Organic-inorganic hybrid materials, incorporating nanostructured silica networks within a poly(ethylene oxide) matrix (PEO), were produced via the sol-gel process from water solution mixtures of poly(ethylene oxide) and prehydrolyzed tetraethylorthosilicate (TEOS) in the presence of a trialkoxysilane compatibilization agent, ␥ -glycidyloxypropyltrimethoxysilane (GOTMS). These mixtures were cast into films by evaporating the solvent and finally drying in an air-circulating oven at 60• C. By varying the composition of the alkoxysilane solution mixture and mixing conditions, different morphologies were obtained, ranging from semi-interpenetrating networks of PEO within highly cross-linked siloxane domains, to finely dispersed nanostructured systems exhibiting either co-continuous or particulate structure. The effects of pH, type of solvents, mixing temperatures and time, as well as the concentration of the compatibilization agent was found to be extremely important in controlling the morphology and properties of the final PEO-SiO 2 hybrid films. C

The radiation stability of the pre-irradiated copolymer of polypropylene containing 2.5 wt.-To ethylene units is compared with a copolymer of polypropylene with a nucleating agent with regard to radiation sterilization of medical devices. It is found that transparency property of the propylene-ethylene copolymer is improved through pre-irradiation processes. This finding was compared with the co-polypropylene with nucleating agent which also gives a better transparency property. In comparison, it is found that pre-irradiated copolymer exhibits better radiation stability during irradiation and during storage after irradiation. The radiation stability of the pre-irradiated copolymer is due to its lower crystallinity caused by the formation of branches during the pre-irradiation process. ZUSAMMENFASSUNG:Die Strahlungsbestandigkeit von vorbestrahltem Polypropylen mit 2,5 Gew.-To Ethylenanteil wurde mitr einem Copolymeren aus Polypropylen und einem nukleierenden Agens im Hinblick auf die Strahlungssterilisation von medizinischen Geraten verglichen. Die Transparenz des Propylen-Ethylen-Copolymeren wurde durch die Vorbehandlung verbessert. Im Vergleich mit der ebenfalls verbesserten Transparenz des Copolymeren aus Polypropylen und dem nukleierenden Agens wurde durch die Vorbestrahlung die Strahlungsbestandigkeit wahrend der Bestrahlung und bei der Lagerung des bestrahlten Materials verbessert. Dies wird auf die geringere Kristallinitat des vorbestrahlten Polypropylens aufgrund von bei der Bestrahlung gebildeten Verzweigungen zuriickgefiihrt.

No abstract