Abstract
Stress relaxation and hysteresis curves were measured for six types of surgical sutures, i.e. Plain and Chromic Catguts, Dexon, Silk, Nylon and Nespolen, by means of the Tensilon (UTM-4L, Toyo Baldwin). The relative relaxation strength or the per cent decrease of stress at 10m was high in Silk and Nylon, while low in Plain and Chromic Catguts. The relative relaxation strength did not depend significantly on the size in each kind of sutures except Silk, Nylon and Nespolen with size No.1-0. Stress relaxation was measured over the time range of 0.01s-600s. The results were well reproduced through f(t)=f0/(t-t0)m. The constants f0, t0 and m were evaluated by the least square method. The relaxation spectra H(τ) for simple elongation were analytically derived as H(τ)=(tm/τ)m{Eg/Γ(m)}exp(-tm/τ) by using the inverse Laplace transformation of the relaxation modulus E(t), where Eg is the glasslike elastic modulus, tm=t1-t0, t1 time with the practically maximum stress, Γ(m) the gamma function.
