The densification mechanism of polyacrylonitrile carbon fibers during carbonization

Chen

Journal of Micro and Nano-Manufacturing

et al. 2017

In this work, an electrohydrodynamic casting approach was used to manufacture a carbon nanofiber (CNF) composite material containing bismuth telluride (Bi2Te3) particles. A 10% polyacrylonitrile (PAN) polymer solution was taken as the precursor to generate nanofibers. Bismuth telluride microparticles were added into the polymer solution. The particle-containing solution was electrohydrodynamically cast onto a substrate to form a PAN-based nanofiber composite mat. High temperature heat treatment on the polymeric matrix composite mat in hydrogen atmosphere resulted in the formation of a microparticle-loaded CNF composite material. Scanning electron microscopic (SEM) analysis was conducted to observe the morphology and reveal the composition of the composite material. Energy conversion functions in view of converting heat into electricity, electromagnetic wave energy into heat, and photon energy into electricity were shown. Strong Seebeck effect, hyperthermia, and photovoltaics of the composite mat were found. In addition, the potential applications as sensors were discussed.

Section: Energy Conversion Propertymentioning

confidence: 82%

Electrohydrodynamic Casting Bismuth Telluride Microparticle-Loaded Carbon Nanofiber Composite Material With Multiple Sensing Functions

Chen

Journal of Micro and Nano-Manufacturing

et al. 2017

J of Applied Polymer Sci

“…At the following stage, the grooves and ridges in fiber surface were not as obvious as the former samples and almost disappeared for sample LF750, with some discontinuous small bulges and fragments on the longitudinal surface. During low temperature carbonization, the residual linear molecular chains and unstable isolated rings decomposed during the pyrolysis reaction 23,28 and the crystallite size decreased in internal, which resulted in damage of the regular grooves and ridges. Some slender uniform streaks and bulges were observed on the longitudinal surface after high temperature carbonization.…”

Section: Surface Topography Evolution Of Pan Fibers During Heat Treat...mentioning

confidence: 99%

“…The carbon elements further accumulate, and the carbon basal planes further condenses in the high temperature carbonization stage, delivering graphite-like microcrystalline structure finally. [26][27][28] A lot of scientific researches have been dedicated either to the structural evolution in the thermal oxygen stabilization stage, 5,10,12 or the microstructure evolution 25,29 in the carbonization stage, or to the structural changes in the final sample using isothermal heating method. 5 Considering the poor thermal conductivity of PAN fibers, stepwise heating mode 8 is widely used in the actual industrial production process in order to avoid heat accumulation caused by long-term isothermal heating mode which would result in the decrease of fiber quality.…”

Section: Introductionmentioning

confidence: 99%

Study on the structural evolution of polyacrylonitrile fibers in stepwise heat treatment process and its relationship with properties

Liu

Shang

2021

The structural evolution of polyacrylonitrile fibers in stepwise heat treatment process and its relationship with properties were investigated systematically.Results demonstrated that the cyclization degree and dehydrogenation index of fibers reached 84.13% and 1.361, respectively after stabilization at 265 C.The oxygen reaction was enhanced after stabilized at 245 C. Refinement of the microcrystalline structure took effect during stabilization and low temperature carbonization, while growth of microcrystalline dominated during high temperature carbonization. The results of surface topography study not only provided the evolution characteristics of surface microstructure under the influence of chemical reaction, but also further complements the internal aggregation structural rearrangement process from the side. Additionally, the temperature zone from 245 to 265 C was the key stage of the formation of the skin-core structure, which would be transmitted to the resultant carbon fiber.Tensile strength and tensile modulus decreased during stabilization stage, reaching 4.273 GPa and 221.132 GPa, respectively after high temperature carbonization. The elongation at break which first increased and then decreased proved a toughness failure to brittleness failure. The investigation elucidated the relationship between the mechanical property with chemical and physical microstructure. And the possible rearrangement process of the aggregation structure was proposed.

Bull. Chem. React. Eng. Catal.

“…On the contrary, the pore size and pore volume were relatively independent on temperature when the carbonization time was longer than 1 h which took the value of approximately 3.0 nm and 0.7 cm 3 /g, respectively. During carbonization process, the non-carbon elements are released from PEG, enriching carbon content through condensation and pyrolysis reactions [25]. The pyrolysis reactions produce many pores left by the release of the small, noncarbon molecules.…”

Section: Characteristic Of Silica-carbon Compositementioning

confidence: 99%

Sulfonated Mesoporous Silica-Carbon Composite Derived from a Silicate-Polyethylene Glycol Gel and Its Application as Solid Acid Catalysts

Julaika

Fadli

Widiyastuti

et al. 2021

Solid acid catalyst is a promising alternative to the counterpart homogeneous acid for esterification reaction from the viewpoint of reusability and environmental concerns. This work aims to develop sulfonated mesoporous silica-carbon composite as solid acid catalyst for the esterification. The catalyst was synthesized from sodium silicate as the silica precursor and polyethylene glycol (PEG) as both carbon precursor and template via a sol-gel route in an aqueous system. Then, it was carbonized to produce mesoporous silica-carbon composite. Using the proposed method, the surface area of the silica-carbon composite could reach as high as 1074.21 m2/g. Although the surface area decreased to 614.02 m²/g when it was functionalized with sulfonate groups, the composite had a high ionic capacity of 5.3 mEq/g and exhibited high catalytic activity for esterification reaction of acetic acid with ethanol. At a reaction temperature of 80 °C, the acetic acid conversion reached 76.55% in 4 h. In addition, the catalyst had good reusability, which can be comparable with the commercial catalyst Foltrol F-007. It appears that the sulfonated silica-carbon composite prepared from sodium silicate using PEG as the carbon source a promising candidate as catalyst for esterification and the related area. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).