Enhanced toughness and gas permeabilities of polyimide composites derived from polyimide matrix and flower-like polyimide microparticles

摘要

The flower-like polyimide (PI) based on 3,3 ',4,4 '-benzophenone tetracarboxylic dianhydride and benzidine was successfully obtained via solvothermal method. Using the flower-like PI as organic fillers, the flower-like PI/PI composites were fabricated by using 4,4 '-diaminodiphenyl ether and 1,2,4,5-pyromellitic dianhydride as monomers through in situ polymerization and thermal imidization. The residual amino groups on the surface of flower-like PI microparticles easily lead to the formation of chemical linkage between the flower-like PI and PI matrix, which are benefit for tight interface and uniform dispersion. These experimental results showed that the broken elongation of the composites was significantly improved from 9.8% (pure PI) to 33.5% (PI-4%), but the tensile strength and Young's modules were slightly sacrificed. The glass transition temperatures were mainly concentrated at around 352 degrees C, while the 5% and 10% thermal decomposition temperature were slightly reduced. Furthermore, the light transmittance remarkably decreased from 75.9% (pure PI) to 4.3% (PI-5%) at 550 nm. When the incorporation of flower-like PI was 5%, an obvious increase of water uptake from 2.05% to 2.89% was noticed, and the water surface contact angle increased from 67.5 degrees to 89.4 degrees, indicating the increasing hydrophobicity. Additionally, with the increase of flower-like PI fillers, the gas permeation flux of H-2, CO2, O-2, and N-2 enhanced by more than two times, and the selectivities of O-2/N-2 and CO2/N-2 increased first and then decreased. Therefore, the flower-like PI microparticles will be promising functional fillers to improve the properties of polyimide materials.