Kinetics, evolving thermal properties, and surface ignition of carbon fiber reinforced epoxy composite during laser-induced decomposition. (June 2018)

• Record Type: Journal Article
• Authors: Herr, Nicholas C.; Gonzales, Ashley E.; Perram, Glen P.
• Is Part Of: Polymer degradation and stability. Volume 152(2018)
• Page Start: 147
• Page End: 161
• Publication Date: 2018-06
• Subjects: Carbon fiber reinforced polymer -- Fiber laser damage -- Thermal imagery -- Emissivity; Polymers -- Deterioration -- Periodicals; Stabilizing agents -- Periodicals; Polymères -- Dégradation -- Périodiques; Stabilisants -- Périodiques; 668.9
• DOI: 10.1016/j.polymdegradstab.2018.04.007
• Languages: English
• ISSNs: 0141-3910

Abstract

Abstract: The decomposition kinetics, heats of reaction, evolving thermal conductivity and emissivity, and surface ignition conditions of carbon fiber reinforced polymer (CFRP) composites during laser-induced polymer matrix decomposition were investigated. Woven carbon fiber-epoxy panels of different thicknesses were irradiated with a 1.07-μm, 2-kW ytterbium fiber laser at irradiances of 5–525 W/cm 2 . The changing front and backside surface temperatures were measured using a mid-wave infrared camera, adjusted using measured emissivity of irradiated and un-irradiated CFRP samples. The evolving temperature maps were fit to a 3D, explicit, finite difference, thermal model to estimate Arrhenius kinetic rate parameters, heats of reaction, and thermal conductivity during a two-step epoxy decomposition reaction and a single stage char oxidation reaction. The kinetics is not strongly dependent on heating rates of 20–700 °C/sec and parameters determined at lower laser powers extrapolate well to higher powers. Surface ignition occurs at critical surface temperatures of 1198 ± 50 °C. Highlights: CFRP thermal properties and kinetics were estimated from temporal surface temperature maps during laser-heated degradation. Decomposition kinetics were not found to be strongly dependent on laser-heating at rates of 20–700 °C/s. Surface temperatures of 1198 ± 50 °C were necessary for surface ignition, rather than combustible concentrations at surface. These results can improve the modeling of surface heating, degradation, and thermal transport during laser heating of CFRPs.