bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bridged polyaromatics: Synthesis, structure, and isomorphous properties of methyl‐substituted polymers containing CH2, O, and S bridges
Authors: Montaudo G. , Bruno G. , Maravigna P. , Bottino F. 
Published: April 2003

AbstractLinear, crystalline polymers corresponding to the general formulas
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where X is CH2, O, or S, were synthesized, and their isomorphous relationships were studied. The results point out that a close structural relationship exists within each series of compounds investigated.
Monte Carlo studies of nonstationary polymerization processes. I. Grafting of styrene onto preirradiated cellulose acetate
Authors: Yasukawa Tamio , Sasaki Yasunori , Murakami Kenkichi 
Published: April 2003

AbstractThe molecular weight distribution (MWD) of polystyrene grafted onto 4 Mrad‐preirradiated cellulose acetate at 50°C has been calculated on the basis of simulating reaction with several models. A model in which the coupling probability of graft radicals is proportional to the reciprocal of the square root of chain length and the growth rate is dispersed widely around the average value gave a MWD which agreed fairly well with observation. Several factors which affect the MWD of graft chains are also discussed on the basis of simulated reactions.
Application of Bender's salts to the synthesis of S‐vinyl‐O‐tert‐alkylthiocarbonates
Authors: Daly W. H. , Lee Chien‐Da S. 
Published: April 2003

AbstractThree thermally labile Bender's salts were synthesized and utilized to effect quantitative SN2 displacement of primary halides to form tert‐alkylthiocarbonate derivatives. Selective displacement of bromide from 1,2‐bromochloroethane by either VI or VII followed by dehydrohalogenation with potassium tert‐butoxide yielded S‐vinyl‐O‐tert‐butylthiocarbonate (I) and S‐vinyl‐O‐tert‐amylthiocarbonate (X), two excellent vinyl monomer precursors for polymercaptan, in 62 and 51% yield, respectively. Reaction of VI with vinylbenzyl chloride yielded S‐(vinylbenzyl)‐O‐tert‐butylthiocarbonate which polymerized in the presence of free radical initiators to produce a poly(vinylbenzyl mercaptan) precursor. Dilatometric studies of the homopolymerization of I demonstrated that the polymerization rate was proportional to [I]0.765 and [M]1.7, respectively; the monomer exhibited a high chain transfer constant (CM = 3.9 × 10−3).
NMR and ESR studies of the solid‐state polymerization of vinyl monomers. III. Methacrylic acid
Authors: Chachaty C. , Latimier M. , Forchioni A. 
Published: April 2003

AbstractThe kinetics of postpolymerization of γ‐irradiated methacrylic acid at 77°K has been investigated by wide‐line NMR and by ESR spectroscopy. The conversion yield was continuously measured in the temperature range of 260–280°K, from the narrowing of the NMR spectrum due to the progressive “amorphization” of the matrix, releasing the motion of monomer molecules. The rate of postpolymerization decays exponentially with time, independently of the recombination of free radicals. The local concentration of radicals remaining after prolonged annealing is actually the same as initially, showing that no recombination occurs in the microdomains of polymerization. The 13C NMR study of the poly(methacrylic acid) formed by solid‐state polymerization shows a predominent syndiotactic character, with an increasing contribution of isotactic sequences as the postpolymerization temperature is lowered.
Stress–strain relations of crosslinked rubbers under different types of strain
Authors: Bartenev G. M. , Nikiforov V. P. 
Published: April 2003

AbstractExperimental data for the stresses and the deformations for crosslinked rubbers at uniaxial and symmetrical and asymmetrical biaxial extension and pure shear are given. Stressed states up to 100% extension are described by a single parameter, the highly elastic potential of Bartenev and Khazanovich. The classical statistical potential of Kuhn‐James‐Guth‐Treloar is not in agreement with experimental data, as shear modulus G has different values for different types of stressed states.
Synthesis and polymerization of allyloxyacetaldehyde
Authors: Sumitomo Hiroshi , Hashimoto Kazuhiko , Kitao Osamu 
Published: April 2003

AbstractAllyloxyacetaldehyde (AOA) was synthesized by the Williamson reaction between sodium allyl alcoholate and bromoacetaldehyde dimethyl acetal. Highly reactive crystalline poly(allyloxymethyl)oxymethylene was obtained from AOA by using organoaluminum compounds as initiators at low temperature. The influence of initiators, solvents, and temperature on the polymerization was examined. Conspicuous exothermal behavior of the resulting polymer observed in the temperature range of 110–140°C in air with a differential scanning calorimeter, was not only due to an oxidative scission of the polyoxymethylene chain but also due to a chain reaction of neighboring allyl side groups in the polymer chain.
Synthesis of polyimides from N,N′‐bis(phenylsulfonyl)pyromellitimide and aromatic diamines
Authors: Imai Yoshio , Ishimori Motokazu 
Published: April 2003

AbstractA novel and successful synthesis of polyimide has been performed by the two‐step polymerization of N,N′‐bis(phenylsulfonyl)pyromellitimide (BPSP) and bis(4‐aminophenyl) ether (ODA). The ring‐opening polyaddition reaction proceeded in N‐methyl‐2‐pyrrolidone at room temperature through the formation of the open‐chain polyamide, which was subsequently converted by heating to the polyimide along with the elimination of benzenesulfonamide. The polymerization of BPSP with ODA took place fairly rapidly to give the polyamide having inherent viscosity in the range of 0.6–0.8. The polyamide solution was resistant to hydrolysis, but was somewhat susceptible to imidization reaction. The thermal imidization of the open‐chain polyamide occurred far more readily than that of the polyamic acid derived from pyromellitic dianhydride and ODA.
Temperature dependence on the binding of butyl orange by bovine serum albumin: The effect of urea
Authors: Takagishi Toru , Takami Katsushige , Kuroki Nobuhiko 
Published: April 2003

AbstractThe effect of urea on the extent of the binding of butyl orange by bovine serum albumin has been examined by an equilibrium dialysis method. The first binding constants and the thermodynamic parameters for the formation of the first dye anion–protein complex have been calculated. Addition of urea to the binding system causes a marked decrease in the absolute magnitude of the free energy change. The enthalpy change during binding becomes more exothermic, and the entropy change tends to decrease with increasing concentration of urea. These results can be interpreted in terms of the concept that urea reduces the structure of the aqueous environment and hence lowers the tendency of apolar groups of the dye and the albumin to participate in the formation of hydrophobic interactions.
Calorimetric investigation of polymerization reactions. V. Crosslinked copolymerization of methyl methacrylate with ethylene dimethacrylate
Authors: Horie Kazuyuki , Otagawa Atsushi , Muraoka Minoru , Mita Itaru 
Published: April 2003

AbstractThe crosslinked copolymerization of methyl methacrylate with ethylene dimethacrylate (EDMA) in bulk and in toluene has been investigated by differential scanning calorimetry. The appearance of a second peak, in addition to that arising from the gel effect, noted in curves of bulk copolymerization rate (fraction of EDMA mE = 0.20) is explained by the formation of microgels during the copolymerization. With mE = 0.50–1.00, copolymerization proceeds heterogeneously at first, providing opaque microgels, which become transparent polymer in a later stage at a weight fraction of toluene wT ≦ 0.20 and independent polymer particles at wT ≧ 0.30. A diagram is given which illustrates three types of copolymerization depending on initial composition of monomers and toluene. Final conversions for mE ≦ 0.10 agree well with predictions. Copolymerization at mE ≧ 0.20 ceases because of reduction of segmental mobility due to dense network formation in microgel, though the whole system is not yet in glassy state. Data of final conversions in solution copolymerization also support the above mechanism.
Initiated oxidation of solid polystyrene and the effect of antioxidants on this process
Authors: Pokholok T. V. , Karpukhin O. N. , Shlyapintokh V. Ya. 
Published: April 2003

AbstractThe paper is concerned with the kinetics of radical conversions in solid polystyrene (PS) induced by decomposition of free‐radical initiators over the temperature range of 60–90°C. A complex quantitative study of PS oxidation was carried out. The kinetics of initiator decomposition and of hydroperoxide accumulation, the variations in chemiluminescence (CL) intensity accompanying polymer oxidation were studied. The CL spectrum and the changes in molecular weight in the course of oxidation were measured. A method for determination of the relative antiradical activity of antioxidants, based on the competition between the antioxidant and the stable radical for the active radical was proposed. The activity of valence‐saturated antioxidants in the solid phase was found to become more uniform compared to the liquid phase, whereas that of stable nitroxide radicals was abnormally high. Initiated solid PS oxidation occurred by a chain mechanism with formally linear termination of the chain. The chain length of 3.0 ± 0.5 was independent of temperature. A model of initiated PS oxidation is proposed. It implies structural inhomogeneity of the sample, resulting in different probabilities of radical formation in the polymer bulk in the course of initiator decomposition in various sample zones. The model permits quantitative description of the kinetics of hydroperoxide accumulation, stable radical consumption, and of variations in CL intensity during initiated and inhibited PS oxidation.
Pyrolsis of a flexible urethane foam
Authors: Hileman F. D. , Voorhees K. J. , Wojcik L. H. , Birky M. M. , Ryan P. W. , Einhorn I. N. 
Published: April 2003

AbstractPyrolysis of a commercial flexible urethane foam in an inert atmosphere was investigated by use of GCMS and chemical ionization mass spectroscopy. Pyrolysis products were identified and quantified at four pyrolysis temperatures. A mechanism is discussed in terms of the identified products.
Polymer combustion
Authors: Stuetz D. E. , Diedwardo A. H. , Zitomer F. , Barnes B. P. 
Published: April 2003

AbstractExperimental conditions have been defined for the steady‐state combustion of vertically positioned polymer rods burning at the top surface. Temperature and composition profiles through solid and gas phases of the system, polymer consumption rate, and flame height were measured, and the response of these parameters to changes of the oxygen concentration in the environment were determined. Measurements showed that unreacted oxygen diffused from the environment to the burning surface and was absorbed into the polymer, forming a well defined oxygen‐rich layer. Concentration of chemically bound oxygen at the surface of this layer were high, e.g., with polypropylene ca. 26 wt‐%, and identical with the stoichiometry of the gases leaving the surface and serving as fuel for the flame. The composition of the gas phase at the surface indicated the conversion of 11.4% of the hydrocarbon fuel to CO, CO2, and H2O. An energy balance for the system confirmed that fuel production in this surface layer takes place via simultaneous oxidative and pyrolytic degradation of the polymer, with exothermic processes supplying the energy for endothermic processes. Conductive and radiative contributions from the gas phase were found to play a minor role in maintaining fuel formation. The rate of degradation of a polymer to fuel, normalized to the area of the burning surface, was found to be independent of polymer supply rate and to increase with the oxygen concentration in the environment. The degradation process was successfully modeled in TGA experiments at temperatures and oxygen concentrations representative of the burning surface. The existence of an oxidative surface layer was confirmed and the TGA degradation rate related to the surface‐to‐volume ratio of the polymer sample. Compositional analysis of a methane diffusion flame of a geometry identical to that of the polymer flame, revealed the presence of unreacted oxygen throughout the preheating zone and at the surface of the burner. Conversion of fuel to final combustion products at the surface was 6.3%. Temperature and composition changes as a function of oxygen concentration in the environment were determined and compared with the polymer diffusion flame. It was concluded that a polymer flame, because of its autogenerative fuel production, possesses only one degree of freedom, viz., the oxygen concentration in the environment, in contrast to the conventionally fueled diffusion flame for which fuel supply rate is an additional independent parameter. Due to this single degree of freedom, the sensitivity of the polymer flame to environmental influences is increased. Effects caused by these extrinsic factors will be the subject of a separate report.
Crystallizability and thermal properties of phosphorus‐containing polyamides
Authors: Shalaby S. W. , Turi E. A. , Riggi M. H. , Harget P. J. 
Published: April 2003

AbstractBis(2‐carb‐n‐butoxyethyl)methylphosphine oxide was prepared and condensed with 1,2‐diaminoethane, 1,6‐diaminohexane, 1,8‐diaminooctane, 1,10‐diaminodecane, and 1,12‐diaminododecane to form polyamides with an increasing number of methylene groups between the amide moieties. Polyamides made from the 1,10‐ and 1,12‐diaminoalkanes were shown by x‐ray and DSC to be semicrystalline, while those based on the 1,6‐ and 1,8‐diaminoalkanes were amorphous to x‐ray and revealed no first‐order transitions. The repeat distances of the crystalline polymers were determined, and an extended planar zigzag conformation was excluded as a possible conformation for these polymers. The thermal stability of the phosphorus‐containing polyamides, in both oxygen and nitrogen, was studied by TGA and the results were correlated with the chemical structure.
2‐Hydroxy‐3‐ionene chloride
Authors: Noren G. K. 
Published: April 2003

AbstractThe condensation of dimethylamine with epichlorohydrin gave an almost quantitative yield of 2‐hydroxy‐3‐dimethylaminopropyl chloride which was polymerized via the Menschutkin reaction to give 2‐hydroxy‐3‐ionene chloride. This cationically charged polymer was obtained in greater than 90% yields as a white to tan solid when precipitated into acetone. Number‐average molecular weights of up to 10,000 and intrinsic viscosities of up to 0.11 dl/g in 0.4M potassium bromide were found. These low molecular weights were attributed to several impurities that were identified as being produced by side reactions. Thermal analysis of the polymers showed an endothermic transition at 32–39°C with the onset of decomposition occuring at about 200°C.
Thermal and photo‐induced phenomena in γ‐irradiated poly(methyl methacrylate)
Authors: Torikai Ayako , Asai Toshihiro , Suzuki Toshio , Kuri Zen‐Ichiro 
Published: April 2003

AbstractESR spectra and optical absorption spectra of γ‐irradiated poly(methyl methacrylate) (PMMA) at 77°K and the photo‐ and thermal bleaching behavior have been studied. γ‐Irradiation of PMMA yields a singles spectrum with a line width of 6 G which is bleachable with visible light. This species is assigned to the polymer cation. The unbleached species consists mainly of a four‐line spectrum and is assigned to a polymer radical having a different CH2 conformation from the usual nine‐line spectrum. On subsequent warming to room temperature, the spectrum changes into the nine‐line spectrum. γ‐Irradiation of PMMA containing biphenyl as an additive at 77°K gives biphenyl cation. Yield of polymer radical is reduced by the addition of biphenyl and 2‐methyltetrahydrofuran. A mechanism is proposed which is consistent with the experimental results.
Polyfluoroethers from 2,2,3,3,4,4‐hexafluoropentanediol and bis(chloromethyl) ether and bishalomethyl‐substituted aromatic compounds
Authors: Johncock Peter , Hewins Maurice A. H. 
Published: April 2003

AbstractThe polyfluoroethers \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm \rlap{--}[OCH}_{\rm 2} {\rm XCH}_{\rm 2} {\rm OCH}_{\rm 2} ({\rm CF}_{\rm 2} )_3 {\rm CH}_{\rm 2} \rlap{--} ]_n $\end{document} (X = O, 1,3‐C6H4, 1,4‐C6H4 or 4,4′‐C6H4OC6H4) and copolymers (X = 1,3‐ and 1,4‐C6H4) having inherent viscosities in acetone >0.5 dl/g were prepared in good yields by treatment of the mixture of sodium salts obtained from 2,2,3,3,4,4‐hexafluoropentanediol and an excess of sodium hydride in tetramethylene sulfone (TMS)‐tetrahydrofuran or TMS‐petroleum ether with the appropriate bishalomethyl compound. The polymers varied from highly extensile elastomeric gums when X = O or 1,3‐C6H4 to a leathery material when X = 4,4′‐C6H4−OC6H4. Glass transition temperatures ranged from ‐43°C when X = 0 to 6°C when X = 4,4′‐C6H4OC6H4. The polymers started to lose weight (by thermogravimetry) at 220–250°C in oxygen and at 250–290°C in nitrogen. However, the xylylene polymers underwent structural changes even at room temperature, as reflected by changes in solution viscosity. Attempts to cure the polymer when X = O with peroxides were unsuccessful.
Effect of copolymers of 4(5)‐vinylimidazole and quaternary imidazolium salts on the hydrolysis rates of charged and neutral esters. II
Authors: Overberger C. G. , Pacansky T. J. 
Published: April 2003

AbstractThe effects of copolymeric catalysts containing hydrophobic binding sites (quaternary imidazolium salts) and catalytically active nucleophilic sites (imidazole) on the hydrolysis of long‐chain anionic esters were investigated. The quaternary imidazolium salt groups contained hydrocarbon chains of varying length. Their solubility relationships and viscosity measurements followed a trend governed by the hydrocarbon chain length of the quaternary imidazolium salt. These investigations revealed that increasing the hydrocarbon chain length of the quaternary imidazole groups along the copolymer chain or the chain length of the ester substrate resulted in an increase of the catalytic rate of ester hydrolysis. Increasing the ethanol content decreased the catalytic activity and greatly reduced the apolar binding between the catalyst and substrate. For the cases of low ethanol content and high chain length of the substrate, the ester hydrolysis reactions in the presence of the copolymeric catalysts preceeded by a Michaelis‐Menten kinetic scheme.
Formation of free radicals in photoirradiated cellulose. II. Effect of moisture
Authors: Hon Nyok‐Sai 
Published: April 2003

AbstractThe effect of moisture content upon free radical formation in celluloses irradiated with ultraviolet light has been studied by means of ESR spectroscopy at 77°K. As studied from the variation of the line‐shape and the relative signal intensity of the spectra observed, it is clear that moisture content in the sample greatly influences the formation of free radicals when irradiated with ultraviolet light. The moisture content in the range of 5–7% leads to a significant decrease of radical formation; and alternatively, when moisture content is lower or higher than this range, the formation of free radicals is increased.
Enhancement of stereospecificity in isoprene polymerization with alkylaluminum–titanium chloride catalysts through use of carbon disulfide
Authors: Perry Dale C. , Farson Frank S. , Schoenberg Emanuel 
Published: April 2003

AbstractThe effect of CS2 on isoprene polymerization with triisobutylaluminum‐titanium tetrachloride catalysts was studied at Al/Ti ratios of optimum (0.9) and higher values. In the absence of CS2, appreciable amounts of low molecular weight oils (“extractables”) were formed at the expense of cis‐1,4‐polyisoprene with higher than optimum Al/Ti ratios. Small amounts of CS2 were found to prevent extractables formation and allow attainment of higher yields of cis‐1,4‐polyisoprene. The optimum CS2/Ti chloride molar ratio (0.1) was independent of the Al/Ti ratio of the catalyst. Polymer microstructure and dilute solution viscosity were unaffected by CS2. The results support the theory that the catalyst surfaces hold two types of active sites: p‐sites, which initiate polymerization, and o‐sites, which lead to oligomerization. CS2 appears to enhance polymerization by coordinating selectively at the o‐sites. The predominance of oligomerization at the higher Al/Ti ratios was attributed to a destruction of p‐sites by excess trialkyl‐aluminum.
Aromatic polyethers, polysulfones, and polyketones as laminating resins. IV. Polymers with p‐cyclophane units for crosslinking
Authors: Sivaramakrishnan K. P. , Samyn C. , Westerman Ira John , Wong Daniel Ting‐Man , Marvel C. S. 
Published: April 2003

Abstract1,3‐Bis(p‐phenoxybenzenesulfonyl)benzene, 4,4′‐bis(p‐phenoxybenzenesulfonyl)diphenyl ether, and 4,4′‐diphenoxydiphenyl sulfone were polymerized with isophthaloyl or terephthaloyl chlorides in Friedel‐Crafts type polymerizations. These polymers had [2,2]p‐cyclophane units in the backbone, introduced by employing 3,9‐bis(p‐phenoxybenzoyl) [2.2]p‐cyclophane as part of the polyaryl ether component. Thermolysis of the dimethylene bridge of the [2.2]p‐cyclophane monomer produced diradicals which combined across polymer chains to provide crosslinks. p‐Cyclophane polymers with 1,3‐bis‐(p‐phenoxybenzenesulfonyl)benzene showed potential as high performance, thermally stable laminating resins.
Aromatic polyethers, polysulfones, and polyketones as laminating resins. V. Polymers containing acetylenic side groups
Authors: Samyn C. , Marvel C. S. 
Published: April 2003

Abstract1,3‐Bis(p‐phenoxybenzenesulfonyl)benzene and 4,4′‐diphenoxydiphenyl sulfone were polymerized with isophthaloyl and terephthaloyl chloride in Friedel‐Crafts type polymerizations. These polymers had 2,4‐diphenoxyacetophenone in the backbone. The acetyl group was then converted into an acetylene group. They were crosslinked effectively by cyclization of the acetylene groups with a catalyst or by cyclo‐addition with bisnitrile oxides.
Synthesis and characterization of poly‐n‐alkylmalonamides: Formation of a partially disordered layer structure
Authors: Corradini P. , Lanzetta N. , Maglio G. , Palumbo R. , Riva F. 
Published: April 2003

AbstractPolyamides from n‐alkylmalonic acids and linear aliphatic diamines, with paraffinic side chains of 3–18 carbon atoms, were prepared by melt polycondensation or by low‐temperature interfacial polycondensation and were characterized by infrared, differential scanning calorimetry (DSC), and x‐ray diffraction techniques. First‐order transitions were found in the range of 130–210°C, depending on the number of carbon atoms in the side chain. The x‐ray diffraction indicated substantially amorphous systems for polyamides with 8–18 carbon atoms in the side chain. However, long‐range order arises in these polymers from a solid‐state structure in which polyamide and hydrocarbon layers having partially disordered chain conformations alternate.
Synthesis and polymerization of optically active trans‐(R)(–)‐5‐phenyl‐1,3‐hexadiene and trans‐(R)(–)‐6‐phenyl‐1,3‐heptadiene
Authors: Radovanović‐Kiprijanova R. , Fleš D. 
Published: April 2003

AbstractThe monomers trans‐(R)(–)‐5‐phenyl‐1,3‐hexadiene (I) and trans‐(R)(–)‐6‐phenyl‐1,3‐heptadiene (II) were prepared by dehydration of (R)(–)‐3‐acetoxy‐5‐phenyl‐1‐hexene and (R)(–)‐3‐acetoxy‐6‐phenyl‐1‐heptene, respectively. Monomers I and II were polymerized in heptane with three catalyst systems: γ‐TiCl3–Al(i‐Bu)3, VCl3–Alet3, and nBuLi. Polymers of identical structures were obtained with all three catalysts; according to infrared and NMR spectra, only the 1,4 structure was present. Acetone‐insoluble fractions of poly‐I and poly‐II have higher optical rotations than the corresponding monomers ([M]D of poly‐I, ‐46.45°, of monomer I, ‐28.6°: [M]D of poly‐II, ‐46.8°, of monomer II, ‐32.55°). There is no difference in the rotation of poly‐I and poly‐II.