A new Test and Apparatus for Characterizing the Time-Dependent Recovery of Polymeric Fibres and Yarns From Bending

A new test and the relevant apparatus for characterizing the mechanical response of fibers or yarns to bending forces and more specifically their capability to recover their original conformation after bending are presented. The inherent viscoelastic behaviour of single fibers and yarns, and its time-dependence, is considered. The most important novelty with respect to previous techniques is the possibility of monitoring and recording the evolution of the deformation displayed by a fiber or a yarn after bending, thus providing information about its kinetics. Other important features of the apparatus are the fully automated system of mechanical operation and data acquisition, the control of environmental conditions (i.e. temperature and humidity) and a multispecimen facility to observe and account for the inherent variability of samples. Some examples of preliminary results are reported.