MATERIALS | MEDICAL TUBING
Exgineering says that transitional extrusion integrates dissimilar materials more
smoothly, which can improve quality and reduce cost
Transition extruded component
Traditional assembly
Here, the company has applied its new concept
of ‘etched’ PTFE liners, which have internal diam- eters down to 0.1mm.
Transitional devices Stephen Davis, a scientist at Switzerland- based Exgineering, said that ‘transitional extru- sions’ could improve the quality – and potentially reduce the cost – of extruded medical devices. Transitional extrusion allows the ‘blending’ of two separate materials in an extruded product like a catheter tube. However, the integration between the two is smoother, he said, and avoids some disadvantages of the traditional ‘segmented’ approach. “The goal of this technology is meant to gener-
ate a paradigm shift around the way catheters are designed,” he said. Part of the approach is to understand – and manipulate – the flow behaviour of the two differ- ent materials, he said. In Exgineering’s case, it was using two different medical grades of Pebax – 4033 and 7233. Ordinarily, he said, the two Pebax tubes would be made separately, then aligned over a core and joined using butt welding. Here, the ‘blended’ tube can be made in a single process. The ability to make the catheter tube in a single
operation has several advantages, including: a wider variety in Shore D hardness between the materials; simpler production; greater bond strength between the two materials; and better pushability and kink resistance. For instance, the bond strength of a tube made using the traditional (segmented) approach was around 5lbs, had low elongation and failed at the weld. Using the transitional approach, the strength was closer to 7lbs, and had high elongation. The push force required for the transitional
product was also smoother, he said. Davis added that one advantage of this method included was that it allowed direct extrusion
18 PIPE & PROFILE EXTRUSION | May 2020
through the braid. “It’s an enabler of complex design – optimising device performance based on material properties required rather than assembly limitations,” he said.
Flexible friend Arkema – which manufactures Pebax – talked about advances in the material for medical applications. Mohana Nagda, a business development engineer at Arkema Technical Polymers, told delegates that the elastomeric materials have a wide range of properties (such as hardness), so are appropriate for many catheter components. A development grade, called 72R53, is aimed at medical tubing and balloon catheters, she said. In comparison with an established grade – 7233 – it boasted a higher modulus, higher yield stress and strain – and thus a better mechanical performance for balloon catheters. “For multi-layer catheters, 72R53 – which is
PA11-based – will have a good adhesion with PA12-based layers,” she said. Another PA-11 based material, Rilsan Besno Med (which is bio-based), showed superior modulus and a burst pressure almost twice that of Pebax grades. n AMI’s forthcoming Medical Tubing & Catheters conference takes place in San Diego, USA on 23-24 September 2020. For more details, visit the conference website, or contact event organiser Lorna Grey (
lorna.grey@
ami.international) on +1 610 478 0800.
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.apollomedex.com �
www.dsm.com �
www.ineos.com �
www.teel.com �
www.junkosha.co.jp �
www.exgineering.com �
www.arkema.com �
www.ami.international
www.pipeandprofile.com
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