Sterilisable and autoclavable plastics

In accordance with DIN EN 285, all surfaces of the objects being sterilised must be exposed to pure saturated water vapour at 134 °C for at least three minutes. Steam sterilisation or autoclaving is regarded as the safest and cheapest of all the sterilisation methods. However, the high process temperatures involved makes it less suitable for materials sensitive to heat and hydrolysis.

• PEEK medical grade
  TECAPEEK MT shows no significant loss of mechanical properties, even at more than 1,500 sterilisation cycles. Also, further negative influences like discolouration or colour change (yellowing), or even calcification are not seen above 1,500 cycles.
• PPSU medical grade
  TECASON P MT shows no significant loss of mechanical properties until 800 sterilisation cycles. Also, significant discolouration is not seen below 1,000 sterilisation cycles. 
• POM-C medical grade
  Acetal copolymers used in health care applications will not typically show significant loss of the mechanical properties up to 800 sterilisation cycles. However, discolouration may be seen at 200 cycles. At around 500 sterilisation cycles, a colour change (yellowing) may also be seen.
• PP medical grade
  TECAPRO MT shows no significant loss of mechanical properties until 800 sterilisation cycles. However, discolouration and colour change (yellowing) is seen at 200 sterilisation cycles (does not apply to TECAPRO MT black). 

Sterilisation tests were performed using plastic test specimens without cleaning cycles. The sterilisation temperature was 134°C with a sterilisation time of 10 min. and a drying time of 20 min. The chamber pressure was 3 bar. Other effects influencing the cleaning process (with Ecolab, Borer etc.) were not investigated. Due to the chemical resistance of the individual materials and practical experience it must be assumed that the cleaning cycles have a significant influence on the sterilisation resistance. The sterilisation resistance, in particular of PP-HT and to a lesser degree POM-C, is significantly impaired by this. It must therefore be assumed that the sterilisation resistance will be significantly lower than described. We typically define PP-HT with approx. 200 sterilisation cycles and POM-C with approx. 300 - 400 cycles.

With hot air sterilisation, germs are killed off by dry heat under high thermal load (180°C) over a period of at least 30 minutes. This process is no longer permitted due to a large number of uncertain factors and has therefore now been replaced by other methods in most cases.

Medical grade materials which are very resistant to hot air are:

• TECAPEEK MT
• TECAPEEK MT CF30
• TECAPEEK MT CLASSIX^TM

Resistant MT materials are:

• TECASON P MT

TECAPRO MT is not resistant.

Sterilisation with hydrogen peroxide plasma is suitable for all plastics, however, it is costly and requires elaborate equipment. Highly reactive hydroxy and hydroxyl radicals kill the microorganisms at temperatures of just 45°C over periods of 45 to 80 minutes; the plasma is removed by ventilation. The risk of corrosion is almost non existent, and there is no toxic residue that would require prolonged degassing.

Medical grade materials which are resistant to plasma are:

• TECAPEEK MT
• TECAPEEK MT CF30
• TECAPEEK MT CLASSIX^TM
• TECASON P MT
• TECAPRO MT

Sterilisation using a microbiocidal gas such as formaldehyde or ethylene oxide is always carried out at temperatures between 48 and 60°C. Due to the low temperatures, this process is suitable for temperature sensitive materials. The efficiency of formaldehyde is comparable to that of ethylene oxide, but its lower toxicity permits shorter degassing times. Both are mainly used for disposable articles.

Medical grade materials which are resistant to gas are:

• TECAPEEK MT
• TECAPEEK MT CF30
• TECAPEEK MT CLASSIX^TM
• TECASON P MT
• TECAPRO MT

Sterilisation by radiation is a gentle method that is suitable for almost all types of plastic and uses either gamma rays or a beam of highly accelerated electrons. These processes are cost and equipment intensive, so they are mainly used for sterilisation of disposable products on an industrial scale.

Medical grade materials which are resistant to gamma radiation are:

• TECAPEEK MT
• TECAPEEK MT CF30
• TECAPEEK MT CLASSIX^TM

Resistant MT materials are:

• TECASON P MT

TECAPRO MT is not resistant.