Fig. 2. Procedure for stretching supercontracted fibers. The fiber is allowed to fully supercontract in water at 20°C for 10 min down to a length L_SC (A). The fiber is stretched up to length L_A with a force F_A and their ends are clamped in this position (B). Water is removed after 10 min and the fiber is allowed to dry overnight. Stresses are built in up to a force F_B as a result of drying (C), and are allowed to relax by unloading to a final length L_C (D). The length L_C is considered as the base length to calculate strain. Stresses are calculated under the assumption that the volume remains constant throughout the process. The evolution of the forces during the process are sketched in the inset as an F-L plot. F_A, force required to stretch to length L_A; F_B, force built up in the fiber after drying.