Constructing the Bridge from Isotropic to Anisotropic Pitches for Preparing Pitch-Based Carbon Fibers with Tunable Structures and Properties

Abstract

Synthetic naphthalene pitches (SNPs) with isotropy and anisotropy were prepared by a simple thermal polycondensation method to fabricate pitch-based carbon fibers. The structural characteristic, thermal stability, phase-separation behavior, and melt-spinnability of the SNPs and the structural properties of the derived carbon fibers were systematically investigated. The results show that spinnable SNPs with controllable mesophase contents ranging from 0 to 100 vol % and softening points (210–290 °C) could be easily obtained by a nitrogen-bubbling treatment to improve their thermal stability and melt-spinnability by avoiding the phase separation of liquid crystal (LC) in the pitch. An experimental phase diagram of spinnability and mesophase content is newly proposed for predicting the spinnability of a mesophase-containing pitch. The LC has a significant influence not only on the constituents, structure, and physical properties of the SNPs but also on the final structure and properties of the corresponding pitch-based carbon fibers. The low ash content (less than 0.15 wt %) in the pitch precursor is found to have no obvious effect on the pitch spinnability and the mechanical properties of derivative large-diameter carbon fibers.

Structure–Reactivity Relationships for Petroleum Asphaltenes

“…Figure , right panel, highlights the presence of abundant known PAHs in the hydroconverted asphaltenes. , Understanding the effect of upgrading (i.e., thermal cracking and hydroconversion) on asphaltene structure is central to optimal use of petroleum residues for production of carbon fibers. Critical properties such as pitch spinnability should be highly dependent on sample’s molecular structure and the presence of alkyl-depleted PAHs, which are highly abundant in heavy fractions from upgraded petroleum residues.…”

Maltene and Asphaltene Contributions to the Formation of Water-Soluble Emerging Contaminants from Photooxidation of Paving Materials

“…It is critical to highlight that extra heavy fractions of crude oil (e.g., vacuum residues and asphaltenes) are extensively used in the built environment. Applications include road paving, asphalt sealers, roofing materials, waterproofing systems, and potentially material science (e.g., production of carbon fibers). ,− However, the chemistry of the emerging contaminants from fossil fuels in the built environment is not widely understood, with reports by Bowman et al, Giger and Blumer, and Magi and Di Carro, which suggest that they contribute to the release of carcinogenic polycyclic aromatic hydrocarbons (PAHs) into the environment as a result of the weathering. Moreover, fossil fuel products are known to be highly complex at the molecular level.…”

Nitrogen-Doped and Carbon-Coated Activated Carbon as a Conductivity Additive-Free Electrode for Supercapacitors

“…According to the XPS spectra, the best result of MS could be attributed to the doping effect of the electron-rich nitrogen in the carbon layer (C-N) and π-π* graphitic structure [14,28,34]. The pitch-derived THF has an isotropic structure and the characteristic that its graphitization is not as good as that of an anistropic structure [35,36].…”