Preparation and mechanical properties of carbon fibers with isotropic pyrolytic carbon core by chemical vapor deposition

• A novel carbon fiber with obvious core/sheath structure was developed by CVD.
• The core of the fiber was isotropic pyrolytic carbon.
• This carbon fiber has shown excellent performance in mechanical properties.
• The fiber shows same mechanical properties in both axial and radial directions.

This paper reports the development of a novel carbon fiber with isotropic pyrolytic carbon core via isothermal–isobaric catalyst-free CVD of propylene. The morphological and microstructural characterizations of the carbon fibers developed were carried out by polarized light microscopy, scanning electron microscopy and transmission electron microscopy. Both the elastic modulus and hardness of the two components of these carbon fibers were measured using nanoindentation technique. The results show that the isotropic pyrolytic carbon core has a homogeneous and complex microstructure, which accounts for approximately 64% of the whole carbon fiber volume. It is this unique core structure that enables these carbon fibers to possess excellent overall mechanical properties with nearly isotropic performance in both the axial and radial directions.