Effects of Heat Treatment Atmosphere and Temperature on the Properties of Carbon Fibers

• Published in: Polymers Vol. 14; no. 12; p. 2412
• Main Authors: Kim, Gyungha, Lee, Hyunkyung, Kim, Kyungeun, Kim, Dae Up
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 14.06.2022; MDPI
• Subjects: carbon fiber; Carbon fibers; Carbonyl groups; Carbonyls; Chemical properties; Composite materials; Contact angle; Emission analysis; Environmental impact; Field emission; Free energy; functional group; Functional groups; Heat treating; Heat treatment; Hydroxyl groups; Mechanical properties; mechanism; Nitrogen; Oxidation; Oxygen; Photoelectrons; R&D; Rare gases; Recycling; Research & development; Room temperature; Shear strength; surface free energy; Tensile properties; Tensile strength; X ray photoelectron spectroscopy
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym14122412

In this study, carbon fibers were heat-treated in a nitrogen and oxygen atmosphere according to temperature to elucidate the mechanism of chemical state changes and oxygen functional group changes on the carbon fiber surface by analyzing the mechanical and chemical properties of carbon fibers. Carbon fibers before and after heat treatment were analyzed using FE-SEM (Field Emission Scanning), UTM (Universal Tensile Testers), XPS (X-ray Photoelectron Spectroscopy), and surface-free energy. In the nitrogen atmosphere, which is an inert gas, the tensile strength was equivalent to that of the virgin up to 500 °C but decreased to 71% with respect to the virgin at 1000 °C. Furthermore, as the temperature increased from room temperature to 1000 °C, the oxygen functional group and the polar free energy gradually decreased compared with the virgin. On the other hand, in the oxygen atmosphere, which is an active gas, the tensile properties were not significantly different from those of the virgin up to 300 °C but gradually decreased at 500 °C. Above 600 °C, the carbon fibers deteriorated, and measurement was impossible. The oxygen functional group decreased at 300 °C, but above 300 °C, among the oxygen functional groups, the hydroxyl group and the carbonyl group increased. Furthermore, the lactone group formed and rapidly increased compared with the virgin, and the polar free energy increased as the temperature increased.