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  • 1
    Electronic Resource
    Electronic Resource
    Graft copolymers having hydrophobic backbone and hydrophilic branches. XI. Preparation and thermosensitive properties of polystyrene microspheres having poly (N-isopropylacrylamide) branches on their surfacesFor Part X, see Riza et al.16 (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 2213-2220 
    Details
    ISSN: 0887-624X
    Keywords: macromonomer ; poly(N-isopropylacrylamide) ; polystyrene microspheres ; thermosensitivity ; water dispersibility ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermosensitive microspheres with 0.4-1.2 μm diameter consisting of a polystyrene core and poly(N-isopropylacrylamide) (polyNIPAAm) branches on their surfaces were prepared by the free radical polymerization of a polyNIPAAm macromonomer and styrene in ethanol. Electron spectroscopy for chemical analysis (ESCA) of the microsphere surface suggested that polyNIPAAm chains were favorably located on the surface of the microspheres. The morphology of the microspheres was observed by transmission electron micrograph (TEM) and the particle size of was estimated by submicron particle analyzer. The molecular weight of the polyNIPAAm macromonomer, the ratio of the macromonomer and styrene, and the polymerization temperature affected the particle size. Thermosensitive properties of polyNIPAAm-coated polystyrene microspheres were evaluated by the turbidity of their dispersion solutions and the hydrodynamic size of the miocrospheres. The transmittance in dispersion solutions changed clearly, similar to oligoNIPAAm and polyNIPAAm macromonomers. In addition, the particle size of microspheres decreased with rising temperature. These results were explained by the thermosensitivity of polyNIPAAm branches on the microsphere surface. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Graft copolymers having hydrophobic backbone and hydrophilic branches. XVIII. Poly(styrene) nanospheres with novel thermosensitive poly(N-vinylisobutyramide)s on their surfaces (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2581-2587 
    Details
    ISSN: 0887-624X
    Keywords: poly(N-vinylisobutyramide) ; free radical polymerization ; macromonomer ; nanosphere ; thermosensitive property ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(styrene) nanospheres having poly(N-vinylisobutyramide)s (PNVIBA)s, which are structurally the same composition as well-known thermosensitive poly(N-isopropylacrylamide)s (PNIPAAm)s and show the thermosensitive property as well, on their surfaces were synthesized by the free radical polymerization of hydrophilic PNVIBA macromonomers and hydrophobic styrene with AIBN as a radical initiator in ethanol as a polar solvent and were characterized in regard to their thermosensitive properties. Both the NVIBA oligomers and PNVIBA macromonomers that we synthesized showed a lower critical solution temperature (LCST) at around 40°C, as was predicted by our previous research. The nanospheres were spherical in form and have a narrow size distribution. Their sizes could be controlled by varying the molecular weight of the macromonomers and the amount of it in feed. The size in the nanosphere became small above the LCST of the corresponding macromonomer, possibly due to thermosensitive shrinking of the PNVIBA on the nanosphere surface, while transmittance of its dispersion did not change at all at studied temperature range. The nanospheres having the PNVIBA on their surfaces, which response sharply to atmospheres such as dispersion temperature, can be significant and useful materials in technological and medical fields. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2581-2587, 1998
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Preparation of sulfonated polysulfone/polysulfone and aminated polysulfone/polysulfone blend membranes (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 61 (1996), S. 1205-1209 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Sulfonation and amination of polysulfone (PSf) were performed in this study to improve the hydrophilicity of PSf membranes. The sulfonated polysulfone (SPSf) and aminated polysulfone (APSf) membranes with a higher degree of reaction exhibited a higher water flux and worse mechanical strength than that of the original PSf membranes. Therefore, SPSf/PSf and APSf/PSf blended membranes were prepared in this study to improve their individual properties. By altering the formulations of casting solutions and forming conditions of the membranes (e.g., blending ratios of both polymers, additives, evaporation time, and gelation temperature), different SPSf/PSf and APSf/PSf blending membranes were prepared; and their performance in water flux and salt rejection were measured and are discussed. A difference in salt rejection was also observed between both SPSf/PSf and APSf/PSf blending membranes that rejected the various salts. Experimental results indicated that water flux increased and salt rejection decreased with an increase of the SPSf/PSf blending ratio from 1: 9 to 2: 1. The order of salt rejection, in which the SPSf/PSf blended membranes rejected four varieties of salts, was Na2SO4 〉 MgSO4 〉 NaCl 〉 MgCl2. Furthermore, the opposite order was obtained by the APSf/PSf blended membranes. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Analysis of crystallization kinetics of poly(ether ether ketone) (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1335-1348 
    Details
    ISSN: 0887-6266
    Keywords: PEEK ; growth rate ; crystallization ; kinetics ; regime ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An optical microscope equipped with a video photograph system was used to follow the growth of spherulites. Under nitrogen atmosphere, the growth rates at 290 and 300°C suggest that when the melt of PEEK has been equilibrated for 15 min at 400°C, the subsequent crystallization behavior was nearly independent of the prior thermal history. Linear growth rates of crystallization of PEEK have been measuredin the temperature range of 260-325°C for melt-pressed films and solvent cast films. Detailed kinetic analysis indicated that PEEK exhibited an unmistakable regime II → III transition at 296 ± 1°C. The II → III transition was clearly present irrespective of the rather drastic changes in U*. It is interesting that the branching and crosslinking retarded the growth rate of PEEK, but a transition from regime II to regime III still existed. For melt-pressed films after equilibration at 400°C for 15 min, values of σ and q suggest that U* should be taken nearer to 1500 cal/mol in the case of T∞ = Tg - 30 K and 2000 cal/mol in the case of T∞ = Tg - 51.6 K. The Kg(III)/Kg(II) ratio (1.32) was not as close to the predicted value of 2 as was Hoffman's ratio. For PEEK, the Thomas-Staveley constant (β) should be closer to 0.25 or 0.3 instead of 0.1. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1335-1348, 1998
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Thermal stability and nonisothermal crystallization of short fiber-reinforced poly(ether ether ketone) composites (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2225-2235 
    Details
    ISSN: 0887-6266
    Keywords: PEEK ; composite ; stability ; nonisothermal ; crystallinity ; melting ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermal stability of a short carbon-fiber-reinforced PEEK composite was assessed by thermogravimetry and by a Rheometrics dynamic analyzer. The results indicated that holding for 10 min at 380°C was a suitable melting condition to avoid the thermooxidative degradation under air. After proving that the heating rate of 50°C/min can be used to evaluate the crystallinity, a heating stage was used to prepare nonisothermally crystallized specimens using cooling rates from 1 to 100°C/min after melting at 400°C for 3 or 15 min. The degree of crystallinity and the melting behavior of these specimens were investigated by DSC at a heating rate of 50°C/min. The presence of three or four regions indicated that the upper melting temperature, Tm, changed with the crystallization temperature. The first region with the highest Tm, which corresponded to the cooling rate of 1°C/min, can be associated with the crystallization in regime II. There was a second region where Tm decreased as the amount of crystals formed in regime II decreased with increasing cooling rate from 5 to 20°C/min. The third region, a plateau region, corresponded to regime III condition in which the crystals were imperfect. In the fourth region, the cooling was so fast that crystallization was incomplete during the cooling for the melting condition of 400°C for 15 min. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2225-2235, 1998
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Thermal stability and crystallization kinetics of poly(ether ether ketone) (1998)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 199 (1998), S. 1623-1629 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermogravimetric analysis (TGA), dynamic rheological analysis and polarized light microscopy were used to assess the thermal stability of poly(ether ether ketone) (PEEK). Samples were exposed to temperatures in the range 385-415°C for times up to 30 min in both air and nitrogen atmosphere. The results indicated that neither TGA nor dynamic rheological analysis detected PEEK degradation at temperatures up to 415°C and heating times up to 30 min in nitrogen. It is suspected that degradation, chain branching, and crosslinking occur in PEEK at high temperatures in the melt. In nitrogen atmosphere, the growth rates of spherulites at 290°C and 300°C leveled off for melting temperatures around 400°C and decreased with increasing melting temperature. This study suggests that when the melt of PEEK has been equilibrated at 400°C for 15 min in nitrogen, the subsequent crystallization behavior (isothermal and nonisothermal) is nearly independent of the prior thermal history. The rates of crystallization of PEEK then were measured in the temperature range of 270-325°C. Kinetic analysis indicated that PEEK exhibits a regime II → III transition at 296°C.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Analysis of crystallization kinetics of poly(ether ether ketone) by a nonisothermal method (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2393-2399 
    Details
    ISSN: 0887-6266
    Keywords: PEEK ; nonisothermal ; growth rate ; crystallization ; kinetics ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: During cooling at a rate of 10°C/min from the melt state of PEEK we have followed the growth of spherulites using an optical microscope equipped with a camera. The isothermal growth rates of crystallization in the temperature range of 266-308°C could be estimated by means of a differential equation. These continuous growth rate data were used further for kinetic analysis, which indicated that PEEK exhibited an unmistakable regime II → III transition at 296°C. The results compared favorably with those obtained by the traditional isothermal method, which is time consuming. Due to chain folding, the Thomas-Staveley constant should be closer to 0.25 instead of 0.1 or 0.3. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2393-2399, 1998
    Additional Material: 4 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Preparation and characterization of polymer dispersed liquid crystal films using photosensitive polymers (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 231 (1995), S. 109-121 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Flüssigkristalle 4-Butyl-N-(4-methoxybenzyliden)anilin (MBBA) und 4-Butyl-N-(4-ethoxybenzyliden)anilin (EBBA) wurden synthetisiert. Die hydrophilen Monomeren 2-Hydroxyethylmethacrylat (HEMA) und Acrylsäure (Aa) wurden eingesetzt, um die polymere Matrix für Flüssigkristalle zu bilden, die dispergieren und einen Polymer-Flüssigkristall-Film (PDLC) bilden, Um solche PDLC-Filme herzustellen, wurden MBBA, EBBA oder die kommerziellen Flüssigkristalle ZLI-2444, 2452, 2459 und BDH-E7 mit HEMA, Aa und photoempfindlichen Stoffen gemischt und mit UV-Licht bestrahlt. Das elektrooptische Verhalten und die Mikrostruktur der PDLC-Filme wurden mit einem He-Ne-Laser bzw. mit der Rasterelektronenmikroskopie (SEM) untersucht. Die Effekte der UV-Bestrahlung und des Monomerverhältnisses auf das Verhalten der PDLC-Filme wurden ebenso untersucht wie die Reproduzierbarkeit und die Speicherstabilität der Filme.
    Notes: 4-Butyl-N-(4-methoxybenzylidene)aniline (MBBA) and 4-butyl-N-(4-ethoxybenzylidene)aniline (EBBA) liquid crystals were synthesized. To investigate the applications of hydrophilic monomers and polymers on the field of polymer dispersed liquid crystal (PDLC) films, 2-hydroxyethyl methacrylate (HEMA) and acrylic acid (Aa) were selected as monomers for the polymer matrix. To prepare the PDLC films, MBBA, EBBA, and commercial liquid crystals ZLI-2444, 2452, 2459 and BDH-E7 were mixed with HEMA, Aa and photosensitive materials and then irradiated by UV light. The electrooptical behavior and the microstructure of the PDLC films were investigated by He-Ne laser and scanning electron microscopy (SEM), respectively. The effects of UV-light irradiation and monomer ratio on the electrooptical behavior of PDLC films, and the reproducibility and storage stability of the PDLC films were investigated.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052310110
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