scholarly journals Effects of Bromination-Dehydrobromination on the Microstructure of Isotropic Pitch Precursors for Carbon Fibers

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3059
Author(s):  
Dingcheng Liang ◽  
Deqian Liu ◽  
Shuai Yang ◽  
Changyu Lu ◽  
Qiang Xie ◽  
...  
Keyword(s):  
Carbon Fibers ◽  
Aromatic Hydrocarbons ◽  
Condensation Reaction ◽  
Raw Material ◽  
Substitution Reactions ◽  
Isotropic Pitch ◽  
Aggregation Structure ◽  
Polycyclic Aromatic ◽  
Tof Ms ◽  
Pitch Formation

In this work, isotropic pitch precursors are synthesized by the bromination-debromination method with ethylene bottom oil (EO) as the raw material and bromine as the initiator for pitch formation and condensation reactions. The aggregation structure, molecular weight distribution, and molecular structure of isotropic pitch precursors are characterized by thermal mechanical analyzer (TMA), MALDI TOF-MS, and 13C NMR, respectively, for revealing the mechanism of synthesis of isotropic pitch precursors. The results show that at low bromine concentrations, polycyclic aromatic hydrocarbons (PAHs) were mainly ordered in cross-linked structures by bromination-debromination through substitution reactions of side chains. The condensed reactivity can be improved by the effect of bromine, meaning that condensation reaction was aggravated by the method of bromination-dehydrobromination. In the presence of excess bromine, the cross-linked stereo structure of PAHs changed to the planar structure of condensed PAHs, which was not conducive to the subsequent spinning and preparation of carbon fibers.

Analysis of Polycyclic Aromatic Hydrocarbons on Vapor-Grown Carbon Fibers

1991 ◽  
pp. 199-212 ◽  
Author(s):  
T. C. Pederson ◽  
C. A. Powell ◽  
J. Santrock ◽  
L. Rosenbaum ◽  
J. Siak ◽  
...  
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Carbon Fibers ◽  
Aromatic Hydrocarbons ◽  
Polycyclic Aromatic

Characterization of Bistre Pigment Samples by FTIR, SERS, Py-GC/MS and XRF

2014 ◽  
Vol 1656 ◽  
pp. 139-148 ◽  
Author(s):  
María L. Roldan ◽  
Silvia A. Centeno ◽  
Adriana Rizzo ◽  
Yana van Dyke
Keyword(s):  
Aromatic Hydrocarbons ◽  
Rapid Identification ◽  
Raw Material ◽  
Brown Pigment ◽  
Silver Surface ◽  
Phenolic Components ◽  
Polycyclic Aromatic ◽  
Alkaline Conditions ◽  
Present Characteristic

ABSTRACTA combination of FTIR, normal Raman, SERS, Py-GC/MS and XRF was used to analyze commercial bistre samples to determine specific biomarkers that will allow for a rapid identification of the pigment in works of art. The results of the XRF analysis showed that potassium, calcium and iron are the main elements present. Characteristic bands belonging to phenolic components of lignin were observed in the FTIR spectra. The SERS analysis provided a fingerprint that may originate in the polymerization of the phenolic components catalyzed by the presence of the nanostructured silver surface under alkaline conditions. The Py-GC/MS analysis revealed the presence of lignin and cellulose biomarkers and a series of polycyclic aromatic hydrocarbons. The similarities observed between the commercial samples studied suggest that both originate in the same raw material, hardwood. The results demonstrate the potential of the multi-technique approach used for the characterization of this complex black-brown pigment.

scholarly journals Biodiesel: An Overview II

2021 ◽  
Author(s):  
Michelle Rezende ◽  
Ana Lúcia de Lima ◽  
Bárbara Silva ◽  
Claudio Mota ◽  
Ednildo Torres ◽  
...  
Keyword(s):  
Aromatic Hydrocarbons ◽  
Carbonyl Compounds ◽  
Heterogeneous Catalysts ◽  
Major Ions ◽  
Raw Material ◽  
Biodiesel Production ◽  
Pollutant Emissions ◽  
Microalgae Biomass ◽  
Polycyclic Aromatic ◽  
Production Technologies

The crescent number of scientific articles published per year shows that research on biodiesel continues to play an important role to support the growing demand for this biofuel. The second edition of Biodiesel: An Overview presents the worldwide research in the last 15 years. Microalgae biomass is the most studied raw material alternative in this period and several studies have been carried out to develop basic heterogeneous catalysts for biodiesel production. Concerning to production technologies, supercritical conditions and intensification process have been extensively investigated. The development of new antioxidants additives has focused mainly on biomass-derived formulations and there are few studies on biocide candidates. In terms of pollutant emissions, in general, the studies showed that the addition of biodiesel generates lower concentrations of polycyclic aromatic hydrocarbons (PAH), CO and n-alkanes pollutants, but carbonyl compounds, major ions and NOx are emitted in a higher concentration compared to pure diesel.

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