Comparative study of isotropic and mesophase pitches derived from C9 alkylbenzenes

Sakanishi, Akemi; Korai, Yozo; Mochida, Isao; Yanagida, Kazuhiro; Noda, Matu-Tarow; Thunori, I.; Tate, Kazuhito

doi:10.1016/0008-6223(92)90044-w

Cited by 23 publications

(8 citation statements)

References 5 publications

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“…I ar of CP340‐3‐0, CP340‐3‐5 and CP340‐3‐10 were 0.6016, 0.5772 and 0.5446, respectively. While the condensed degree of polynuclear aromatic hydrocarbons Ab880/Ab1600 (isolated aromatic C−H/aromatic C=C ratios structure) of CP340‐3‐0, CP340‐3‐5 and CP340‐3‐10 were 1.044, 1.102 and 1.108, respectively. These results indicated that SEBS could introduce alkyl (especially methylene), significantly reduced I ar and increased the condensed degree in resultant pitch during asphaltene with SEBS thermal polymerization, so, the spinnability of resultant pitch could be improved.…”

Section: Resultsmentioning

confidence: 98%

Chemical Modification of Asphaltene with SEBS as Precursor for Isotropic Pitch‐Based Carbon Fiber

Jiang

Shen

2019

ChemistrySelect

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A high yield spinnable pitch for isotropic pitch-based carbon fiber was successfully prepared by air oxidation polycondensation of asphaltene with styrene-ethylene-butylene-styrene. The effects of reaction temperature and time, added styreneethylene-butylene-styrene amount on the composition and spinning properties of resultant pitches were investigated. The resultant pitch with a concentrated molecular weight distribution of 300-700 Da was prepared at 340°C for 3 h under air blowing with 5% styrene-ethylene-butylene-styrene, moreover, its more alkyl structure (mainly methylene), lower apparent viscosity above the softening point, and good spinnability endowed the resultant pitches more prone to oxygen crosslinking during the stabilization process. The average tensile strength of resultant pitch-based carbon fibers was over 800 MPa after carbonization at 1000°C for 10 min. It provided a simple method to adjust the spinnable pitch for pitch-based carbon fiber preparation.

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Section: Resultsmentioning

confidence: 98%

Chemical Modification of Asphaltene with SEBS as Precursor for Isotropic Pitch‐Based Carbon Fiber

Jiang

Shen

2019

ChemistrySelect

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“…Their physical properties (i.e., high softening points up to 300 °C, non-whole anisotropic content) listed in Table 2 are not easily controlled because they are very sensitive to the heat-soaking temperatures. Therefore, C 9 aromatic hydrocarbons and petroleumderived paving pitch seem to be unsuitable as precursors for preparing high-quality mesophase pitch (unless C 9 aromatic hydrocarbons were pretreated through CH 2 coupling treatment and the solvent-separated fractions were used as a feedstock 25 ). Anthracene, naphthalene synthetic pitch, coal tar-based impregnating pitch, and C 5 −C 9 aromatic hydrocarbons exhibit an initial stage (or period) of mesophase formation behavior (i.e., generation and growth of anisotropic liquid crystalline spheres with different sizes in a continuous isotropic phase) 26 as shown in Figure 3a−c,f under a soaking temperature of 420 °C for 4 h. The liquid crystalline spheres appeared in the mesophase pitch products from naphthalene synthetic pitch, coal tar-based impregnating pitch, and C 5 −C 9 aromatic hydrocarbons are sporadic and small, i.e., optically anisotropic small spherules suspended in the optically isotropic pitch matrix.…”

Section: Methodsmentioning

confidence: 99%

Effect of Carbonaceous Precursors on the Structure of Mesophase Pitches and Their Derived Cokes

et al. 2018

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Using six representative feedstocks as carbonaceous precursors, various mesophase pitches and their derived cokes were obtained by a heat-soaking method at a temperature range of 400−450 °C and a pyrolysis treatment at 900 °C, respectively. The optical texture and microstructure of the different mesophase pitches and their derived cokes were characterized by polarized-light microscope, scanning electron microscope, and X-ray diffraction. The results show that the formation and development abilities of liquid crystalline mesophase are obviously different for the various feedstocks. C 9 aromatic hydrocarbons and petroleum-derived paving pitch possess relatively high thermo-chemical reactivity due to the existence of low molecular substances and aliphatic groups, leading to form liquid crystalline mesophase easier and faster than those of naphthalene synthetic pitch and coal tar-based impregnating pitch under a similar condition, which however is undesirable to develop a bulk mesophase. Anthracene possesses a characteristic of forming a homogeneous bulk mesophase with a streamline texture under a suitable condition. The liquid crystalline transformation behavior of C 5 −C 9 aromatic hydrocarbons is unexpectedly similar to that of naphthalene synthetic pitch and markedly different from that of C 9 aromatic hydrocarbons. Carbonaceous precursors have a significant effect on the anisotropic content and the optical texture of the mesophase pitch products, which leads to the microstructure variety of the resultant cokes. Fine-grained and coarse-grained mosaic textures are, respectively, present in the cokes derived from C 9 aromatic hydrocarbons and petroleum-derived paving pitch. The cokes derived both from coal tar-based impregnating pitch and from C 5 −C 9 aromatic hydrocarbons possess a supra mosaic texture mingled with a local flow-induced orientation domain. A well-oriented lamellar texture is clearly found in the cokes derived from anthracene and naphthalene synthetic pitch.

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“…During thermogravimetric analysis in an air atmosphere, both the MP and IP exhibited a weight increase in the range of 200 to 400 °C as a result of the oxidation reaction. It is reported that preparing MP requires more thermal and purification processes than preparing IP 41 . Elemental analysis (EA) and inductively coupled plasma atomic emission spectrometry (ICP-AES) confirmed that more carbon and fewer impurities are present in the MP, as mentioned above.…”

Section: Methodsmentioning

confidence: 99%

Investigation of the degradation of pitch-based carbon fibers properties upon insufficient or excess thermal treatment

Lim

Yeo

2017

Sci Rep

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To overcome the disadvantages of discontinuous conventional batch extruders, a continuous screw extruder is introduced to manufacture pitch-based carbon fibers. For a carbon fiber preparation process, an oxidation time of 8 h was determined to be optimal for obtaining desirable mechanical properties of the fibers acquiring employing the screw extruder. It is hypothesized that the differences in the properties of the carbon fibers fabricated utilizing the batch and screw extruders originate from the melt spinning time; therefore, a combined equation for the total amount of heat treatment from the pitch precursor through the oxidation process is established in this study. The crystallinity of the carbon fibers is confirmed to correspond to the differences in mechanical properties as the oxidation time increases. The poor mechanical properties of the carbon fibers that are insufficiently oxidized are a result of irregular oxidation from the sheath to the core of the fiber cross section. However, the over-oxidized carbon fibers also show poor mechanical properties than the optimal fibers. This result further affirms that excessive oxidation times cause unstable chemical bonding, which interrupts the formation of stable crystal structures after carbonization.

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Comparative study of isotropic and mesophase pitches derived from C9 alkylbenzenes

Cited by 23 publications

References 5 publications

Chemical Modification of Asphaltene with SEBS as Precursor for Isotropic Pitch‐Based Carbon Fiber

Chemical Modification of Asphaltene with SEBS as Precursor for Isotropic Pitch‐Based Carbon Fiber

Effect of Carbonaceous Precursors on the Structure of Mesophase Pitches and Their Derived Cokes

Investigation of the degradation of pitch-based carbon fibers properties upon insufficient or excess thermal treatment

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