Medical packages have to meet highly specific criteria over and above other types of packages. Protection of contents from microbial contamination and physical damage is a priority. The permeability to sterilizing gas; retention of properties and appearance after sterilizing radiation; printability and aseptic presentation all have to be present at reasonable cost. The most important is maintenance of sterile integrity. In order to have sterile integrity, the medical package must have high barrier properties. Sterility maintenance is the ability of porous packaging materials to act as barriers to microorganisms. The random non- woven structure of spunbonded olefin creates a highly complex maze through the sheet. This torturous path coupled with infinitesimally small openings presents bacteria with an impossible task to penetrate the spunbonded olefin. Thus by virtue of the properties exhibited similar to the "Size Exclusion" principle, spunbonded olefin maintains permeability for gas sterilization but not for microorganisms. The immediate consequences of this morphology are: high opacity, high filtration efficiency, acceptable to high air permeability and excellent strength. Strength of a spunbonded sheet is directly related to the strength of the individual fibers and how are they bonded. It is clear that to have an effective material; strength, permeability and barrier have to be balanced in an optimum structure. Packages made from spunbonded olefin can be sterilized by ionizing irradiation which is commercially exposure to ionizing radiation, high energy electron from electron beams or gamma rays from Cobalt-60 or Cesium- 137 radioisotopes. Irradiation does not leave a residue in the spunbonded olefin and it does not make it radioactive. The low energy level of Cobalt and Cesium isotopic gamma rays does not induce any radioactivity. Although, irradiation has the same sterilizing effect on spunbonded olefin packages as ethylene oxide gas treatment, it does not appreciably raise the temperature of the medical product as does an Eto cycle. One of the characteristic advantages of the irradiation process is that the medical product can be irradiated even after package has been sealed so recontamination after processing is prevented. It is not possible for the medical product itself to become radioactive, and there are no residues of any kind left by this process. Once treated, medical packages are considered sterile and ready for use.
Library of Congress Subject Headings
Polyethylene--Effect of radiation on; Polyethylene--Permeability--Testing; Plastics in packaging; Plastics--Effect of radiation on
Department, Program, or Center
Packaging Science (CAST)
Sheth, Samir A., "Effect of low level radiation on the barrier qualities of spunbonded olefin" (1991). Thesis. Rochester Institute of Technology. Accessed from
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