The polymer PTFE (Polytetrafluorethylen) is an outstanding polymer regarding its performance in many ways. It shows a very broad temperature resistance from minus 200°C up to 280°C in permanent exposure. PTFE is also the polymer with the highest chemical resistance among all plastics due to the extremely strong bond between the carbon and the fluor atom. So it is considered as chemically inert. And the third key characteristic is its very low friction coefficient of around 0,1 , which is in the same range as 2 blocks of ice. Beside that it is totally UV resistant and completely hydrophobic.
Lenzing PROFILEN® PTFE yarns
Normally such a number of great advantages are accompanied with some disadvantages; in case of PTFE the disadvantage is the difficulty to produce fibres and filaments out of this polymer. Nevertheless Lenzing Plastics GmbH was able to overcome this hurdle and is producing PTFE fibres and filaments now since more than 30 years sold as Lenzing PROFILEN®. In the beginning the above mentioned key benefits of Lenzing PROFILEN® PTFE were mainly valued in the technical textiles industry, such as the field of filtration or compression packing. Applications were every other textile material is getting destroyed rapidly and the use of PTFE fibres is absolutely necessary.
Nevertheless over the years Lenzing Plastics explored new markets, were PTFE can add value to existing or new products, one of those is the market of medical textiles and permanent implants. PTFE is nearly chemically inert and does not react with any substance, resulting in a very high biocompatibility of Lenzing PROFILEN® PTFE fibres.
Biocompatibility – human cell growth on Lenzing PROFILEN® fabric (day 0 to 8)
And the low friction coefficient and the related low surface tension of PTFE bring two benefits in the medical surrounding: very low skin irritation when used in medical textiles outside the body and the “non-stick effect”. Due to this low surface tension and the slippery surface nothing is sticking on a PTFE fabric.
Coefficient of friction of different fibres
Additionally to those key advantages the strong hydrophobia of PTFE enables an efficient moisture management in a fabric and Lenzing PROFILEN® fibres are extremely durable in contact with the skin. Even many industrial washing cycles will not attack the fibre, as the high temperature window and the chemical resistance prevent the fibre from any damage.
Over the last few years Lenzing Plastics was working to support customers in developments in many fields of medical applications and currently in the following areas Lenzing PROFILEN® PTFE fibres are used successfully:
- Surgical sutures and yarns for permanent implants (heart valves)
Key benefits: excellent biocompatibility, softness, “non-stick effect”
- Garments for patients suffering Psoriasis
Key benefits: low friction of fibre on the skin; “non stick effect”
- Bed sheets for hospitals to prevent Decubitus / Pressure ulcer
Key benefits: low friction, perfect moisture management, “non-stick effect”
In all three applications clinical trials were done to prove the effect of PTFE in the respective surrounding and all showed very positive results, which will be summarized in the following section.
Surgical sutures and yarns for permanent implants:
Every medical device for permanent or partial implant constructed with Lenzing PROFILEN® yarns has to be certified and approved by regulatory affairs in the region it is meant to be sold in. Lenzing Plastics itself got certified with ISO 13485. So far there are no cases where Lenzing PROFILEN® yarns did not pass the evaluation and already several devices are sold regularly, starting from heart valves (class 3 implants) to relatively simple surgical sutures (sterilized yarn with a needle attached)
Garments for patients suffering Psoriasis
Psoriasis is a non-curable disease were actually 4% of Western countries population is suffering from with a clear trend to increase. Current treatment is mainly creams to reduce the itching and prevent further damage of the skin. One of our customers developed a product line using 50 to 100% of Lenzing PROFILEN® PTFE fibres sold as TEPSO® in form of socks, underwear, shirts, sleeves and bed sheets. See also www.tepso.com
TEPSO® garments are not a cure but an effective instrument that provides relief and an increased sense of wellbeing.
To prove the effect of the TEPSO® fabric containing Lenzing PROFILEN® PTFE fibres the following clinical tests were conducted: pilot study, palmoplantar psoriasis study and pustular palmoplantar psoriasis study. In all three studies patients were randomly equipped with garments (socks) either out of the TEPSO® product line or similar products out of 100% cotton. With a quality of life judgement by the patients based on visual analogue scale (VAS) and a global assessment by a physician both products were evaluated after a period of 4 weeks of testing. In all three clinical studies with a total of 52 patients there was a clear statistical significance for the improvement of patient’s global satisfaction as well as positive assessment by the physician. All studies were done by the Dermatological department of the hospital of Prato.
TEPSO® garment for Psoriasis
Bed sheets for Decubitus / pressure ulcer prevention
Decubitus or pressure ulcers, also known as bedsores, are localized injuries to the skin and/ or underlying tissue as a result of pressure in combination with shear and/or friction. Especially in hospitals treating immobile patients this is a major challenge for nursing staff taking a lot of actions to prevent. As it is also a mayor cost factor, medical technology has recognized the problem. There are many approaches to increasing the comfort of those at risk of developing pressure ulcers. But some of these methods are not sufficiently effective, while others – such as mattresses with changing areas of pressure – are still very expensive.
Therefore the Swiss company Schöller Medical AG developed together with Swiss EMPA and the Swiss paraplegic centre bed sheets that reduce friction and enhance the wellbeing of patients. Core component of this fabric are Lenzing PROFILEN® yarns. The new fabric was tested extensively in the lab scale to show the better friction behaviour compared to standard hospital bed sheets (see journal Tribology International 46 (2012) 208 – 214) against a skin model. Later on a clinical study on 20 patients was conducted, all with a subacute spinal cord injury during the last period of the in-patient rehabilitation. Summarized the new bed sheet was favoured to the conventional one by patients and physiological skin examinations showed certain tendencies that underline the positive effects of the new bed sheet. Currently some hospitals specialized on paraplegic patients are equipped with the bed sheets to also get some long term data on a big number of patients. In the relevant group of physicians and textile specialists the new product was received very positively and even presented in the Swiss television as important innovation within the medical technology.
SA scanning electron microscope (SEM) image of the new bed linen showing the dot-matrix like structure (PTFE on the surface) in comparison with a standard cotton bed sheet currently used in hospitals.
The above three market areas with their clinical studies show clearly the positive impact of PTFE for medical textiles in certain areas. Additional to that there are R&D projects in the field of wound dressings containing PTFE yarns. The “non-stick effect” can lead here to a faster healing as recovering skin will not be damaged during exchange of wound dressing.
Lenzing Plastics with its specialized PTFE multifilament yarns is continuing to work hard to support customers who are developing or already selling products in this very promising but also challenging area of medical textiles.