Design, Processing, and Properties of Anisotropic Electrospun Rubber/Rubber Microcomposites
Open Access
- Author:
- Hoagland, Sophia
- Area of Honors:
- Chemical Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Patrick Mather, Thesis Supervisor
Scott Thomas Milner, Thesis Honors Advisor - Keywords:
- polymer
material
thermoplastic polyurethane
silicone
anisotropic
composite
electrospinning
electrospun
rubber
elastomer
SEM
DMA
Pellethane
Sylgard
tensile
fiber - Abstract:
- The objective of this work was to develop tougher, more elastic anisotropic rubber-rubber composites by using oriented, electrospun thermoplastic polyurethane (TPU) fibers to reinforce a silicone (PDMS) matrix. Such flexible and variably anisotropic materials appear in natural human and animal tissues and have potential applications in the biomedical and biomimicry fields. Composite materials were fabricated by electrospinning fibrous webs from Pellethane (a commercial TPU) solutions, then saturating with Sylgard 184 (a commercial crosslinked PDMS). The TPU webs and TPU-silicone composites were morphologically characterized using scanning electron microscopy (SEM) and porosity measurements, showing that orientation was achieved by high drum collector rotation speeds but was not a linear function of rotation speed alone. Thermal characterization through dynamic mechanical analysis (DMA) showed that the composite materials retain the phase transitions of the constituents; the relevant peaks are the Sylgard glass transition and melting region around -116 °C and -70 °C to -40 °C, respectively, as well as two Pellethane glass transitions at -118 °C and -30 °C, and Pellethane melting onset around 90 °C. Finally, mechanical analysis through tensile testing demonstrated that the TPU-silicone composites are 10-20× more fracture resistant than Sylgard 184 based on specific work of fracture (wf), and anisotropic for highly oriented samples that were electrospun at a high RPM. The stiffness measured through Young’s modulus (E) showed a reduction for unoriented TPU-silicone composites compared to Sylgard or an unoriented TPU web, and a general trend of lower E for transverse-oriented (90°) samples compared to the equivalent longitudinally oriented (0°) samples. Overall, the electrospun Pellethane/Sylgard composites successfully showed increased toughness and reduced stiffness compared to Sylgard, with a limited ability to adjust anisotropy through fiber orientation based on electrospinning collector rotation speed.