Mechanical properties of small-diameter polyurethane vascular grafts reinforced by weft-knitted tubular fabric.

Polyester filament yarns of different Deniers were knitted into tubular fabrics with different densities and thicknesses on a specially designed weft-knitting machine. The developed tubular fabric was used to reinforce polyurethane vascular graft and thus a kind of composite vascular graft was fabricated with a small inner diameter of 4 mm. Tensile properties of the reinforced composite vascular grafts were compared with the control tubular fabric and the pure PU vascular grafts. Elasticity and strength of the reinforced vascular grafts were improved compared with the weft-knitted tubular fabrics. Strength of the reinforced composite vascular grafts was almost 5-10 times of the strength of the pure PU vascular grafts. As the PU content increased in the reinforced composite vascular grafts, the wall thickness of the vascular graft and its strength increased, but the initial modulus of the reinforced composite vascular grafts remained similar to that of the weft-knitted tubular fabric, and the PU content showed little influence on the initial modulus of the reinforced composite vascular grafts. Microporous structure can also be fabricated in the wall of the reinforced composite vascular grafts.