomer. Specifically, the synthesis of Cl‐PIB‐Cl was achieved by the p‐dicumyl chloride/BCl3/isobutylene/CH2Cl2 system. According to the inifer mechanism each Cl‐PIB‐Cl contains two terminal tertiary chlorines and one phenyl group at the interior of the chains. The structure of this new symmetric telechelic polymer has been established by detailed characterization studies including a sensitive new gel permeation chromatography (UV plus RI) analysis method, 1H‐NMR, kinetic experiments, and chemical derivatization. The Cl‐PIB‐Cl molecule is a key intermediate for the synthesis of hosts of new materials, e.g., triblock copolymers, α,ω‐diolefins, and α,ω‐difunctional polymers.
New telechelic polymers and sequential copolymers by polyfunctional initiator‐transfer agents (inifers). III. Synthesis and characterization of poly(α‐methylstyrene‐b‐isobutylene‐b‐α‐methylstyrene)
Authors: Kennedy Joseph P. , Smith Robert Alan 
Published: April 2003

AbstractThe synthesis of a new glassy‐rubbery‐glassy triblock copolymer poly(α‐methylstyrene‐b‐isobutylene‐b‐α‐methylstyrene) has been demonstrated. The key to the synthesis was the preparation by inifer method of a perfectly bifunctional polyisobutylene which carries tert‐chlorine end groups Cl‐PIB‐Cl. In conjunction with Et2AlCl coinitiator, the telechelic Cl‐PIB‐Cl molecule initiates the polymerization of α‐methylstyrene at both ends of the prepolymer. Triblock composition can be controlled by the judicious selection of synthesis conditions; that is, Cl‐PIB‐Cl molecular weight, α‐methylstyrene concentration, and solvent polarity. Theoretical triblock Mn calculated from Mn of Cl‐PIB‐Cl and triblock overall composition is in excellent agreement with experimental Mn which indicates negligible homopolymer contamination. Extraction with a series of hydrocarbon solvents reveals broad composition distribution. The stress‐strain profile of a triblock is similar to that of a poly(styrene‐b‐butadiene‐b‐styrene) thermoplastic elastomer of similar composition.
Monte Carlo‐studium der reversiblen copolymerisation. I. Theorie, memøry‐6 programm, anwendungen
Authors: Motoc I. , Vancea R. 
Published: April 2003

AbstractThe binary reversible copolymerization, taking into account the length of the terminal sequence, are studied by the Monte Carlo method. We discuss the theoretical model, the algorithm, and a FR̃RAN program. Finally, the α‐methylstyrene‐methyl methacrylate copolymerization is studied by means of the proposed Monte Carlo model, and the results obtained are compared with those obtained using the Markov chain model and Wittmer's equations.
Characterization of polychloroprenes and cationically modified polychloroprenes by thermal dehydrochlorination
Authors: Iván Béla , Kennedy Joseph P. , Plamthottam Sebastian S. , Kelen Tibor , Tüdos Ferenc 
Published: April 2003

AbstractThermal dehydrochlorination of polychloroprenes and modified polychloroprenes was studied and was found to be rapid, readily reproducible, and reliable for the characterization of these rubbers. The rates of thermal dehydrochlorination of polychloroprenes and modified polychloroprenes are first order at 190°C under nitrogen. Significantly, the plot of dehydrochlorination rate (VHCl) versus dehydrochlorination extent (ζHCl) for polychloroprenes shows three regions. These data may be attributed to three dehydrochlorination regimes associated with four contributing repeat structures that have been identified by 13C‐NMR spectroscopy:
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In contrast to polychloroprene, VHCl vs. ζHCl plots for modified (cyclopentadienylated and grafted) polychloroprenes, i.e., polychloroprenes that do not contain allylic chlorines, exhibit only one region suggesting only one dehydrochlorination mechanism in these materials. The slopes of the VHCl vs. ζHCl plots of the modified polychloroprenes are virtually identical. Moreover, the slopes of the VHCl vs. ζHCl plots for modified polychloroprenes and that of the latest of the three regions for unmodified polychloroprene are indistinguishable. This similarity in the VHCl vs. ζHCl curves suggests dehydrochlorination by a fundamentally similar mechanism in these materials, most likely one involving the CH2C(Cl)CHCH2 structure common to all of them. Concentration of labile chlorines in polychloroprene may be estimated by the differences in the dehydrochlorination kinetics of polychloroprene and modified polychloroprenes.
Synthesis of polyamides by a new direct polycondensation reaction using triphenyl phosphite and lithium chloride
Authors: Higashi Fukuji , Goto Mitsuyoshi , Kakinoki Hideo 
Published: April 2003

AbstractMetal salts such as lithium chloride were found to facilitate significantly the reaction of carboxylic acids and amines promoted by triphenyl phosphite, and the reaction was applied successfully to the direct polycondensation reaction of dicarboxylic acids and diamines and of p‐aminobenzoic acid. Among metal salts tested, lithium chloride was most effective to the reaction; the chloride was involved catalytically in the reaction, its addition of about twice equivalent to triphenyl phosphite giving the most favorable results. Triphenyl phosphite was most effective, whereas diphenyl phosphite was less effective, and alkyl esters gave no polymers. The reaction was also markedly affected by solvents, the most favorable results being given in N‐methylpyrrolidone (NMP). Various polyamides of high molecular weight were obtained in quantitative yield.
Polymidines. V. Poly[(3,3‐diphenyl‐2,6‐phthalimidinediyl)‐carbonyl(3,3‐diphenyl‐6,2‐phthalimidine)]s
Authors: Lohr Raymond A. , Cassidy Patrick E. , Kutac Andrew 
Published: April 2003

AbstractA new diphthalide monomer, bis(3,3‐diphenyl‐6‐phthalidyl) ketone, was polymerized with six diamines: 1,6‐diaminohexane, benzidine, p‐phenylene diamine, p,p′‐diaminodiphenyl ether, p,p′‐diaminodiphenylmethane, and 4,4′‐diaminodiphenylsulfone. Solution polymerization in benzhydrol, biphenyl, or p‐phenylphenol solvents gave low‐molecular‐weight polymers (inherent viscosity 0.13 dl/g or less) which were soluble in chloroform and dimethylformamide. TGA data showed 10% weight losses at 445–525°C in air and 475–540°C in nitrogen for the aromatic backbones. Yields ranged from 47 to 78%. The application of continuous vacuum to the polymerization allowed the removal of water by‐product and resulted in a light‐colored polymer.
A new universal GPC calibration method
Authors: Hester R. D. , Mitchell P. H. 
Published: April 2003

AbstractA model of GPC separation phenomenon with a new calibration method has been developed based on the probability of molecular size exclusion from a porous packing material. The model was shown to give a theoretical explanation of instrument range and sensitivity. With data from the literature, the new calibration method was shown to be statistically superior to the standard method suggested by Grubisic.
Polymerization of aromatic nuclei. XXIII. Investigation of oligomer and pyrrole red from pyrrole and trichloroacetic acid
Authors: Lamb Bruce S. , Kovacic Peter 
Published: April 2003

AbstractA reinvestigation of the oligomerization of pyrrole by trichloroacetic acid was carried out to establish the structure of the product. Comparison of spectral data with those of model compounds suggests that the oligomer is best represented by I. Further comparison was made to the known trimer I, dimer V, and other substituted pyrroles and pyrrolidines. In addition, microanalytical and molecular weight data were obtained. Structure I is in disagreement with that of Wassermann et al., who proposed the presence of units possessing aliphatic unsaturation for the same product. Mechanistic aspects are discussed. A limited study was carried out with pyrrole red.
Polymerization of allyl esters of unsaturated acids. V. Cyclopolymerization of methyl allyl fumarate
Authors: Urushido Kunio , Matsumoto Akira , Oiwa Masayoshi 
Published: April 2003

AbstractThe kinetics of radical polymerization of methyl allyl fumarate (MAF) is discussed in terms of cyclopolymerization and compared with the polymerization results of methyl allyl maleate (MAM) as a cis isomer. In the polymerization of MAF, the rate and degree of polymerization were quite enhanced compared with MAM, and gelation occurred at low conversion. The content of the unreacted allylic double bonds of the MAF polymer was quite large; whereas those of the unreacted fumaric double bonds and the cyclic structural units showed reverse tendencies. Only a slight presence of a five‐membered ring was observed in the MAF polymer. The cyclization constants KA and KV, the ratios of the rate constants of the unimolecular cyclization reaction to those of the bimolecular propagation reaction of the uncyclized allylic and fumaric radicals, were estimated to be 2.73 and 1.48 mole/liter, respectively. These values suggest the great difference in the cyclopolymerization behavior between two isomeric monomers. These results are discussed in detail in connection with the high reactivity of the fumaric double bond compared to the maleic double bond. In addition, the formation mode and the sequence distribution of the structural units of the polymer produced are discussed on the basis of these analytical results. Thus, for the MAF polymer obtained in the bulk polymerization, about 60% of the cyclic structure can be formed via the intramolecular attack of the uncyclized fumaric radical on the allylic double bond, as opposed to the case of MAM via the predominant intramolecular attack (ca. 90%) of the uncyclized allylic radical on the maleic double bond; these results and the low probability for the succession of cyclic structures and the rather high probability of a vinyl‐to‐vinyl addition are presented.
New processable polyaromatic amides curable by Diels‐Alder cycloaddition
Authors: Sankaran V. , Marvel C. S. 
Published: April 2003

AbstractNew processable polyaromatic amides were prepared from the acid chloride of bis‐m‐carboxyphenyl acetylene (V), the acid chloride of 1,4‐bis‐m‐carboxyphenyl‐1,3‐butadiene (VI), and several aromatic diamines. The polyamides that contained acetylene units were cured by Diels‐Alder cycloaddition reaction with 1,4‐diphenyl‐1,3‐butadiene, whereas the polyamides with 1,3‐butadiene units were cured with N‐phenyl maleimide. Cured polyamides showed an increase in tg, thermal, and heat stabilities. The polyamides can be cast into films and produce good glass‐fiber laminates.
Mechanism of thermal degradation of polyurethanes investigated by direct pyrolysis in the mass spectrometer
Authors: Ballistreri A. , Foti S. , Maravigna P. , Montaudo G. , Scamporrino E. 
Published: April 2003

AbstractDirect pyrolysis in the mass spectrometer (MS) yielded unequivocal evidence regarding the mechanism of thermal decomposition of N‐monosubstituted and N‐disubstituted polyurethanes. It was ascertained that direct pyrolysis in the MS detects the primary thermal fragments that originate from polyurethane pyrolysis. This is particularly useful when, as in the thermal decomposition illustrated in eq. (1), it is necessary to distinguish between primary and secondary thermal fragments in order to assess the thermal degradation mechanism. Our results indicate that N‐monosubstituted polyurethane V undergoes a quantitative depolycondensation process. Instead, the thermal decomposition of the N‐disubstituted polyurethane VI which occurs selectively in eq. (1) is demonstrated by the detection of thermal fragments that contain secondary amine and olefinic end groups. Finally, polyurethane VI shows a higher thermal stability with respect to polymer V because of the absence of the depolycondensation process, which accounts for the thermal degradation of the N‐monosubstituted polyurethane V.
Synthesis and biodegradability of amylose block copolymers
Authors: Lynn M. M. , Stannett V. T. , Gilbert R. D. 
Published: April 2003

AbstractThe synthesis of amylose block co‐and terpolymers is described. Fully acetylated amylose triacetate was hydrolyzed by hydronium ions to give a hydroxy‐terminated amylose triacetate oligomer (HATA), which was reacted with diisocyanates to produce block copolymers. Prepolymers of HATA and MDI or TDI were reacted with both hydroxy‐terminated polybutadiene and polypropylene glycol to form block terpolymers. Block co‐ and terpolymer formation was demonstrated by intrinsic viscosity increases, gel permeation chromatographic results, and NMR and IR spectroscopy. The products were easily deacetylated by NaOMe in methanol to yield amylose block co‐ and terpolymers. These polymers were readily degraded by α‐amylase. The enzymatic hydrolysis was monitored by intrinsic viscosity measurements. The rate of biodegradation was influenced by the DS of the amylose block and the composition of the block terpolymers.
MacromolecularN‐nitroso‐acylamines as initiators for polyreactions. I. Synthesis of block copolymers from polycondensates and olefinic monomers,
Authors: Craubner Hans 
Published: April 2003

AbstractThe synthesis of block copolymers in three‐step reactions from linear polycondensates (e.g., nylon 6. nylon 6,6, nylon 6,10 and polyurethane) and olefinic monomers (e.g., styrene, acrylic acid and acrylonitrile, methyl methacrylate, vinyl acetate, vinyl chloride, and isoprene) is reported. Macromolecular radicals are formed by the thermal decomposition of partly nitrosated peptide group containing polycondensates at elevated temperatures (60–200°C). These polyradicals initiate the copolymerization of the olefinic monomers. The conversion and reaction rates were generally high (up to 100% within a few hours). Most of the block copolymers prepared were soluble in organic solvents. Some, however, were insoluble or rubberlike. The reaction mechanism involved are analyzed. Applications are discussed.
Promotion by supports of the reactivity of propagating species of Ziegler supported catalytic systems for the polymerization and copolymerization of olefins
Authors: Ivanchev S. S. , Baulin A. A. , Rodionov A. G. 
Published: April 2003

AbstractKinetics for the polymerization of ethylene and the copolymerization of ethylene and propylene were studied by using highly effective heterogeneous metal organic catalysts produced by coating different organic and inorganic supports with the components of Ziegler systems. The activity of a supported Ziegler catalyst is characterized by the physical parameters of the support structure and its chemical nature. The active role of magnesium‐containing supports was established for the formation and functioning of the propagating species on their surfaces. This role is expressed not only by an increase in the portion of transition metal included in the propagating species, compared with typical Ziegler catalysts, but also by an increase in the reactivity of the propagating species, change in the nature of the elementary processes for polymerization and copolymerization, including control of copolymerization constants, and modification of the molecular structure of the polymers and copolymers. It was shown that by choice of support it is possible to control the activity of the same catalytic system and characteristics of the structure and properties of the polymers it produces under identical polymerization conditions.