bluuebunny/crossref_metadata_2025_split huggingface dataset:
13C NMR spectroscopic study of epoxidized 1,4‐polyisoprene and 1,4‐polybutadiene
Authors: Gemmer Robert V. , Golub Morton A. 
Published: April 2003

AbstractPartly epoxidized cis‐ and trans‐1,4‐polyisoprenes and cis‐and trans‐1,4‐polybutadienes were prepared, and their 13C NMR spectra examined. All the prominent resonances in the spectra of the epoxidized polymers were assigned by using lanthanide shift reagent and off‐resonance decoupling experiments. A 13C NMR method of quantitative assessment of the epoxide content was developed following determination of relative spin‐lattice relaxation time (T1) and nuclear Overhauser effect (NOE) parameters of the various carbons in the epoxidized polyisoprenes and polybutadienes.
Radical block polymerization of vinyl chloride. III. Physical properties and morphology of block copolymers of PVC
Authors: Overbergh N. , Weinand G. , Smets G. 
Published: April 2003

AbstractSome physical properties of the block copolymers with PVC, described in Parts I and II, are discussed. The effect of chemical composition, molecular architecture, and film preparation conditions on their two‐phase structure is shown. Especially in the case of high PVC content, the morphological aspect is largely influenced by the molecular architecture—pronged‐fork polymer chains—and the nature of the solvent for casting. The incorporation of rubbery poly(alkyl acrylate) particles in the PVC matrix leads to an interesting stress–strain behavior. A relation between this behavior and the morphology is established.
Thermal degradation studies of PVC with time‐resolved pyrolysis GC and derivative TGA
Authors: Liebman S. A. , Ahlstrom D. H. , Foltz C. R. 
Published: April 2003

AbstractThis thermal degradation study reports the application of “time‐resolved” pyrolysis gas chromatography (PGC) in addition to derivative thermogravimetric analysis (DTGA) to a series of PVC homopolymers with differing branch content and to a model copolymer series with low amounts of propylene in an otherwise vinyl chloride chain. Benzene and toluene generation and decay envelopes were determined during the controlled thermal degradation and related to the derivative TGA experiments. These data allowed interpretation as to the microstructure of the respective polymers and its effect on the degradative pathways. It was concluded that the branch content was not a dominant factor in the initiation of thermal degradation, although it was a factor in other stages of the complex mechanism. A unique fragmentation step was noted only under oxidative thermal exposures, which gave additional support for the theory of low‐level unsaturation sites as being significant triggers in the decomposition mechanism.
Chemical stability and electroconductivity of 7,7,8,8‐tetracyanoquinodimethane salts containing polycation polymers
Authors: Mizoguchi Katsuhiro , Tsuji Shoichi , Tsuchida Eishun , Shinohara Isao 
Published: April 2003

AbstractThe chemical and electrical stabilities of 7,7,8,8‐tetracyanoquinodimethane (TCNQ) salts composed of neutral TCNQ (TCNQˆ), anion radicals of TCNQ(TCNQ−·), and polycation polymers were studied by measuring their electronic spectra and resistivities (ρ). The results of spectral and chemical analyses confirmed that TCNQ−· in TCNQ salts was decomposed to α,α‐dicyano‐p‐toluoylcyanide (DTC−) as the final product by the intermediate formation of TCNQˆandp‐phenylenediamalononitrile (H2TCNQ) and that H2O played an important part in the reaction. From these results it was concluded that TCNQ salts are decomposed by two reaction processes:The resistivity of TCNQ salts increases with the decomposition of TCNQ−·. Studies on electroconductivity of TCNQ salts assume that the change in resistivity arises from the loss of unpaired electrons which become conduction carriers and also from the disintegration of the TCNQˆand TCNQ−· complex which forms the conduction path.
Emulsifier‐free emulsion polymerization of tetrafluoroethylene by radiation. II. Effects of reaction conditions on polymer particle size and number
Authors: Suwa Takeshi , Watanabe Terutaka , Seguchi Tadao , Okamoto Jiro , Machi Sueo 
Published: April 2003

AbstractThe size, distribution, and number of PTFE particles formed by radiation‐induced emulsifier‐free polymerization were measured by electron microscope and automatic particle analyzer (centrifugation method). From the electron micrographs we found that the particles are formed within 5 min. The change in the number of polymer particles (np) with reaction time (t) depends on the relative concentration of growing polymer chains to stabilizing species produced by the radiolysis of water and monomer; that is, it was governed by TFE pressure/dose rate ratio and classified into three cases: case I, dnp/dt = 0 (e.g., at 3 × 104 rad/hr and 20 kg/cm2); case II, dnp/dt < 0 (e.g., at dose rate below 1.9 × 104 rad/hr and 20 kg/cm2); case III, dnp/dt > 0 (e.g., at 3 × 104 rad/hr and 2 kg/cm2). The polymer molecular weight above 106 is almost independent of the particle size. The polymerization loci are mainly on the surface of polymer particles dispersed in the aqueous phase in cases I and II except in the initial stage. In case III new particles are formed successively during polymerization. Therefore the polymerization loci are mainly in the aqueous phase. Especially in case I, we concluded that after the generation of particles the propagation proceeds mainly on the surface of polymer particles like the core shell model proposed by Granico and Williams.
1H‐NMR spectra of poly(ethylene glycols) in the presence of shift reagent
Authors: Okada Tadashi 
Published: April 2003

AbstractTo determine the content of trans‐gauche‐trans (TGT) conformation in poly(ethylene glycol) (PEG) 1H‐NMR spectra were measured with tris(1,1,1,2,2,3,3‐heptafluoro‐7,7‐dimethyl‐1,4,6‐octanedinato)europium(III) [Eu(fod)3] as a shift reagent. As a result the peaks assigned to the ethylene protons in the polymeric segments separated from those assigned to four ethylene protons as the “near‐end” groups, and the singlet peak in the former at the lowest field was assigned to the TGT conformation of the COCCOC sequence. It was confirmed that the conformation of the polymeric segments in PEG complexed with Eu(fod)3 remained unchanged with benzene‐d6 content as the solvent. The concentration of TGT conformation increased with the number‐average molecular weight (Mn): it increased rapidly until about 70% at Mn = 1500.
Effect of structure on properties of aromatic‐aliphatic polybenzimidazoles. II
Authors: Varma I. K. , Veena  
Published: April 2003

AbstractPolybenzimidazoles (PBI) with p‐phenylene and/or cis‐vinylene groups in the backbone were prepared from terephthalic acid (T), maleic acid (M), and 3,3′ diamino‐benzidine tetrahydrochloride dihydrate (DAB) in poly(phosphoric acid) (PPA). Five polymer samples were prepared by varying the M:T molar ratios in the following order: 1:0, 1:1, 2:1, 1:2, and 1:4. The polymers were characterized by intrinsic viscosity, density, electronic fluorescence, and IR spectra. The effect of composition on the solubility of the polymers in various organic solvents was also investigated. The relative thermal stability of the polymers was evaluated by dynamic thermogravimetry in air and polybenzimidazoles (PBI) with cis‐vinylene groups were found to be less stable.
Ferrocene‐containing polymers. I. Radiation‐induced polymerization of ferrocenylmethyl methacrylate
Authors: Tsubakiyama Kyoji , Matsuo Togoro , Sasaki Takashi , Yoshida Kenzo , Fujimura Takashi , Araki Kunio 
Published: April 2003

Abstractγ‐Ray‐induced polymerizations of ferrocenylmethyl methacrylate (FMMA) in crystalline and amorphous states were investigated with kinetical and ESR methods. In the crystalline state the polymerization of FMMA proceeded slowly and gave low‐molecular‐weight polymers, whereas in the amorphous state it proceeded rapidly and gave polymers of much higher molecular weight. Molecular weight distributions of these polymers were binodal. The temperature dependence and the dose‐rate dependence of the polymerization rates were different between the two states. Wide‐line nuclear magnetic resonance (NMR) spectra of the amorphous monomer suggested that the polymerization proceeded in a supercooled state. Electron spin resonance (ESR) spectra of γ‐irradiated FMMA and 1,1′‐ferrocenyl‐di(methyl methacrylate) showed that ferrocene radicals and methacrylic radicals were formed simultaneously at low temperature; with increasing temperature the former radicals disappeared, whereas the latter changed into growing chain radicals. The yields of radicals were relatively low; this means that ferrocene groups in the monomers behave as a radiation energy absorber.
Ring retention in the homopolymerization of cyclic olefins by rhenium olefin metathesis catalysts
Authors: Tsonis Christos , Farona Michael F. 
Published: April 2003

AbstractThe homogeneous catalyst system, Re(CO)5Cl/C2H5AlCl2, was found to promote the homopolymerization of cyclic olefins containing 5‐, 6‐, 7‐, and 8‐member rings to low‐molecular‐weight materials. The final compounds, which polymerize only at elevated temperatures, were found by nuclear magnetic resonance (NMR) and infrared (IR) studies to be totally saturated systems. Various bands in the IR spectra indicate that the ring systems are preserved and that the final products are made up of repeating 1,2‐, or a combination of 1,2‐ and isomerized single‐bond units. Although the active catalyst initially contains a coordinated carbene, a mechanism similar to that of polymerization by a Ziegler—Natta catalyst is proposed.
Thermal decomposition of poly(butylene terephthalate)
Authors: Lum Richard M. 
Published: April 2003

AbstractDetailed results of the overall thermal degradation of poly(butylene terephthalate) are reported. Laser microprobe analysis and dynamic mass spectrometric techniques were used to identify the primary volatile degradation products and initial pyrolysis reactions that control polymer degradation. A complex multistage decomposition mechanism was observed which involves two major reaction pathways. Initial degradation occurs by an ionic decomposition process that results in the evolution of tetrahydrofuran. This is followed by concerted ester pyrolysis reactions that involve an intermediate cyclic transition state and yield 1,3‐butadiene. Simultaneous decarboxylation reactions occur in both decomposition regimes. Finally, the latter stages of polymer decomposition were characterized by evolution of CO and complex aromatic species such as toluene, benzoic acid, and terephthalic acid. Activation energies of formation for the main pyrolysis products were determined from the dynamic measurements of the major ion species and indicate values of E = 27.9 kcal/mole for the production of tetrahydrofuran and E = 49.7 kcal/mole for the production of butadiene.
Copolymerization of carbon disulfide and N‐(β‐cyanoethyl)ethylenimine
Authors: Soga Kazuo , Hattori Iwakazu , Sato Masaru , Ikeda Sakuji 
Published: April 2003

AbstractIt was found that carbon disulfide copolymerizes with N‐(β‐cyanoethyl) ethylenimine by using water as a catalyst. The copolymerization was conducted in detail by using water as a catalyst in the temperature range between 0 and 50°C with various initial concentrations of carbon disulfide and N‐(β‐cyanoethyl)ethylenimine in the absence of solvent. The copolymer obtained was always composed of the two monomers: 1:1 ratio, independent of the initial concentration of the monomers. The copolymer was white solid material soluble in dimethyl sulfoxide, insoluble in other usual organic solvents and decomposed at 155°C. Spectroscopic analysis of the copolymer combined with the results of elemental analysis indicates that the copolymer had the following structure:
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Photocrosslinking of poly(methyl acrylate)s containing the 1,3‐dioxolane structure as a pendant group
Authors: Nakashima Yoshihiro , Fukuda Hiroyuki 
Published: April 2003

Abstract(2‐Ethyl‐2‐methyl‐1,3‐dioxolan‐4‐yl)methyl‐ and (2‐methyl‐2‐phenyl‐1,3‐dioxolan‐4‐yl) methyl acrylates were synthesized and polymerized. The photochemical behavior of the resulting polymers was investigated to determine whether the polymers pending on the 1,3‐dioxolane structure were readily crosslinked with ultraviolet (UV) irradiation. The degree of crosslinking was estimated by the weight‐loss method by immersion in acetone, with the result that the polymer with an aromatic substituent was more photocrosslinkable than the polymer that bore the aliphatic substituent. The catalytic effect on photocrosslinking of polymers was also studied by using benzoin and cobalt naphthenate. The infrared (IR) spectra of polymers irradiated in air that showed the new band at 3450 cm−1 were attributed to a hydroxyl group; however, the spectra of polymers irradiated in vacuum displayed little absorption at 3450 cm−1. To explain the mechanism of crosslinking model compounds were prepared and irradiated with UV light. It was concluded that crosslinking proceeds mainly from the fission of the 1,3‐dioxolane ring and the coupling of the yielding radicals, together with autooxidation by atmospheric oxygen.
A new organic semiconducting polymer from Cu2+ chelate of poly(vinyl alcohol)and iodine
Authors: Higashi Fukuji , Cho Chong Su , Kakinoki Hideo , Sumita Osao 
Published: April 2003

AbstractA new, easily processed, organic semiconductor was prepared from poly(vinyl alcohol) (PVA). The Cu2+ chelate of PVA exhibited excellent surface resistivity around 103 Ω cm−2 when modified with iodine. Favorable conditions for preparing the chelate effective for the conduction were investigated. The resistivity was significantly affected by the amounts of cupric salts and iodine, satisfactory results being given by more than 15 wt% of cupric salts and about 4 wt% of iodine. Effects of molecular weight of PVA and the chelate structure were also studied.
Vinyl polymerization. 361. Polymerization of 2,2,4‐trimethyl‐3‐on‐1‐pentyl methacrylate
Authors: Ouchi Tatsuro , Arita Yoshitaka , Imoto Minoru 
Published: April 2003

Abstract2,2,4‐Trimethyl‐3‐on‐1‐pentyl methacrylate (TMPM) was first synthesized from the condensation reaction of 2,2,4‐trimethyl‐1‐pentanol‐3‐on with methacrylic acid. Second, the polymerization of TMPM and the copolymerization of TMPM with styrene (St) were carried out in benzene at 60°C, using 2,2′‐azobisisobutyronitrile (AIBN) as an initiator. As the result of kinetic investigation, the rate of polymerization (Rp) could be expressed by: Rp = k[AIBN]0.5 [TMPM]1.0. Kinetic constants of polymerization of TMPM were obtained as follows: kp/k = 0.27 dm3/2 mole−1/2 sec−1/2, 2fkd = 1.23 × 10−5 sec−1, f = 0.73, Cm = 2.6 × 10−5, Cs = 1.1 × 10−5. From the results the reactivity of TMPM was found to be larger than that of methyl methacrylate. The overall activation energy was calculated to be 110 kJ mole−1. The following monomer reactivity ratios and Q, e values were obtained: TMPM(M1) − St(M2): r1 = 1.50, r2 = 0.14, Q1 = 2.63, E1 = 0.45.
Effect of amount of monomer on radiation‐induced polymerization of styrene adsorbed on silica gel
Authors: Kusama Yasuo , Udagawa Akira , Takehisa Masaaki 
Published: April 2003

AbstractThe effect of amount of monomer on radiation‐induced polymerization of styrene adsorbed on silica gel was investigated with the monomer amounting from less than monolayer adsorption to more than the equilibrium adsorption. The rate of graft polymerization and the molecular weight of the polymer changed with the amount of monomer adsorbed on silica gel. Maximum grafting efficiency was obtained at monolayer adsorption. The molecular weight of graft polymer was higher than that of homopolymer in both radical and cationic polymerizations, and the ratio in molecular weight of graft polymer to that of homopolymer tends to be unity with increasing amount of adsorbed monomer. These results can mainly be explained in terms of the number of initiating species (radical and cation) that change in relation to the amount of adsorbed monomer. Propagation and termination change with amount of adsorbed monomer in relation to the molecular mobility of adsorbed monomer. A very high‐molecular‐weight graft polymer is formed only with a small amount of adsorbed monomer in the initial stage. The grafting percent with a large amount of adsorbed monomer increased after most of the monomer has been polymerized. Secondary effect of radiation on the graft and homopolymers due to energy transfer from silica gel is suggested from the complicated phenomena in the later stage of the reaction.
Stabilization of high nitrile polymers. II. Effects of metal ions and oxygen on the stabilization reaction of dienophiles
Authors: Marien Bruce A. 
Published: April 2003

AbstractThe color stability of high nitrile polymers is increased by dienophilic stabilizers; however, the stabilization reaction is greatly affected by the presence of residual metal ions. This effect is correlated with electronegativity considerations of the metal ion. Metal ions affect the stability of the polymer whether they are used to coagulate the latex or postadded to the dry resin. Coagulation with group IIA metal ions results in polymer capable of stabilization by dienophiles. The mechanisms of stabilization and degradation in the presence of residual metals are discussed.
Emulsifier‐free emulsion polymerization of tetrafluoroethylene by radiation. V. Effect of reaction conditions on the stability of polytetrafluoroethylene latex
Authors: Suwa Takeshi , Watanabe Terutaka , Okamoto Jiro , Machi Sueo 
Published: April 2003

AbstractThe stability of PTFE latex prepared in the absence of emulsifier by radiation‐induced polymerization was investigated by electrophoresis and conductometric titration. The storage stability depends on total dose rather than dose rate, and the stable latex can be obtained in the region log D > 0.026 V1 − 0.6, where D is the total dose (104 rad) and V1 is a polymer concentration in latex (g/liter). The stability increases only during polymerization in the presence of enough TFE monomer. The ζ potential of the latex particles lies in the region from −25 to −50 mV in an as‐polymerized state (near pH 3) and from −50 to −65 mV at pH 10. The number of carboxyl end groups and surface charge density were examined by conductometric titration with NaOH and calculation from the G values of radiolysis of water. All the surface charge densities measured by conductometric titration are larger than those calculated from the G values. These results suggest that some acids have been formed on the surface of the particles. The acids may be the carboxyl end groups of polymer chains or hydrofluoric acid (HF) adsorbed on the surface. PTFE particles prepared in this polymerization system are stabilized mainly due to the carboxyl end groups and adsorptions of OH− and HF on the particles.
Radiation‐induced copolymerization of hexafluoroacetone with 2‐methyl‐1‐pentene
Authors: Watanabe Shojiro , Matsuda Osamu , Okamoto Jiro , Machi Sueo , Ishigure Kenkichi , Tabata Yoneho 
Published: April 2003

AbstractCopolymerization of hexafluoroacetone (HFA) with 2‐methyl‐1‐pentene (2MP) in trichlorotrifluoroethane (R‐113) was carried out by γ‐ray irradiation in a low‐temperature region of −100 to 0°C. Though HFA does not homopolymerize and 2MP scarcely does, the copolymerization took place at various monomer compositions. The copolymerization rate and the molecular weight in the low‐temperature region were much higher than those at 0°C. Above room temperature the copolymerization did not take place and only the adduct of monomers was formed. The copolymerization was inhibited to some extent by cation scavengers, but not by radical or electron scavengers. Elemental analysis and nuclear magnetic resonance (NMR) spectra show that the copolymer consists of almost equimolar monomer units and has two types of structure, head to tail and head to head or tail to tail. It has been concluded that copolymerization probably proceeds via a cationic mechanism to form an alternating copolymer.
Effect of pyridine on the kinetics of polymerization of styrene initiated by benzoyl peroxide and azobisisobutyronitrile at 60°C
Authors: Ghosh P. , Mukhopadhyay G. 
Published: April 2003

AbstractKinetics of solution polymerization of styrene was studied using pyridine as solvent and BZ2O2 and azobisisobutyronitrile (AIBN) as initiators at 60°C. Normal kinetic features (Rp ∝ [AIBN]0.5 · [styrene]1.0) were observed for the AIBN‐initiated polymerization, with pyridine playing the role of an inert diluent; but in the BZ2O2‐initiated polymerization, the monomer exponent was found to vary from a low value of 0.45 at a relatively low initiator concentration (1 × 10−2 mole/liter) to a value higher than the usual value of unity (1.18) at a much higher concentration of the initiator (16 × 10−2 mole/liter). The initiator exponent value was found to be 0.5 (usual) up to 20% v/v dilution with pyridine, but it showed a tendency to decrease with increase in pyridine content beyond 20% v/v. The k/kt value for each initiator system, however, was found to remain constant over the whole concentration range of pyridine. The unusual kinetic features were explained on the basis of predominance of one or the other of two competitive reactions in BZ2O2‐initiated system: (a) higher rate of decomposition of BZ2O2 in pyridine and (b) primary radical depletion by reaction with pyridine, depending upon the concentration of BZ2O2 and pyridine.
Small‐angle x‐ray scattering measurements on dilute solutions of polyisobutene by use of kratky cone collimation
Authors: Lederer K. , Klapp H. , Zipper P. , Wrentschur E. , Schurz J. 
Published: April 2003

AbstractSAXS measurements on dilute solutions of polyisobutene inn‐hexane (Mν= 25,600−3.55 × 106,c< 53 g/liter) were carried out by combining conventional slit collimation with the new cone collimation technique. With a fractionated sample (Mν= 25,600;U< 0.2) the radius of gyration (R= 48 Å), the cross‐sectional radius of gyration (Rq= 3.9 Å), the molecular weight per unit length (M/L= 22.8 Å−1), and the Porod persistence length (a*= 8.1 Å) are found. The persistence length appears to be dependent on the molecular weight. The partial specific volumeνof polyisobutene inn‐hexane also depends on the molecular weight according toν= 1.025 + 105/Mν(cm3/g).
Thermoelastic properties of crosslinked polyurethanes
Authors: Dzierża W. 
Published: April 2003

AbstractThermoelastic (stress–temperature) measurements in elongation have been carried out on polyurethane elastomers obtained from poly(ethylene adipate), poly(ethylene maleate), poly(ethylene glycol), and 4,4′‐diphenylmethane diisocyanate. The elastomers were crosslinked by an excess of diisocynate and some of them were additionally crosslinked by dicumyl peroxide. Values of the temperature coefficient d ln r/dT of the unperturbed dimensions of the network chains and the fraction fe/f of the stress, which is due to energetic effects, were calculated from measurements of unswollen samples and samples swollen in benzene to a constant volume fraction ν2 of about 0.6. The coefficient d ln r/dT and the ratio fe/f for unswollen samples were positive but dependent on the extension ratio α and crosslinking density. The fe/f ratio displayed a tendency to decrease with increasing α and this decrease was smaller for elastomers of higher crosslinking density. Additional crosslinking due to dicumyl peroxide reduced the dependence of fe/f on α. Swollen samples had lower positive values of fe/f; which were somewhat independent of α and crosslinking density. Departures from the molecular theories of rubberlike elasticity are explained by intermolecular effects, which, in general, are influenced by crosslinking.