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  • 1990-1994  (4)
  • Polymer and Materials Science  (3)
  • Fertilization
  • 1
    Digitale Medien
    Digitale Medien
    Radiation-induced crosslinking of polyethylene in the presence of acetylene: A gel fraction, UV-visible, and ESR spectroscopy study (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 807-819 
    Details
    ISSN: 0887-6266
    Schlagwort(e): polyethylene, polyene formation on irradiation with acetylene present in ; polyene formation in irradiation of polyethylene with acetylene present ; crosslinking in polyethylene irradiated with acetylene present ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Electron-spin resonance (ESR) and altraviolet (UV) visible spectroscopic evidence has been found for the formation of diene, triene and tetraene, following the irradiation of polyethylene in the presence of acetylene. The polyenes are formed by a mechanism which is different from that observed under vacuum or with inert gas saturation. The sum of the G (polyene) values obtained by UV spectroscopy is almost half that of initial radical formation. It is concluded that polyene bridges, predominantly diene, form crosslinks between radical pairs. G (X) values determined from gel fraction data, using Saito-Kang-Dole theory, are found to be greatly in error and misrepresentative of crosslink changes. © 1993 John Wiley & Sons, Inc.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/polb.1993.090310709
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  • 2
    Digitale Medien
    Digitale Medien
    An infrared spectroscopic study of changes in unsaturation resulting from irradiation of isotropic and uniaxially oriented polyethylene films in the presence of acetylene (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 469-479 
    Details
    ISSN: 0887-6266
    Schlagwort(e): polyethylene ; acetylene ; FTIR ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Interchain bridges of unsaturated double bonds have been proposed to form in amorphous regions, when polyethylene is irradiated in the presence of acetylene. We have corroborated the formation of these bridges by infrared spectroscopic studies. The double bonds are composed mainly of trans-olefin and vinyl end groups, formed as a result of competing radical-radical termination and hydrogen atom abstraction reactions. The hydrogen atom abstraction reaction becomes insignificant in uniaxially oriented high-density polyethylene having a draw ratio of 7.5, because of the alignment and positioning of the initiating radical pairs. During in vacuo irradiation and annealing only in-chain trans-olefins are usually formed. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/polb.1994.090320308
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  • 3
    Digitale Medien
    Digitale Medien
    A study of the transport properties of acetylene through a highly oriented polyethylene fiber (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 819-826 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The transport properties of acetylene in a high modulus polyethylene fiber have been studied in detail over the temperature range of 25 to 65°C. Diffusion coefficients for the fiber are about four orders of magnitude lower than values cited for isotropic high density polyethylene. In keeping with this, a much higher apparent activation energy of diffusion (ca. 80.64 ± 0.53 kJ mol-1) was found. The solubility of acetylene in the fiber (ca. 0.158 cm3 C2H2 STP/cm3 PE @ 76 cm Hg), is lower, but of the same order of magnitude as that expected for isotropic polyethylene. The apparent heat of solution was determined, within experimental limits, to be zero. It is concluded that the acetylene is neither chemically nor physically absorbed onto the fiber, but freely diffuses, according to Fick's law, through the amorphous regions of the polymer.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1992.070450508
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  • 4
    Digitale Medien
    Digitale Medien
    Characterization of low Mr Zona Pellucida binding proteins from boar spermatozoa and seminal plasma (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 33 (1992), S. 108-115 
    Details
    ISSN: 1040-452X
    Schlagwort(e): Zona binding proteins ; Seminal plasma ; Fertilization ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: A group of low Mr (16 kDa - 23 kDa) glycoproteins on ejaculated boar spermatozoa have been shown to have high affinity for homologous zona pellucida glycoproteins (ZPGPs). These ZPGP binding proteins are derived from seminal plasma as shown by their absence from epididymal spermatozoa and their presence in seminal plasma as identified by N-terminal amino acid sequence analysis. They bind to ZPGPs by a polysulphate recognition mechanism similar to that found for proacrosin-ZPGP interactions. The haemagglutination activity of boar seminal plasma is also associated with these low Mr glycoproteins. It is suggested that they play a role in regulating the rate of sperm capacitation and survival in the female reproductive tract. © 1992 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mrd.1080330115
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