Fabrication of carbon fibers from the cupric ion impregnated and thermally stabilized poly(hexamethylene adipamide) precursor

Abstract

The conversion of poly (hexamethylene adipamide) or polyamide 66 precursor fiber to carbon fibers was accomplished through thermal stabilization and carbonization processes. Thermal stabilization was conducted of cupric chloride (CuCl2)–ethanol-impregnated polyamide 66 (PA66) fibers in the air. To determine the influence of heating rate on the fiber structure and properties of the resultant carbon fibers, carbonization experiments were performed at selected temperatures of 500, 700, 900, and 1100°C using 2.5 and 5 °C/min heating rates with no dwelling. The results conclusively revealed that the volume density and tensile properties of the PA66 fiber were higher at 2.5 °C/min heating rate. After fixing the heating rate as 2.5°C/min, further carbonization experiments were conducted at temperatures from 500 to 1100°C, using increments of 100°C with no dwelling time. Linear density, volume density, fiber diameter, carbon yield, elemental composition, tensile, and electrical properties exhibited a strong dependence on the carbonization temperature. After taking into account the effects of structural defects (i.e., microvoids), tensile strength, and tensile modulus of the carbon fibers increased to 794 MPa and 92.4 GPa, respectively, when carbonized at 1100°C. X-ray diffraction analysis of the carbon fibers further revealed the existence of a greatly disordered (i.e., amorphous) structure, which developed during the carbonization process. FT-IR analysis confirmed the formation of highly aromatic carbon clusters at temperatures of 500°C and higher. The outcomes of electrical conductivity in this study confirm that the PA66 precursor was converted into a semi-conducting state once it was carbonized.

The impact of guanidine carbonate incorporation on the molecular structure of polyacrylonitrile precursor fiber stabilized by a multistep heat treatment strategy

“…The untreated PAN and thermally stabilized samples were tested in the 2θ range between 5° and 40°. [ 62,63 ]…”

“…The test results were presented as the average of 20 measurements. [62,63] 2.1.5 | Differential scanning calorimetry DSC experimental results were obtained from a Seiko DSC-6200 EXSTAR machine. The sample weight was approximately 5 mg, the heating rate was 10 C min À1 , and the nitrogen gas flow rate was determined as 50 ml min À1 .…”

“…The untreated PAN and thermally stabilized samples were tested in the 2θ range between 5 and 40 . [62,63] For the thermally stabilized samples, the X-ray conversion index [66] was calculated using Equation ( 3), where I o is the (100) reflection intensity at 2θ = 17 of the untreated PAN, and I is the (100) reflection intensity at 2θ = 17 of thermally stabilized samples.…”