Characterization of amorphous carbon fibers produced from thermally stabilized polyamide 6 fibers

Abstract

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.

Fracture Failure Mechanisms of Long Single PA6 Fibers

“…The material properties of PA6 fibers vary according to the manufacturing technique employed in their production, and a number of manufacturing techniques have been developed [ 14 , 15 , 16 ]. Zhang et al [ 14 ] successfully produced fine-denier PA6 fibers using additives containing lanthanide compounds, and the crystallization and phase transition of the resulting PA6 fibers were investigated during spinning and drawing processes.…”

“…Zhang et al [ 14 ] successfully produced fine-denier PA6 fibers using additives containing lanthanide compounds, and the crystallization and phase transition of the resulting PA6 fibers were investigated during spinning and drawing processes. Polyvinylidene fluoride (PVDF) fiber mats with average fiber diameters of 200–2000 nm were fabricated under controlled electro-spinning conditions [ 16 ]. The testing conducted in this work employed PA6 (polyamide Nylon 6) trimmer line monofilament fabricated by slice spinning (Nantong NTEC Monofilament Technology Co., Ltd., Nantong, China).…”

“…The characteristics of fiber failure were examined by SEM using a JSM-5610LV (JEOL, Tokyo, Japan) field emission scanning electron microscope with an accelerating voltage of 20 kV. We note that polymeric materials are very sensitive to electron beam damage [ 16 , 17 , 18 ]. However, in their study of PVDF molecules in nanofibers imaged at an atomic scale by aberration-corrected electron microscopy, Lolla et al [ 17 ] found that the sensitivity of fibers to electron radiation damage increased with decreasing fiber diameter.…”

Accurate measurement of pitch-based carbon fiber electrical resistivity

“…Volume resistivity is an important performance indicator for carbon fibers, applied to the evaluation of process parameters along its production steps: spinning [13][14][15] , stabilization [16,17] , carbonization [18,19] , and graphitization [19][20][21][22] . It can also be applied in the evaluation of pre and post-processing steps such as intercalation [23,24] , annealing [25] , and coating [26][27][28][29] .…”

Preparation and evaluation of isotropic and mesophase pitch-based carbon fibers using the pelletizing and continuous spinning process

“…Carbon fibers have attracted the interest of many researchers due to their excellent mechanical, electrical, and thermal properties and low densities [1,2]. Recently, another area of interest has been the cost reduction of the fibers [3–6].…”