In this study, various amounts of carbon nanotubes (CNTs), nanosilver (AgNPs), and polyaniline (PANI) were incorporated at the same pot into the structure of composite polyacrylonitrile (PAN) nanofibers, which were produced by electrospinning process in order to see synergistic effect of the additives on the final properties of the composite materials. Performance and characteristic properties of composite nanofibers were analyzed by tensile tester, electrical conductivity meter, Fourier Transform Infrared Spectroscopy, differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, and antimicrobial activity test. Statistical analysis (analysis of variance) was performed to see whether the differences were statistically significant or not. It was seen that samples with AgNPs had higher breaking strength and electrical conductivity than the samples with CNTs. Generally, PANI improved the crystallinity of the composite material more than the nanoparticles (CNTs and AgNPs). Even though each of the nanoparticles was used in low concentrations, the composite materials (PAN–1CNT–1AgNO3–R and PAN–PANI–1AgNO3–R) gained antimicrobial properties due to the synergistic effect of additives. The results suggested that PAN composite nanofibers with 3 wt% PANI and 1 wt% AgNO3 generally presented better performance than the other samples in terms of electrical conductivity, antimicrobial activity, mechanical strength, crystallization, and thermal stability.

The effect of dispersion technique, reduction method, and the amount of silver nanoparticles on the properties of composite polyacrylonitrile nanofiber containing silver nanoparticles is analyzed using differential scanning calorimetry, scanning electron microscopy, electrical conductivity, tensile testing, X-ray diffraction, and antimicrobial efficiency measurements.Composite nanofibers reduced by hydrazine hydroxide result in smaller diameter, higher electrical conductivity, higher breaking strength, higher cyclization enthalpy than the samples reduced by xenon arc method. Reduction process results in smaller diameter and higher breaking strength than those of non-reduced nanofiber web containing AgNO 3 nanoparticles. Dispersion by ultrasonic homogenizer/bath provides higher breaking strength, electrical conductivity than the samples dispersed by only magnetic stirrer. An increase of silver nanoparticle generally results in an increase of enthalpy, a decrease of both cyclization temperatures and crystallinity. While 1 wt% AgNO 3 loading is suitable for high breaking strength, 3 wt% AgNO 3 loading is suitable for both high electrical conductivity and antimicrobial properties. Insulator polyacrylonitrile polymer becomes a semiconducting material.

There are several studies regarding polyacrylonitrile composite nanofibers with polyaniline doped with dodecylbenzene sulfonic acid and solved by N,N 0 -dimethyl formamide which were mostly performed to analyze the thermal and morphological properties. In this study, camphor sulfonic acid-doped polyaniline and polyacrylonitrile composite nanofibers were electrospun from solutions in dimethylsulfoxide and the effect of polyaniline content and the application of different dissolution methods on the morphology, chemical structure, conductivity, crystallinity, mechanical, and thermal properties of nanowebs were investigated. Morphology, nanofiber diameters, chemical structure, crystallinity, mechanical properties, and thermal properties of the nanofibers were all affected by the polyaniline addition. Compared to the conductivity of neat polyacrylonitrile nanofibers, the conductivity of the composite nanofibers was improved, reaching a value higher than 10 À6 S/cm with 3 wt% polyaniline content which was in the range for electrostatic discharge applications (10 À9 to 10 À6 S/cm). Increase in dissolution time and application of ultrasonic homogenization affected the diameter, mechanical properties,

Amorphous carbon fiber from polyamide 6 (PA6) precursor was produced using a multi-step procedure consisting of oxidative stabilization in air at 180℃ in the presence of cupric chloride impregnation, pre-carbonization at 250℃ and carbonization at temperatures ranging from 500℃ to 1000℃ in nitrogen. The results obtained from thermal analysis data suggested that cupric chloride impregnation enhanced thermal stability. During the oxidative stabilization process, a polymorphic structure consisting of α- and γ-phases was eliminated due to the decrystallization process. The pre-carbonization step was found to be necessary to enhance the thermal stability of oxidatively stabilized PA6 fiber prior to carbonization. The results suggested that the pre-carbonization step improved the aromatization and crosslinking reactions. The results obtained from the experimental data suggested that the carbonization temperature had an effective role on the molecular structure and properties of the resulting carbon fibers. The carbon fibers obtained from stabilized and pre-carbonized PA6 fibers showed physical and structural changes with rising temperature. They were characterized by a reduction in fiber diameter, linear density, carbon fiber yield, hydrogen and nitrogen content values due to the removal of non-carbon elements together with increases in the values of density, crystallite thickness, carbon content, C/H ratio and electrical conductivity values. The results obtained from X-ray diffraction, IR spectroscopy and elemental analysis suggested that the crystalline structure was totally lost and converted to a carbonized structure at 500℃ and above due to the formation of an amorphous carbon structure during carbonization reactions.

The oxidative thermal stability of microcrystalline plant-based viscose rayon cellulose fiber was improved in the presence of an ammonium sulfate solution. The structural characterization of the oxidized samples was carried out using a combination of fiber thickness, linear density, burning test, X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and infrared (IR) spectroscopy measurements. Oxidized viscose rayon fibers showed physical and chemical transformations with increasing oxidation temperature and were characterized by a reduction in fiber diameter and linear density values together with color changes with increasing oxidation temperature. The results obtained from XRD analysis showed the loss of crystallinity due to the amorphization processes. XRD analysis also showed increasing conversion to a highly crosslinked and cyclized structure with progressing temperature. The DSC and TGA measurements indicated that there was an improvement in thermal stability. The results obtained from IR spectra showed the progress of dehydrogenation and dehydration reactions. IR spectra in the 2000-800 cm À1 region showed a loss of crystalline structure confirming the results of XRD. The IR spectra of the oxidized samples also showed the conversion of primary hydroxyl (OH) groups to carbonyl (C¼ ¼O) groups and the presence of C¼ ¼C double bonds arising from the formation of a cyclized and crosslinked structure.