POM medical grade

POM intended for medical or healthcare applications is an engineering plastic that is resistant to multiple cleaning and disinfecting materials, as well as to a number of solvents. Furthermore, POM medical grades can be hot steam sterilised by the medical industry's usual methods.

Fields of application are diverse and have consisted of medical segments such as joint reconstruction, traumatology, spinal procedures and many more. While medical grade POM products as TECAFORM AH MT have historically been used for such medical devices as sizing trials in knee, hip and shoulder replacement procedures for quite some time, Ensinger favors slightly higher performance materials such as PPSU (polyphenylsulfone) or PEEK (polyetheretherketone) because of their superior physical, chemical resistance, and biocompatible properties. These biocompatible plastics are sold under the tradenames TECASON P MT (PPSU) and TECAPEEK MT (PEEK).

Key characteristics

A basic feature of medical POM is its strength. The material is stiff, firm and hard, has good sliding and friction properties and has very good electrical insulation. Other properties include:

High chemical resistance, especially to alkalis, solvents and fuels
High strength, hardness and spring stiffness
Low moisture absorption
Good dimensional stability

Steam sterilisation resistance

Hot steam sterilisation: for the most part, POM for healthcare applications shows no significant loss of mechanical properties up to 800 sterilisation cycles. However, discolouration could be seen at 200 sterilisation cycles. At around 500 cycles, colour change (yellowing) could also be seen. For these reasons, Ensinger may recommend higher performance material options such as PPSU (polyphenylsulfone) or PEEK (polyetheretherketone).

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.