Environmental Engineering Reference
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stretching with plasticizer. The post spinning modifi cations indirectly affect and
ease the stabilization in several ways such as reducing the activation energy of
cyclization, decreasing the stabilization exotherm, increasing the speed of cycli-
zation reaction, and also improving the orientation of molecular chains in the
fi bers. One of the well-known posts spinning treatment for PAN fi ber precursor
is modifi cation through coatings. The PAN fi bers are coated with oxidation re-
sistant resins such as lubricant (fi nishing oil), antistatic agents, andemulsifi ers,
which are basically used as, spin fi nish on the precursor fi ber. Coating with certain
resins also acts in the same manner as the comonomer in reducing the cycliza-
tion exotherm thus improving the mechanical properties of the resulting carbon
fi bers. Due to their excellent lubricating properties, silicone based compounds are
mostly used as the coating material for PAN precursor fi bers. Tensile load and tear
strength of electrospun PAN membranes increased with thickness, accompanied
with a decrease in air permeability; however, burst strength was not signifi cantly
infl uenced by the thickness [101-103].
Electrospun PAN nanofi ber membranes were stabilized in air and then acti-
vated at 800°C with KOH as the activating agent to make activated carbon nanofi -
bers. Stabilized PAN membranes showed different breaking behaviors from those
before stabilization. The activation process generated micropores which contrib-
uted to a large surface area of 936.2 m
2
/g and a micropore volume of 0.59 cc/g.
Pore size distributions of electrospun PAN and activated carbon nanofi bers were
analyzed based on the Dubinin-Astakhov equation and the generalized Halsey
equation. The results showed that activated carbon nanofi bers had many more
micropores than electrospun PAN, increasing their potential applications in ad-
sorption. Based on a novel solvent-free coextrusion and melt-spinning of polypro-
pylene/(phenol formal dehydepolyethylene)-based core/sheath polymer blends,
a series of activated carbon nanofi bers (ACNFs) have been prepared and their
morphological and microstructure characteristics analyzed by scanning electron
microscopy, atomic force microscopy (AFM), Raman spectroscopy, and X-ray
diffractometry with particular emphasis on the qualitative and quantitative AFM
analysis. Post spinning treatment of the current commercial PAN fi ber based on
the author's knowledge, reports on the post spinning modifi cation process of the
current commercial fi ber are still lacking in the carbon fi ber manufacturers' prod-
uct data sheet, which allows us to assume that the current commercial carbon
fi bers still do not take full advantage of any of these treatments yet. During stabi-
lization and carbonization of polymer nanofi bers, they showed signifi cant weight
loss and shrinkage, resulting in the decrease of fi ber diameter [104-107].
From an application point of view, some of best application of carbon nano-
fi bers include: ACNF as anodes in lithium-ion battery, Organic removal from
waste water using, ACNF as cathode catalyst or as anodes for microbial fuel cells
(MFC), Electrochemical properties of ACNF as an electrode for super-capaci-
tors, Adsorption of some toxic industrial solutions and air pollutants on ACNF
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