Kinetic studies of polyamide-imide synthesis

Abstract

To understand the kinetic of synthesis of polyamide‐imide (PAI) via p‐chlorophenol‐(PCP) blocked 4,4′‐diphenyl methane diisocyanate (MDI) with trimellitic anhydride (TMA), a series of reactions of blocked MDI with excess phthalic anhydride (PA) and benzoic acid are designed. PCP‐blocked phenyl isocyanate (BPI) which also released isocyanate at higher temperatures was used as a model compound for BMDI. The dissociation constants of BPI and BMDI in the presence of excess PA or BA was measured by collecting the evolved CO2. The effect of the catalyst concentration and temperatures were combined by a Hostettler equation. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1703–1710, 1997

Obtaining kinetic parameters of polyamide imide reaction

“…3.1 FTIR, 1 H-NMR and elemental analysis Unlike Ho and colleagues (Ho et al, 1997) whose reaction was followed at 2:1 molar ratio of TMA:MDI, in the present work the conventional chemical reaction for the formation of polyamide-imide (PAI) was based on the interaction of TMA with MDI in NMP at a 1:1 molar ratio of TMA:MDI, the temperature remained constant in each synthesis routes at 110, 127, 140 and 150°C in nitrogen atmosphere for a period of 24 hours. The appearance within the first 10 minutes of reaction was faint orange color, after this time it began to change to a dark brown color which remained until the reaction ended (unlike the polymer of Sintès (Sintès et al, 1993) who added benzoic acid into the reaction, obtaining a yellow powder).…”

Two‐component modified polyurethane sealant for insulating glass: Design, preparation, and application

“…However, isocyanate‐terminated resin is particularly vulnerable to the moisture vapor because of its high reaction activity toward H 2 O, and therefore such two‐component PU sealants have a short storage period. It has been reported that isocyanate‐terminated PU blocked with active hydrogen compound such as phenols, oximes, amides, imides, sodium bisulfite, imidazoles, amindines, and lactams is not sensitive to H 2 O and therefore exhibited good storage stability. Moreover, the blocking isocyanate‐terminated PU could be deblocked with strong nucleophile agents.…”

Structure-property relationship of blocked diisocyanates: synthesis of polyimides using imidazole-blocked isocyanates

“…Although polyimides can be prepared successfully by a one‐step reaction of free diisocyanates and dianhydrides,24 we have synthesized them using imidazole blocked‐diisocyanates with PMDA in the presence of 4‐DMAP as a catalyst in DMPU. Compared to the use of alcohol and phenol‐blocked isocyanate in the preparation of polyimides,19, 20, 25, 26 the present approach is relatively new and experimentally more viable because the blocking agent released is basic and can accelerate the imidization reaction 24. Farrissey and co‐workers25, 27 examined the reaction of isocyanate and anhydride, and found that high temperatures were required in non‐polar solvents such as diglyme and dioctylphthalate.…”