With the exception of what happens to the particles included in the 0.2–1.0-μm range, with bigger particles, we did not observe
a significant variation in their percentage ratio compared with the total calculation. This probably means that the physical
degradation of the material in analysis, which leads to particle release, does not vary qualitatively during the autoclave
cycles, although there is acceleration after the twentieth cycle.
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We concluded that visors subjected to repeated autoclave cycles show an increase in particle release dependent on the number
of cycles to which they are submitted. Particles of 0.2- and 0.4-μm diameters increase proportionally in greater measure;
those particles that are present on the exterior surface of the sample and not incorporated in the polymer are washed away
from the glasses' surface during the autoclaving.
Check of the elastic strip particle release. The treatment of elastic strips in autoclave cycles shows a remarkable increase in particle release after five autoclave
cycles. The particles then settled until the end of 30 cycles of treatment. The biggest increase is that of the particles
of about 0.2-μm diameter.
Figure 3 shows the percentage variation of particles of various sizes. There is an interesting absence of variation of particle
composition after 30 autoclave cycles. In the 2.0–1.0 μm range, the increase in the particles released for strips follows
a linear course proportionate to the number of autoclave cycles. The most important percentage is constituted by 2.0 μm-dimension
The increase in the particle release from the elastic strip in the considered range is related to the number of autoclave
cycles to which the strips are subjected. Based on these data, we concluded that elastic strips subjected to repeated autoclave
cycles show an increase in the particles released dependent on the number of cycles to which they are submitted. Specifically,
the number of 2.0-μm particles increased more than the others. Later, the number of 0.2-μm particles released decreased and
the number of larger particles decreased, probably because of the second phase of material degradation.
Based on the data, the masks that are currently available have been further developed by the manufacturer, both in the frame
color and in the elastic strip material, to better satisfy pharmaceutical customer' needs. These adjustments contribute to
a reduction in the particles released, thus improving the masks' performance and usefulness in controlled-contamination areas.
Maurizio Battistini is the general manager of APP Pharmaceutical Partners, Switzerland, Via Cadepiano 24, CH-6917 Barbengo, Switzerland, Maurizio
Submitted: March 2, 2006\. Accepted: April 14, 2006
Keywords: aseptic processing, cleanroom, clothing systems, microbial sterilization