Strain rate effect on toughening of nano-sized PEP-PEO block copolymer modified epoxy

Jia (Daniel) Liu, Hung Jue Sue, Zachary J. Thompson, Frank S. Bates, Marv Dettloff, George Jacob, Nikhil Verghese, Ha Pham

Research output: Contribution to journalArticlepeer-review

69 Scopus citations

Abstract

A bisphenol A-based epoxy was modified with an amphiphilic poly(ethylene-alt-propylene)-b-poly(ethylene oxide) (PEP-PEO) block copolymer as a toughening agent. PEP-PEO molecules self-assemble into spherical micelles in epoxy with an average diameter of 15 nm and give rise to 180% improvement in fracture resistance. The fracture and tensile behaviors of the PEP-PEO-modified epoxy were investigated at loading rates ranging from 0.51 to 508 mm min-1. The toughened epoxy exhibits mechanical properties that are significantly more rate dependent than the neat epoxy material. As expected, a higher test rate leads to a more brittle behavior of the material and a lower fracture toughness value. With careful systematic study of their micromechanical deformation processes, the observed strain rate dependence is explained. The implications of the current findings on nano-sized rubber toughening of epoxy are also discussed in detail.

Original languageEnglish (US)
Pages (from-to)2691-2701
Number of pages11
JournalActa Materialia
Volume57
Issue number9
DOIs
StatePublished - May 2009

Bibliographical note

Funding Information:
The authors from Texas A&M University thank the Microscopy and Imaging Center for TEM technical assistance. Financial support from the U.S. Department of Energy through subcontract to UT-Battelle No. 4000041622 is gratefully acknowledged by the authors from the University of Minnesota. This research is also funded by The Dow Chemical Company.

Keywords

  • Block copolymer
  • Epoxy
  • Nanoparticle
  • Rubber toughening
  • Strain rate dependence

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