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American Chemical Society, polymer Preprints, Division of polymer Chemistry 1999年第2期40卷 370-371页

作者： Pollack, Steven K. Singer, Dirk U. Morgan, André M. Department of Chemistry Polymer Science and Engineering Program Howard University Washington DC 20059 United States

Styrene/oxazoline diblock copolymers were obtained using the hydrolyzed form of the Hawker initiator (R = OH) as an anionic initiator for the ring opening polymerization of cyclosiloxanes followed by nitroxide mediated free-radical polymerization (NMRP) of styrene. This approach allows for the preparation of new materials with a variety of topologies. The use of NMRP allows for the creation of these polymers under relatively simple conditions making preparation of materials on a commercial scale more economically feasible.

关键词： Block copolymers

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In-situ characterization of surface molecular orientation of polymer films by fiber optic UV reflection dichroism

American Chemical Society, Polymer Preprints, Division of Po...

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American Chemical Society, polymer Preprints, Division of polymer Chemistry 1999年第2期40卷 673-674页

作者： Weir, Michael D. Sung, Chong Sook Paik Sung, Nak Ho Polymer Program Institute of Materials Science University of Connecticut Storrs CT 06269-3136 United States Department of Chemical Engineering Tufts University Medford MA 02155 United States

The surface molecular orientation of polyethylene terephthalate (PET) films is measured using a bifurcated fiber-optic probe. The use of bifurcated fiber-optic probe in the measurement of UV dichroism using reflection techniques is successful when the polarizer is placed at the probe end, which minimizes the depolarization effect of birefringence due to external factors acting upon the fiber. This is seen by the close agreement of the dichroic ratio and orientation function when using either the specular reflection accessory or the bifurcated fiber optic. While the magnitude of reflection may change using different methods, then overall orientation measured stays relatively constant.

关键词： Plastic films

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17th international Herman F. Mark Symposium: polypropylene—a material of the future

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Progress in polymer science 1999年第8期24卷 1205-1215页

作者： H. Roder O. Vogl PVC and Environmental Advise Ges.m.b.H. Untere Viaduktgasse 53/5a A-1030 Vienna Austria Department of Polymer Science and Engineering University of Massachusetts Amherst MA 01003-4350 USA

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The effect of phase-separated morphology on the rheological properties of polystyrene/poly(vinyl methyl ether) blend

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Journal of polymer science 1999年第9期37卷

作者： Jin Kon Kim Hye Won Son Yongbok Lee Jinhwan Kim Department of Chemical Engineering and Polymer Research Institute School of Environmental Engineering Pohang University of Science and Technology Pohang Kyungbuk 790-784 Korea Department of Polymer Science and Engineering SungKyunKwan University Suwon 440-746 Korea

The effect of phase-separated morphology on the rheological properties of polystyrene/poly(vinyl methyl ether) (PS/PVME) blend was investigated by optical microscopy (OM), light scattering (LS) method, and rheology. The blend had a lower critical solution temperature (LCST) of 112°C obtained by turbidity experiment using LS at a heating rate of 1°C/h. Three different blend compositions (critical 30/70 PS/PVME by weight) and two off-critical (50/50 and 10/90)) were prepared. The rheological properties of each composition were monitored with phase-separation time after a temperature jump from a homogeneous state to the preset phase-separation temperature. For the 30/70 and 50/50 blends, it was found that with phase-separation time, the storage and loss moduli ( G ′ and G ″) increased at shorter times due to the formation of co-continuous structures resulting from spinodal decomposition. Under small oscillatory shearing, shear moduli gradually decreased with time at longer phase-separation times due to the alignment of co-continuous structures toward the flow direction, as verified by scanning electron microscopy. However, for the 10/90 PS/PVME blend, the rheological properties did not change with phase-separation times. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 889–906, 1999

关键词： phase-separating morphology rheological properties PS/PVME blends

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Small-angle X-ray scattering studies of zinc stearate-filled sulfonated poly(ethylene-co-propylene-co-ethylidene norbornene) ionomers

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Journal of polymer science 1999年第21期37卷

作者： D. A. Jackson J. T. Koberstein R. A. Weiss Polymer Science Program Department of Chemical Engineering University of Connecticut Storrs Connecticut 06269-3136

The crystallization, melting, and dissolution behavior of zinc stearate (ZnSt) in ZnSt-filled sulfonated poly(ethylene-co-propylene-co-ethylidene norbornene) (SEPDM) ionomers was studied by synchrotron small-angle X-ray scattering (SAXS). The melting temperature of ZnSt in the ionomer was considerably lower than in the pure state, which was consistent with the existence of very small ZnSt crystalline domains and a specific interaction between the metal sulfonate groups of the SEPDM and the metal carboxylate groups of ZnSt. Temperature-resolved SAXS showed that, on melting, some or all of the ZnSt rapidly dissolved into the ionomer. Ionic aggregates in the neat ionomer persisted up to 300°C. Microphase separation was also observed at elevated temperatures for the ZnSt-filled ionomers, but the composition of the microdomains was believed to be quite different than that of the microdomains in the neat SEPDM. The time and temperature dependence of the ZnSt crystallization in the filled ionomers was characterized by time-resolved SAXS experiments following a temperature quench from the melt. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 3141–3150, 1999

关键词： ionomer X-ray scattering sulfonated EPDM stearate introduction

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Effect of the liquid–liquid phase separation on the crystallization behavior and mechanical properties of poly(ethylene-ran-vinyl acetate) and paraffin wax blend

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Journal of polymer science 1999年第16期37卷

作者： Jin Kon Kim Byoung-Kee Kim Department of Chemical Engineering and Polymer Research Institute School of Environmental Engineering Pohang University of Science and Technology Pohang Kyungbuk 790-784 Korea

The effect of liquid–liquid phase-separation (LLPS) on the crystallization behavior and mechanical properties of poly(ethylene- ran -vinyl acetate) (EVA) with various amounts of vinyl acetate and paraffin wax blend was investigated. The blend of EVA-H (9.5% vinyl acetate) and the wax became homogeneous at temperatures greater than its upper critical solution temperature (UCST) (98°C), and an LLPS was observed between UCST and the melting point of 88°C for EVA-H in the blend. The existence of the LLPS is attributed to the relatively large amount of the hydrophilic component of vinyl acetate in EVA, although the molecular weight of the wax was just 560. However, LLPS did not occur for the EVA/wax blend when the content of vinyl acetate in EVA was less than 3%. This behavior was explained by using the Flory–Huggins lattice model with an effective interaction parameter. The degree of crystallinity of EVA-H in the EVA-H/wax blend, judged from a melting endothermic peak in differential scanning calorimeter (DSC) thermograms obtained during heating runs, decreased with increasing duration time in the LLPS region. The flexural modulus of the EVA/wax blend became maximum at certain blend composition (about 30 ∼ 40 wt % EVA depending upon the amount of vinyl acetate). This behavior can be explained by the fact that this blend composition has the largest relative degree of crystallinity of EVA measured by DSC and wide-angle X-ray scattering method. We found that the flexural modulus of the binder itself is directly related to that of a feedstock consisting of larger amounts of metal powder and the binder, which can help someone to develop a suitable binder system for a powder injection molding process. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1991–2005, 1999

关键词： liquid–liquid phase separation crystallization mechanical properties powder injection molding EVA/wax blends

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Synthesis and characterization of dextran-maleic acid based hydrogel

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Journal of Biomedical Materials Research Part B: Applied Biomaterials 1999年第2期46卷

作者： Sin-Hee Kim Chee-Youb Won Chih-Chang Chu Fiber and Polymer Science Program Department of Textiles & Apparel and Biomedical Engineering Program Cornell University Ithaca New York 14853-4401

A new class of hydrogel precursor, dextran-maleic acid (Dex-MA), was synthesized by the reaction of dextran with maleic anhydride in the presence of the catalyst triethylamine. The effects of temperature, time, catalyst amount, and reactant concentration on the degree of substitution (DS) by MA was studied to establish an optimum reaction condition. The new hydrogel precursor had excellent solubility in various common organic solvents. The hydrogels based on Dex-MA precursor were made by the irradiation of Dex-MA with a long wave UV lamp. The Dex-MA hydrogels showed a very high swelling ratio in water, and the magnitude of swelling depended on the pH of the medium and the DS by MA. The Dex-MA hydrogels exhibited the highest swelling ratio in neutral pH, followed by acidic (pH 3) and alkaline pH (10). The most distinctive characteristic of Dex-MA hydrogels was that a carboxylic acid group was generated by the reaction of dextran with maleic anhydride. As a result, the swelling ratio increased with an increase of the DS of the MA segment (ionizable moiety that affects swelling ratio) in the Dex-MA hydrogel. © 1999 John Wiley & Sons, Inc. J Biomed Mater Res, 46, 160–170, 1999.

关键词： dextran maleic anhydride photocrosslinked hydrogel swelling hydrolytic degradation

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Measurement of thermal diffusivity in polymer melts using forced Rayleigh light scattering

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Journal of polymer science 1999年第11期37卷

作者： D. C. Venerus J. D. Schieber H. Iddir J. D. Guzman A. W. Broerman Department of Chemical and Environmental Engineering and Center of Excellence in Polymer Science and Engineering Illinois Institute of Technology 10 West 33rd Street Chicago Illinois 60616

Thermal diffusivity measurements on three polymer melts were made using the Forced Rayleigh Light Scattering technique. The polymers, which were tested at room temperature where they are in the molten state, included a polydimethylsiloxane and two polyisobutylenes. The optical setup and procedures developed in this study to conduct thermal Forced Rayleigh Light Scattering experiments are shown to be capable of producing thermal diffusivity data with a high degree of accuracy and precision. From measurements on a reference fluid (ethanol), experimental error was estimated to be no greater than 2%, and could be reduced to less than 1% by appropriate design of a series of experiments. Discrepancies of 4 and 14% in thermal diffusivity data on the polymer samples between measured values and those found in the literature were observed. It is suggested that these deviations are attributable to either sample variations or to errors in the techniques used in previous investigations. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1069–1078, 1999

关键词： thermal diffusivity polymer melts forced Rayleigh light scattering

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Crosslinking of chitosan fibers with dialdehydes: Proposal of a new reaction mechanism

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Journal of polymer science 1999年第11期37卷

作者： Jonathan Z. Knaul Samuel M. Hudson Katherine A. M. Creber Department of Chemistry and Chemical Engineering Royal Military College PO Box 17000 Station Forces Kingston Ontario K7K 7B4 Canada Fiber and Polymer Science Program Box 8301 Centennial Campus North Carolina State University Raleigh North Carolina 27695-8301

A highly deacetylated chitosan from shrimp with a degree of deacetylation of 95.28 ± 3.03% was prepared and spun into a monofilament fiber using a solution of 4% (w/v) chitosan in 4% (v/v) aqueous acetic acid. Samples of the spun fibers were immersed in aqueous solutions containing glutaraldehyde and glyoxal, and subsequently washed and dried. When the concentration of crosslinking agent was varied at room temperature over a constant time of 1 h, dry mechanical properties improved up to a point after which increasing concentrations resulted in degradation. Immersion time was also varied between 1 and 60 min at 25.8°C, and temperature was varied between 25.8 and 70.0°C, at fixed concentrations of both glyoxal and glutaraldehyde. It was demonstrated that mechanical improvements might be rendered at higher temperatures over lesser times. However, it was also shown that at higher temperatures, fiber mechanical properties would begin to diminish. Chitosan films were subjected to similar treatments in aqueous crosslinking solutions. Fourier transform infrared data (FTIR) on the films suggest that some interaction is occurring between the glutaraldehyde or glyoxal and the amine group on the chitosan backbone. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1079–1094, 1999

关键词： chitosan fiber crosslinking mechanical films FTIR wet spinning

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Miscibility of polyimide with polymeric primer and its influence on adhesion of polyimide to the primed copper metal: Effect of precursor origin

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Journal of polymer science 1999年第19期37卷

作者： J. Yu M. Ree T. J. Shin X. Wang W. Cai D. Zhou K.-W. Lee Department of Chemistry Polymer Research Institute and School of Environmental Engineering Pohang University of Science & Technology San 31 Hyoja-dong Pohang 790-784 Korea Department of Applied Chemistry Harbin Institute of Technology Harbin Heilongjiang Province 150001 China Department of Electrical Engineering Harbin Institute of Technology Harbin Heilongjiang Province 150001 China IBM Research T. J. Watson Research Center Yorktown Heights New York 10598

Poly(amic acid) (PAA) and poly(amic diethyl ester) (PAE) precursors of poly(4,4′-oxydiphenylene biphenyltetracarboximide) (BPDA-ODA PI) were synthesized. Miscibility behaviors of these precursors with poly(arylene ether benzimidazole) (PAEBI), which is a good adhesion primer for copper metal, were investigated in N -methyl-2-pyrrolidone (NMP) as well as the condensed state and the imidized state. For the PAA/PAEBI blend over the whole range of compositions, no cloud point was measured either in the NMP solution, the condensed state, or the imidized state. Furthermore, no aggregation of PI chains in the blend films was detected by X-ray diffraction. These results indicate that the PAA and PAEBI are completely miscible at the molecular level, consequently leading to the miscible PI/PAEBI blend. This miscibility might result from the strong interaction via the complex formation of imidazole groups of the PAEBI and carboxylic acid groups of the PAA precursor. In contrast, the miscibility of PAE/PAEBI blend in NMP was limited up to a concentration of 13.5–36.3 wt %, leading to a phase separation in the soft-baked and imidized blend. The blend films rich with one component were optically transparent, which might be due to the phase-separated domains much smaller than 1 μm. The immiscibility might result from the relatively weak interactions of imidazole groups of PAEBI with both the ester and amide linkages in the PAE precursor. The difference in the miscibilities of PAEBI with the PAA and PAE precursors was reflected in the adhesion of PI/PAEBI/copper joints: higher miscibility gave higher adhesion strength. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2806–2814, 1999

关键词： poly(arylene ether benzimidazole) primer polyimide precursor origin miscibility phase diagram adhesion copper peel test

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