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

Abstract

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 niacroscale creep compliance was calculated using the aforementioned nanocreep data. Using the continuous contact compliance (CCC) analysis, the phase lag angle, tan (ô), 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 viscoeiastic properties of the epo.xy was invoked. The comparison of the creep .strain rate sensitivity parameter, Ald(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 (ô) 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 viscoeiastic mechanical properties have been improved.

Improvement of Interfacial Shear Strength of Mendong Fiber (Fimbristylis globulosa) Reinforced Epoxy Composite Using the AC Electric Fields

“…Li and Kessler [45] show that the liquid crystalline thermoset was able to be oriented by a magnetic field at the crystal peaks at angles 2 = 5 ∘ . The arrangement of polymer chains due to the work of the external field causes changes in the polymer chain axis and the microstructure [46]. The chain arrangement is a result of the orientation of the dipole matrix derived from the movement of polar group matrix [47].…”

“…International Journal of Polymer Science may be done by adding a functional polymer matrix [20] like both plasticizers and rubber [21], modifying the structure through molecular orientation by using shear flow, such as injection molding and extrusion, or using the external field such as electric field, magnetic field, and a combination of both [22]. The presence of the DC electric current and electromagnetic fields cause an increase in the impact strength of carbon fiber composite polymer by 24.7% and 43.6% for DC current of 25 A and 50 A, respectively [23], and also the interaction of static load and electromagnetic fields able to decrease in defflection of the reinforced carbon composite plate by 60% in electromagnetic infuluence of 1 Tesla.…”