A new sensitive method is described for measuring the permeation and diffusion of oxygen through polymer films. For these measurements an ethyl cellulose film containing 9,lO-dimethylanthracene (DMA) and erythrosin may be either tightly sealed between two pieces of sample film in a simple cell or sealed in a pouch made from the test material, and is used to absorb oxygen which has passed through the polymer film sample from the air. On illumination this oxygen is converted by the erythrosin to singlet oxygen which then reacts with the DMA. After an initial scavenging period, the rate of permeation of oxygen under the atmospheric pressure gradient across the film is monitored by determining the rate of disappearance of DMA spectrophotometrically.
ZUSAMMENFASSUNG:Es wird eine neue, empfindliche Methode fur die Messung der Durchdringung und Diffusion von Sauerstoff durch Polymerfilme beschrieben. Ein Ethylcellulosefilm, der 9,lO-Dimethylanthrazen (DMA) und Erythrosin enthdt, wird fur die Absorption von Sauerstoff venvendet, der aus der Luft durch die Polymerfilmprobe dringt. Bei Belichtung wird der Sauerstoff durch das Erythrosin in die Singulettform uberfuhrt, die dann mit dem DMA reagiert. Nach einer anfanglichen Reinigungsperiode wird die Durchdringungsgeschwindigkeit vom Sauerstoff unter dem atmosphLischen Druckgefdle durch den Film verfolgt, indem man die Geschwindigkeit des Verschwindens vom DMA spektrophotometrisch bestimmt. Fur diese Messungen kann der Ethylcellulosefilm entweder in einer einfachen Zelle dicht zwischen zwei Probefilmstucken eingefugt oder in einem Beutel von Probematerial eingeschlossen sein.
Das Endoperoxid (Il)," das zur Herstellung von Singulett‐Sauerstoff unter milden wasserfreien Bedingungen dient, wird aus Tetramethylnaphthalin (I) hergestellt.
SynopsisA novel method for measuring the permeation of water vapor through polymer films is described. A cellulose detector film incorporating cobalt chloride in a blue anhydrous form is sealed between two pieces of test film in a specially designed cell. The cell is placed in a controlled temperature and humidity cabinet, and the disappearance of the blue color of the cobalt chloride is recorded spectrophotometrically as water vapor diffuses through the test film into the detector film. This simple method of determining water-vapor-transmission rates is more rapid than standard gravimetric procedures because of the highly sensitive detection technique.
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