Aiming at the low volumetric shrinkage, a novel aromatic polyimide foam is successfully prepared from polymethane polyphenyl isocyanate (PAPI) and a poly(amic-acid) precursor which has been synthesized from 3,4'-oxydianiline (3,4'-ODA) and pyromellitic dianhydride (PMDA). In this research, five polyimide foams, with different contents of 3,4'-ODA, are comparatively studied including structural, thermal, mechanical, shrink, and degradation properties. The results indicate that the content of 3,4'-ODA has minor influence on chemical structures, but significant influence on cell structures of the foams. With the increase of 3,4'-ODA, the volumetric shrinkages, apparent densities and the compressive and flatwise tensile strengths of the materials decrease. The glass transition temperatures (Tg) decrease from 301 degrees C to 279 degrees C, and the 5% weight loss temperatures (T5%) increase from 323 degrees C to 340 degrees C. Through TG-FTIR analysis, we can observe that the addition of 3,4'-ODA has no influence on the pyrolysis mechanism of polyimide foams. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012