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  • Polymer and Materials Science  (38)
  • General Chemistry  (20)
  • 1995-1999  (58)
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  • 1
    Electronic Resource
    Electronic Resource
    In vitro biocompatibility, mechanical properties, and corrosion resistance of Ti—Zr—Nb—Ta—Pd and Ti—Sn—Nb—Ta—Pd alloys (1995)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 29 (1995), S. 893-899 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: There is much discussion about the toxic effect of vanadium and aluminum contained in Ti—6Al—4V alloy for prosthetic implants. The goal of the present investigation was to develop new titanium alloys with sufficient mechanical properties using more biocompatible alloying elements: zirconium, tin, niobium, tantalum, and palladium. The relative growth rates of L929 and MC3T3-E1 cells were significantly higher when cultured with the extraction of Ti—10Zr—8Nb—2Ta—0.2Pd or Ti—15Zr—4Nb—2Ta—0.2Pd alloys than when cultured with the extraction of Ti—6Al—4V ELI alloy. The tensile strength, elongation, and reduction of area for Ti—15Sn—4Nb—2Ta—0.2Pd alloy were 989 MPa, 14.4%, and 49.3%, respectively, surpassing Ti—6Al—4V ELI alloy (ASTM F138—84); those for Ti—15Zr—4Nb—2Ta—0.2Pd alloy were 725 MPa, 23.6% and 54.9%, respectively. More than 15% addition of tin as well as zirconium deteriorated the tensile properties. Titanium release into a 5% hydrochloric acid solution from the new titanium alloys was 20-50 μg/cm2 per day, though that from Ti—6Al—4V ELI alloy was 1300 μg/cm2 per day. The optimum alloy compositions are Ti—15Zr—4Nb—2Ta—0.2Pd and Ti—15Sn—4Nb—2Ta—0.2Pd, judging from cytocompatibility, corrosion resistance, and mechanical properties. The former is characterized by its high level cytocompatibility and corrosion resistance, while the latter is characterized by mechanical properties. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820290715
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis of polymers with pendant hydroxyl groups by polyaddition of bis(oxetane)s with dithiols (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2873-2880 
    Details
    ISSN: 0887-624X
    Keywords: polyaddition ; bis(oxetane) ; aromatic dithiol ; catalyst ; quaternary onium salt ; crown ether complex ; new reactive polymer ; pendant primary hydroxyl group ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Addition reaction of (3-methyl-3-oxetanyl)methyl acetate (MOMA) with bis(4-mercaptophenyl) sulfide (BMPS) was examined in certain organic solvents. When the reaction of MOMA with BMPS was performed without any catalyst in hexamethylphosphoric triamide (HMPA) and N-methyl-2-pyrrolidone (NMP) at 130°C for 24 h, conversions of the corresponding adduct were 96 and 36%, respectively, which was confirmed by 1H-NMR spectra. On the other hand, when the reaction was carried out using tetraphenylphosphonium bromide (TPPB) as a catalyst under the same conditions, conversions of the adduct were 96 and 81% in HMPA and NMP, respectively. This result shows that although the addition reaction of oxetane compound with aromatic dithiol proceeds without any catalyst in HMPA, the reaction was strongly enhanced by adding TPPB in NMP. On the basis of the above results, polyadditions of bis((3-methyl-3-oxetanyl)methyl) terephthalate (BMOT) and bis((3-ethyl-3-oxetanyl)methyl) terephthalate with BMPS were performed using TPPB as the catalyst in NMP at 130°C for 24 h. As a result, the corresponding high molecular weight polymers 1 (Mn = 22,400) and 2 (Mn = 12,800) with pendant primary hydroxyl groups were obtained in 83 and 89% yields without any gel products, respectively. Furthermore, a low molecular weight oligomer was obtained from the polyaddition of BMOT with aliphatic dithiol, bis(mercaptomethyl)benzene, under the same reaction conditions. The catalytic activity on the polyaddition of BMOT with BMPS was also examined, and it was found that thermally stable TPPB and crown ether complexes at the reaction temperature (130°C) have higher catalytic activity than tetrabutylammonium bromide and tetrabutylphosphonium bromide to produce polymer 1 with high molecular weight. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2873-2880, 1998
    Additional Material: 1 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Simultaneous polymerization and formation of polyacetylene film on the surface of concentrated soluble Ziegler-type catalyst solution (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 2533-2542 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A direct method of simultaneously polymerizing and forming acetylene monomer to produce uniformly thin films of polyacetylene was investigated in terms of catalyst system, catalyst concentration, and polymerization temperature. The best catalyst was a Ti(OC4H9)4,-AI(C2H5)3 system (Al/Ti = 3-4) and the critical concentration was 3 mmole/l. of Ti(OC4H9)4. Below the critical concentration, only a solid or a powder was obtained. The configuration of the polymers obtained depends strongly upon the polymerization temperature. Thus an all-cis polymer was obtained at temperatures lower than -78°C, whereas an all-trans polymer resulted at temperatures higher than 150°C. Observations either in an electron microscope by direct transmission or in a scanning electron microscope showed that the film is composed of an accumulation of fibrils about 200-300 Å in width and of indefinite length.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1996.854
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesis and properties of germanium-containing poly(diphenylacetylenes) (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 2925-2929 
    Details
    ISSN: 0887-624X
    Keywords: substituted polyacetylene ; poly(diphenylacetylene) ; germanium-containing polymer ; metathesis polymerization ; tantalum catalyst ; thermal stability ; gas permeability ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Phenyl-2-[m-(trimethylgermyl)phenyl]acetylene (m-Me3GeDPA) and 1-phenyl-2-[p-(trimethylgermyl)phenyl]acetylene (p-Me3GeDPA) polymerized with TaCl5-cocatalyst systems to provide in high yields new polymers having weight-average molecular weights over 1 × 106. Poly(m-Me3GeDPA) was a yellow solid, which completely dissolved in toluene, chloroform, etc., to form a tough film by solution casting. Poly(p-Me3GeDPA) was also a yellow solid and partly insoluble in any solvents. The onset temperatures of weight loss for these polymers in the thermogravimetric analysis in air were as high as ca. 400°C. The oxygen permeability coefficient of poly(m-Me3GeDPA) was 1100 barrers (25°C), which is about twice that of poly(dimethylsiloxane). © 1996 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Radical polymerization of methyl trans-β-vinylacrylate (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1059-1067 
    Details
    ISSN: 0887-624X
    Keywords: radical polymerization ; methyl trans-β-vinylacrylate ; kinetics propagation radical ; monomer reactivity ratios ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyl trans-β-vinylacrylate (MVA) undergoes radical polymerization with α,α′-azobis(isobutyronitrile) (AIBN) in bulk and solution. The polymer obtained consists of 85% trans-1,4 and 15% trans-3,4 units. Poly(MVA) (PMVA) is readily soluble in common organic solvents, but insoluble in n-hexane and petroleum ether. PMVA exhibits a glass transition at 60°C, and loses no weight up to 300°C in nitrogen. The kinetics of MVA homopolymerization with AIBN was investigated in benzene. The rate of polymerization (Rp) can be expressed by Rp = k[AIBN]0.5[MVA]1.0, and the overall activation energy has been calculated to be 94 kJ/mol. The propagation radical of MVA at 80°C was detected by ESR spectroscopy, which indicated that the unpaired electron of the propagating radical was completely delocalized over the three allyl carbons. Furthermore, the steady-state concentration of the propagating radical of MVA at 60°C was determined by ESR spectroscopy, and the propagation rate constant (kp) was calculated to be 1.25 X 102 L/mol ·s. Monomer reactivity ratios in copolymerization of MVA (M2) with styrene (M1) are r1 = 0.16 and r2 = 4.9, from which Q and e values of MVA are calculated as 4.2 and -0.32, respectively. © 1995 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330708
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  • 6
    Electronic Resource
    Electronic Resource
    Photo-induced polarity alteration and photodegradation behavior of O-acryloyl acetophenone oxime and phenyl vinyl ketone copolymers (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 2181-2187 
    Details
    ISSN: 0887-624X
    Keywords: acyl oxime ; polarity alteration ; main-chain scission ; energy transfer ; photoresist ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemical reactions of copolymers of O-acryloyl acetophenone oxime (AAPO) and phenyl vinyl ketone (PVK) in the solid phase were investigated. The decrease of molecular weight of these copolymers in the photolysis was limited compared to that of PVK homopolymer. Results of IR and elemental analyses showed that pendant acyloxyimino (AOI) groups were phototransformed into the pendant amino groups. This behavior suggests that PVK units in this copolymer worked as a sensitizer for the photolysis of AOI groups. The energy transfer from PVK units to AOI groups was confirmed to proceed via an excited triplet state by the quenching study of phosphorescence of a PVK homopolymer by a model compound, O-cyclohexanecarbonyl acetophenone oxime. Dissolution alteration of AAPO copolymers before and after irradiation was also investigated. © 1996 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Crystallization of carboxylic acid salts in poly(ethylene oxide) oligomers at higher temperatures (1995)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 6 (1995), S. 248-253 
    Details
    ISSN: 1042-7147
    Keywords: poly(ethylene oxide) ; carboxylate ; solubility ; phase separation ; crystallization ; 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
    Notes: Many alkali metal carboxylates when dissolved in poly(ethylene oxide) (PEO) oligomers, are phaseseparated by heating. These were revealed to be the crystals of the initially dissolved corresponding salts from the X-ray diffraction patterns. Some acetate salts achieve the lower limit of the lattice energy for phase separation of ordinary inorganic salts by heating in PEO oligomers. These carboxylate salts were therefore expected to show crystallization behavior in PEO oligomers by heating. The effects of cation size, alkyl chain length and molecular weight of PEO on the solubility are summarized. Negative temperature dependence of solubility of these acetate salts is seen in the PEO oligomers only when the salts have long alkyl chains. The salts containing larger cations needed a longer chain length of PEOs for crystallization by heating. These salts with longer alkyl chains showed positive temperautred dependence in lower molecular weight polyethers, but negative temperature dependence in solubility in PEO with molecular weights higher than 400. In PEO400, all the carboxylates with longer alkyl chains were phase separated by heating.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1995.220060405
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  • 8
    Electronic Resource
    Electronic Resource
    Studies on the structure and formation mechanism of carbon gel in the carbon black filled polyisoprene rubber composite (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 61 (1996), S. 1345-1350 
    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: The structure and formation mechanism of carbon gel in carbon black filled polyisoprene composites were studied by the pulsed NMR technique. The composites were prepared from a wide range of molecular weights by a solution blend. The carbon gels were extracted from the composites by a solvent-extraction method. The content of carbon gel was not governed by the molecular weight of rubber but was controlled by the viscosity of rubber solutions which were used for the blend. Three rubber phases, having different spin-spin relaxation times, were detected in all the carbon gels. The increase of carbon gel content in the composites was mainly from the increase of highly mobile rubber phase, and the gel became soft with the development of this phase. On the other hand, the content and structure of glassy rubber phases were not affected by the size of the carbon gel, and they showed almost a constant value despite the large change in the carbon gel content. A part of the highly mobile rubber phase in the gels could be removed by solvent extraction at high temperature. These results suggest that the formation of carbon gel is primarily governed by two factors: One is the well-known rubber-carbon black interaction, and the other is a physical crosslink between the carbon gel and unbound rubber molecules during blend. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of modifier characteristics on toughness of poly(vinyl chloride) (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 62 (1996), S. 1387-1393 
    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: The effects of the mechanical properties of an acrylic graft copolymer and a silicone/acrylic composite rubber graft copolymer on the toughening of poly(vinyl chloride) (PVC) are examined. In the experiment for improvement of impact resistance of PVC, toughness of the blend polymer of a silicone/acrylic composite rubber graft copolymer is improved remarkably. The effect is attributed to the suppression of stress concentration below the fibril strength of the polymer alloy effectively by releasing the constraint of strain resulting from easy void formation at low stress. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Positron annihilation lifetime study of vapor sorption in polypropylene and polytetrafluoroethylene (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 56 (1995), S. 779-791 
    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: Positron annihilation lifetime (PAL) spectra were measured for two different kinds of polymers: polypropylene (PP) and polytetrafluoroethylene (PTFE), during sorption of vapors of the following molecules: n-hexane, cyclohexane, benzene, methyl methacrylate, acrylic acid, and water. The behavior of ortho-positronium (o-Ps) annihilation parameters: lifetime, τ3, and intensity, I3, can be explained by considering different sorption mechanisms in rubbery and glassy polymers. The mean size of the intermolecular-space holes and the relative free-volume fraction of PP and PTFE were estimated before and during the sorption process from the o-Ps parameters obtained. Sorption of n-hexane, cyclohexane, and benzene in both polymers affect the o-Ps component in a systematic way, for PP τ3 and I3 tend to decrease, while in PTFE, τ3 stay almost constant and I3 diminishes. These effects are interpreted in relation to the different states of the polymers studied: rubbery for PP and glassy for PTFE. In case of methyl methacrylate molecules, the behavior of o-Ps parameters was more complicated. For acrylic acid and water, their associated polarity provokes a diminution in I3, which is explained from the viewpoint of the spur model of positronium formation. Large changes in the mean size and the fraction of free volume, as well as their constant behavior in some cases, were interpreted to be due to positive or negative interactions, respectively, between vapor molecules and PP and PTFE, which could be correlated with the solvent-interaction parameters calculated. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070560703
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