Mechanical Properties of Synthetic Artificial Grafts

Abstract

By using a tensile testing instrument (UTM-4L Toyo Baldwin) and a Log-timer (Japan Synthetic Rubber Co.) stress-strain diagrams and stress relaxation curves were examined with three kinds of synthetic artificial grafts, Tricot knitted Dacron (TD), Woven Dacron (WD) and Gore Tex (GT), in wet and dry states. Each graft was cut up into equal pieces with the initial length of ca. 10 mm and the width of 5.0 mm. The specimen of WD was composed of 22 warps in longitudinal (Lon) and 20 wefts in circumferential (Cir) directions and the specimen of TD was composed of 15 wales in Lon and 8 courses in Cir. In the wet state, the strips were immersed in Ringer's solution at 20°C or 37°C while in the dry state the strips were kept at 20°C with 60-65% in humidity or at 37°C with 64-67% in humidity. Stress-strain curves were fitted by an exponential function: σ=σ0{exp (γ/γ0)-1}, where σ is the stress, γ is the Green-St. Venant strain and σ0 and γ0 are constants evaluated by a non-linear least squares method for the stress up to 5×107dyn/cm2 The relaxation force f (t) was fitted to an equation f(t)=f0/(t-t0)m with f0, t0 and m being constants determined by a least squares method. It is discussed in relation to the structure and the material of the artificial grafts. © 1989, The Society of Rheology, Japan. All rights reserved.