Modification of polyacrylonitrile stabilized fibers via post-thermal treatment in nitrogen prior to carbonization and its effect on the structure of carbon fibers

Wu, Shuai; Gao, Aijun; Wang, Yu

doi:10.1007/s10853-017-1894-8

Cited by 15 publications

(18 citation statements)

References 44 publications

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“…Materials : The polyacrylonitrile (PAN)‐based CFs of 7 µm in diameter were produced according to the protocol as described below . PAN precursor fibers made of PAN copolymer with 97.5 wt% of acrylonitrile (AN) and 2.5 wt% of itaconic acid (IA) were stabilized with increasing step temperatures from 180 to 260 °C in air within 1 h; and then carbonized by treatment under 680 and 1300 °C in high pure nitrogen to obtain the final product CFs.…”

Section: Methodsmentioning

confidence: 99%

High Modulus Conductive Hydrogels Enhance In Vitro Maturation and Contractile Function of Primary Cardiomyocytes for Uses in Drug Screening

Gao

Liu

et al. 2018

Adv Healthcare Materials

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Effective and quick screening and cardiotoxicity assessment are very crucial for drug development. Here, a novel composite hydrogel composed of carbon fibers (CFs) with high conductivity and modulus with polyvinyl alcohol (PVA) is reported. The conductivity of the composite hydrogel PVA/CFs is similar to that of natural heart tissue, and the elastic modulus is close to that of natural heart tissue during systole, due to the incorporation of CFs. PVA/CFs remarkably enhance the maturation of neonatal rat cardiomyocytes (NRCM) in vitro by upregulating the expression of α‐actinin, troponin T, and connexin‐43, activating the signaling pathway of α5 and β1 integrin‐dependent ILK/p‐AKT, and increasing the level of RhoA and hypoxia‐inducible factor‐1α. As a result, the engineered cell sheet–like constructs NRCM@PVA/CFs display much more synchronous, stable, and robust beating behavior than NRCM@PVA. When exposed to doxorubicin or isoprenaline, NRCM@PVA/CFs can retain effective beating for much longer time or change the contractile rate much faster than NRCM@PVA, respectively, therefore representing a promising heart‐like platform for in vitro drug screening and cardiotoxicity assessment.

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Section: Methodsmentioning

confidence: 99%

High Modulus Conductive Hydrogels Enhance In Vitro Maturation and Contractile Function of Primary Cardiomyocytes for Uses in Drug Screening

Gao

Liu

et al. 2018

Adv Healthcare Materials

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“…The commonly accepted scheme of this stabilization process have been assumed to consist of three distinct chemical reactions for a long time, and the concept is widely used for the explanation of experimental results even in very recent reports [1,[6][7][8][9]. The three reactions are called cyclization, dehydrogenation and oxidation (sometimes cross-linking), and they are usually assigned to the exothermic peaks of thermograms obtained in differential scanning calorimetric (DSC) measurements.…”

Section: Introductionmentioning

confidence: 99%

“…The three reactions are called cyclization, dehydrogenation and oxidation (sometimes cross-linking), and they are usually assigned to the exothermic peaks of thermograms obtained in differential scanning calorimetric (DSC) measurements. PAN is studied predominantly in oxidative atmosphere, since the common industrial process used in practice is based on oxidative stabilization [2,4,5,9,10]. The approach yields complicated overlapping exothermic signals, the resolution of which depends primarily on the rate of heating and the weight of the sample used for DSC analysis.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, some groups report results obtained in a non-oxidative, partial stabilization process of PAN, which excludes oxidative processes. Only a few groups studied the behavior of PAN in a two-step stabilization procedure, which consists of an inert pre-treatment and a subsequent oxidative step [7,9,11,12]. The two-step approach provides a deeper insight into the chemical changes taking place during stabilization as compared to the direct oxidation of PAN.…”

Section: Introductionmentioning

confidence: 99%

“…The goal of our study was to answer yet unclear questions regarding the stabilization 4 of PAN. These include the stereochemistry of cyclization [3,[13][14][15][16], the requirement of a cyclized structure for oxygen inclusion [9,17], the effect of inert pre-treatment on oxygen up-take [9], the average zip-length of cyclization [7,15,16], the relationship between chemical changes and exothermic peaks observed in DSC measurements [1,[6][7][8][9]11,12] and the mechanism of the reactions occurring. The complexity of the stabilization process makes the answering of these questions extremely difficult.…”

Section: Introductionmentioning

confidence: 99%

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The mechanism of thermal stabilization of polyacrylonitrile

Szepcsik

Pukánszky

2019

Thermochimica Acta

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The two-step stabilization of a thoroughly characterized PAN homopolymer was studied by various methods including thermogravimetric analysis (TGA), evolved gas analysis (EGA), differential scanning calorimetry (DSC), Fourier transformed infrared spectroscopy (FTIR), oxygen microanalysis and theoretical energy calculations. Stabilization was carried out with pre-treatment in inert atmosphere, and the reactions taking

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Effects of ambient pressure on structural characteristics of polyacrylonitrile pre‐oxidized fibers

Shen

Lan

Wang

et al. 2022

J of Applied Polymer Sci

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During the pre‐oxidation process, skin‐core structure is easily formed in the fibers due to the competitive mechanism of oxygen capture and oxygen diffusion, which would degrade the tensile properties of the resulting carbon fibers. To prepare high‐performance carbon fibers, it is vital to optimize the radial structure of polyacrylonitrile (PAN) pre‐oxidized fibers. Methods commonly used to solve the skin‐core structure would result in low productivity and comprehensive performance. Here, we examine the effects of pressure on the chemical structure and the evolution of radial structure in PAN pre‐oxidized fibers under 225°C in the air, by using 13C Solid‐state NMR analysis (13C‐NMR), Optical density test (OD), and Thermogravimetric Analysis (TG). It was found out that under the positive pressure of 30 kPa, the reaction area expands to the core of the fibers with the shell thickness increasing from 88.11% under normal pressure to 98.67%, and the radial structure homogeneity is effectively improved. As the pressure increases above 22 kPa, oxygen diffusion is accelerated, allowing for breaking the barrier of the fiber surface capture and promoting the oxygen catalytic cyclization reaction in the core. Consequently, PAN pre‐oxidized fibers prepared under positive pressure have a more uniform radial structures and higher thermal stability. The carbonization yield at 800°C of the fibers prepared at 30 kPa is 13.10% higher than that of the fibers prepared at atmospheric pressure.

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Modification of polyacrylonitrile stabilized fibers via post-thermal treatment in nitrogen prior to carbonization and its effect on the structure of carbon fibers

Cited by 15 publications

References 44 publications

High Modulus Conductive Hydrogels Enhance In Vitro Maturation and Contractile Function of Primary Cardiomyocytes for Uses in Drug Screening

High Modulus Conductive Hydrogels Enhance In Vitro Maturation and Contractile Function of Primary Cardiomyocytes for Uses in Drug Screening

The mechanism of thermal stabilization of polyacrylonitrile

Effects of ambient pressure on structural characteristics of polyacrylonitrile pre‐oxidized fibers

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