Kinetics of carbonization and graphitization of PBO fiber

Abstract

SYNOPSISPBO [poly(p-phenylenebenzobisoxazole)] fiber has been shown to convert to an ordered carbon fiber without the need for stabilization. This article presents the first detailed analysis of the carbonization and graphitization behavior of this unique material. The carbonization process was modeled as a series of free-radical reactions, and thermogravimetric analysis was used to determine an activation energy of 76 f 6 kcal/mol for the thermal initiation of free radicals. The initiation reaction data then were applied to determine the temperature dependence of the termination reaction. Additionally, the development of long-range order in the graphitizing fiber was examined. The spacing between graphene planes was shown to decrease with increasing treatment temperature and soak duration. Carbonized PBO fibers developed more long-range order than carbon fibers produced from other polymers, which may partially explain why these PBO-based fibers display excellent lattice-dependent properties. Finally, an Arrhenius analysis found the activation energy for graphitization to be 120 f 17 kcal/mol.

The structural evolution of thin multi-walled carbon nanotubes during isothermal annealing

“…(8)) provides the estimation of the apparent activation energy as the order of 90 kJ/mol for graphitization of our MWNTs in the temperature range from 1800 to 2600°C. This value is significantly lower than those of various carbon fibers (from 100 to 250 kcal/mol) [21].…”

In situ carbon deposition in polyetherimide/SAPO‐34 mixed matrix membrane for efficient CO2/CH4 separation

“…The resulting mixture was stirred vigorously for 15–30 min and was kept stirring overnight to produce a homogeneous sol. The molar composition of the sol used for the synthesis was Al 2 O 3 :SiO 2 :P 2 O 5 :H 2 O 1:0.3:1:66 . The prepared homogeneous sol was kept in an autoclave and held at 170 °C for 120 h. At the end of the synthesis, the powder was centrifuged at 12,000 rpm for 15 min and washed with distilled water.…”

Carbonfasern: Präkursor‐Systeme, Verarbeitung, Struktur und Eigenschaften

“…Die Schädigung der Faser während der Freisetzung von Stickstoff ist für den Fall, dass kleine Kristallite in die CF‐Struktur überführt werden, deutlich geringer. Eine eingehende Untersuchung der Kinetik von Carbonisierung und Graphitisierung von PBO‐Fasern offenbarte eine Aktivierungsenergie von (318±25) kJ mol −1 für die thermische Initiierung freier Radikale 200. Der Abstand zwischen den einzelnen Graphenebenen verringerte sich bei steigender Temperatur.…”