Clariant has introduced new polymer compounds with the objective to limit or even eliminate hydrolytic degradation which effects certain materials commonly used in catheters.
The resins offered under the Mevopur brand name will be presented at the MD&M West tradeshow in Anaheim.
In polyether block amides (PEBAs) and thermoplastic polyurethanes (TPUs), the absorbed moisture is likely to cause a breakdown of the polymer chains and reduce the mechanical properties and thus making the materials brittle. This is visible to physicians and surgeons when exposed to X rays and is very prominent in resins with radiopaque fillers.
Hydrolysis remains a risk even after careful pre-drying of the ingredients before compounding and tube extrusion because the moisture can condense from the atmosphere even inside the foil-lined packaging since it’s prone to temperature changes during transition or storage.
Eric Rohr, Medical and Pharmaceutical Segment Manager in North America for Clariant, said: “This hydrolysis effect is variable and difficult to predict. Uncontrolled it creates quality and reliability risks, increasingly the need for vigilance in QA procedures.”
“In addition, the shelf-life of the polymer compounds is less predictable and may be shortened to only a few months. After several years of research and testing, we are pleased to be able to limit the risk of hydrolysis and breakage in these materials, thereby helping device manufacturers improve the reliability of catheters.”
The first and primary indication of chain scission is an increased melt-flow index (MFI) and thus, Clariant researchers compared the MFI of a standard and unmodified tungsten-filled PEBA 35 Shore A compound with a sample of the new Mevopur.
Post ten weeks of storage under the humid conditions, it was revealed that the unmodified compound had more than double the original MFI values and a wider spread. This indicates chain scission and reduction in molecular weight as compared to the Mevopur compound which maintained its MFI values in the same range as prior to the test.
Tensile strength and elongation properties in standard test bars molded from the test materials were similarly unaffected in Mevopur compounds, while the standard material showed signification degradation in these critical properties. Clariant credits the superior performance of the MEVOPUR materials to their proprietary formulation and specially developed processing technology.