Date of Award
Master of Science in Engineering (MSE)
Polymer nanofibers are used to develop materials that possess customized characteristics for diverse applications. The applications of nanofibers are influenced by their significant surface-to-volume ratio, the porosity of the nanofiber lattice, and distinctive physicochemical characteristics. The molecular orientation of electrospun nanofibers is a crucial and intricate feature that has a direct impact on the structures and properties of the nanofiber mat. The utilization of Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and X-Ray Diffractometry (XRD), facilitated the determination of the morphology, chemical structure, and thermal properties of nanofibers. The SEM analysis revealed that the nanofibers exhibited a random and interconnected orientation. The findings indicate that the level of crystallinity exhibited by the magnesium oxide-incorporated PCL (ε-caprolactone) nanofibers, surpassed that of the PCL nanofibers. Increased crystallinity indicates chain mobility changes, leading to improved mechanical characteristics. Further evaluation was conducted on the DSC findings. The study delved into the kinetics of non-isothermal crystallization of PCL and MgO-PCL nanofibers with varying cooling rates.
The study used DSC-3 apparatus produced by Mettler Toledo to acquire crystallization information and investigate the kinetics behavior of the two types of nanofibers under different cooling rates ranging from 0.5-5 K/min. Several mathematical models, including Jeziorny, Ozawa, and Mo's models, were utilized to determine the parameters of non-isothermal crystallization kinetics. Mo's approach generates consistent ratios of Avrami exponent to Ozawa exponent (α) that are approximately 1.4 for PCL, MgO-PCL nanofibers, and bulk-PCL. The similarity of α values indicates that the structures of crystallization formed at different levels of relative crystallinity were analogous. The investigation with the Friedman method exhibited an increase in relative crystallinity was associated with a decrease in temperature and a rise in activation energy. According to the Kissinger and Friedman methodologies, it was observed that the activation energy of bulk-PCL was comparatively lower than that of PCL and MgO-PCL nanofibers. The observed phenomenon can be attributed to the nanoconfinement effect, which is characterized by geometric constraints imposed on PCL nanofibers.
Sheena M. Reeves
Prairie View A&M University
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Date of Digitization
John B Coleman Library
City of Publication
Gicheha, D. (2023). Physicochemical Properties Of Poly (Ε-Caprolactone) And Magnesium Oxide Incorporated Poly (Ε-Caprolactone) Nanofibers. Retrieved from https://digitalcommons.pvamu.edu/pvamu-theses/1521