Advisory Committee Chair
Shane Catledge
Advisory Committee Members
Uday Vaidya
Yogesh K Vohra
Document Type
Thesis
Date of Award
2008
Degree Name by School
Master of Science (MS) College of Arts and Sciences
Abstract
Nanocomposite scaffolds based on nanofibrous polycaprolactone (PCL) and nanohydroxyapatite (nanoHA) with fixed polymer compositions (7.5wt%) but different total wt% were prepared by electrostatic co-spinning to mimic the nanofeatures of the natural extracellular matrix (ECM) for natural bone tissue. Electrospinning is used to produce ultra-fine fibers using a high-voltage electrostatic field. The proposed concentrations of NanoHA in polymer were 0wt%, 10wt%, 20wt%, 30wt%, 40wt%, 50wt%. NanoHA was found to be well dispersed in polymers up to the addition of 30wt%, whereas substantial beading, electro-spraying and agglomeration of HA particles was observed in 40wt% and 50wt%. There are several factors which may be responsible for the agglomeration of nanoparticles in solution (such as their shape, size, charge, nature of solvent etc), poor HA dispersion is believed to also be related to the viscosity of solution. The composite scaffolds were characterized for structure and morphology using XRD, EDX, SEM and FTIR. The combined data from EDX, FTIR and XRD analyses have confirmed the presence of nanoHA in the fibrous scaffold. SEM helped in determining morphology of fibers such as presence of beads and agglomeration of HA particles in scaffolds mode with different concentrations. As the nanoHA content in the fibers increases, the surface of fibers observed to become rougher due to presence of beads and agglomeration of iii nanoHA particles. The nano-mechanical property measurement of the electrospun composites was done by nanoindentation technique which reveals that as the nanoHA content increases, Elastic modulus and hardness increases. The average fiber size decreased with increase in concentration of nanoHA in scaffolds, also believed to be due to low viscosity of solution. This is because addition of more nanoHA solution for a given fixed polymer concentration (7.5wt %) made the composite solution less and less viscous. To verify the experimental results from nanoindentation, a theoretical approach using the Halphin-Tsai model [Ref: Fiber-Reinforced Composites by P.K. Mallick] and a generalized law of mixtures was used. The results from theoretical model when plotted against volume fraction of nanoHA showed similar trend, although with higher values, of increase in Young’s modulus with increase in nanoHA in composites as observed experimentally.
Recommended Citation
Tyagi, Parul, "Study Of Nano-Mechanical Properties Of 3D Scaffolds Prepared From Polycaprolactone And Hydroxyapatite" (2008). All ETDs from UAB. 3644.
https://digitalcommons.library.uab.edu/etd-collection/3644