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  • 1
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 1077-1082 
    ISSN: 0887-624X
    Keywords: fluoroelastomers ; tetrafluoroethylene ; radiation ; terpolymerization ; kinetics ; mechanism ; properties ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Terpolymerization of tetrafluoroethylene (TFE) with propylene (P) and n-butyl vinyl ether (NBVE) induced by γ-rays at room temperature at dose rate 5 × 105 rad/h and P/NBVE molar ratio from 49/1 to 10/40 was carried out. An alternating copolymerization between TFE and two α-olefins was found to take place in this system, so that 50 mole % of TFE containing terpolymer is always formed at various monomer compositions. The terpolymer composition can be explained successfully by the treatment by a complex mechanism. The complex reactivity ratios of rI (TFE-complex) and rII (TFE-NBVE complex) were calculated to be 0.5 and 0.6, respectively, assuming a complex mechanism. The polymerization rate and molecular weight increase with NBVE concentration in the monomer mixture. Colorless transparent rubber-like polymers were obtained at each monomer composition. The glass transition temperature sharply decreases with NBVE concentration in the terpolymer but the thermal and chemical resistances of the terpolymer slightly decrease. Considering these results together with the mechanical properties it has been concluded that the 45/48/7 terpolymer of TFE/P/NBVE molar ratio is good as a practical elastomer useful at relatively low temperatures.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 31 (1996), S. 157-166 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study describes the potentiality of hydrogels composed of gelatin and poly(L-glutamic acid) (PLGA) as a biological glue for soft tissues and compares its effectiveness with that of a conventional fibrin glue. Water-soluble carbodiimides (WSC) were used to crosslink the aqueous mixture of gelatin and PLGA. The mixed aqueous solution of gelatin and PLGA set to a hydrogel by use of WSC as rapidly as BOLHEAL® fibrin glue. An addition of PLGA to gelatin aqueous solution reduced not only its gelation time but also the WSC concentration necessary for hydrogel formation. The cured hydrogel exhibited firm adhesion to the mouse skin and other soft tissues with a higher bonding strength than BOLHEAL® fibrin glue. Cohesive failure in the hydrogel was observed when the gel-tissue bond was broken, in contrast to BOLHEAL® fibrin glue. The bonding strength of the gelatin-PLGA hydrogel became higher with the increasing PLGA concentration. The inflammatory reaction around the gelatin-PLGA hydrogel subcutaneously implanted in mice was mild, and the hydrogel was gradually absorbed with time in vivo. A toxicity test demonstrated that the concentration of WSC necessary as a biological glue was low enough not to induce its toxicity. © 1996 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 16 (1978), S. 729-741 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Initial processes of radiation-induced cationic polymerization of styrene and α-methylstyrene have been studied by means of microsecond pulse radiolysis. For styrene, absorption bands caused by the monomer cation radical St+• appear at 630 and 350 nm in a mixture of isopentane and n-butyl chloride at about -165°C. In parallel with the decay of St+•, three absorption bands appear in the near-infrared (IR) region, and at 600 and 450 nm. The IR and 600 nm bands are assigned to the associated dimer cation radical St2+•, and the 450 nm band to the bonded dimer cation radical St-St+•. The kinetic behavior of these species shows that reaction of St+• with styrene monomer forms both St2+• and St-St+•. With the decay of St-St+•, another absorption band appears at 340 nm, and the lifetime of this band is relatively long. The 340 nm band may be due to carbonium ions of the growing polystyrene. For α-methylstyrene, the monomer cation radical (at 690 and 350 nm), the associated dimer cation radical (in the near-IR region and at 620 nm) and the bonded dimer cation radical (at 480 nm) behave in a manner similar to that of the corresponding styrene species. The absorption band caused by carbonium ions of growing poly(α-methylstyrene) appears at 340 nm.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 104 (1967), S. 236-243 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Effects of pressure on the ring opening polymerization of diketene in the solid state were investigated at 1 and 5000 kg/cm2.The polymerization reactivity was substantially elevated by applying high pressure while the reactivity under normal pressure was decreased by pre-treatment under high pressure.Further it was confirmed, that the vinyl polymerization can proceed also in the solid state to some extent, and that this reaction is suppressed by high pressure.
    Notes: Druckeffekte auf die Ringöffnungspolymerisation des Diketens im festen Zustand wurden bei 1 und 5000 kg/cm2 untersucht.Die Polymerisationsreaktivität wird durch die Verwendung von Hochdruck beträchtlich erhöht, während die Reaktivität bei Normaldruck durch eine vorherige Behandlung unter Hochdruck vermindert wird.Weiter wurde festgestellt, daß die Vinylpolymerisation auch im festen Zustand in gewissem Maße verlaufen kann und daß diese Reaktion durch hohen Druck unterdrückt wird.
    Additional Material: 9 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 81 (1965), S. 223-233 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß des Druckes auf die Geschwindigkeit der strahleninduzierten Polymerisation festen Acrylamids wurde im Druckbereich von 1-5000 Atm. und bei Temperaturen von 28-70°C untersucht.Bei niedrigen Temperaturen wird die Polymerisationsgeschwindigkeit durch Druck erniedrigt, in der Nähe des Schmelzpunktes des Acrylamids jedoch erhöht.Weiter wurde gefunden, daß die Reaktionsgeschwindigkeit bei konstanter Temperatur im Anfangsstadium der Polymerisation durch Druck erniedrigt, später jedoch erhöht wird.Die Anzahl der erhaltenen Polymermoleküle wird durch den Druck nicht verändert; sie hängt nur von der Bestrahlungsdosis ab. Dieser Befund zeigt, daß der Druck die Initiierungsreaktion nur wenig, die Wachstumsreaktion aber stark beeinflußt.Die Wirkung des Druckes auf die Polymerisation des festen Acrylamids wird mit der Druckabhängigkeit der Aktivierungsenthalpie (ΔH
    Notes: The effect of pressure on the radiation-induced solid state polymerization of acrylamide has been studied in a pressure range of 1 to 5000 atm. over a temperature region of 28 to 70°C. Rates of polymerization and molecular weights have been measured.It was found that the rate of polymerization is suppressed by pressure at the lower temperatures; in the contrary, the rate is accelerated near the melting point.On the other hand, it was also found that the rate of polymerization is suppressed by pressure in an initial stage of polymerization, while it is accelerated in a later stage of polymerization at the same temperature.The number of polymer chains obtained is not affected by pressure; it depends on the irradiation dose only. These results indicate that the pressure has very little effect on the rate of initiation but that the propagation rate constant is profoundly affected by pressure.The effect of the pressure on the solid state polymerization of acrylamide is attributed to the pressure dependence on the activation enthalpy (ΔH
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die durch Strahlung ausgelöste Polymerisation von Acetylen wurden in Lösung und in festem Zustand des Monomeren untersucht. Die Versuchsergebnisse lassen auf einen kationischen Mechanismus bei der Polymerisation in flüssiger Phase schließen, während die Polymerisation im festen Zustand nicht durch einen radikalischen oder ionischen Mechanismus im gewöhnlichen Sinne zu beschreiben ist.Wir fanden, daß die Struktur der in Lösung erhaltenen Polymeren sich von derjenigen der bei der Polymerisation in Substanz erhaltenen unterscheidet; ersteres ist hauptsächlich cis-Polyacetylen, letzteres liegt überwiegend in der trans-Form vor. Daraus ergibt sich, daß eine stereospezifische Polymerisation in Substanz möglich ist, wenn man ionisierende Strahlung einwirken läßt. Es wird ein Mechanismus für die durch Strahlung ausgelöste Polymerisation des Acetylens in dampfförmiger, flüssiger und fester Phase aufgestellt.
    Notes: Radiation-induced polymerization of acetylene was investigated in the liquid and solid states of the monomer.It was concluded from these experimental results that the liquid phase polymerization proceeds by a cationic mechanism and the solid phase polymerization proceeds by a cationic mechanism and the solid phase polymerization not by a radical or ionic mechanism, in an ordinary sense.The structure of the polymer obtained in the liquid and the solid state polymerization is quite different, that is, the former is mainly cis-form polyacetylene and the latter mainly trans-form one. These facts confirm that a stereospecific polymerization is possible in solid state polymerization, using ionizing radiation, as was previously pointed out by the authors.Radiation-induced polymerization mechanism in the vapor, liquid and solid phases of acetylene were proposed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Letters 2 (1964), S. 23-25 
    ISSN: 0449-2986
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Letters 1 (1963), S. 409-411 
    ISSN: 0449-2986
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 3991-4001 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Terpolymerization of tetrafluoroethylene (TFE) with propylene (P) and isobutylene (iB) by γ radiation at temperatures of -78 to 40°C, a dose rate of 5 × 104-5 × 105 rad/hr, and an iB/P molar ratio of 40/10-5/45 in the monomer mixture was carried out. Alternating copolymers of TFE and α-olefins, that is, P and iB, were formed at various monomer compositions. No crystalline structure was observed in the terpolymer obtained below an iB/P molar ratio of 15/35 in the monomer mixture but a partly crystalline order increased with the amounts of iB in terpolymer. The crystal lattice of the TFE-iB copolymer was affected by the introduction of P. The dose rate dependencies of the polymerization rate and inherent viscosity were 0.8 and -0.2, respectively. The activation energy of polymerization was 2.4 kcal/mole, and the relative reactivity ratio of iB and P for a TFE radical chain end was estimated as 4.50 by the treatment of the free propagating mechanism.
    Additional Material: 10 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A: General Papers 2 (1964), S. 3333-3338 
    ISSN: 0449-2951
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The stereoregularity of polymethacrylonitrile was determined by examining the infrared and NMR spectra of poly(methyl methacrylate) derived from polymethacrylonitrile. Methacrylonitrile was polymerized by n-butyllithium, azobisisobutyronitrile, benzoyl peroxide, and γ-ray irradiation. The J values of the derived poly(methyl methacrylate) are in a range of 56-59, indicating a stereoblock structure. The NMR spectra of the derived poly(methyl methacrylate) showed that the polymers are composed mainly of isotactic-heterotactic structures.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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