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About Sterilization of
Plastics
One of the greatest difficulties
with sterilization of medical devices is the range of plastics
used in any given device or kit. A simple device or kit may
contain up to 10 different plastics for a range of uses, e.g.
housings, tubing, connectors, valves, and seals. The plastics used
may be chosen for a variety of reasons such as transparency,
mechanical strength, or inertness depending on the application.
The difficulty is that every plastic behaves in a different manner
to the various sterilization methods used. Manufacturers can
easily find that the completed device cannot be effectively
sterilized. If manufacturers make unwise material choices, then it
may be impossible to adequately sterilize the completed device.
The possible sterilization methods
therefore need to be considered as an integral and early part of
the materials selection process for all medical devices using
plastics. An additional complication in the materials selection
process is the multiplicity of grades available, even for a
nominally identical plastic material. For example, PVC is
available in several different major materials families depending
on the production method, (e.g. suspension PVC, emulsion PVC and
mass polymerized PVC, and in tens of thousands of different grades
which will vary according to plasticizers), fillers and other
additives.
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