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A Real Time Study on the Mechanoptical Behavior of Polyvinyl Alcohol: Effect of Water

Wang, Enmin
http://rave.ohiolink.edu/etdc/view?acc_num=akron1367237525

Abstract Details

2013, Master of Science, University of Akron, Polymer Engineering.
Detailed understanding of fundamental relationships between processing parameters is important to control the desired properties. In conventional polymer film processing, the materials undergo complex sequence of events that are difficult to capture by off line measurements on intermittently captured samples as the structural “events” that occur at later stages tend to mask earlier ones. It is especially difficult to capture fast “transient events”. To address this problem, our group has developed real time on-line measurement system where true stress, strain, birefringence can be continuously monitored while subjecting the film to heating, stretching, holding and cooling cycles of any combination mimicking the actual processing conditions. Using this system, we investigated the stress and strain optical behavior of PVA films and quantified the influence of water on these relationships. First the evolution of structural events that take place during drying from cast solution was investigated using JOEY real time measurement system that captures temporal evolution of thickness, weight, birefringence (both in and out of plane). The initially isotropic solution rapidly loses solvent during the early stage and beyond a critical time, it develops optical anisotropy as evidenced by rapid rise of out of plane birefringence. In plane birefringence remains zero indicating the material exhibit uniaxial optical symmetry with the symmetry axis oriented in the normal direction. Stretching the dried films in solid state yields three-regime non-linear stress and strain-optical behavior at temperatures. The effect of temperature on the mechanoptical properties of PVA films stretched in solid state is different from that in partially molten state, since orientation plays a dominant role in determining birefringence in the former state and upon partial melting relaxation becomes pronounced in the latter state. The films swollen with water, exhibit linear relationship between birefringence and true strain. The addition of moisture promotes relaxation during deformation of PVA films by acting as plasticizer. As a result, the photoelastic constant determined during stretching in solid state was found to decrease as the water content. Strain optical constant was found to increase with water content.
Mukerrem Cakmak, Dr. (Advisor)
David Simmons , Dr. (Committee Member)
Kevin Cavicchi , Dr. (Committee Member)
106 p.
Polymers

Recommended Citations

Citations

  • Wang, E. (2013). A Real Time Study on the Mechanoptical Behavior of Polyvinyl Alcohol: Effect of Water [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1367237525

    APA Style (7th edition)

  • Wang, Enmin. A Real Time Study on the Mechanoptical Behavior of Polyvinyl Alcohol: Effect of Water. 2013. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1367237525.

    MLA Style (8th edition)

  • Wang, Enmin. "A Real Time Study on the Mechanoptical Behavior of Polyvinyl Alcohol: Effect of Water." Master's thesis, University of Akron, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1367237525

    Chicago Manual of Style (17th edition)

akron1367237525
601
© 2013, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.