Kinetics and Mechanism of Thermal Cyclization of Polyamic Acids

Laius, L. A.; Tsapovetsky, M. I.

doi:10.1007/978-1-4615-7637-2_20

Cited by 24 publications

(15 citation statements)

References 1 publication

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“…A number of other researchers have noted and studied the reaction kinetics of imide formation [8][9][10][11][12]. There seems to be some agreement that the imidization reaction from the amide-acid proceeds through an initial fast step and a later slower step, although there are differing views on the cause of this difference.…”

Section: Discussionmentioning

confidence: 99%

15N NMR spectroscopy as a method for comparing the rates of imidization of several diamines

Johnston

Kuczmarski

2006

Polym. Compos.

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The relative rates of the conversion of amide-acid to imide was measured for a series or aromatic diamines that have been identified as potential replacements for 4,4'-methylene dianiline (MDA) in high-temperature polyimides and polymer composites. These rates were compared with the 15 N NMR resonances of the unreacted amines. The initial rates of imidization track with the difference in chemical shift between the amine nitrogens in MDA and those in the subject diamines. This comparison demonstrated that 15 N NMR spectroscopy is appropriate for the rapid screening of candidate diamines to determine their reactivity relative to MDA, and can serve to provide guidance to the process of creating the time-temperature profiles used in processing these materials into polymer matrix composites.3

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Section: Discussionmentioning

confidence: 99%

15N NMR spectroscopy as a method for comparing the rates of imidization of several diamines

Johnston

Kuczmarski

2006

Polym. Compos.

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“…22, No. 8,1990 9 were not well resolved in the spectrum, the mole fraction of le was derived from eq 1, and that of Id from eq 2.…”

Section: Partial Imidization Of Paamentioning

confidence: 99%

“…The reaction kinetics of imidization have been studied extensively. 1 -17 Several ideas have been proposed to account for the apparent two-step cyclization, including a two-stage physico-chemical process 8 in which both the molecular mobility of polymer matrix and the physical state of intrachain groups transformed into the imide rings play an important role, and the nonequivalent kinetic state of amic acid groups. However, it is yet to be possible to decide which, if any, of these ideas is responsible for the kinetic behavior of imidization since the method used, mostly based on infrared spectroscopy, only provided overall imide ring concentration which cannot distinguish the different species from imidization.…”

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confidence: 99%

Reactivity of Poly(amic acid) Isomers in Thermal Imidization

Chu

Huang

1990

Polym J

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ABSTRACT:The reactivity of isomers ofpoly(amic acid) prepared from 4,4'-oxydianiline and pyromellitic dianhydride in thermal imidization was investigated both in solution and in solid state at l 30°C. FT-NMR was the main tool used to measure the mole fraction of various species formed in partial imidization, using diphenyl pyromellitamic acid as a model compound to verify its applicability. The results were modeled by kinetic equations. It showed that the terephthalamide isomer reacted 4.14 times faster than isophthalamide isomer when imidized in solution. On the other hand, the isophthalamide isomer reacted 3.25 times faster than the terephthalamide isomer when reacted in solid state.KEY WORDS Poly(amic acid) / Imidization / Kinetics / Aromatic polyimides have outstanding thermal, electrical and mechanical properties. They are an important class of high-performance polymers, applied extensively in insulation film for electrical equipment and electronic devices, such as flexible printed circuit board and multilevel metallization of LSis.Polyimides, in general, show a lack in thermoplasticity and solubility for processing. These marterials are unsually processed in the form of their precursors, the poly(amic acid)s, in solution, followed by thermal imidization. The reaction kinetics of imidization have been studied extensively.

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“…Rheological analysis was per-1000 as the resin. The dihydrooxadiazinone CBA, also acting as a plasticizer, was incorporated at 30 formed on a Rheometrics Mechanical Spectrometer (model 800) equipped with 1-in-diameter parto 50% loading into the polyetherimide at 188 to 199ЊC. This ''concentrated'' resin was then blended allel plates.…”

Section: Introductionmentioning

confidence: 99%

New method for producing high-performance thermoplastic polymeric foams

Brandom

Desouza

Baird

et al. 1997

J. Appl. Polym. Sci.

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ABSTRACT:A new method for the production of foamed thermoplastic polymers from blends of a poly(aryl ether ketone) (PAEK) and polyetherimide (PEI) is presented. The blowing agent for the foaming process is water which is produced at elevated temperatures in an extruder, via an in situ reaction between an amine end group on the PEI, and a ketone functionality on the backbone of the PAEK chain. The effect of composition, mixing, time, and temperature are investigated.

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Kinetics and Mechanism of Thermal Cyclization of Polyamic Acids

Cited by 24 publications

References 1 publication

15N NMR spectroscopy as a method for comparing the rates of imidization of several diamines

15N NMR spectroscopy as a method for comparing the rates of imidization of several diamines

Reactivity of Poly(amic acid) Isomers in Thermal Imidization

New method for producing high-performance thermoplastic polymeric foams

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