Quantitative microscopic investigation of mode I fracture surfaces of nanosilica-filled epoxies

Aniruddh Vashisth, Todd C. Henry, Charles E. Bakis

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The addition of functionalized nanosilica (NS) particles to epoxy resins is known to improve certain mechanical properties such as modulus of elasticity and fracture toughness. In the current investigation, epoxies with and without NS reinforcement were investigated. Four NS concentrations were evaluated: 0, 15, 25 and a maximum wt% NS dependent on which of the two curing agents was used. The tensile modulus of elasticity and quasi-static Mode I fracture toughness were measured and the Mode I fracture surfaces were examined using a field emission scanning electron microscope for general imaging and a scanning laser confocal microscope for quantitative information on surface morphology. Fracture toughness, as measured by critical strain energy release rate (G Ic ), and fracture surface area increased monotonically with increased NS content in the epoxy cured with diethyltoluenediamine (DETDA). However, for the material cured at a higher temperature with 4-4′ diamino diphenyl sulfone (DDS), G Ic and surface area reach their respective peaks at NS concentrations less than the maximum value. The primary morphological toughing mechanisms observed were particle pullout and crack deflection. The DDS cured system had higher surface area than DETDA system for any non-zero NS content, but less G Ic . Analysis of the experimental results led to the conclusion that G Ic of the DETDA was mostly explainable in the context of NS particle pullout, as both fracture surface area and G Ic varied in rough proportion to NS content. In the DDS system, however, such proportional behavior was not observed and it is believed that competing mechanisms influence G Ic at NS concentrations above 15 wt%.

Original languageEnglish (US)
Title of host publication33rd Technical Conference of the American Society for Composites 2018
PublisherDEStech Publications Inc.
Pages1375-1387
Number of pages13
ISBN (Electronic)9781510872073
StatePublished - Jan 1 2018
Event33rd Technical Conference of the American Society for Composites 2018 - Seattle, United States
Duration: Sep 24 2018Sep 27 2018

Publication series

Name33rd Technical Conference of the American Society for Composites 2018
Volume3

Other

Other33rd Technical Conference of the American Society for Composites 2018
CountryUnited States
CitySeattle
Period9/24/189/27/18

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All Science Journal Classification (ASJC) codes

  • Mechanics of Materials
  • Surfaces, Coatings and Films
  • Metals and Alloys

Cite this

Vashisth, A., Henry, T. C., & Bakis, C. E. (2018). Quantitative microscopic investigation of mode I fracture surfaces of nanosilica-filled epoxies. In 33rd Technical Conference of the American Society for Composites 2018 (pp. 1375-1387). (33rd Technical Conference of the American Society for Composites 2018; Vol. 3). DEStech Publications Inc..