Mechanical & Materials Engineering, Department of


First Advisor

Yuris Dzenis

Second Advisor

Nicolas Delpouve

Date of this Version

Summer 7-16-2021




A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Mechanical Engineering and Applied Mechanics, Under the Supervision of Professor Yuris Dzenis. Lincoln, Nebraska: July, 2021

Copyright © 2021 Justin Busnot


This thesis presents a study on the thermomechanical properties of Bombyx Mori silk nanofibers. These nanofibers were obtained from silkworm cocoons which were degummed to separate the fibroin and the sericin, the two proteins that make up silk. The fibroin was then centrifuged to remove insoluble particles and stored and 4°C before the electrospinning process. A parametric study of the electrospinning process was carried out in order to identify the factors allowing to obtain optimal mechanical properties. The current as well as the flow rate applied, the diameter of the syringe, the distance separating the syringe from collector or even the environmental conditions and the concentration of the solution are all parameters influencing the specific characteristics of the nanofibers obtained, in particular their diameter, their distribution and their orientation. A range of concentrated solutions from 1% to 6% silk fibroin were prepared with Hexafluoroisopropanol (HFIP) as a solvent. These solutions were electrospun using process parameters which corresponded to the best conditions for electrospinning. The morphologies of these nanofibers were characterized by scanning electron microscopy (SEM). Their mechanical properties have also been evaluated using the lab nanomechanics testing system specially designed for single fiber tensile testing enabling to link the influence of electrospinning parameters to the final properties of silk nanofibers. The thermal properties of the degummed silk fibroin were also investigated using differential scanning calorimetry (DSC) which allowed to determine the specific phase transitions and crystallinity of degummed silk fibroin and silk nanofibers. Moreover, Raman spectroscopy has been performed to characterize the molecular composition and the external structure of degummed silk and silk nanofibers.

Advisor: Yuris Dzenis