Abstract
The research addresses the limited understanding of the deformation behaviour in mechanically loaded orientated electrospun nanofiber mats, which are crucial for applications such as filtration, catalysis, and sensing. Focussing on polyacrylonitrile (PAN) as a reference polymer, we investigated the mechanical properties of PAN nanofiber membranes with aligned fibre orientations, specifically examining their response to mechanical stresses introduced by notches and punch holes. Mechanical testing revealed that these membranes showed a consistent deformation pattern at the macroscale until fracture. In particular, we observed significant variations in key parameters such as elastic modulus, ultimate strength, and critical stress in different membrane samples, which were also compared with an analytical model. The presence of a notch in the nanofiber mat reduced the strength by 48 %, indicating a remarkable fracture resistance, even in pre-damaged membranes. Furthermore, elongation of fibres along the loading direction was observed to cause the tip of the crack to not grow, providing local reinforcement to the membrane by undamaged nanofibers and enhancing its overall mechanical robustness.