Machine Design

Anticlot PVC copolymer

The tendency of blood to clot or coagulate when it contacts foreign objects poses problems during open heart surgery, dialysis, platelet collection, wound dress, and catheter insertion procedures.

One application for the resin is a heat exchanger for out-of-body processing of blood during critical medical procedures. A thin layer of the Vestolit compound will be coextruded with standard grade PVC to produce tubing, catheters, and other medical devices to help prevent blood clots.

A new resin from German-based Vestolit incorporates blood-clot-preventing molecules that permanently affix to the PVC polymer backbone. These bioactive components simulate the anticlotting (antithrombogenic) messages generated in living blood vessels by the presence of naturally occurring heparin in the body. Engineers with Teknor Apex, Pawtucket, R.I. (, estimate that it will take about two years to develop compounds based on the resin.

Coextruded tubing, catheters, extracorporeal circuits, and other medical devices made from the new PVC copolymer and standard medical-grade PVCs reportedly will offer significant cost saving compared to antithrombogenic coatings currently applied to the inner surfaces of such devices. "While compounds based on these specialized copolymers will cost more than standard-grade vinyl, designers can minimize costs by coextruding the compound onto standard PVCs in thin layers," says Peter M. Galland, industry manager for Teknor.

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