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  • 1
    Electronic Resource
    Electronic Resource
    Polyamides incorporating phosphine oxide groups. I. Wholly aromatic polymers (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 1561-1566 
    Details
    ISSN: 0887-624X
    Keywords: phosphine oxide ; polyamide ; polycondensation ; thermal properties ; fire-retardant materials ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Five novel polyamides incorporating phosphine oxide groups have been synthesized by the condensation reaction of bis(4-carboxyphenyl)phenylphosphine oxide with a series of aromatic diamines. The thermal properties of these polymers were investigated by differential scanning calorimetry and thermogravimetric analysis. Glass transition temperatures in the 225-254°C range were recorded, together with good thermooxidative stability (5% weight loss occurring at 〉420°C) and high char yield upon prolonged heating at 650-800°C (24-50%). Also, good solubility in aprotic polar solvents was observed for all polyamides synthesized. © 1996 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Polyamides incorporating phosphine oxide groups. II. Aromatic polymers containing sulfone functionality (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 493-497 
    Details
    ISSN: 0887-624X
    Keywords: phosphine oxide ; diarylsulfone ; polyamide ; polycondensation ; thermal properties ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four novel polyamides have been prepared in high yields by the polycondensation reactions of bis(3-carboxyphenyl)- and bis(4-carboxyphenyl)phenylphosphine oxide with 3,3′- and 4,4′-diaminodiphenylsulfone. The thermal properties of these materials were studied using differential scanning calorimetry and thermogravimetric analysis. It was found that the presence of both phosphine oxide and sulfonyl groups within the polymer backbone brought about remarkable modifications in the thermal behavior. Glass transition temperatures 40-50°C lower than those of conventional polyamides i.e., in the range 170-200°C, were recorded. However, we observed greater thermooxidative stability (5% weight loss at 〉410°C) and high char yield upon prolonged heating at 800°C (20-34%). Also, good solubility in polar aprotic solvents was observed for all polyamides together with some solubility in aqueous solvent mixtures, e.g. tetrahydrofuran/water (95:5). © 1997 John Wiley & Sons, Inc.
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  • 3
    Electronic Resource
    Electronic Resource
    Polyamides incorporating phosphine oxide groups. III. Polymerisation of bis[4-(2-aminoethyl)aminophenyl]-phenylphosphine oxide with dicarboxylic acids (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 2865-2870 
    Details
    ISSN: 0887-624X
    Keywords: phosphine oxide ; aromatic-aliphatic polyamides ; polycondensation ; thermal properties ; fire retardant materials ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new polymerisation monomer bis[4-(2-aminoethyl)aminophenyl]-phenylphosphine oxide (p-BAPPO) was prepared in good yield by the nucleophilic substitution reaction between bis(4-fluorophenyl)phenylphosphine oxide and a large excess of 1,2-diaminoethane. Five novel polyamides, incorporating phosphine oxide groups within the polymer backbone were synthesised by the condensation reaction of p-BAPPO with a series of aromatic and aliphatic dicarboxylic acids. The thermal properties of these polymers were investigated by differential scanning calorimetry and thermogravimetric analysis. Glass transition temperatures in the 180-215°C range were recorded. Although we observed their thermooxidative stabilities (5% weight loss 〉 345°C) to be lower by 40-70°C than those previously found for wholly aromatic polyamides with phosphine oxide groups within the parent chain, char yields upon prolonged heating at 650°C were still excellent (26-38%). Also, good solubility in aprotic polar solvents was observed for all polyamides synthesised. The new polyamides clearly represent significant progress in the quest for processible fire retardant materials. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2865-2870, 1997
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  • 4
    Electronic Resource
    Electronic Resource
    Competitive reactivity as a probe for reaction coordinates in gas-phase ion-molecule chemistryDedicated by J.E.B. to Professor F. G. Bordwell: research director, mentor and guide on the frontier of science. (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 585-589 
    Details
    ISSN: 0894-3230
    Keywords: competitive reactivity ; reaction coordinates ; gas-phase ion-molecule chemistry ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: ---Using the method of competitive reactivity of two functional groups in the same molecule, anionic elimination reactions show considerable kinetic selectivity for small differences in leaving group thermochemistry, in structures of the general type YCH2CH2CH2Z, where Y and Z are good anionic leaving groups. © 1997 John Wiley & Sons, Ltd.
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  • 5
    Electronic Resource
    Electronic Resource
    Studies of temperature and time-dependent network formation in commercial epoxy resins using modified imidazole curing agents (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 41 (1996), S. 159-168 
    Details
    ISSN: 0959-8103
    Keywords: epoxy resins ; imidazoles ; copper (II) complexes ; curing agents ; dynamic viscometry ; gel permeation chromatography ; high performance liquid chromatography ; 1H nuclear magnetic resonance spectroscopy ; 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: Two commercial epoxy resins, MY750 and MY720, were cured over a range of cure temperatures with a series of novel curing agents based on modified imidazoles. A combination of techniques, including dynamic viscometry, proton nuclear magnetic resonance spectroscopy, differential scanning calorimetry, high performance and gel permeation chromatography, were used to analyse the reaction mixture. It appears that for a given formulation and given resin, the viscosity behaviour near gelation is different for different cure temperatures and the mechanism appears to be dependent not only on the nature of the imidazole curing agent, but also on the cure temperature. Higher temperature cure appears to lead to the formation of a less ‘homogeneous’ reaction mixture at the gel point, containing oligomeric chain lengths of higher polydispersity, whereas in the lower temperature cure, oligomers of a smaller range of chain lengths are present.
    Additional Material: 6 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of simulated low earth orbit radiation on polyimides (UV degradation study) (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 1847-1856 
    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: UV degradation of polyimide films in air and vacuum were studied using UV-visible, ESR, FTIR, and XPS spectroscopies. The UV-visible spectra of polyimide films showed a blue shift in the absorption compared to Kapton. This behavior was attributed to the presence of bulky groups and kinks along the polymer chains which disrupt the formation of a charge-transfer complex. The UV-visible spectra showed also that UV irradiation of polyimides result extensively in surface degradation, leaving the bulk of the polymer intact. ESR spectra of polyimides irradiated in vacuum revealed the formation of stable carbon-centered radicals which give a singlet ESR spectrum, while polyimides irradiated in air produced an asymmetric signal shifted to a lower magnetic field, with a higher g value and line width. This signal was attributed to oxygen-centered radicals of peroxy and/or alkoxy type. The rate of radical formation in air was twofold higher than for vacuum irradiation and reached a plateau after a short time. This suggests a continuous depletion of radicals on the surface via an ablative degradation process. FTIR, XPS, and weight loss studies supported this postulate. An XPS study of the surface indicated a substantial increase in the surface oxidation after irradiation in air. The sharp increase in the C—O binding energy peak relative to the C—C peak was believed to be associated with an aromatic ring-opening reaction. © 1995 John Wiley & Sons, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070581023
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  • 7
    Electronic Resource
    Electronic Resource
    Surface properties of fluorinated polyimides exposed to VUV and atomic oxygen (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 1857-1864 
    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 effect of atomic oxygen flux and VUV radiation alone and in combination on the surface of fluorinated polyimide films was studied using XPS spectroscopy. Exposure of fluorinated polyimides to VUV radiation alone caused no observable damage to the polymer surface, while an atomic oxygen flux resulted in substantial oxidation of the surface. On the other hand, exposure to VUV radiation and atomic oxygen in combination caused extensive oxidation of the polymer surface after only 2 min of exposure. The amount of oxidized carbon on the polymer surface indicated that there is aromatic ring-opening oxidation. The changes in the O1s/C1s, N1s/C1s, and F1s/C1s ratios suggested that an ablative degradation process is highly favorable. A synergistic effect of VUV radiation in the presence of atomic oxygen is clearly evidenced from the XPS study. The atomic oxygen could be considered as the main factor in the degradation process of fluorinated polyimide films exposed to a low earth orbit environment. © 1995 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070581024
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  • 8
    Electronic Resource
    Electronic Resource
    New caerin antibacterial peptides from the skin glands of the Australian tree frog Litoria xanthomera (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 3 (1997), S. 181-185 
    Details
    ISSN: 1075-2617
    Keywords: Litoria xanthomera ; skin glands ; glandular secretion ; antibacterial peptides ; caerins 1 ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The secretion of the skin glands of the ‘orange-thighed frog’ Litoria xanthomera contains seven peptides. One of these is the known hypotensive peptide caerulein. Two new peptides, caerin 1.6 [GLFSVLGAVAKHVLPHVVPVIAEKL(NH2)], and caerin 1.7 [GLFKVLGSVAKHLLPHVAPVIAEKL(NH2)] show antibacterial properties. Two other peptides lack the first two amino acid residues of caerins 1.6 and 1.7 and show no antibacterial activity. The identification of the peptides in Litoria xanthomera confirms that this species is related to Litoria caerula, Litoria gilleni and Litoria splendida but not as closely as those three species are related to each other. © 1997 European Peptide Society and John Wiley & Sons, Ltd.
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  • 9
    Electronic Resource
    Electronic Resource
    The Maculatin peptides from the skin glands of the tree frog Litoria genimaculata: a comparison of the structures and antibacterial activities of Maculatin 1.1 and Caerin 1.1 (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 4 (1998), S. 111-115 
    Details
    ISSN: 1075-2617
    Keywords: Litoria genimaculata ; skin glands ; glandular secretions ; peptides ; antibiotic activity ; maculatins 1 ; caerin 1.1 ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Six peptides have been isolated and characterized from the dorsal glands of the tree frog Litoria genimaculata. One of these is the known hypotensive peptide caerulein; the others have been named maculatins. The amino acid sequences of the maculatin peptides have been determined using a combination of fast atom bombardment mass spectrometry and automated Edman sequencing. Four of the maculatin peptides show antibiotic activity, with maculatin 1.1 [GLFGVLAKVAAHVVPAIAEHF(NH2;)] showing the most pronounced activity, particularly against Gram-positive organisms. Maculatin 1.1 resembles the known caerin 1 antibiotic peptides, except that four of the central amino acid residues (of the caerin 1 system) are missing in maculatin 1.1. A comparison of the antibiotic activity of maculatin 1.1 with those of caerin 1.1 is reported. ©1998 European Peptide Society and John Wiley & Sons, Ltd.
    Additional Material: 1 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Correlation entropy of the H2 molecule (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 61 (1997), S. 935-941 
    Details
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Correlation of a quantum many-body state makes the one-particle density matrix nonidempotent. Therefore, the Shannon entropy of the natural occupation numbers measures the correlation strength on the one-particle level. Here, it is shown how this general idea of a correlation entropy must be adapted for two-electron systems in view of conservation laws which mix Slater determinants even in the noninteracting limit. Results are presented for the correlation entropy s of H2 as a function of the nucleus-nucleus separation R. In the ground state, the entropy of the spatial factor of the wave function maximizes 1.7 bohr beyond the Coulson-Fischer separation. The role of the correlation entropy in density functional theory is also discussed. © 1997 John Wiley & Sons, Inc.
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