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An Investigation on Compressive Mechanical Properties of Syndiotactic Polystyrene Gels and the Conductive Behavior of Syndiotactic Polystyrene Ionogels

Ariza, Nathan Robert, Ariza
http://rave.ohiolink.edu/etdc/view?acc_num=akron1541783363046921

Abstract Details

2018, Master of Science, University of Akron, Polymer Engineering.
The term `gel’ encompasses a broad group of materials that range in application from topical ointments to contact lenses and beyond. Gels have been considered as drug delivery vehicles, as artificial tissue, and as scaffolds for bone and tissue growth. In some of these applications, the physical properties of the gels are paramount to the success of its implementation. However, the liquid component of these gels may change over the course of its lifetime due to natural diffusion with the surrounding environment or may be replaced strategically after the gels are synthesized. A serious design question must then be raised. Will this change affect the physical properties of the gel significantly? In the first part, this thesis seeks to determine if there are any changes in the material properties of a gel when different liquids are used to fill the porous solid networks. In the second part, the conductive properties of the iongels are investigated. An ionogel is obtained by replacing the original synthesis solvent with an ionic liquid. Thermoreversible syndiotactic polystyrene gels are fabricated and then used to create various gels by utilizing a simple method based on solvent exchange. This method isolates the solid component and allows the liquid component of the gel to be the sole variable. Five different gel types with various polymer contents for each are fabricated and tested – one aerogel as control material and four different liquid gels. The aerogels are found to have the largest compressive modulus value in uniaxial compression. The gels, in contrast, have widely varying moduli depending upon the liquid that fills the pores. The gels also exhibit different forms of mechanical failure during compression testing further showing that the uniqueness in mechanical properties is originating from the liquid components. Tests using differential scanning calorimetry do not yield any information on the changes in the solid material properties e.g., due to plasticization effects. The mechanical property changes in the gel samples provide a detailed example for the importance of considering the environmental changes a material may endure, especially in highly porous materials. The ionogel specimens show high electrical conductivity. In view of this, a broadband dielectric spectroscope method is used to study the effect of different levels of polymer content on the conductivity of the ionogel. Monolith samples are compared to the bulk ionic liquid over a large temperature range and are found to have a Vogel-Fulcher-Tammann temperature dependence at temperatures above ~-35°C. Below this temperature, the ionic liquid undergoes freezing, thus resulting in a drastic decrease in the monolith’s conductivity. Monoliths with the lowest polymer content (and therefore highest percent ionic liquid) are found to have the highest conductivity with values ranging between 0.23-0.37 S/m. A reduction of the polymer content also leads to reduction of strength of the ionogel to an extent where physical handling breaks the material, emphasizing the importance of balancing the material strength and electrical conductivity of this set of materials.
Sadhan Jana, Dr. (Advisor)
Kevin Cavicchi, Dr. (Committee Chair)
Erol Sancaktar, Dr. (Committee Member)
72 p.
Materials Science; Polymers
Syndiotactic Polystyrene; Gels; Aerogels; Ionogels; Compression; Dielectric; Conductivity; Compressive; Vogel; Fulcher; Tammann; Battery

Recommended Citations

Citations

  • Ariza, Ariza, N. R. (2018). An Investigation on Compressive Mechanical Properties of Syndiotactic Polystyrene Gels and the Conductive Behavior of Syndiotactic Polystyrene Ionogels [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1541783363046921

    APA Style (7th edition)

  • Ariza, Ariza, Nathan. An Investigation on Compressive Mechanical Properties of Syndiotactic Polystyrene Gels and the Conductive Behavior of Syndiotactic Polystyrene Ionogels. 2018. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1541783363046921.

    MLA Style (8th edition)

  • Ariza, Ariza, Nathan. "An Investigation on Compressive Mechanical Properties of Syndiotactic Polystyrene Gels and the Conductive Behavior of Syndiotactic Polystyrene Ionogels." Master's thesis, University of Akron, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1541783363046921

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Akron and OhioLINK.
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