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Magnetic resonance imaging of elastomers and ion exchange resins

Kogovsek, Laurie Maylish
http://rave.ohiolink.edu/etdc/view?acc_num=case1057869238

Abstract Details

1994, Doctor of Philosophy, Case Western Reserve University, Chemistry.
Magnetic resonance imaging is a noninvasive technique used to study the properties of materials. For this research, various imaging methods were utilized to examine the morphology of elastomers and ion exchange resins. Several imaging techniques were employed to study the properties of elastomers. Both spin-echo and multi-slice sequences were used to acquire images of polyisoprene with 10% carbon black to determine the distribution of carbon black. Variable temperature imaging was employed to image samples with short spin-spin relaxation times: filled and/or cured samples of styrene-butadiene rubber. Also a variable temperature multi-slice technique was used to image a portion of a tire tread that contained fibers. With multi-slice imaging the size and shape of defects within the elastomers and tire tread were determined in three dimensions without cutting into the material. Magnetic resonance imaging was not only utilized to locate defects within elastomeric material but also used in determining their identity. The quantification of signal loss artifacts in gradient-echo images, when compared to a spin-echo image, could provide insight to the identity of the substance in the defect. A greater signal loss at their interface reflects a larger susceptibility diff erence between the two substances. Several models were designed with rectangular defects that created a carbon black/polyisoprene and an air/polyisoprene interface. In some models, a greater signal loss was seen at the air/polyisoprene interface than at the carbon black/polyisoprene interface. Also the signal loss in the gradient-echo images increased with increasing echo time. A model consisting of agar gel and four circular defects was also imaged. Two of the defects contained air while the other two contained carbon black. This model design better resembled the round voids seen in the elastomer and tire tread samples. The two defects that contained air exhibited a smaller signal loss than the defects containing wet clumps of carbon black. Also spin-echo imaging was used to examine the morphology of ion exchange resins. A multiple bead mount was developed to investigate the consistency of a sample of styrene divinyl benzene beads. Also several different types of styrene divinyl benzene beads, both cationic and anionic, were exposed to extremely acidic and basic environments after being swelled in deionized water. Images of the resins suggested that the average signal area of the beads changed. These changes were dependent on the solution and resin type. Signal loss due to a reduction in spin-spin relaxation below the echo time of the imaging sequence was ruled out by Carl-Purcell-Meiboom-Gill relaxation experiments.
William Ritchey (Advisor)
201 p.
Magnetic resonance imaging; elastomers; ion exchange resins

Recommended Citations

Citations

  • Kogovsek, L. M. (1994). Magnetic resonance imaging of elastomers and ion exchange resins [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1057869238

    APA Style (7th edition)

  • Kogovsek, Laurie. Magnetic resonance imaging of elastomers and ion exchange resins. 1994. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1057869238.

    MLA Style (8th edition)

  • Kogovsek, Laurie. "Magnetic resonance imaging of elastomers and ion exchange resins." Doctoral dissertation, Case Western Reserve University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1057869238

    Chicago Manual of Style (17th edition)

case1057869238
517
© 1994, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.