Date of Award

May 2019

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biomedical and Chemical Engineering

Advisor(s)

Ian D. Hosein

Keywords

Electrospinning, Material Science, Polymer

Subject Categories

Engineering

Abstract

Electrospinning is a versatile and inexpensive method to fabricate micron-sized polymer fibers, and it has been employed in this work to develop highly anisotropic fibrous composites. Previous work has detailed the properties of using electrospinning to fabricate fibrous anisotropic composites that was achieved by embedding stiff fibers in an elastomeric matrix. The goal of this work is to achieve anisotropic composites through creating a layering of rigid and elastic fibers in a laminate structure using primarily electrospinning in the fabrication. The composite produced has a unique deformation pattern when strained perpendicularly. The rigid fibers experienced no entanglement with each other and were able to separate from each other without hindrance. This allows a large differential in the stiffness in different directions. Through changes of the composite variables like polymer fiber diameter, and the percentage of the elastic polymer in the laminate, an optimization of anisotropy was determined.

Shape memory induced optical change in a new sensing materials was investigated using a thermomechanically active polymeric film incorporating dispersed silica nanoparticles. This was an improvement upon prior research where a similar effect was achieved using an elastomeric matrix. The advantage to using a shape memory polymer is that the actuation and optical change of the material can occur at a moment triggered by environmental thermal stimulus. Through a thermal change, the material recovers programmed strain and returns from a temporarily opaque state to with base state of optical clarity. This idea was expanded upon by incorporating the process of functional grading to the polymerization process. This is a method to spatially grade the material’s glass transition temperature using a post cure heating stage. The staged recovery of this material has been demonstrated with a change in its optical translucency following the same recovery.

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Open Access

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