טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentBurman Michael
SubjectInvestigation of Mechanical Properties of Polymer Nanofibers
DepartmentDepartment of Mechanical Engineering
Supervisor Professor Eyal Zussman
Full Thesis textFull thesis text - English Version


Abstract

Polymer nanofibers, as well as polymer nanotubes, are intriguing one-dimensional nano-materials due to their unique mechanical and thermodynamic properties, and large surface area-to-volume ratio. These properties make them ideal building blocks for the development of next-generation solar cells, sensor systems, and tissue engineering scaffolds.

Also, mechanical characterization of such nano-objects, is a challenging technological task.  The main difficulties arise due to a lack of technology in handling and further on mounting of such nano-scale objects. The requirements associated with application and measurement of nano-Newton scale forces and nanometer scale deformations further increase the inherent complexity associated with nano-mechanical testing.

In this work, individual polymer nanofibers (Nylon 6,6) were characterized by tensile and bending deformation. As a part of the mechanical characterization, a new non-destructive method for mechanical characterization of polymer nanofibers has been developed as well, as a nano-tensile experimental mechanical system based on utilization of optical microscope.

The elastic modulus of the nanofibers was found to abruptly increase once the fiber diameter decreased below a critical value. Analysis of these results, together with microstructural analysis, revealed that this phenomenon is not attributed to the influence of the surface energy of the material, which becomes significant as the object's size decreases, but rather to the confinement of the polymer's supermolecular structures, which results from a decrease in the diameter of the nanofibers.