Investigation of clay modifier effects on the structure and rheology of supercritical carbon dioxide-processed polymer nanocomposites

Robert J. Bellair, Mihai Manitiu, Esin Gulari, Rangaramanujam M. Kannan

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Superior property enhancements in polymer-clay nanocomposites can be achieved if one can significantly enhance the nanoclay dispersion and polymer-clay interactions. Recent studies have shown that nanoclays can be dispersed in polymers using supercritical carbon dioxide (scCO2). However, there is need for a better understanding of how changing the clay modifier affects the clay dispersability by scCO2 and the resultant nanocomposite rheology. To address this, the polystyrene (PS)/clay nanocomposites with "weak" interaction (Cloisite 93A clay) and "strong" interaction (Cloi- site 15A clay) have been prepared using the supercritical CO2 method in the presence of a co-solvent. Transmission electron microscopy images and small-angle X-ray diffraction illustrate that composites using 15A and 93A clays show similar magnitude of reduction in the average tactoid size, and dispersion upon processing with scCO2. When PS and the clays are coprocessed in scCO2, the "dispersion" of clays appears to be independent of modifier or polymer-clay interaction. However, the low-frequency storage modulus in the scCO2-proc essed 15A nanocomposites is two orders of magnitude higher than that of 93A nanocomposites. It is postulated that below percolation (solution blended composites), the strength of polymer-clay interaction is not a significant contributor to rheological enhancement. In the scCO2-processed nanocom- posites the enhanced dispersion passes the percolation threshold and the interactions dictate the reinforcement potential of the clay-polymer-clay network.

Original languageEnglish (US)
Pages (from-to)823-831
Number of pages9
JournalJournal of Polymer Science, Part B: Polymer Physics
Issue number8
StatePublished - Apr 15 2010
Externally publishedYes


  • Nanocomposite
  • Polymer-clay nanocomposites
  • Polystyrene
  • Rheology
  • Supercritical carbon dioxide processing

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Materials Chemistry


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