Evolution mechanism of cyclized structure of PAN-based pre-oxidized fiber during low temperature carbonization process

Abstract The low temperature carbonization process is an important stage to realize the structural transition from the organic cyclized structure of PAN based pre-oxidized fiber to the inorganic pseudo-graphite structure of the ultimate carbon fiber. In the present paper, the evolution mechanism of cyclized structure and aggregation structure of PAN stabilized fiber during low temperature carbonization was studied by means of TGA, 13C-NMR, XRD, XPS and Raman. The results indicated that when the heat-treated temperature was lower than 450 °C, the mainly chemical reactions were the dehydrogenation and pyrolysis reactions in acyclic linear molecular chain or partial cyclized structure. At this stage, the growth of cyclized structure was not obvious. While the original ordered structure was destroyed gradually and the internal stress increased significantly. It induced the cyclized structure to be further oriented. When the temperature was higher than 450 °C, the polycondensation and reconstruction in aromatic heterocyclic structure was more important. The early aromatic heterocycles had many different structural scales, poor homogeneity and many defects in the heterocycles. At this stage, a new pseudo-graphite crystalline structure gradually formed and the d-spacing of graphite layer decreased slightly and crystallites size increased slowly with the increase of heat-treated temperature. When the temperature was higher than 550 °C, the pseudo-graphite base structure gradually formed. The d-spacing were further reduced slightly, and the crystallites size increased slowly. A new ordered basis structure was gradually developed into carbon fiber.

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Low-temperature fabrication of crystalline MnCoO spinel film on porous carbon paper for efficient oxygen evolution reaction

Chemical Communications ◽

10.1039/d1cc00706h ◽

2021 ◽

Author(s):

Sunglun Kwon ◽

Ha Eun Lee ◽

Donghoon Han ◽

Jong Hyeon Lee

Keyword(s):

Thin Film ◽

Carbon Fiber ◽

Low Temperature ◽

Oxygen Evolution ◽

Porous Carbon ◽

Oxygen Evolution Reaction ◽

Carbon Paper ◽

Carbon Fiber Paper

A thin film of MnxCo3−xO4 (MnCoO) nanocatalyst on a porous carbon fiber paper (CFP) electrode for efficient oxygen evolution reaction (OER).

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Investigating the efficacy of machine learning tools in modeling the continuous stabilization and carbonization process and predicting carbon fiber properties

Carbon ◽

10.1016/j.carbon.2020.12.044 ◽

2020 ◽

Author(s):

Narayan Shirolkar ◽

Prachi Patwardhan ◽

Aowabin Rahman ◽

Ashley Spear ◽

Satish Kumar

Keyword(s):

Machine Learning ◽

Carbon Fiber ◽

Learning Tools ◽

Carbonization Process ◽

Fiber Properties

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High Mechanic Enhancement of Chopped Carbon Fiber Reinforced-Low-Density Unsaturated Polyester Resin Composite at Low Preparation Temperature with Facile Polymerization

Materials ◽

10.3390/ma14154273 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4273

Author(s):

Jian Zhang ◽

Xiaojun Wang ◽

Xinjun Fu

Keyword(s):

Composite Materials ◽

Carbon Fiber ◽

Low Temperature ◽

Surface Defect ◽

Polyester Resin ◽

Unsaturated Polyester ◽

Unsaturated Polyester Resin ◽

Low Density ◽

Fiber Reinforced ◽

Preparation Temperature

Chopped carbon fiber-reinforced low-density unsaturated polyester resin (CCFR-LDUPR) composite materials with light weight and high mechanical properties were prepared at low temperature and under the synergistic action of methyl ethyl ketone peroxide (MEKP-II) and cobalt naphthenate. Optimal preparation conditions were obtained through an orthogonal experiment, which were preparation temperature at 58.0 °C, 2.00 parts per hundred of resin (phr) of NH4HCO3, 4.00 phr of chopped carbon fibers (CCFs) in a length of 6.0 mm, 1.25 phr of initiator and 0.08 phr of cobalt naphthenate. CCFR-LDUPR composite sample presented its optimal properties for which the density (ρ) was 0.58 ± 0.02 g·cm−3 and the specific compressive strength (Ps) was 53.56 ± 0.83 MPa·g−1·cm3, which is 38.9% higher than that of chopped glass fiber-reinforced low-density unsaturated polyester resin (CGFR-LDUPR) composite materials. Synergistic effects of initiator and accelerator accelerated the specific polymerization of resin in facile preparation at low temperature. Unique “dimples”, “plate microstructure” and “surface defect” fabricated the specific microstructure of the matrix of CCFR-LDUPR composite samples, which was different from that of cured unsaturated polyester resin (UPR) with “body defect” or that of CGFR-LDUPR with coexistence of “surface defect” and “body defect”.

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Low-temperature fracture toughness of a heat-treated mild steel

Journal of Materials Engineering and Performance ◽

10.1007/bf02682708 ◽

1995 ◽

Vol 4 (1) ◽

pp. 70-81 ◽

Cited By ~ 1

Author(s):

C. C. Chama

Keyword(s):

Fracture Toughness ◽

Low Temperature ◽

Mild Steel ◽

Heat Treated ◽

Temperature Fracture

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Catalytic activity of pitch-based activated carbon fiber of large surface area heat-treated at high temperature and its regeneration for NO–NH3 reaction at ambient temperatures

Fuel ◽

10.1016/s0016-2361(01)00096-5 ◽

2001 ◽

Vol 80 (15) ◽

pp. 2227-2233 ◽

Cited By ~ 14

Author(s):

Isao Mochida ◽

Shizuo Kawano ◽

Noriaki Shirahama ◽

Takashi Enjoji ◽

Seung Hyun Moon ◽

...

Keyword(s):

Catalytic Activity ◽

Activated Carbon ◽

High Temperature ◽

Carbon Fiber ◽

Surface Area ◽

Activated Carbon Fiber ◽

Large Surface Area ◽

Ambient Temperatures ◽

Heat Treated

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Characteristics of Black Ginseng (Panax ginseng C.A. Mayer) Production Using Ginseng Stored at Low Temperature after Harvest

Metabolites ◽

10.3390/metabo11020098 ◽

2021 ◽

Vol 11 (2) ◽

pp. 98

Author(s):

Hyo Bin Oh ◽

Ji Won Lee ◽

Da Eun Lee ◽

Soo Chang Na ◽

Da Eun Jeong ◽

...

Keyword(s):

Heat Treatment ◽

Low Temperature ◽

Panax Ginseng ◽

Low Temperatures ◽

Sugar Content ◽

Base Material ◽

Free Sugar ◽

Drying Process ◽

Heat Treated ◽

Black Ginseng

Ginseng processing often involves multiple drying and heat treatments. Ginseng is typically processed within one week of harvesting or is stored at low temperatures to prevent spoilage. Black ginseng (BG) is manufactured by repeating the heat treatment and drying process of ginseng several times. We compared the suitability of low-temperature stored ginseng (SG) and harvested ginseng (HG) as the components for black ginseng production. SG and HG were processed into black ginseng and the appearance change, free sugar content, and benzo[a]pyrene (BAP) content were observed. Appearance observations showed the SG to be suitable in terms of quality when heat-treated at a temperature of 95 ℃ or higher. The BAP content of the SG increased significantly as the steaming process was repeated. A maximum BAP concentration of 5.31 ± 1.12 μg/kg was measured in SG steamed from 2 to 5 times, making it unsuitable for processing into BG. SG and HG showed similar trends in the content of sucrose, fructose, and glucose during steaming. This study aimed to facilitate the proper choice of base material to improve the safety of black ginseng by limiting BAP production during processing.

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Dlts-Studies on the “New Oxygen Donor” in Heat Treated and Hydrogenated CZ-Grown SI

MRS Proceedings ◽

10.1557/proc-59-481 ◽

1985 ◽

Vol 59 ◽

Cited By ~ 4

Author(s):

Karlheinz Hölzlein ◽

G. Pensl ◽

M. Schulz ◽

N. M. Johnson

Keyword(s):

Low Temperature ◽

Heat Treatments ◽

Experimental Results ◽

Interface Model ◽

Trap States ◽

High Concentration ◽

Oxygen Donor ◽

Heat Treated ◽

Processing Steps

ABSTRACTCz-grown Si samples containing a high concentration of oxygen are investigated after various processing steps by DLTS. Heat treatments ranging from 500°C–1000°C are performed to study the formation and annihilation of the “New Oxygen Donor” (ND) traps. Hydrogenation at low temperature leads to a reduction of the ND trap states. The experimental results confirm the “SiOx Interface Model” which assumes two differing types of interfacerelated states.

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