The thermal degradation of aromatic polybenzoxazoles

Kardash, I. E.; Ardashnikov, A.Ya.; Праведников, А.Н.

doi:10.1016/0032-3950(69)90459-6

Cited by 8 publications

(4 citation statements)

References 8 publications

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“…Interesting results concerning the influence of residual solvent on the properties of PI films were obtained for PIs containing hydroxyl groups in the diamine fragment in the ortho ‐position to the nitrogen atom of the imide group (Table ). These PIs are capable of intramolecular thermochemical reaction (ITR) with the elimination of CO 2 resulting in the formation of an insoluble polymer with a new structure and consequently with new physical and chemical properties …”

Section: Resultsmentioning

confidence: 99%

“…Quantum chemistry computations performed earlier have shown that the first stage of the ITR passes through the transitional state I − II (TS I − II, Scheme ) regardless of its further path; this transitional state causes the subsequent rearrangement to an insoluble product of reaction …”

Section: Resultsmentioning

confidence: 99%

“…To study the impact of the residual solvent on the course of the intermolecular thermochemical reaction the PI films were formed from different solvents and were annealed in an inert atmosphere (nitrogen) with a heating rate of 5 °C min –1 in the temperature range 225–450 °C, which is above T g but below the degradation temperature of all PIs.…”

Section: Methodsmentioning

confidence: 99%

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Influence of residual solvent on physical and chemical properties of amorphous glassy polymer films

et al. 2013

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One of the most important areas of current research is the study of the influence of the prehistory of samples of amorphous glassy polymers on their physical and chemical properties. The study of structural changes by high temperature IR spectroscopy compared with of quantum chemical calculations allows for an understanding of the mechanism and nature of such processes. The changes in the structure of the polymer chain depending on the type of solvent used in the formation of the films are demonstrated using the examples of several different classes of polymers. In turn, the impact of such changes in the structure on the physical and chemical properties of the polymer films is demonstrated. © 2013 Society of Chemical Industry

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Influence of residual solvent on physical and chemical properties of amorphous glassy polymer films

et al. 2013

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“…[5][6][7][8][9][10] As a result, the activation energy and reaction order of the thermal imidization of PAA have been calculated, [11][12][13] and the effects of solvent, film thickness, and heating temperature on the thermal imidization have also been thoroughly studied. [14][15][16] Fewer studies have examined the detailed pathways of thermal imidization; in particular, the cyclization process during thermal imidization needs further investigation. Only a few papers have discussed plausible pathways for imide ring closure.…”

Section: Introductionmentioning

confidence: 99%

Two-Dimensional Raman Correlation Spectroscopy Study of the Pathway for the Thermal Imidization of Poly(amic acid)

2003

Bulletin of the Korean Chemical Society

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The pathway producing imide ring closure during the thermal imidization of poly(amic acid) (PAA) was investigated in detail using a new analytical method, two-dimensional (2D) Raman correlation spectroscopy. The signs of the cross peaks in synchronous spectra provided evidence of the thermal imidization of PAA into PI as the heating temperature increased. The signs of the cross peaks in asynchronous spectra suggested that the imide-related modes changed prior to the amide or carboxylic mode, which indicates that cyclization occurred before the amide proton was abstracted.

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The thermal breakdown mechanism of polybenzoxazoles and polybenzothiazoles

Ehlers

Fisch

Powell

1973

J. polym. sci., C Polym. symp.

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Polybenzoxazoles, when heated up to 660°C in vacuum, lose most of their oxygen as carbon monoxide and carbon dioxide and possibly form Schiff base‐type structures. The carbon required for the formation of carbon monoxide is predominantly supplied by the benzene rings. About one out of every six CN linkages is eliminated as hydrogen cyanide, and some free nitrogen from this group is reduced to ammonia. The elimination of about 1 hydrogen atom per polymer unit (in the form of free hydrogen, hydrogen cyanide, ammonia, and methane) results in free radical formation and crosslinking. Carbon monoxide and carbon dioxide are also some of the major decomposition products of the benzoxazole in poly‐2,2′‐(1,8‐perfluorooctane)‐6,6′‐bibenzoxazole. In addition, fluorine from the perfluoroalkyl chain combines with ring hydrogen to form hydrogen fluoride, which in turn attacks the quartz of the crucible and reaction vessel to form silicon tetrafluoride. A polybenzothiazole, on heating to 625°C, crosslinks with elimination of some hydrogen. One out of every ten sulfur atoms is removed, essentially as hydrogen sulfide, leaving a Schiff‐base linkage; very few of the CN‐groups are eliminated as hydrogen cyanide. Two less stable polybenzothiazole systems, heated to 660 and 670°C, lose about 50% of their sulfur, mainly as hydrogen sulfide, and 20% of their nitrogen as hydrogen cyanide. Flash pyrolysis of model benzoxazoles and benzothiazoles was tried as a means to provide supporting data.

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The thermal degradation of aromatic polybenzoxazoles

Cited by 8 publications

References 8 publications

Influence of residual solvent on physical and chemical properties of amorphous glassy polymer films

Influence of residual solvent on physical and chemical properties of amorphous glassy polymer films

Two-Dimensional Raman Correlation Spectroscopy Study of the Pathway for the Thermal Imidization of Poly(amic acid)

The thermal breakdown mechanism of polybenzoxazoles and polybenzothiazoles

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