Direct observation of the compression behavior of polystyrene microbeads in a diamond anvil cell

TL;DR

This study directly measures how polystyrene microbeads compress under high pressure up to 6 GPa using a diamond anvil cell, providing new insights into their bulk modulus behavior at high pressures.

Contribution

It presents the first direct observation of polystyrene microbeads' compression behavior at high pressures using optical microscopy in a diamond anvil cell.

Findings

Bulk modulus increases with pressure up to 6 GPa.

Volume change data aligns with existing low-pressure equations of state.

Comparison with Brillouin spectroscopy data validates the measurements.

Abstract

The pressure dependence of the bulk modulus of glassy polystyrene (PS) was measured in the relatively high-pressure regime, up to 6 GPa, at ambient temperature. For the measurements, PS microbeads were immersed in a pressure medium consisting of a mixture of methanol and ethanol, and the sample was placed in a diamond anvil cell capable of generating high and hydrostatic pressure. The volume change of the PS beads was observed under an optical microscope. The results demonstrated that the volume change in this study is consistent with an equation of state determined from the earlier studies in the low-pressure range up to 0.2 GPa. The bulk modulus was obtained as the derivative of the microbead volume with respect to pressure, and compared with the earlier data obtained from Brillouin spectroscopy.