Imidization of polypromellitamic acid based on 4,4′‐methylenedianiline

Abstract

Imidization of polyamic acid prepared from pyromellitic dianhydride and 4,4'-methylenedianiline was investigated at 373-493 K. A t a certain degree of imidization, depending on the reaction temperature, the reaction is significantly slowed down. For this reason, imidization was divided into two phases, a fast and a slow one, and the rate constants were calculated from the kinetic equation of a first-order reaction. At imidization temperature above 443 K the activation enthalpy of the reaction decreases, probably due to the thermal decomposition of complexes of o-carboxybenzamide groups with residues of the solvent. At higher imidization temperatures also the activation entropy of imidization decreases; this is probably caused by the higher rigidity of the film because of evaporation of the solvent which acts as a plasticizer. Ar, Ar': aromatic structuresUsually, technological applications call for an increase in temperature from ca. 373 K to 573 K4). Only at high temperatures (>573 K) a complete transformation of ocarboxybenzamide groups into benzimide structures can be achieved. A very high degree of imidization is important predominantly in microelectronic applications, 0 1990, Hiithig & Wepf Verlag, Base1CCC 0025-1 16X/90/$03.00

Effect of pre-imidization on the structures and properties of polyimide fibers

“…24 The intrinsic viscosities of the PAA solutions were measured using a Germany SCHOTT 52510 Ubbelohde viscometer at 35 C.…”

“…Where S is the area of the absorption band, and subscript p and c represent precursor bers and the fully cured PI bers, respectively. 24 The intrinsic viscosities of the PAA solutions were measured using a Germany SCHOTT 52510 Ubbelohde viscometer at 35 C.…”

Research on N,N′‐carbonyldiimidazole: A novel low‐temperature imidization accelerator of polyimide

“…The ID is usually expressed by the ratio of C-N stretching vibration peak (1371 cm À1 ) on imide ring to the stretching vibration peak (1498 cm À1 ) on benzene ring, ID 1 was calculated by Equation (1). [25][26][27]…”

Effect of chemical structure and preparation process on the aggregation structure and properties of polyimide film

“…According to a reported method,28 the band at 1380 cm −1 (stretching vibration of CN) was selected for quantifying pre‐ID, and the aromatic band at 1500 cm −1 (CC stretching of the p ‐substituted benzene backbone) was selected as the internal standard. All the experimental pre‐IDs are calculated according to the eq.…”