Ethylene Vinyl Acetate Films Research Articles

The morantel sustained release trilaminate: A device for the controlled ruminal delivery of morantel to cattle

In vitro, in vivo performance, and model calculations of drug release from the morantel sustained release trilaminate (MSRT, Paratect Flex® bolus — Pfizer Inc.) are presented. The device consists of an extruded sheet containing drug and ethylene vinyl acetate (EVA) sandwiched between thin films of EVA; a symmetrical pattern of circular perforations is punched through the sheet. Drug release occurs from the uncoated edges of the central lamina. Model release profiles for the device are presented; factors affecting the release rate and release profile are discussed. Both in vitro and in vivo release performance of devices containing morantel tartrate were evaluated and found to compare favorably with one another and the model. The MSRT demonstrated controlled delivery of morantel for 90 days both in vitro and in vivo.

Migration of Irganox 1010 from ethylene-vinyl acetate films to foods and food-simulating liquids

In a series of experiments on the migration of the antioxidant Irganox 1010 from ethylene-vinyl acetate (EVA) films into food-simulating liquids and foods, the antioxidant was found to migrate rapidly from EVA film into n-heptane, 100% ethanol and corn oil. The rate of migration into these media was greater from EVA than from low-density polyethylene (LDPE) under comparable conditions. In contrast, little migration of Irganox 1010 was recorded on exposure of the EVA film to aqueous media, whereas migration from LDPE into such media was relatively high.

The morphology of ethylene—vinyl acetate emulsion

Direct observation through an electron microscope of the microstructure of an emulsion particle of ethylene—vinyl acetate was done by using a freeze-etching method. The spherical emulsion particle is composed of regular-shaped microspheroids ca. 500 Å in diameter. The structure of the emulsion film was also observed with electron microscopy. The contour of emulsion particles and the constituent microspheroids were visible in the surface of ethylene—vinyl acetate film using partially hydrolyzed poly(vinyl alcohol) as an emulsifier. But no contour was observed in the surface of emulsion film using poly(oxyethylenealkylphenol) as a nonion surface-active agent. Partially hydrolyzed poly(vinyl alcohol), strongly adsorbed on the surface of the microspheroids, prevents the spheroids from deforming upon the film forming process. When a nonionic surface-active agent is used mutual interdiffusion of polymer chains and emulsifier may occur and make the polymer film homogeneous.