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Fibers are promising materials being utilized in electronics, principally in the areas of capacitors and sensors. In this study, we examine the effect of pyrolysis temperature on the electrical conductive behavior and photosensitivity of a carbon-based fiber, which was made by electrospinning a polymer solution containing polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), and dimethylformamide (DMF). Converting the polymeric fiber into a carbon fiber was performed through the controlled pyrolysis during which oxidation, stabilization, and carbonization happened. After oxidation at an elevated temperature, the linear polymer fiber was stabilized to have a backbone structure. Then the oxidized fiber was treated in an even higher temperature range to be partially carbonized under the protection of argon gas. We utilized multiple samples of the fibers treated at various pyrolysis temperatures inside a heat furnace and examined the effects of the temperatures on the properties. The partially carbonized fiber is highly active in view of electron generation under photon energy excitation. The unique electrical and photovoltaic property are due to their semiconducting behavior. The morphology of the specimen before and after the pyrolysis was examined using scanning electron microscopy (SEM). The SEM images displayed the shrinkage of the fiber due to the pyrolysis. There are two stages of pyrolysis kinetics. Stage I is related to the oxidation of the PAN polymer. Stage II is associated with the carbonization and the activation energy of carbonization is calculated as 118 kJ/mol.

The objective of this article is to provide an overview on the current development of micro- and nanoporous fiber processing and manufacturing technologies. Various methods for making micro- and nanoporous fibers including co-electrospinning, melt spinning, dry jet-wet quenching spinning, vapor deposition, template assisted deposition, electrochemical oxidization, and hydrothermal oxidization are presented. Comparison is made in terms of advantages and disadvantages of different routes for porous fiber processing. Characterization of the pore size, porosity, and specific area is introduced as well. Applications of porous fibers in various fields are discussed. The emphasis is put on their uses for energy storage components and devices including rechargeable batteries and supercapacitors.

In this paper, a titanium dioxide particle coated carbon fiber was prepared by reaction spinning. Polyacrylonitrile (PAN) was used as the precursor to generate a continuous carbon nanofiber. A solution containing 10% wt PAN polymer dissolved in dimethylformamide (DMF) was made as the core fluid. The sheath fluid contains 10% titanium (IV) isopropoxide, 85% ethanol, and 5% acetic acid. The two solutions were co-spun onto an aluminium plate covered with a layer of soft tissue paper. A titanium hydroxide layer formed at the surface of the PAN fiber through the hydrolysis of titanium isopropoxide due to the moisture absorption in the co-spinning process. The reaction spun fiber was converted to a partially carbonized nanofiber by the heat treatment in air at 250 °C for two hours, then in hydrogen at 500 °C for two hours. During the early stage of the heat treatment, the titanium hydroxide decomposed and produced titanium dioxide nanoparticles at the surface of the carbon fiber. The structure and composition of the carbonized fiber were studied by scanning electron microscopy (SEM). The photosensitivity of the particle-containing fiber was characterized by measuring the open circuit voltage under visible light excitation. The photoelectric energy conversion behavior of the fiber was confirmed by open circuit potential measurement. The potential applications of the composite fiber for photovoltaics and photonic sensing were discussed.