Diffusion in Entangled Polymer Solutions: Constraint Release

ORAL

Abstract

We have used the proton pulsed-gradient spin-echo NMR method to measure the self-diffusion D of entangled polybutadienes (PBD) in tetrachloromethane at 70$^{\circ}$C, in order to elucidate the origins of the departure of the molecular-weight (M) exponent of D from the reptational -2.0, and to characterize any differences between melt and solution behavior. M(PBD) ranged from 12 kDa to 100 kDa; PBD concentration (volume fraction ) v was 0.350, 0.422, and 0.514. Entanglement ratios R were calculated as M/M$_{e}$(v), where for PBD M$_{e}$(1) = 4.5 kDa and M$_{e}$(v) = M$_{e}$(1)/v$^{1.2}$, yielding a range of R between 2 and 25. Preliminary results, plotted in the form log (DM$^{2}$v$^{1.2})$ \textit{vs.} log R, adhere to a master curve with slope near -1, suggesting at most modest differences from the known behavior of melts. The relatively rapid approach to the melt asymptote, near R = 20, supports our earlier contention that constraint release rather than contour length fluctuation is the cause of the observed M-exponent of D. Further work, using solutions of binary blends based on high-M PBD, is in progress.

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Authors

  • E. von Meerwall

  • Perry Yaney

    Department of Physics, University of Oregon, USAF Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson AFB, Ohio, NHMFL, CRIEPI, UCSD, University of Dayton, L-3 Communications Cincinnati Electronics, University of Georgia, Air Force Research Laboratory, Anteon Corporation, California State University-Chico, The Ohio State University, Univ. Akron, Air Force Institute of Technology, Albion College, Albion, MI 49224, Physics Department, University of Florida, Gainesville, Mound Laser \& Photonics Center, Inc., Hitachi Global Storage Technologies, San Jose, CA 95120, University of Dayton Research Institute, University of South Alabama, Jet Propulsion Laboratory, Anteon, Universidad Michoacana de San Nicolas de Hidalgo, Morelia, Michoac\'{a}n, Mexico, Department of Chemistry, The University of Akron, Department of Physics, The University of Akron, Physics Department and The Future-Chips Constellation, Renssalaer Polytechnic Institute, Local Co-Chair

  • Perry Yaney

    Department of Physics, University of Oregon, USAF Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson AFB, Ohio, NHMFL, CRIEPI, UCSD, University of Dayton, L-3 Communications Cincinnati Electronics, University of Georgia, Air Force Research Laboratory, Anteon Corporation, California State University-Chico, The Ohio State University, Univ. Akron, Air Force Institute of Technology, Albion College, Albion, MI 49224, Physics Department, University of Florida, Gainesville, Mound Laser \& Photonics Center, Inc., Hitachi Global Storage Technologies, San Jose, CA 95120, University of Dayton Research Institute, University of South Alabama, Jet Propulsion Laboratory, Anteon, Universidad Michoacana de San Nicolas de Hidalgo, Morelia, Michoac\'{a}n, Mexico, Department of Chemistry, The University of Akron, Department of Physics, The University of Akron, Physics Department and The Future-Chips Constellation, Renssalaer Polytechnic Institute, Local Co-Chair