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  • 1
    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 Bestrahlungsstabilität von statistischen und Blockcopolymeren aus Propen und Ethen (CP, Copolymeres mit 6% Etheneinheiten) mit und ohne Keimbildner (NA) wurde in bezug auf die Bestrahlungssterilisation von medizinischen Gütern verglichen. In beiden Fällen war die Bestrahlungsstabilität von CP in Gegenwart von NA geringer als ohne.Die Zugabe von NA zu CP verbesserte zwar nicht die Transparenz, die Kristallisation erfolgte aber bei höherer Temperatur. Sie hat deshalb den Vorteil kürzerer Formzeiten bei der Produktion von medizinischen Gütern.Die Bestrahlungsinstabilität von CP mit NA rührt von einer unterschiedlichen Kristallstruktur her, weil sich die Form der Spharolite von der des CP ohne NA unterscheidet. Weiterhin wurde durch Chemiluminiszenz-Analyse ein stärkerer oxidativer Abbau in der Probe mit NA beobachtet.
    Notes: The radiation stability of the random and block poly(propylene-co-ethylene) (CP, copolymer with 6% ethylene units) with and without nucleating agent (NA) was compared in relation to radiation sterilization of medical supplies. In both cases, it was found that the radiation stability of CP in the presence of NA was lower than that of CP without NA.Addition of NA to CP did not improve the transparency but the crystallization occurred at higher temperature. Thus, adding NA to CP has the advantage of shorter moulding time in the production of medical supplies.The radiation instability of the CP with NA was due to a different crystal structure, because the spherulite shape differs from that of CP without NA. Furthermore, by the chemiluminescence analysis, a higher oxidative degradation was observed in the sample with NA.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    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 Gamma-Bestrahlung von Polypropylen (PP) verringert dessen Molekulargewicht; die Abnahme ist in PP mit Keimbildner (NA) größer als in PP ohne NA. Bei DSC-Messungen liegt der Schmelzpunkt (Tm) von PP mit NA im ersten Durchlauf deshalb unter dem von PP ohne NA, wogegen es sich im zweiten Durchlauf genau umgekehrt verhält, da die in PP mit NA nach der Bestrahlung kürzeren Ketten nach dem ersten Durchlauf leichter kristallisieren können.
    Notes: By the addition of nucleating agent (NA), the molecular weight of gamma-irradiated polypropylene (PP) decreases more than that of PP without NA. In the first run of differential scanning calorimetric (DSC) measurement, the melting point (T m) of PP with NA was lower than the one without NA because of larger molecular scission which occurred during irradiation. On the contrary, in the second run, Tm of PP with NA, was found to be higher than that of PP without NA. Due to the presence of NA, the molecular chains become shorter during irradiation and therefore rearrangement of the chains is easier during crystallization after the first run, this contributes to an increase in Tm.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 40 (1990), S. 799-810 
    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 both gamma ray and electron beam irradiations on three rubber gloves are compared in relation to sterilization. Two of these gloves are sulfur vulcanized and the other is radiation vulcanized. It was found that the radiation-vulcanized rubber gloves could be used, even at 25 kGy, the sterilization dose used. For all three gloves, it was found that the tensile strength and elongation at break are not significantly affected after irradiation in either gamma rays or electron beam or during storage. The tear strengths, however, decrease with increasing dose and storage, and it was found that degradation was higher in gamma rays than electron beam. The chemiluminescence data show that the rate of degradation is the highest in latex film followed by radiation-vulcanized and sulfur-vulcanized gloves.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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