Polymer Sterilization Table

The properties of polymers can be affected by the sterilization method used. Some polymers can undergo hydrolysis, chain-scissioning or cross-linking reactions which can cause embrittlement or degradation. Because this sterilization table is for general information only, and does not consider all grades of a specific polymer family, Entec Polymers strongly advises that customers perform their own sterilization testing to ensure that a given plastic material can meet their specific requirements.

The common sterilization methods used are briefly described below.

DRY HEAT STERILIZATION

• Typical cycle of 160°C for 2 hours, 170°C for 1 hour or 180°C for 1 hour.

• Advantages are that it is simple and effective and that it is suitable for polymers that are sensitive to moisture, steam or radiation.
• The main disadvantage is the high temperatures that are used may be too high for some polymers.

GAMMA STERILIZATION

• Gamma sterilization uses high energy radiation from a Cobalt 60 source. Typical dosage is 2.5 MRad (25 kGy).
• Advantages are its simplicity, efficiency, speed, and that it does not involve any chemicals or leave any toxic residue.
• The main disadvantages are the high initial capital investment cost and the incompatibility with many polymers.

E-BEAM STERILIZATION

• E-Beam sterilization utilizes an accelerated electron beam with a common dosage of 3.5 MRad (35 kGy).
• The main advantage of E-Beam is that it causes less degradation as compared to gamma sterilization.
• The main disadvantage is the lack of penetration which limits E-Beam to thin polymer parts.

X-RAY STERILIZATION

• Uses ionizing energy from high powered electron beam accelerators to generate X-rays.
• Advantages of X-Ray sterilization include similar penetrating properties as Gamma, but faster, more flexible and more environmentally friendly.

AUTOCLAVE (STEAM) STERILIZATION

• Typical cycle is conducted at 42°C for 2.5 hours or 55°C for 1 hour at 75% relative humidity.
• Advantages are its efficiency, the low temperatures used, the high penetration and the compatibility with most polymers.
• The main disadvantages are that it leaves a toxic residue and it has some reactivity with certain function groups like aminos.

ETHYLENE OXIDE STERILIZATION

• Typical cycle is conducted at 121°C for 30 minutes or 134°C for 7 minutes.
• Advantages are that it is fast, simple, and leaves no toxic residue.
• The main disadvantages are the high temperatures, pressures and moisture make it unsuitable for many polymers.

NO2 STERILIZATION

• Uses low temperature with minimal pressure, fast cycle times with no toxic residue.

VHP STERILIZATION

• VHP sterilization is vaporized hydrogen peroxide. It can be used for many heat sensitive or moisture sensitive polymers.
• Advantages of VHP include safety, effectiveness, low moisture environment and no toxic residue.
• The main disadvantages are that this will damage nylon based materials and is very expensive.

VPA STERILIZATION

• VPA sterilization is vaporized peracetic acid. It can be used with heat sensitive devices that can be immersed.
• Main advantages of VPA sterilization include safety, short cycle times and no toxic residue.
• Disadvantages of VPA sterilization are that it is only suitable for small items and they have to soak in the solution.

OZONE STERILIZATION

• Ozone sterilization is a low temperature (30 - 35°C) sterilization method that takes about 4 hours.
• Main advantages of Ozone sterilization are its low cost and safety and it requires no aeration period and leaves no toxic residue.
• The main disadvantage of Ozone sterilization is that it is not compatible with many polymers and rubbers.

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