Understanding competing mechanisms for glass transition changes in filled elastomers

Charles D. Wood, Amin Ajdari, Craig W. Burkhart, Karl W. Putz, L. Catherine Brinson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

In polymeric nanocomposites, shifts in the glass transition temperature (Tg) that increase monotonically with particle loading have been attributed to the interphase, in ideally dispersed, attractive systems. However, in elastomeric composites a trend has emerged that shows Tg shifts first towards higher and then towards lower temperatures with increasing filler volume fraction, when measured via mechanical methods (DMA). At high filler loadings (>10 vol%), glass transition temperatures have been recorded below that of the base polymer, even for systems with attractive interactions between polymer and filler. One-dimensional analytical models and three-dimensional finite elements models were used to investigate the source of a mechanically-induced negative Tg shift in highly filled systems. The results attribute the origin of the shift towards higher temperatures as an effect of the interphase, while the subsequent shift to lower temperatures as an apparent relaxation time shift that arises solely due to the addition of stiff elastic particles. These replicated shifts explain a consistent trend across the literature and provide some considerations for those designing elastomeric composites with high filler loading.

Original languageEnglish (US)
Pages (from-to)88-94
Number of pages7
JournalComposites Science and Technology
Volume127
DOIs
StatePublished - Apr 28 2016

Keywords

  • Dynamic mechanical thermal analysis (DMTA)
  • Finite element analysis (FEA)
  • Interphase
  • Nano composites
  • Thermomechanical properties

ASJC Scopus subject areas

  • Ceramics and Composites
  • Engineering(all)

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