bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis, characterization, and thermal properties of ladderlike polyepoxysiloxanes
Authors: Lin Yuhui , Pramoda K. P. , He Chaobin , Chen Wei‐Yu , Chung T. S. 
Published: October 2004

AbstractStarting from trichlorosilanes and using 1,4‐phenylenediamine as a template, we have synthesized some ladderlike poly(glycidyl‐co‐alkyl/aryl)siloxanes (polyepoxysiloxanes or polyepoxies for short). The structures of copolymers were confirmed through IR, 1H NMR, elemental analyses, and gel permeation chromatography. Curing behaviors of these polyepoxies in the absence and presence of a curing agent have been studied with DSC. It was shown that these epoxies could be cured without any curing agent. Copolymers having aromatic groups showed higher curing reactivity than those having alkyl groups. The experimental results also demonstrate that the curing reaction occurred solely via epoxy functionality, not via the condensation reaction of the hydroxy groups located at the end of polymer main chains. The thermal stability of the cured polymers was examined by thermogravimetric analysis. The results confirm that polyepoxies with aromatic groups had better thermal stability than those with alkyl groups. It was also found that polyepoxies cured with a diamine have a higher thermal stability than those cured in the absence of a curing agent. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2215–2222, 2001
Replacement of benzene with regulators for the catalyzed polymerization of 1,3‐butadiene to high cis‐1,4‐polybutadiene
Authors: Cass Peter , Pratt Kerry , Mann Terry , Laslett Bob , Rizzardo Ezio 
Published: October 2004

AbstractThe polymerization regulators mesitylene and 1,3,5‐trimethoxybenzene were investigated as suitable substitutes for benzene in the cobalt(II) octanoate/diethylaluminum chloride/water‐catalyzed polymerization of 1,3‐butadiene to high cis‐1,4‐polybutadiene. The propagation rates were reduced by 50% with the inclusion of 18 mM mesitylene or 0.17 mM trimethoxybenzene. Mesitylene was found to be an inefficient polymerization regulator because it reduced the propagation rate by a combination of regulation and destruction of the active catalyst complex. Not only did trimethoxybenzene reduce the propagation rate by effective regulation at low concentration, it also increased the percentage activity of cobalt to 200%, indicating that two polymer chains were propagating simultaneously from each active center. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2244–2255, 2001
Aromatic poly(1,3,4‐oxadiazole)s and poly(amide‐1,3,4‐oxadiazole)s containing ether sulfone linkages
Authors: Hsiao Sheng‐Huei , Chiou Jiun‐Hsiang 
Published: October 2004

AbstractPolyhydrazides and poly(amide‐hydrazide)s were prepared from two ether‐sulfone‐dicarboxylic acids, 4,4′‐[sulfonylbis(1,4‐phenylene)dioxy]dibenzoic acid and 4,4′‐[sulfonylbis(2,6‐dimethyl‐1,4‐phenylene)dioxy]dibenzoic acid, or their diacyl chlorides with terephthalic dihydrazide, isophthalic dihydrazide, and p‐aminobenzhydrazide via a phosphorylation reaction or a low‐temperature solution polycondensation. All the hydrazide polymers were found to be amorphous according to X‐ray diffraction analysis. They were readily soluble in polar organic solvents such as N‐methyl‐2‐pyrrolidone and N,N‐dimethylacetamide and could afford colorless, flexible, and tough films with good mechanical strengths via solvent casting. These hydrazide polymers exhibited glass‐transition temperatures of 149–207 °C and could be thermally cyclodehydrated into the corresponding oxadiazole polymers in the solid state at elevated temperatures. Although the oxadiazole polymers showed a significantly decreased solubility with respect to their hydrazide prepolymers, some oxadiazole polymers were still organosoluble. The thermally converted oxadiazole polymers had glass‐transition temperatures of 217–255 °C and softening temperatures of 215–268 °C and did not show significant weight loss before 400 °C in nitrogen or air. For a comparative study, related sulfonyl polymers without the ether groups were also synthesized from 4,4′‐sulfonyldibenzoic acid and the hydrazide monomers by the same synthetic routes. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2271–2286, 2001
Formation of regioregular head‐to‐tail poly[3‐(4‐butylphenyl)thiophene] by an oxidative coupling polymerization with vanadium acetylacetonate
Authors: Hayakawa Teruaki , Fukukawa Ken‐Ichi , Morishima Makoto , Takeuchi Kazuhiko , Asai Michihiko , Ando Shinji , Ueda Mitsuru 
Published: October 2004

AbstractThe mechanism for the formation of head‐to‐tail (H–T) poly[3‐(4‐butylphenyl)thiophene] by oxidative coupling polymerization with a catalytic amount of vanadium acetylacetonate was investigated. Polymerization was carried out in the presence of vanadium acetylacetonate, trifluoromethane sulfonic acid, and trifluoroacetic anhydride under an oxygen atmosphere in 1,2‐dichloroethane at room temperature. Polymers and oligomers obtained after several polymerization times were characterized by gel permeation chromatography, IR, and NMR spectroscopies. With these findings and the reactivity of monomer and dimers based on ab initio density functional theory, the polymerization was found to proceed mainly through the formation of H–T linkages due to the high spin density at the 2‐position of 3‐(4‐butylphenyl)thiophene and the calculated total energy of dimers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2287–2295, 2001
End‐capped carbosilane dendrimers with benzoxazole, quinoline, and pyrone derivatives
Authors: Kim Chungkyun , Park Eunmi 
Published: October 2004

AbstractDendritic carbosilanes containing benzoxazole, quinoline, and pyrone derivatives on the periphery were prepared. The parent dendrimers in the inner shell were prepared by the use of iterative hydrosilation and alkenylation cycles. The end generations were obtained by the reaction of terminal SiCl groups on each periphery with HOR [HOR = 2‐(2‐hydroxyphenyl)‐benzoxazole, 8‐hydroxyquinoline, and 3‐hydroxy‐2‐methyl‐4‐pyrone] in the presence of amine. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2308–2314, 2001
Rigid‐chain metallomesogenic polymers containing vanadyl or copper(II) ions coordinated in the main chain
Authors: Caruso U. , Panunzi B. , Roviello A. , Sirigu A. , Spasiano D. 
Published: October 2004

AbstractRigid‐chain metallomesogenic polymers containing Cu(II) or VO(II) were prepared and characterized. All the polymers were soluble and melted without decomposition. They showed a thermotropic liquid–crystal (LC) behavior, and the mesophases were invariably preserved for a long time at room temperature in a metastable condition, with respect to the semicrystalline state. The nature of the mesophases of the Cu(II)‐containing polymers was similar to that observed in analogous organic rigid‐chain polymers having long lateral alkyl chains packed as extended ribbons. The VO(II)‐containing polymers showed an LC polymorphism involving a smectic A and a nematic phase. For all the polymers in a smectic or smecticlike state at room temperature, X‐ray diffraction data suggested short mean distances among the metal ions arranged in layers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2342–2349, 2001
1H NMR study of the kinetics of substituted aniline polymerization. II. Copolymerization of 2‐methoxyaniline and 3‐aminobenzenesulfonic acid
Authors: Mav Ida , Žigon Majda 
Published: October 2004

AbstractWe investigated the kinetics of the oxidative chemical copolymerization of 2‐methoxyaniline (OMA) and 3‐aminobenzenesulfonic acid (MA) by monitoring monomer depletion with 1H NMR spectroscopy. We adapted a semiempirical kinetic model, previously used for OMA homopolymerization, for the consumption of both OMA and MA monomers with a large difference in their reactivities. The OMA polymerization rate and end conversion showed a similar dependence on the reaction conditions, as described in the first part of this series, for its homopolymerization. Generally, the MA comonomer had an inhibition effect on the OMA polymerization rate. However, an increase in the initial MA concentration resulted in an increased OMA initiation rate. Because of the higher reactivity of OMA compared with that of MA, the OMA conversion began before the MA conversion, and both the initiation and propagation rates were higher than those for MA. The molar ratios of the converted monomers (MA/OMA) were always significantly lower than the corresponding MA/OMA feed fractions. They depended on the reaction conditions used for the copolymerization. In particular, higher oxidant or MA concentrations, higher temperatures, and a 1 M DCl concentration favored MA conversion, that is, its insertion into the copolymer. The MA end conversion was much smaller than that of OMA, only up to 23%; for a low oxidant concentration (oxidant/monomer‐deficient molar ratio), it was only 6%. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2482–2493, 2001
Equilibrium polymerization behavior in the cationic single ring‐opening polymerization of bicyclo orthoesters
Authors: Sanda Fumio , Hitomi Masakatsu , Endo Takeshi 
Published: October 2004

AbstractThe synthesis and cationic polymerization of the following bicyclo orthoesters were examined: 4‐ethyl‐2,6,7‐trioxabicyclo[2.2.2]octane, 1,4‐diethyl‐2,6,7‐trioxabicyclo[2.2.2]octane, 4‐ethyl‐1‐phenyl‐2,6,7‐trioxabicyclo[2.2.2]octane, 4‐ethyl‐1‐(4‐methoxyphenyl)‐2,6,7‐trioxabicyclo[2.2.2]octane, and 4‐ethyl‐1‐(4‐nitrophenyl)‐2,6,7‐ trioxabicyclo[2.2.2]octane. All the monomers underwent equilibrium polymerization, which was confirmed by the relationships between the polymerization temperature and monomer conversion. The obtained polymers afforded the original monomers via an acid‐catalyst treatment with a low reagent concentration in CH2Cl2 at 20 °C. The equilibrium monomer concentration was constant, regardless of the initial reagent concentration, in both polymerization and depolymerization. The bicyclo orthoesters with a bulky and electron‐withdrawing substituent showed a larger equilibrium monomer concentration. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3159–3167, 2001
Correlation between mechanical adhesion and interfacial properties of starch/biodegradable polyester blends
Authors: Biresaw G. , Carriere C. J. 
Published: October 2004

AbstractBiopolymers are preferred ingredients for the manufacture of materials because they are based on abundantly available and renewable raw materials that have benign environmental problems associated with their production, fabrication, use, and disposal; however, the wide use of biopolymers in engineering applications has not been achieved, mainly because of the inferior quality of many biopolymer‐based products. To overcome this limitation, studies have been initiated on blends of biopolymers and biodegradable synthetic polymers. We used the contact angle of probe liquids to measure the surface energy of polystyrene, the biodegradable polyesters polycaprolactone, poly(hydroxybutyrate‐co‐hydroxyvalerate), polylactic acid, polybutylene adipate terephthalate, and adipic poly(hydroxy ester ether), and normal starch. The surface energies were used to estimate the starch/polymer interfacial energy and work of adhesion. The calculated starch/polyester work of adhesion showed mixed correlation with published starch/polyester mechanical properties, indicating that factors other than interfacial properties might be dominant in determining the mechanical properties of some starch/polyester blends. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 920–930, 2001
Water‐vapor permeation in semicrystalline and molten poly(octadecyl acrylate)
Authors: Mogri Z. , Paul D. R. 
Published: October 2004

AbstractThe water‐vapor permeability of poly(octadecyl acrylate) (PA‐18) was measured as a function of temperature in the region traversing its melting point (50 °C). The molten‐state permeability of PA‐18 is comparable to that of shorter side‐chain methacrylate polymers. Water permeability in the semicrystalline state of PA‐18 is similar to that of polyethylene at comparable crystallinity levels. The permeation switch, or change in permeability with the traversing of the melting point, for water is discussed in the context of previous results for other penetrants in this and other side‐chain crystalline polymers. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 979–984, 2001
Properties of nitrocellulose‐coated and polyethylene‐laminated chitosan and whey films
Authors: Gällstedt M. , Törnqvist J. , Hedenqvist M. S. 
Published: October 2004

AbstractChitosan (chitosan acetic acid salt) and whey (65% protein) films were coated with a nitrocellulose lacquer or laminated with polyethylene to enhance their water resistance and gas barrier properties in humid environments. The barrier properties were measured by the Cobb60test and water‐vapor (100% relative humidity) transmission and oxygen (90% relative humidity) permeability tests. Mechanical properties were obtained with tensile tests. Packaging properties were studied with crease and folding tests. The Cobb60test revealed that the coated films were resistant to liquid water, at least for a short exposure time, if the coating thickness was at least 10–17 μm. Water‐vapor transmission rates comparable to those of polyethylene‐laminated films were obtained for coated chitosan at a coating thickness of 5–7 μm. The coated films possessed low oxygen permeability despite the high humidity. Coated films dried for 3 weeks showed oxygen permeabilities at 90% relative humidity that were similar to values for dry ethylene‐co‐vinyl alcohol at 0% relative humidity. The lacquer partly penetrated the whey films, and this led to excellent adhesion but poor lacquer toughness. The lacquer coating on chitosan was tougher, and it was possible to fold these films 90° without the coating fracturing if the coating thickness was small. The coated whey films were readily creasable. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 985–992, 2001
Crystallization behavior of polypropylene with or without sodium benzoate as a nucleating agent
Authors: Jang Gu‐Su , Cho Won‐Jei , Ha Chang‐Sik 
Published: October 2004

AbstractThe crystallization kinetics of polypropylene (PP) with or without sodium benzoate as a nucleating agent were investigated by means of DSC and polarized optical microscopy in isothermal and nonisothermal modes. A modified Avrami equation was applied to the kinetic analysis of isothermal crystallization. The addition of the nucleating agent up to its saturation concentration increased the crystallization temperature by 15 °C and shortened both the isothermal and nonisothermal crystallization half‐times. It was concluded that the sodium benzoate acted as a good nucleating agent for α‐form PP. By adding the nuclefier to PP, adequately controlled spherulites increased the mechanical properties including especially the Izod impact strength and shortened cycle time of PP. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1001–1016, 2001
Synthesis and characterization of ion‐conducting polymer systems based on EPDM blends
Authors: Bashir H. , Linares A. , Acosta J. L. 
Published: October 2004

AbstractThis work reports the preparation and characterization of new polymeric ionomers based on etylene–propylene–diene copolymer (EPDM) with a high norbornene content. The sulfonation level was determined with X‐ray photoelectron spectroscopy, and the microstructural characterization was obtained through differential scanning calorimetry and dynamic mechanical analysis. In addition, the effects of certain plasticizers and polymers on the microstructures and conducting properties of these materials were studied, with special attention paid to the latter because of the interest aroused by these materials as membranes in polymer fuel cells. On the basis of the results, some of the synthesized membranes could be used for fuel cells because of their high conductivity (≥10−2 S/cm) and good dimensional stability (any shrinkage observed). © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1017–1026, 2001
Surface modification of polystyrene by blending substituted styrene copolymers
Authors: Chen Xianyi , Jankova Katja , Kops Joergen , Larsen Niels B. , Batsberg Walther , Johannsen Ib 
Published: October 2004

AbstractThe surface modification of polystyrene (PS) by the blending of 4‐acetoxystyrene polymers and their corresponding hydrolysis products, 4‐hydroxystyrene polymers, was investigated on the basis of X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and contact‐angle measurements. According to XPS and AFM measurements, when polystyrene‐block‐poly(4‐acetoxystyrene) (PS‐b‐PAS) or polystyrene‐block‐poly(4‐hydroxystyrene) (PS‐b‐PHS) was incorporated into PS, the block copolymer was preferentially segregated at the highest surface region of the blend. This segregation increased to a plateau value when more than 5 wt % of either PS‐b‐PHS or PS‐b‐PAS was added. The contact angle of the modified PS by PS‐b‐PAS or PS‐b‐PHS was slightly lower than that of homopolystyrene, but no further decrease was observed with the blend ratio of the diblock copolymer increasing from 5 to 20 wt %. For a PS/PS‐b‐PHS blend, the surface atomic concentration ratio O/C increased linearly with the molecular weight of poly(4‐hydroxystyrene) blocks in diblock copolymer PS‐b‐PHS in the range of our study. The different structures of 4‐acetoxystyrene polymers and their hydrazinolyzed materials may affect the surface compositions of their blends with PS; among these polymers, PS‐b‐PHS and PS‐b‐PAS appeared to be most effective. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1046–1054, 2001
Control of bending electrostriction in polyurethane films by doping with salt
Authors: Watanabe Masashi , Kato Takahiro , Suzuki Makoto , Hirako Yoshiyuki , Shirai Hirofusa , Hirai Toshihiro 
Published: October 2004

AbstractWe systematically investigated the effect of doping with salt on the bending electrostriction in polyurethane films. When a film was doped with sodium acetate, it was bent toward the cathode side by the application of an electric field. However, when a film was doped with zinc bromide, it was bent toward the anode side. Thus, we found a way of controlling the bending direction. We also investigated the mechanism of the effect of the doping. Doping is believed to be a treatment that can control the bending deformation through modification of the charge injection, the major origin of the deformation. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1061–1069, 2001
Reversible and irreversible heat capacity of poly[carbonyl(ethylene‐co‐propylene)] by temperature‐modulated calorimetry
Authors: Pyda M. , Di Lorenzo M. L. , Pak J. , Kamasa P. , Buzin A. , Grebowicz J. , Wunderlich B. 
Published: October 2004

AbstractThe heat capacity of poly[carbonyl(ethylene‐co‐propylene)] with 95 mol % C2H4CO (Carilon EP®) was measured with standard differential scanning calorimetry (DSC) and temperature‐modulated DSC (TMDSC). The integral functions of enthalpy, entropy, and free enthalpy were derived. With quasi‐isothermal TMDSC, the apparent reversing heat capacity was determined from 220 to 570 K, including the glass‐ and melting‐transition regions. The vibrational heat capacity of the solid and the heat capacity of the liquid served as baselines for the quantitative analysis. A small amount of apparent reversing latent heat was found in the melting range, just as for other polymers similarly analyzed. With an analysis of the heat‐flow rates in the time domain, information was collected about latent heat contributions due to annealing, melting, and crystallization. The latent heat decreased with time to an even smaller but truly reversible latent heat contribution. The main melting was fully irreversible. All contributions are discussed in the framework of a suggested scheme of six physical contributions to the apparent heat capacity. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1565–1577, 2001
Comparison of semicrystalline ethylene–styrene and ethylene–octene copolymers based on comonomer content
Authors: Chen H. Y. , Chum S. P. , Hiltner A. , Baer E. 
Published: October 2004

AbstractThe structure and properties of homogeneous copolymers of ethylene and styrene (ES) and ethylene and octene (EO) were compared. Semicrystalline copolymers presented a broad spectrum of solid‐state structures from highly crystalline, lamellar morphologies to the granular, fringed micellar morphology of low‐crystallinity copolymers. The combined observations from density, thermal behavior, and morphology with primarily atomic force microscopy revealed that the crystalline phase depended on the amount of comonomer but was not strongly affected by whether the comonomer was styrene or octene. This was consistent with the exclusion of both comonomers from the crystal. However, ES and EO showed strong differences in the amorphous phase. ES had a much higher β‐relaxation temperature than EO, which was attributed to restrictions on chain mobility imposed by the bulky phenyl side group. The deformation behavior of ES and EO exhibited the same trends with comonomer content, from necking and cold drawing typical of a semicrystalline thermoplastic to uniform drawing and high recovery characteristic of an elastomer. Aspects of deformation behavior that depended on crystallinity, such as yielding and cold drawing, were determined primarily by comonomer content. However, the difference in the β‐relaxation temperature resulted in much higher strain hardening of ES than EO. This was particularly evident with low‐crystallinity, elastomeric copolymers. A classification scheme for semicrystalline copolymers based on comonomer content, previously developed for EO, was remarkably applicable to ES. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1578–1593, 2001
Crystallizability of ethylene homopolymers by crystallization analysis fractionation
Authors: Nieto J. , Oswald T. , Blanco F. , Soares Joao B. P. , Monrabal Benjamin 
Published: October 2004

AbstractThe effect of molecular weight and long‐chain branching on the crystallization analysis fractionation (CRYSTAF) of ethylene homopolymers was investigated. Several ethylene homopolymers were prepared with different molecular weights and levels of long‐chain branching to isolate these effects from the dominant effect of comonomer content on crystallizability measured by CRYSTAF. Molecular weight effects might be significant for samples with number‐average molecular weights below 5000, but this effect can be corrected if terminal methyl groups are taken into account. Long‐chain branching has only a very small effect on the CRYSTAF profile of the samples investigated in this study. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1616–1628, 2001