Wavy Graphene-Like Network Forming during Pyrolysis of Polyacrylonitrile into Carbon Fiber.
J Am Chem Soc
; 145(22): 12244-12254, 2023 Jun 07.
Article
in En
| MEDLINE
| ID: mdl-37248959
ABSTRACT
Carbon fiber (CF) obtained by pyrolysis of polyacrylonitrile (PAN-CF) surpasses metals in properties suitable for diverse applications such as aircraft manufacture and power turbine blades. PAN-CF obtained by pyrolysis at 1200-1400 °C shows a remarkably high tensile strength of 7 GPa, much higher than pitch-based CF (pb-CF) consisting of piles of pure graphene networks. However, little information has been available on the atomistic structure of PAN-CF and on how it forms during pyrolysis. We pyrolyzed an acrylonitrile 9-mer in a carbon nanotube, monitored the course of the reaction using atomic-resolution electron microscopy and Raman spectroscopy, and found that this oligomer forms a thermally reactive wavy graphene-like network (WGN) at 1200-1400 °C during slow graphitization taking place between 900 and 1800 °C. Ptychographic microscopic analysis indicated that such material consists of 5-, 6-, and larger-membered rings; hence, it is not flat but wavy. The experimental data suggest that, during PAN-CF manufacturing, many layers of WGN hierarchically pile up to form a chemically and physically interdigitated noncrystalline phase that resists fracture and increases the tensile strengthâthe properties expected for high-entropy materials. pb-CF using nearly pure carbon starting material, on the other hand, forms a crystalline graphene network and is brittle.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
J Am Chem Soc
Year:
2023
Document type:
Article
Affiliation country:
Japan