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 (Ks, 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.
Jiayu Wanga, Xiaogang Zhaob, Erik B. Berdac, Chen Chena, Kai Wanga, Shuanglong Chena, Bo Zoua, Bingbing Liua, Qiang Zhoua, Fangfei Lia, Danming Chaob
Polyimide, Brillouin scattering, Elastic modulus, Piezochromism