Creep of PVDF monofilament sutures: service performance prediction from short-term tests

摘要

Isothermal short-term creep of poly(vinylidene fluoride) (PVDF) monofilament sutures was determined at several temperatures between 10 and 90 deg C under the stress of 10 MPa. Long term service performance was predicted for 10 decades of time. The compliance master curve as a function of time fits a hyperbolic sine equation. The temperature shift factor as a function of the temperature a_T (T) is accurately represented by a general equation based on free volume. A simple relationship between the two parameters of the equation is explored. The viscoelasticity of PVDF is also seen in dynamic mechanical analysis performed at the frequency of 1 Hz. The origin of the viscoelastic character well present in the deformability of the PVDF in service is due to the occurrence of the alpha_c relaxation that is active at approx 50 deg C (E'' peak at 1 Hz).