ID-12-P-2873 The response of nanofibrous mats to mechanical stress

Nanofibrous materials are being utilised in various industries, for example, biomedicine, pharmacy, filtration, cosmetics, etc. Even though commercial nanofibers are produced as nonwoven fabric mats, a single fibre is usually tested for mechanical properties and not the whole mat. As far as the final products differ, for instance, in the fibre density, sheet thickness or surface finishing process (plasma treatment, etc.), the mechanical properties differ, too. Unfortunately, there is an absence of a reliable method that provides sufficient mechanical feedback on the nanofibrous mats for the users and manufacturers.
Mainly the fragility, inhomogeneity and geometrical characteristics are the major pitfalls for assigning the results to standard mechanical constants. The home-built device solves these problems and correlates the stress and strain states with the changes in the nanofibrous sheet. The stress is applied to the nanofibrous mat inside the chamber of a SEM microscope and simultaneously the mat is imaged from the top and from its side at different magnifications. The results that include the changes in the thickness of the mat, thickness of the fibres, density of the fibres and fibre orientation, are directly related to the mechanical properties of the mat. The approach reveals the true stress in the mat, the level of isotropy while stress is applied, brittleness and the inner interactions of fibres within the mat. Even the mechanical constants such as elastic modulus are determined with higher precision. The conclusions based on this analysis can help to target specific mechanical properties in the process of manufacturing or to choose the material which is most suitable for certain application (cell seeding, filtering, etc.).