bluuebunny/crossref_metadata_2025_split huggingface dataset:
High temperature polymers. III. Diphenyl sulfone‐based polyamide‐imides
Authors: Kwiatkowski George T. , Brode George L. , Kawakami James H. , Bedwin Albert W. 
Published: April 2003

AbstractHigh temperature thermoplastic polyamide‐imides were prepared from a new series of aromatic diamines containing the diphenylsulfone unit and alternatively, oxydiphenyl and diphenylisopropylidene units. The polymers were prepared in their completely imidized form by using a facile in situ chemical imidization reaction which offers several advantages over the conventional thermal imidization process. The sulfone‐based polyamide‐imides exhibited an excellent combination of moldability, thermal stability, mechanical properties and solvent resistance. Analysis of the properties of these polymers in terms of structural variations permits a useful correlation of the effect of various structural units on performance. The polar diphenyl sulfone and amide‐imide units increase the glass transition temperature and improve solvent resistance while the oxydiphenyl and diphenylisopropylidene units improve thermoplasticity. Sulfone ether diamine polyamide‐imide (VI) offers the best combination of high temperature performance and moldability.
Aromatic polyethers, polysulfones, and polyketones as laminating resins. II
Authors: Sivaramakrishnan K. P. , Marvel C. S. 
Published: April 2003

Abstract1,3‐Bis(p‐phenoxybenzenesulfonyl)benzene and 4,4′‐bis(p‐phenoxybenzenesulfonyl)‐diphenyl ether were polymerized with isophthaloyl and terephthaloyl chloride in Friedel‐Crafts type polymerizations. These polymers had 5‐cyanoisophthaloyl units in the backbone, obtained by using 5‐cyanoisophthaloyl chloride as part of the acid chloride monomer. A number of catalysts were screened to effect the trimerization of the pendant nitrile groups in the polymer to the triazines. Model reactions were carried out for each polymer. Physical and thermal properties of the laminates obtained from these polymers are discussed.
Stereochemical regulation of polypropylenes prepared with various Ziegler‐Natta catalysts
Authors: Mitani Katsuo , Suzuki Toshimitsu , Matsuo Akihiro , Takegami Yoshinobu 
Published: April 2003

AbstractThe 220‐MHz proton magnetic resonance and infrared spectra of stereoregular polypropylenes polymerized with a number of Ziegler‐Natta catalysts and isotactic polymers of low molecular weight obtained by thermal degradation of a highly isotactic polypropylene were measured in an attempt to obtain some information on the local regularity. The fraction of thermally degraded polymer soluble in diethyl ether shows stereorandomness (tactie sequence length is quite short), and the portion soluble in n‐pentane has stereoblock character. The results so obtained provide strong evidence that racemic dyads of whole polymer consist of two models of racemic dyad isolated and racemic dyads in groups. The polymers prepared with vanadium catalyst systems show stereorandom character and these polymers have \documentclass{article}\pagestyle{empty}\begin{document}$\hbox{-\hskip-1pt-}\hskip-4pt({\rm CH}_2 \rlap{--} )$\end{document} groups formed by two propylene units in a tail‐to‐tail linkage. Syndiotactic polypropylene has head‐to‐head and tail‐to‐tail arrangements of two propylene units and this is the origin of randomness of syndiotacticity.
Photoinduced polymerization of maleic anhydride in dioxane
Authors: Nagahiro Isao , Nishihara Koji , Sakota Naokazu 
Published: April 2003

AbstractMaleic anhydride (MAn) was irradiated with ultraviolet light in dioxane at 35°C without initiator, and predominantly a MAn oligomer was obtained with a small quantity of cyclic dimer of MAn. Mass spectrometric, NMR, and elementary analysis investigation of the oligomer showed that it is composed of about four MAn units and one dioxane molecule per molecule.
Determination of crystallinity in polycaproamide fibers by the method of half‐integral intensity
Authors: Włochowicz A. , Jeziorny A. 
Published: April 2003

AbstractThe rectilinear relationship between the integral intensity Bi and fiber density d is used as the basis of a new method for evaluation of the crystallinity index of polyamide fibers (PA‐6). To calculate the value of the crystallinity index of the fibers one should have the integral intensity value of the sample and the integral intensities of crystalline and amorphous samples determined under defined instrumental conditions. The method provides a quick and simple means for determining the crystallinity. The method of half‐integral intensity may be used only with care when the α‐monoclinic polymorphic form dominates in the PA‐6 fiber.
Synthesis of zirconium poly‐O‐amidoximes
Authors: Carraher Charles E. , Frary Ronald A. 
Published: April 2003

AbstractSynthesis of zirconium poly‐O‐amidoximes was affected by using both interfacial and aqueous solution techniques.
Reaction is rapid. The yield for the synthesis of analogous titanium product is Cp2ZrCl2 > Cp2TiCl2 which is consistent with that predicted by the hard‐soft acid–base theory.
Cyclopolymerization. II. Mechanism of the free‐radical polymerization of N‐n‐propyldimethacrylamide
Authors: Kodaira Toshiyuki , Aoyama Fumio 
Published: April 2003

AbstractThe mechanism of cyclopolymerization was investigated by using N‐n‐propyldimethacrylamide (PDMA). Completely cyclized polymers were formed on polymerization of PDMA by a radical initiator. Moreover, those copolymers of PDMA and various monomers, such as styrene, methyl methacrylate, and vinyl acetate, obtained did not contain any detectable pendent double bonds. The kinetic investigation showed that the termination reaction proceeded between the cyclized radicals. The attempted polymerization of N‐n‐propyl‐N‐isobutyrylmethacrylamide, the monofunctional counterpart of PDMA, was failed. These results appear to confirm that cyclopolymerization of PDMA proceeds through a concerted mechanism which has been proposed for the mechanism of the cyclopolymerization of various difunctional monomers. Measurement of the ESR spectra of propagating radical has, however, revealed that the rate‐determining step of the cyclopolymerization of PDMA is not intermolecular propagation but intramolecular cyclization, which indicates that the cyclization reaction proceeds in a stepwise way. This apparent contradiction was explained based upon thermodynamic considerations.
H2O2‐photosensitized emulsion copolymerization of tetrafluoroethylene with propylene
Authors: Suzuki Nobutake , Okamoto Jiro 
Published: April 2003

AbstractThe H2O2‐photosensitized emulsion copolymerization of tetrafluoroethylene with propylene was carried out at room temperature in the presence of gaseous monomers of 50 mole‐% tetrafluoroethylene content. The conversion increased almost linearly with irradiation time. The rate of polymerization was proportional to the 1.0 power of H2O2 concentration up to 3.5 × 10−3M H2O2 and the 0.46 power of H2O2 concentration above 3.5 × 10−3M H2O2. The result obtained at low H2O2 concentration was almost consistent with that obtained in the radiation‐induced method. The rate of polymerization was proportional to the 0.58 power of the emulsifier concentration, and the degree of polymerization was independent of the emulsifier concentration. The H2O2‐photosensitized emulsion copolymerization of tetrafluoroethylene with propylene is terminated mainly by degradative chain transfer of the propagating radical to propylene at low H2O2 concentration and by the reaction of the propagating radical with OH radical from photolysis of H2O2–aqueous solution at high H2O2 concentration.
Cyclotrimerization of acetylene by the tris(acetylacetonato)titanium(III)–diethylaluminum chloride system
Authors: Shirakawa Hideki , Ikeda Sakuji 
Published: April 2003

AbstractReaction of acetylene with tris(acetylacetonato)titanium(III) and diethylaluminum chloride system leads to formation of benzene, a trace of ethylbenzene, and a small amount of polyacetylene. The isotopic composition of products obtained from cyclotrimerization of acetylene‐d2 and an equimolar mixture of acetylene and acetylene‐d2 is investigated to elucidate the mechanism of the cyclotrimerization. The results suggest a mechanism in which an acetylene inserts into the metal—ethyl bond formed by reaction of Ti(acac)3 and Al(C2H5)2Cl, followed by insertion of two acetylene molecules and elimination of a hydrogen atom from the first inserted acetylene to yield an ethylbenzene and a metal hydride intermediate. The metal hydride intermediate catalyzes acetylene cyclotrimerization to give benzene. During the reaction, the hydrogen atom in the metal hydride intermediate does not exchange with the hydrogen atom in the inserted acetylene molecules.
Energy transfer processes involving ultraviolet stabilizers: Nickel dibutyldithiocarbamate in polypropylene films
Authors: Guillory J. P. , Becker Ralph S. 
Published: April 2003

AbstractThe energy transfer behavior of an ultraviolet stabilizer, nickel dibutyldithiocarbamate (BTN), is examined in solution and in thin polypropylene films. The rate of photosensitized dissociation of this nickel chelate by 4‐methyl‐2‐pentanone in solution was found to be approximately ten times that of its photodissociation after direct ultraviolet excitation. The rate of photodissociation of BTN in preoxidized polypropylene films was also measured. It was found that BTN does not quench the excited carbonyl groups in degassed polymer films. These results are compared to those for nondegassed preoxidized polypropylene samples and are discussed in terms of singlet oxygen quenching. A phenolic antioxidant was found to have no effect on the photodissociation of BTN in either degassed or nondegassed polypropylene films.
Stereoelective polymerization of tert‐butyl thiirane
Authors: Dumas Philippe , Spassky Nicolas , Sigwalt Pierre 
Published: April 2003

AbstractThe polymerization in bulk of racemic tert‐butyl thiirane with a chiral initiator resulting from the reaction between diethylzinc and ()3,3‐dimethyl‐1,2‐butanediol produces an optically active polymer by preferential consumption of R enantiomer. The unreacted monomer is enriched in S enantiomer. The relative rate r of consumption of R enantiomer versus S enantiomer is as high as 2.8. Obtained polymer could be separated into two crystalline fractions: an optically active fraction, formed from regular sequences of R type enantiomeric units, and an optically inactive fraction which corresponds to a racemate. Experimental results are consistent with a stereospecific mechanism of addition, the two enantiomers being chosen by two different type of sites. The stereoelective process is due to an unequal number of these two types of sites.
Near‐infrared spectrum of cellulose: A new method for obtaining crystallinity ratios
Authors: Basch A. , Wasserman T. , Lewin M. 
Published: April 2003

AbstractAbsorption bands in the near‐infrared (NIR) spectrum of cellulose were correlated with crystalline and noncrystalline regions and used to derive a new crystallinity ratio. NIR crystallinity ratios of both natural and regenerated celluloses were measured and compared with x‐ray diffraction values. The data indicates that the NIR crystallinity ratio may also depend upon crystallite size.
Polymers having stable radicals. II. Synthesis of nitroxyl polymers from 4‐methacryloyl derivatives of 1‐hydroxy‐2,2,6,6‐tetramethylpiperidine
Authors: Kurosaki Toshikazu , Takahashi Osamu , Okawara Makoto 
Published: April 2003

AbstractPolymers having stable pendant . radicals were synthesized through their precursor polymers by oxidizing them in air or by H2O2–Na2WO4. Hydrochlorides and sulfates of 4‐methacryloylamino‐ and 4‐methacryloyloxy‐1‐hydroxy‐2,2,6,6‐tetramethylpiperidines were synthesized as precursor monomers and polymerized by using α,α′‐azobisisobutyronitrile under appropriate conditions to precursor polymers of high molecular weight: poly‐4‐methacryloylamino‐/oxy‐1‐hydroxy‐2,2,6,6‐tetramethylpiperidinehydrochlorides and sulfates. The precursor polymers were converted to polymers having nitroxyl stable radicals, i.e., poly‐4‐methacryloylamino‐/oxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyls, by oxidation in air or with H2O2–Na2WO4 without any main‐chain scission. The structure of the resultant stable radical polymers was determined by infrared, ultraviolet, and ESR spectroscopy. Based on the results of spectroscopic analysis and Kjeldahl analysis, the transformation from precursors to nitroxyl stable radical polymers was found to be quantitative. Investigations on the applicability of polymeric nitroxyl radicals to oxidation‐reduction reactions were attempted by means of polarography; the reduction half‐wave potential was found to be −1.16 V for the mercury pool.
Wetting properties of bis(trifluoromethyl)carbinyl acrylate polymers
Authors: Roitman James N. , Pittman Allen G. 
Published: April 2003

AbstractA series of bis(trifluoromethyl)carbinyl acrylate monomers [Y‐C(CF3)2 OCOCHCH2] in which Y is CH3, CH3CH2, CH3CH2CH2, CH3CH2CH2CH2, C6H5, H, F, CF3, N3, CN, and CH3OCH2CH2O, was prepared. Polymers were easily prepared from all of these monomers except where Y = CN, wherein a variety of initiation methods failed to produce high molecular polymer. Wettabilities of the polymer films were examined by means of contact angle measurements by using n‐alkane test liquids and water. Values of the dispersion force contribution (γsd) and the polar force contribution (γsp) to the solid surface energy were calculated by employing both geometric and harmonic mean approximations. Values of γsd calculated by either method agreed well with γc (critical surface tension) values determined graphically from contact angle data employing n‐alkane test liquids, confirming the suggestion that γc is an approximate measure of the dispersion force contribution to solid surface energy. Values of γsd ranged from 15 dyne/cm (Y = F or CF3) to 25 dyne/cm (Y = C6H5). Values of the polar force contribution to solid surface energy (γsp) varied from 0.6 dyne/cm (Y = CH3CH2CH2CH2) to 3.4 dyne/cm (Y = CH3OCH2CH2O) when calculated by the geometric mean equation. The values of γsp obtained from the harmonic mean equation followed the same trend upon varying substituents, but were larger in value, ranging from 2.9 dyne/cm (Y = CH3CH2CH2CH2) to 7.5 dyne/cm (Y γ CH3OCH2CH2O).
Synthesis and copolymerizations of 3,3‐difluorocyclobutene‐1‐carbonitrile
Authors: Hall H. K. , Okamoto Y. 
Published: April 2003

Abstract3,3‐Difluorocyclobutene‐1‐carbonitrile (DFCB) was synthesized via cycloaddition of 1‐chloro‐2,2‐difluoroethylene and acrylonitrile, followed by dehydrochlorination with 1,4‐diazabicyclo[2.2.2]octane in tetrahydrofuran. Unlike cyclobutene‐1‐carbonitrile, this monomer did not homopolymerize either under radical or anionic conditions. As an electron‐poor monomer it copolymerized in the presence of free radicals with electronrich monomers such as styrene in good yield. It also copolymerized with electron‐poor monomers such as acrylonitrile, although in lower yields. The extent of incorporation of DFCB in the copolymers also depended on the electronic characteristics of the comonomers: high incorporation occurred with electron‐rich monomers, low incorporation with electron‐poor monomers. One extremely electron‐poor monomer, trimethyl ethylenetricarboxylate, did not copolymerize with DFCB.
Intersequence cyclization in copolymers of N‐vinyl carbamates
Authors: Guilbault L. J. , Harwood H. James 
Published: April 2003

AbstractMonomer reactivity ratios determined for the copolymerization of tert‐butyl N‐vinylcarbamate (rA = 0.55 ± 0.05) with phenyl N‐vinylcarbamate (rB = 2.08 ± 0.15) indicate that the monomer units are distributed randomly along the polymer chains. The following sequence of reactions was used to cause intersequence cyclization between tert‐butyl N‐vinylcarbamate and phenyl N‐vinylcarbamate units in the copolymers. The extent of cyclization obtained was in accord with that expected for random copolymers.
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Solid‐state reactions of vinylpyridine coordination complexes. II
Authors: Agnew N. H. , Brown M. E. 
Published: April 2003

AbstractCrystals of the trans‐octahedral complex Co(4‐Vpy)4(NCS)2 on being heated below the melting point decompose with liberation of 4‐vinylpyridine (Vpy) and concurrent polymerization of the free monomer. The two reactions have been followed by differential scanning calorimetry, thermogravimetry, and optical microscopy. Polymerization is inhibited by inclusion of hydroquinone during recrystallization of the complex. This has allowed the kinetic analysis of the decomposition and polymerization to be simplified. Isothermal mass‐loss determinations under reduced pressure (10−2 torr), at various temperatures in the range 120–160°C, on hydroquinone‐inhibited crystals corresponded to the loss of up to three molecules of vinylpyridine per molecule of starting complex. With uninhibited crystals over the same temperature range the total number of ligands lost was approximately two with a marked decrease near 175°C owing to rapid polymerization. Isothermal decomposition curves for inhibited and uninhibited crystals approximated to the Avrami‐Erofeev equation. Values of n varied with temperature. Activation energies for decomposition and polymerization for both types of crystal were estimated from Arrhenius plots.
Heterogeneous reactions of singlet molecular oxygen with solid polymers
Authors: Breck A. K. , Taylor C. L. , Russell K. E. , Wan J. K. S. 
Published: April 2003

AbstractThe effect of gas‐phase singlet molecular oxygen (1ΔO2) upon several solid polymers was investigated by using electron paramagnetic resonance, infrared spectroscopy, and chemical detection techniques. The study was performed by use of 1ΔO2 produced by microwave discharge. The application of this method to polymer studies was closely examined. The saturated‐chain polymers polystyrene, polyurethane, and polyethylene were found to be inert within the experimental conditions to reaction with 1ΔO2, while the unsaturated polymers cis‐polybutadiene, trans‐polybutadiene, and trans‐polyisoprene were found to react quite readily in an apparently surface or near‐surface limited reaction to produce hydroperoxide and/or peroxide groups. The introduction by homogeneous mixing of some known metal‐chelate 1ΔO2 quenchers into the polymer trans‐polyisoprene appeared to significantly decrease the rate of oxidation observed.
Effects of structure on properties of some new aromatic‐aliphatic polybenzimidazoles
Authors: Tsur Yoel , Levine Harold H. , Levy Moshe 
Published: April 2003

AbstractPolybenzimidazoles were prepared in poly(phosphoric acid) from isophthalic, m‐ and p‐phenylene diacetic, succinic, adipic, suberic, and sebacic acids and 3,3′‐diaminobenzidine, 3,3′,4,4′‐tetraaminodiphenyl ether and 3,3′,4,4′‐tetraaminodiphenylmethane. The thermal, mechanical, and bonding properties were studied. A 3:1 copolymer of isophthalic and m‐phenylenediacetic acid with 3,3′‐diaminobenzidine showed the best results as far as isothermal oxidation resistance and thermal and processing characteristics.
Effect of temperature on the radiation‐induced polymerization of ethylene in various media
Authors: Wada Takeshi , Watanabe Terutaka , Takehisa Masaaki , Machi Sueo 
Published: April 2003

AbstractThe effects of temperature on the radiation‐induced polymerization of ethylene in bulk and in the presence of ethyl alcohol, n‐butyl alcohol, tert‐butyl alcohol, cyclohexane, 2,2,4‐trimethylpentane, and 2,2,5‐trimethylhexane were studied. The changes of the amounts of polymerized monomer with the reaction temperature were different from each other in these reaction systems, especially in the range lower than 60–80°C. At temperatures lower than 60–80°C, as the reaction temperature increases, the amount of polymerized monomer decreased in bulk and in the presence of tert‐butyl alcohol. The amount was almost constant in the presence of ethyl alcohol and 2,2,4‐trimethylpentane, and it increased in the presence of n‐butyl alcohol, cyclohexane, and 2,2,5‐trimethylhexane. However, in the temperature range higher than 60–80°C, the amount of polymerized monomer increased with increasing temperature in every reaction system except for bulk polymerization. The molecular weight of polymer decreased with increasing temperature in every reaction system except at temperatures lower than 25°C. The molecular weight of polymer formed in bulk, in tert‐butyl alcohol, and also in 2,2,4‐trimethylpentane were relatively higher than that in other reaction systems. A bimodal molecular weight distribution was observed for the polymer formed in bulk and in tert‐butyl alcohol at 40–60°C. These results are discussed in connection with the heterogeneity of the reaction system. The differences due to temperature in each reaction system are explained as due to the difference in affinity of the reaction system for the propagating chain and in the facility of chain transfer to the medium.
Electron spin resonance studies on radiation graft copolymerization. I. Grafting initiated by alkyl radicals trapped in irradiated polyethylene
Authors: Seguchi Tadao , Tamura Naoyuki 
Published: April 2003

AbstractThe behavior of trapped radicals in polyethylene which is irradiated in air at room temperature, under grafting of methylmechacrylate or butadiene has been studied by electron spin resonance. Part of the alkyl radicals are converted to allyl radicals by reaction with double bonds and the others disappear by recombination under vacuum. The active species of grafting are alkyl radicals when the vapor pressure of monomers is relatively high, while at low pressure allyl radicals also play a role as well as alkyl radicals. In the grafting at 20°C, the grafting yields depend mainly on the decay rate of alkyl radicals which come out of the crystalline regions of polyethylene. The decay rate of alkyl radicals and the rate of grafting at the initial stage increase with decreasing crystallite size of polyethylene.
Dilatometric constant for polymerization of α‐methylstyrene
Authors: Lowry George G. , Petiet John 
Published: April 2003

AbstractBy measurement of the specific volume of solutions of poly‐α‐methylstyrene in α‐methylstyrene monomer at 25°C, the dilatometric constant was found to be KD = (0.002007 ± 0.000030)%−1. Estimation of the temperature dependence resulted in the equation (KD)t = 1.81 × 10−3 + 7.82 + 10−6 t, where t denotes temperature in °C.
A basis for the determination of branching in polymers by use of gel‐permeation chromatography
Authors: Ambler M. R. , Mate R. D. , Purdon J. R. 
Published: April 2003

AbstractThe technique for determining branching in polymers by using a combination of GPC and intrinsic viscosity data has been extended beyond current methods. Equations used in these analyses are presented. The derivations are based upon the assumption that branching is present only when there is a measurable reduction in the intrinsic viscosity. Techniques for calculating the functionality of the star branch point in starbranched polymers are given. Three random‐branching parameters are calculated from a knowledge of the average branching density, \documentclass{article}\pagestyle{empty}\begin{document}$ \bar \lambda $\end{document}: (a) the lowest molecular weight branched polymer that can be measured, M̄*; (b) the average molecular weight between branch points, M̄bp; (c) the weight percentage of polymer that is branched. The applicability of this technique is demonstrated by using an analysis of published data on characterized fractions of a randomly branched polystyrene.