Stabilization of pitch-based carbon fibers accompanying electron beam irradiation and their mechanical properties

Park, Mi-Seon; Ko, Young San; Jung, Min-Jung; Lee, Young-Seak

doi:10.5714/cl.2015.16.2.121

Cited by 18 publications

(4 citation statements)

References 23 publications

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“…The char of the samples formed during combustion and acted as a protective layer such that oxygen diffusion to the surface of the specimen was prevented, resulting in more oxygen necessary for the combustion process. These results were in good agreement with the findings for lyocell fibers modified with a (NH 4 ) 2 SO 4 /NH 4 Cl solution [9]. The relationship between the char yield and LOI could be observed by the regression line between them.…”

Section: Samplesupporting

confidence: 91%

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Effects of an inorganic ammonium salt treatment on the flame-retardant performance of lyocell fibers

Kim¹,

Bai²,

In³

et al. 2016

Carbon letters

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Lyocell fibers are produced by dissolving cellulose in a N-methylmorpholine-N-oxide/ water solution. The resulting cellulose/N-methylmorpholine-N-oxide/water mixture is extruded through an orifice, drawn into an air gap, and then precipitated in a coagulation bath [1]. In contrast with rayon fibers, lyocell fibers have higher tenacity, a higher modulus, lower shrinkage when dried, and lower reductions of tenacity and the modulus when wet. Moreover, lyocell fibers are round and have molecular chains that are highly oriented along the fiber axis, and it is easy to control their fineness [2].However, lyocell fibers are often subjected to high temperatures, which can cause degradation of the fibers. When lyocell fibers are heated, they undergo a series of interrelated physical and chemical changes, including physical changes in weight, strength, color, and crystallinity. In addition, heat treatment can cause the material to move through different transitional phases and expand or contract, melt and recrystallize or undergo major structural changes [3].Thermal decomposition of the lyocell fibers leads to many kind of formations, such as solid residue, high-boiling point volatiles, and gaseous products. These kinds of products are formed through two competitive pathways. The first pathway involves many transformations, such as dehydration, rearrangement, carbonyl groups formation, the evolution of carbon monoxide and carbon dioxide, and the carbonaceous residue formation [4]. These phenomena take place rapidly in the presence of a variety of organic and inorganic catalysts, particularly Lewis acids, which catalyze the dehydration reactions. The second pathway competes with the first pathway and produces many oxygenated compounds and involves the thermal scission of glycosidic bonds between the glucopyranose units of cellulose [5]. These oxygenated compounds account for the majority of the weight loss of the solid residue. Therefore, it is important to control the reaction pathways during the initial pyrolysis stage to generate flame-retardant materials. Thus, flame-retardant enhanced lyocell fibers should be investigated for industrial applications. Recently, various treatment processes have been used to improve the flame-retardant properties of lyocell fibers. Because catalysts accelerate pyrolysis reactions, it is important to study the effects of catalysts on the pyrolysis of lyocell fibers. An effective catalyst should [6,7] decrease the pyrolysis temperature, increase the amounts of water and carbon dioxide produced during the reaction, and increase the amount of char formed.Therefore, it is important to control the reaction pathways during the initial stage of pyrolysis when generating flame-retardant materials. In this study, the effects of two different inorganic ammonium salts, (NH 4 ) 2 SO 4 and NH 4 Cl, on the flame-retardant properties of lyocell fibers were studied. Combining these salts could have a synergistic effect on the pyrolysis of lyocell fibers, including the induction of a slow pathway that invo...

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Section: Samplesupporting

confidence: 91%

“…The step 1 shoulder peak at approximately 200°C was due to the thermal decomposition of (NH 4 ) 2 SO 4 /NH 4 Cl and the release of water and ammonia [9]. Moreover, the profile of the step 2 peak appears to reflect change of the combustion pathway, which was shifted to a higher temperature and became broader.…”

Section: Samplementioning

confidence: 96%

Effects of an inorganic ammonium salt treatment on the flame-retardant performance of lyocell fibers

Kim¹,

Bai²,

In³

et al. 2016

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“…Carbon nanofibers (CFs) have been used in various applications such as gas sensors, automobiles, high-grade sporting goods, wind turbine blades and aircrafts because of their good mechanical and electrical properties [1][2][3][4][5]. Cellulose is a biopolymer that can be used as a CF precursor.…”

Section: Introductionmentioning

confidence: 99%

Deacetylation of cellulose acetate nanofibers by fluorination for carbon nanofibers

Kim

Lee

2016

Materials Letters

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“…Electron beam (E-beam) irradiation has been rapidly developed as a polymer processing technique [9,10]. It is used for polymer modification, such as cross-linking, curing, and grafting, on the basis of the optical transparency of the system and because chemical/photo-for 3 h. Finally, a silver wire (Φ 0.1) was connected to the Pt electrode containing the samples using silver paste (Elcoat P-100, 10 -4 Ω cm Cans, Korea).…”

Section: Introductionmentioning

confidence: 99%

NO gas sensing ability of activated carbon fibers modified by an electron beam for improvement in the surface functional group

Park¹,

Lee²,

Jung³

et al. 2016

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Activated carbon fiber (ACF) surfaces are modified using an electron beam under different aqueous solutions to improve the NO gas sensitivity of a gas sensor based on ACFs. The oxygen functional group on the ACF surface is changed, resulting in an increase of the number of non-carbonyl (-C-O-C-) groups from 32.5% for pristine ACFs to 39.53% and 41.75% for ACFs treated with hydrogen peroxide and potassium hydroxide solutions, respectively. We discover that the NO gas sensitivity of the gas sensor fabricated using the modified ACFs as an electrode material is increased, although the specific surface area of the ACFs is decreased because of the recovery of their crystal structure. This is attributed to the static electric interaction between NO gas and the non-carbonyl groups introduced onto the ACF surfaces.

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Stabilization of pitch-based carbon fibers accompanying electron beam irradiation and their mechanical properties

Cited by 18 publications

References 23 publications

Effects of an inorganic ammonium salt treatment on the flame-retardant performance of lyocell fibers

Effects of an inorganic ammonium salt treatment on the flame-retardant performance of lyocell fibers

Deacetylation of cellulose acetate nanofibers by fluorination for carbon nanofibers

NO gas sensing ability of activated carbon fibers modified by an electron beam for improvement in the surface functional group

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