Polyacrylonitrile PAN-based

Fig. 2.8. Laser Raman spectra obtained (a) for a polyacrylonitrile (PAN)-based HMS4 carbon fiber, and (b) for a pitch-based P75S carbon fiber. After Robinson et al. (1987).

Recall from Section 1.4.5.1 that there are two primary types of carbon fibers polyacrylonitrile (PAN)-based and pitch-based. There are also different structural forms of these fibers, such as amorphous carbon and crystalline (graphite) fibers. Typically, PAN-based carbon fibers are 93-95% carbon, whereas graphite fibers are usually 99+%, although the terms carbon and graphite are often used interchangeably. We will not try to burden ourselves with too many distinctions here, since the point is to simply introduce the relative benefits of continuous-fiber composites over other types of composites, and not to investigate the minute differences between the various types of carbon-fiber-based composites. The interested reader is referred to the abundance of literature on carbon-fiber-reinforced composites to discern these differences. 

Saufi S.M., and Ismail A.F. (2003) Development and characterization of polyacrylonitrile (PAN) based carbon hollow fiber membrane. Songklanakarin J. Sci. Technol. 24, 843-854. 

A study of the hydrophilic sites on the surface of activated carbon fibres has been made recently by Kaneko et al. (1995) with the aid of X-ray photoelectron spectroscopy (XPS). In this work cellulose (CEL)- and polyacrylonitrile (PAN)-based activated carbon fibres were used and samples were either chemically treated with H202 or heated in H2 at 1000°C. As expected, surface oxidation by the H202 treatment increased the initial uptake of water, while the H2 reduction caused a marked decrease in the amount of water adsorbed at low p/p°. Measurement of the peak areas of the XPS spectra provided a means of determining the fractional surface coverage by the hydrophilic sites. In this way a linear relationship was found between the low-pressure adsorption of water vapour and the number of hydrophilic sites (mainly —COOH). 

Less ordered, polyacrylonitrile (PAN)-based high-modulus and high-strength CFs have an intermediate, statistically cylindrical symmetry, which can be... 

Basic nitrogen species present on the surface of activated carbons or carbon fibers, like in the case of H2S, were found to enhance the sulfur dioxide uptake. Polyacrylonitrile (PAN)-based activated carbon fibers are examples of good adsorbents for SO2 removal [82, 92]. Although role of nitrogen present in the carbon matrix was not emphasized by Lee and coworkers [93] in their studies of SO2 adsorption on PAN-based activated carbon fibers, [93] Kawabuchi and coworkers noticed a significant increase in the sorption capacity when activated carbon fibers were modified with pyridine and basic nitrogen functionalities were introduced to the surface [93]. Pyridine provided basic functionality, which increased catalytic removal of SO,. . 

Lee, J.K., Shim, H.J., LimJ.C., et al. (1997). Influence of tension during oxidative stabihzation on SO2 adsorption characteristics of polyacrylonitrile (PAN) based activated carbon fibers. Carbon, 35, 837-43. 

In carbon fiber felts, however, only one kind of pores, interparticle pores, are observed among the fibers (Fig. 27.4). The surface of each fiber is smooth and no pores are inside of the fibers. Felts composed of polyacrylonitrile (PAN)-based and isotropic pitch-based carbon fibers were used as sorbents in the present work. 

PAN, Epoxy I, DGEBA (diglycyl ether of bisphenol A) epoxy resin with 35% w/w of diamino diphenyl sulfone hardener, T300, polyacrylonitrile (PAN)-based C fiber PTEDM, poly(2,2 -thiobisethanol dimethacrylate) PNDM, poly(W-methyldiethanolamine dimethacrylate). Oxyfiuorination is a proprietary treatment of Air Products and Chemicals that results in surface oxidation and fiuorination of fibers. 

Electrochemical pretreatment of activated carbon fibers (ACEs) based on polyacrylonitrile (PAN-based) in a NaN03 solution resulted in an increase in the content of oxygen-containing functional groups in the fiber surface and therefore led to an increase in specific capacitance Cg. ACEs oxidized for 6h contained 1.3mmol/g of O and Co was formed on 76% of them under thermal treatment. Various carbon materials, including anthracite and different carbon fibers, were activated by KOH, NaOH, CO2, or water vapor at 650-750 C. The values of Cg measured for all carbon... 

Yusof N, Ismail AF (2012) Post spinning and pyrolysis processes of polyacrylonitrile (PAN)-based carbon fiber and activated carbon fiber a review. J Anal Appl Pyrol 93 1-13... 

The existence of carbon liber (CFs) came into being in 1879 when Thomas Edison recorded the use of carbon fiber as a filament element in electric lamp. Fibers were first prepared from rayon fibers by the US Union Carbide Corporation and the US Air Force Materials Laboratory in 1959 [41 ]. In 1960, it was realized that carbon fiber is very usefirl as reinforcement material in many applications. Since then a great deal of improvement has been made in the process and product through research work carried out in USA, Japan and UK. In 1960s, High strength Polyacrylonitrile (PAN) based carbon fiber was first produced in Japan and UK and pitch based carbon fiber in Japan and USA. 

Carbon fibers can be produced from a wide variety of precursors in the range from natural materials to various thermoplastic and thermosetting precursors Materials, such as Polyacrylonitrile (PAN), mesophase pitch, petroleum, coal pitches, phenolic resins, polyvinylidene chloride (PVDC), rayon (viscose), etc. [42-43], About 90% of world s total carbon fiber productions are polyacrylonitrile (PAN)-based. To make carbon fibers from PAN precursor, PAN-based fibers are generally subjected to four pyrolysis processes, namely oxidation stabilization, carbonization and graphitiza-tion or activation they will be explained in following sections later [43]. 

To increase the response rates of diffusion limited actuators, the aspect ratio can be increased to allow more surface area to be accessed. A common approach to achieve this is to produce responsive fibers of the polymer, often exploited for polyacrylonitrile (PAN)-based devices. To further improve their actuator behavior, the conductivity of the fibers can be increased by seeding with metallic particles, such as platinum, or by combination with other conductive fibers, such as graphite. ... 

Polyacrylonitrile (PAN)-based carbon felt or spectral pure graphite electrodes and Nation 117 membrane... 

Raman spectroscopy is sensitive to both the chemical and the stmctural variations of a material, liquid or solid/ As an in situ technique, Raman spectroscopy has been used to characterize the crystalline structural variation of graphite anodes and Li vPj and LiMn O cathodes in lithium ion batteries during lithium ion insertion and extraction. In the authors laboratory, Raman spectroscopy was used to extensively study the strong interactions between the components of polyacrylonitrile (PAN)-based electrolytes, the competition between the polymer and the solvent on association with the Li ions, the ion transport mechanisms of both salt-in-polymer and polymer-in-salt electrolytes. Based on the Raman spectroscopic study, Li ion insertion and extraction mechanisms in low-temperature pyrolytic carbon anode have also been proposed. " In many cases, Raman spectroscopy is used as compensation to the IR spectroscopy to give a complete understanding to the structure of a substance though there are as many cases that Raman spectroscopy is used independently. 

The applicability of polyacrylonitrile (PAN)-based negatively charged UF membrane for As removal was demonstrated for the first time by Lohokare et al. (2008). The surface of flat-sheet PAN-based UF membranes was hydrolyzed by using NaOH in cross-flow mode this approach led to the reduction in pore size (as demonstrated by the reduction in water flux and the increased rejection towards proteins and polyethylene glycol) due to the formation of carboxylate (—COO ) groups on both membrane and pore wall surfaces and an increased membrane hydrophilicity. The MWCO after the NaOH treatment was found to be of about 6 kDa. These modified membranes showed excellent As(V) rej actions (close to 100%) when simulated solutions containing 5 0 xg ... 

A. Shindo, Polyacrylonitrile (PAN)-based Carbon Fibers, Comprehensive Composite Materials, Vol. 1 Fiber Reinforcements and General Theory of Composites, Tsu-Wei Chou, Vol. Ed., Anthony Kelly and Carl Zweben, Editors-in-Chief, Pergamon Press, Elsevier Science Ltd., Oxford, 2000. 

Donnet JB, Bansal RC (1984) Carbon Fiber. Marcel Dekker, New York, NY, USA Saufi SM, Ismail AF (2002) Development and characterization of polyacrylonitrile (PAN) based carbon hollow fiber membrane. Songkianakarin J Sci Technol 24 (SuppI) 843-854 Schindler E, Maier F (1990) Manufacture of porous carbon membranes. US Patent 4,919,860 Yoneyama H, Nishihara Y (1990) Porous hollow carbon fiber film and method of manufacturing the same. EP Patent 0,394,449... 

Cellulose(CEL)- and polyacrylonitrile(PAN)-based ACF s and coconut-shell granular activated carbons (AC) were used in this study. Also nonporous carbon black(NPC) whose surface area Is 81 m g" was examined by in situ XRD for comparison. The adsorption Isotherms of water at 298 K and N2 at 77 K on samples were measured gravimetrically. The ACF sample was pre-evacuated at 383 K and 1 mPa for 15 h prior to the adsorption. The evolved gas analyses (EGA) of ACF samples preheated at 373 K under 1 mPa for 15 h were carried out at a heating rate of 10 K min with the aid of a mass filter(ULVAC, MSQ-150A). The elemental analysis for the nitrogen atom of the ACF samples was done the ratios of nitrogen to carbon in wt. % of CEL and PAN were 2 and 6-7, respectively. 

Cycle life data for (a) TANS9S series and (b) TANllS series of graphitic carbons heat-treated at 900°C and 1100°C respectively, with sulphuric acid treatment denoted by S followed by the duration of the treatment in hours. (Reprinted with permission from Carbon, 43, Y.J. Kim et al.. Effects of sulfuric acid treatment on the microstructure and electrochemical performance of a polyacrylonitrile (PAN)-based carbon anode, 2005,163-169, Copyright 2005, Elsevier.)... 

Typical thermal conductivity values (all in W/mK) are 0.2 to 0.3 for pol5Tners, 1 to 2 for carbon black, 10 to 20 for polyacrylonitrile (PAN) based carbon fiber, 100 to 800 (depends on the heat treatment temperature) for petrolaim pitch-based carbon fiber, 400 for copper, and 600 for graphite. Electrical resistivity (1/electrical conductivity) values (all in ohm-cm) for various materials are lO to 10 for polymers, 10" for electrically conductive carbon black, 10 for PAN-based carbon fiber, 10" for pitch based carbon fiber, 10 for graphite, and lO" for metals such as aluminum and copper. One proach to inqjroving the conductivity of a polymer is through the addition of conductive filler, such as carbon and metal [1, 2]. Typically for a bipolar plate, the desired thermal and electricM conductivity are 20 W/mK and 50 S/cm (0.02 ohm-cm). 

For the present investigations, the reinforcement materials used were the polyacrylonitrile (PAN) based carbon fiber (PANEX 35) fabrics manufactured by ZOLTEK... 

---