0
BRIDGING MICROSTRUCTURE, PROPERTIES, AND PROCESSING OF POLYMER-BASED ADVANCED MATERIALS

Effect of Moderate Magnetic Annealing on the Microstructure, Quasi-Static, and Viscoelastic Mechanical Behavior of a Structural Epoxy

[+] Author and Article Information
Mehran Tehrani

 Department of Engineering Science and Mechanics, Virginia Tech, Blacksburg, VA 24061

Marwan Al-Haik1

 Department of Engineering Science and Mechanics, Virginia Tech, Blacksburg, VA 24061alhaik@vt.edu

Hamid Garmestani

 School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332

Dongsheng Li

 Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, MSIN K7-90, Richland, WA 99352

1

Corresponding author.

J. Eng. Mater. Technol 134(1), 010907 (Dec 14, 2011) (10 pages) doi:10.1115/1.4005406 History: Received March 10, 2011; Revised July 29, 2011; Published December 14, 2011; Online December 14, 2011

In this study, the effect of moderate magnetic fields on the microstructure of a structural epoxy system was investigated. The changes in the microstructure have been quantitatively investigated using wide angle X-ray diffraction (WAXD) and pole figure analysis. The mechanical properties (modulus, hardness, and strain rate sensitivity parameter) of the epoxy system annealed in the magnetic field were probed with the aid of instrumented nanoindentation, and the results are compared to the reference epoxy sample. To further examine the creep response of the magnetically annealed and reference samples, short 45 min duration creep tests were carried out. An equivalent to the macroscale creep compliance was calculated using the aforementioned nanocreep data. Using the continuous contact compliance (CCC) analysis, the phase lag angle, tan (δ), between the displacement and applied force in an oscillatory nanoindentation test was measured for both neat and magnetically annealed systems through which the effect of low magnetic fields on the viscoelastic properties of the epoxy was invoked. The comparison of the creep strain rate sensitivity parameter, A/d(0), from short term(80 s), creep tests and the creep compliance J(t) from the long term (2700 s) creep tests with the tan (δ) suggests that former parameter is a more useful comparative creep parameter than the creep compliance. The results of this investigation reveal that for the epoxy system cured under low magnetic fields both the quasi-static and viscoelastic mechanical properties have been improved.

FIGURES IN THIS ARTICLE
<>
Copyright © 2012 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

The axial (MD), normal (ND), and lateral (LD) directions of the sample with respect to the magnetic field

Grahic Jump Location
Figure 2

Schematic diagram of the NanoTest 600 system

Grahic Jump Location
Figure 3

Loading and unloading in nanoindentation of a conical indenter: (a) loading and unloading curves and (b) schematic of loading and unloading surfaces

Grahic Jump Location
Figure 4

Variation of the mechanical properties of reference epoxy sample with maximum indentation load

Grahic Jump Location
Figure 5

Nanoindentation load–displacement hysteresis of a sample that was magnetically processed (left) and the reference epoxy (right). The maximum loads applied were 1, 3, and 5 mN at a loading/unloading rate of 0.05 mN/s. An 80 s creep was carried out.

Grahic Jump Location
Figure 6

Spring dashpot model of the test setup with the sample in place, after [45]

Grahic Jump Location
Figure 7

Cyclic load-hold-partial unload indentations on epoxy for measuring phase lag during hold period

Grahic Jump Location
Figure 8

AFM scan of a nanoindentation showing pile up

Grahic Jump Location
Figure 9

Schematic of the sample with the areas studied with WAXRD; magnetic field strength decreases in the direction of MD

Grahic Jump Location
Figure 10

Pole figures for: (a) neat sample (no-magnetic field) along the LD of the sample; point “M1,” (b) neat sample along the MD of the sample; point “L1,” (c) neat sample along the MD of the sample; point “L2,” (d) magnetically annealed sample along the LD of the sample; point “M1,” (e) magnetically annealed sample along the MD of the sample; point “L1,” and (f) magnetically annealed sample along the MD of the sample; point “L2”

Grahic Jump Location
Figure 11

The two-dimensional stretching effect, a magnetic field exerted on the main chains and crosslinks of an epoxy

Grahic Jump Location
Figure 12

Creep response of magnetically annealed (M) and neat (N) samples at three loads of 1(1N), 3(3N), and 5(5N) mN creep loads collected over a 45 min time span

Grahic Jump Location
Figure 13

Contact creep compliance of magnetically annealed (M) and neat (N) samples at three loads of 1(1N), 3(3N), and 5(5N) mN creep loads collected over a 45 min time span

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In