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NONLINEAR RHEOLOGY OF ENTANGLED POLYMERS

Tapadia, Prashant Subhashchandra
http://rave.ohiolink.edu/etdc/view?acc_num=akron1136007343

Abstract Details

2006, Doctor of Philosophy, University of Akron, Political Science.
A central task in polymer rheology is to search for constitutive equations that relate the flow field with the corresponding stress field in both transient and steady states. A parallel objective is to determine the state of chain conformation as a function of the flow condition. In disagreement with previous studies, our experimental data show that entangled monodisperse polymers respond differently to the applied shear strain and shear stress. In conventional shear strain rate controlled measurement, entangled polymers result in a stress plateau well known as shear thinning while a constitutive entanglement-disentanglement transition takes place when sheared under stress-controlled mode. Direct visualization of the velocity field with particle tracking velocimetry and flow birefringence reveals that entangled polymeric fluids develop non-homogeneous flow field across velocity gradient direction when sheared under rate-controlled mode. Lack of uniform shear deformation is observed when these fluids are subjected to large amplitude oscillatory shear at frequencies beyond overall chain relaxation rate. The combination of rheometry, rheo-optics and particle tracking velocimetry has led to the discovery of an entanglement-disentanglement transition in shear stress mode and the presence of a shear rate gradient across sample thickness in shear rate controlled mode. These first results may provide a reliable phenomenological basis for the future development of a realistic description of nonlinear polymer rheology.
Shi-Qing Wang (Advisor)
137 p.
Nonlinear rheology; entanglement; disentanglement; coil-stretch; transition; constitutive; relaxation; polymer; fluids; solution

Recommended Citations

Citations

  • Tapadia, P. S. (2006). NONLINEAR RHEOLOGY OF ENTANGLED POLYMERS [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1136007343

    APA Style (7th edition)

  • Tapadia, Prashant. NONLINEAR RHEOLOGY OF ENTANGLED POLYMERS. 2006. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1136007343.

    MLA Style (8th edition)

  • Tapadia, Prashant. "NONLINEAR RHEOLOGY OF ENTANGLED POLYMERS." Doctoral dissertation, University of Akron, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1136007343

    Chicago Manual of Style (17th edition)

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© 2005, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.
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