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INVESTIGATION OF THE SHAPE MEMORY BEHAVIOUR OF STEARIC ACID SWOLLEN, CROSSLINKED EPDM ELASTOMERS

Zhou, Lei
http://rave.ohiolink.edu/etdc/view?acc_num=akron155560618552726

Abstract Details

2019, Master of Science, University of Akron, Polymer Engineering.
Shape memory polymers (SMPs) were fabricated by swelling non-latex rubber band with stearic acid. Stearic acid would give SMPs better shape memory properties than other fatty acids. This combination of elastomer and crystalline small molecule has been proven to be a feasible and straightforward path to make SMPs. Stearic acid/non-latex rubber blend SMPs with different wt% fatty acid were fabricated and their shape memory properties and mechanical properties were also investigated to study how their shape memory properties and mechanical properties change with weight fraction of stearic acid in the blend. The commercial non-latex EPDM rubber bands are cheap, easy to get and they do not have strain-crystallization. The swelling process endowed them with shape memory properties. With wt% stearic acid higher than 40% where the temporary networks formed by stearic acid are continuous, the blend exhibits an outstanding shape fixity greater than 90%. One the other hand, all stearic acid swollen EPDM shape memory blend shows excellent recovery greater than 90%. The thermal-mechanical properties of the blend were investigated by conducting oscillating frequency temperature sweeps on prepared samples using Dynamic Mechanical Analysis (DMA). The influence of the weight fraction of stearic acid in the blend on modulus were studied. The higher the wt% of stearic acid, the higher the storage modulus (E’) of the composite. A decreasing loss modulus (E”) with increasing wt% stearic acid was also observed when the blend was heated from 25°C to 120°C. Furthermore, comparisons between stearic acid swollen non-latex EPDM rubber band and stearic acid swollen natural rubber band were studied to determine how the choice of elastomer would affect the properties of elastomer/small molecule shape memory blend. Crosslink densities of both rubbers were tested and calculated with Flory-Rehner equation. Strain sweep tests were conducted on DMA at 1 Hz frequency and 1 to 10,000 μm amplitude. Generally, the higher the SA wt% the higher the storage modulus. The comparison of strain sweep tests results of both rubbers show that EPDM rubber which has lower crosslink density also exhibit a lower storage modulus than SA swollen natural rubber. The comparison indicates the choice of elastomer would affect the mechanical properties of the blend. Finally, the alignment of the stearic acid phase crystalline was tested by SAXS and discussed. SA swollen rubbers do not have a spacing at 46.6 Å compared to SA swollen natural rubber. Since both swollen rubbers acquire excellent shape memory properties, the 46.6 Å spacing is considered insignificant to the shape memory properties of the blend.
Kevin Cavicchi (Advisor)
Bryan Vogt (Committee Member)
Li Jia (Committee Member)
60 p.
Polymers

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Citations

  • Zhou, L. (2019). INVESTIGATION OF THE SHAPE MEMORY BEHAVIOUR OF STEARIC ACID SWOLLEN, CROSSLINKED EPDM ELASTOMERS [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron155560618552726

    APA Style (7th edition)

  • Zhou, Lei. INVESTIGATION OF THE SHAPE MEMORY BEHAVIOUR OF STEARIC ACID SWOLLEN, CROSSLINKED EPDM ELASTOMERS. 2019. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron155560618552726.

    MLA Style (8th edition)

  • Zhou, Lei. "INVESTIGATION OF THE SHAPE MEMORY BEHAVIOUR OF STEARIC ACID SWOLLEN, CROSSLINKED EPDM ELASTOMERS." Master's thesis, University of Akron, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron155560618552726

    Chicago Manual of Style (17th edition)

akron155560618552726
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This open access ETD is published by University of Akron and OhioLINK.