| 摘要 |
<p>A method of forming porous articles with a varying pore distribution by extrusion from a billet with varying lubricant distribution. A single-polymer polytetrafluoroethylene is extruded and then stretched and sintered to provide a differential porous PTFE structure composed of fibers and nodes connected to one another by these fibers. The microfibrous structure has a portion within the cross section that possesses a different pore size, accompanied by a different node and fiber geometry, than adjacent areas within the cross section. A tube (10), having elongate nodes (12), fibrils (14), an inner surface (16) and an outer surface (18), of an expanded, porous fluoropolymer material, which is useful as a vascular graft, is formed. In a vascular graft, the pores taper inwardly, providing a fluid-tight lumen wall structure that prevents leakage, yet promotes cellular growth and natural tissue generation. A node structure of radially-oriented plates provides flexibility, suture strength, and enhanced protection against collapse.</p> |
