The elastic properties and piezochromism of polyimide films under high pressure.

The elastic properties of a fully aromatic polyimide were measured for the first time by Brillouin scattering in a high-pressure diamond anvil cell. Its isothermal compressibility and pressure dependence of mechanical moduli (K s , E, and G) were studied and determined up to 6.4 GPa. Further, piezochromic behavior of the polyimide film was observed and studied in detail by spectroscopic analysis. Pressure-induced red shift of the absorption edge and a hysteretic phenomenon were found, due to an enhancement of the van der Waals interaction upon decreasing the interchain distances and partially collapsing the free volume under extreme pressure. A comprehensive study of elastic properties and piezochromism behavior of polyimide film under high pressure will provide useful information for developing pressure sensitive coatings, pressure sensors, pressure resistance parts and components. [ABSTRACT FROM AUTHOR]