Ion hopping in ethylene-methacrylic acid ionomer melts as probed by rheometry and cation diffusion measurements

Neena K. Tierney, Richard A. Register

Research output: Contribution to journalArticle

64 Scopus citations

Abstract

The dynamics of chain and ionic group motion were investigated in a series of ethylene-methacrylic acid (E/MAA) ionomers of varying cation type and neutralization level, all formed from the same E/MAA copolymer. Low-shear-rate theological measurements were utilized to determine the terminal relaxation time (td) of the polymer chains. The much faster ion-hopping time (τ) was measured through the use of cation diffusion studies, in which a finite slab of one ionomer diffuses into a matrix of a second ionomer. For the Mg/Ca, Mg/Li, Na/Ca, and Na/Li diffusion couples studied, the diffusion coefficient follows inversely with melt viscosity, though τ extracted from the diffusion coefficients depends more weakly on cation type than does td obtained from melt rheometry. For the highly neutralized E/MAA ionomers, τ is 4 orders of magnitude shorter than td, but the two relaxation mechanisms have a similar dependence upon temperature, in agreement with current theories of ionomer dynamics.

Original languageEnglish (US)
Pages (from-to)2358-2364
Number of pages7
JournalMacromolecules
Volume35
Issue number6
DOIs
StatePublished - Mar 12 2002

All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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