Study on the viscoelastic properties of the epoxy surface by means of nanodynamic mechanical analysis

Abstract

The viscoelastic properties of the epoxy surface have been investigated by nanodynamic mechanical analysis (nano-DMA). Both a Berkovich tip and a conospherical tip were used under the condition of different forces (i.e., different penetration depths) in the frequency range of 10-200 Hz. Loss tangent and storage modulus are characteristics that describe the viscoelastic properties. The effect of force frequency, penetration depth, and tip shape on the viscoelastic properties is studied and discussed according to the features of microstructures and mobility of molecular chains. The experimental results show important variations when the penetration depth is shallow (<30 nm). As the depth becomes deeper, the results tend to be stable and become almost constant over 120 nm. The two kinds of indenter tip can cause a slight difference of the storage modulus. A ''master curve'' of the storage modulus as a function of force frequency is established.

Nanoindentation and dynamic mechanical properties of PP/clay nanocomposites

“…Both the samples also showed a decrease in modulus as a function of depth, indicating the presence of a stiffer surface layer. The similar behavior has been observed by other researchers [18,20,[40][41][42]. This change in properties may be a result of inhomogeneous crystalline morphology of the nanoclay composites along the penetration direction [23].…”

“…It was explained to be attributed to the size effect of volume loaded in the composite. In other similar studies, the effect of penetration depth and tip shape on the viscoelastic properties of the same materials (nanosilica/epoxy nanocomposites [18] were reported. Shen et al [23] studied the effect of strain rate on the surface deformation behavior of nylon 66/organoclay nanocomposites by using nanoindentation method.…”

“…The tip defect could significantly affect the measurement of the tested surface since the evaluation of nanomechanical properties directly related to the projected contact area of the tip, (ii) imprecise calibration of the indenter area function at low penetration depth. In addition, the roughness of the sample surface, pile-up or sink-in behavior could also give inaccurate evaluated contact area during the measurement [18,40,43].…”

“…Dynamic nanoindentation is a relatively new development and effective method for nanomechanical characterization. [18][19][20][21]. Dynamic nanomechanical characterization on polymer nanocomposite has been investigated and reported in different research studies.…”

Nanomechanical Analysis of Hybrid Silicones and Hybrid Epoxy Coatings—A Brief Review

“…The visco-elastic properties of epoxy nanocoatings containing nanosilica were studied by Zhang et al [31,32]. The volume fraction of nanosilica in nanocoatings was varied between 1 to 14 wt%.…”