| Poor flame resistance and poor heat resistance are fatal weakness of carbon/epoxy composites,which seriously affect their applications in aerospace.When the temperature rises to a certain temperature,the overall structure of the carbon/epoxy composite will fail.The generation of gases and fumes,and the release of heat increase the difficulty in fire rescue.Therefore,thermal analysis of carbon fiber epoxy composites is particularly important.First,in the paper,the thermal decomposition characteristics of carbon/epoxy laminates were studied,including the analysis of functional groups of epoxy resin matrix,infrared-thermogravimetric analysis of laminates,and the analysis of heat change.It has been found that the pyrolysis reaction of carbon/epoxy laminates has three stages,three exothermic and one endothermic reaction occur in air atmosphere.The thermal decomposition gas products of carbon/epoxy laminates consist mainly of H2O,hydrocarbon,CO2,compounds containing carbonyl,compounds containing aromatic ring and aromatic–aliphatic compound.Then,the effects of experimental conditions and sample factors on the pyrolysis process of carbon/epoxy composites were investigated.It has been found that with the increase of heating rate,ply thickness,sample quality and reduction of oxygen content,the thermogravimetric curve moves toward the high temperature direction.The ply configuration angle has little effect on the pyrolysis process.The foam core material has little effect on the pyrolysis of carbon/epoxy composites.Finally,Kissinger-Akahira-Sunose,Flynn-Wall-Ozawa and Starink methods were used to calculate the kinetic parameters of the decomposition process of carbon/epoxy laminates in air and nitrogen atmosphere.In addition,the corresponding thermodynamic parameters of carbon/epoxy laminates were determined.The apparent activation energy of carbon/epoxy laminates in nitrogen atmosphere was significantly increased compared with that in air atmosphere,and the increase was 59 to 63 kJ mol-1.According to the thermodynamic parameters,the reactions of carbon/epoxy laminate is non-spontaneous processes that require the introduction of energy first and is a highly ordered sequence of the complex in the reaction system in air and nitrogen atmosphere. |
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