Joao F. Mano(a, b), Joao L. Lopes(c), Rui A. Silva(c), Wiltold Brostow(d)

(a) Department of Polymer Engineering, University of Minho, Campus de Azurem, 4800- 058 Guimaraes, Portugal
(b) 3B's Research Group- Biomaterials, Biodegradables and Biomimetics, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
(c) ISEP- Instituto Superior de Engenharia do Porto, CIEA, R Dr. Antonio Bernardino de Almeida, 431 4200-072 Porto, Portugal
(d) Laboratory of Advanced Polymers and Optimized Materials (LAPOM), Department of Material Science and Engineering, University of North Texas, Denton, TX 76203-5310, USA

ABSTRACT

Isothermal short- term creep of poly (vinylidene fluoride) (PVDF) monofilament sutures was determined at several temperatures between 10 and 90 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 hyperbolc sine equation. The temperature shift factor as a function of the temperature aT (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 subscript c) relaxation that is active at ~ 50 C (E (superscript n) peak at 1 Hz).