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Carbon/epoxy composites have been widely used in the aviation industry. However, the flammability of epoxy resins is of great concern within the industry. Currently, vacuum bag and autoclave forming processes are the most commonly used processes for composites. To compare the thermal and fire properties of carbon/epoxy laminate composites manufactured using these two forming processes, a comprehensive experimental investigation and theoretical analysis was carried out in this work. The glass transition temperatures and epoxy resin matrix content in composites were determined. Several thermal and fire properties were quantitatively evaluated, including onset decomposition temperature, time to ignition, mass loss rate (MLR), and heat release rate (HR). The morphologies of specimens before combustion were also observed. For vacuum bag (VB)‐C/ELC and A‐C/ELC, the critical heat flux (14.48 and 20.56 kW m−2), thermal response parameter (165.56 and 204.49 kW s1/2 m−2), heat of gasification (9.13 and 20.10 MJ kg−1), and theoretical heat of combustion (33.27 and 43.82 MJ kg−1) were calculated and compared using the thermal behavior model, MLR model, and heat release rate model, respectively. It has been found that the forming process can significantly affect the fire properties of carbon/epoxy laminate composites. More specifically, the carbon/epoxy laminate composites formed using autoclave forming processes have more combustion resistance and thus have improved fire properties. [ABSTRACT FROM AUTHOR]

Thermal behavior and smoke characteristics of glass/epoxy laminate and its foam core sandwich composite were comprehensively investigated using thermogravimetric analysis, TG–FTIR analysis, smoke density test and cone calorimeter test. The thermal decomposition, thermal interpretation of gas release, smoke density, smoke release, carbon monoxide and carbon dioxide productions were analyzed and compared for glass/epoxy laminate and its foam core sandwich composite. Their kinetic and thermodynamic models were obtained, and the apparent activation energy, pre-exponential factor and thermodynamic parameters were determined correspondingly. The results show that there are significant differences in the thermal behavior and smoke characteristics between these two composites. Compared with glass/epoxy laminate, foam core sandwich composite demonstrates a higher propensity of pyrolysis and combustions and greater hazards to life and property. [ABSTRACT FROM AUTHOR]

Carbon/epoxy laminates and foam‐core sandwich composites are frequently used as engineering materials within the aerospace sector. However, epoxy resin matrix and foam‐core materials are highly flammable. In this work, the thermal behaviors of carbon/epoxy laminates and foam‐core sandwich composites were investigated using thermogravimetric analysis at different heating rates in atmospheric air. The morphological images of specimens and the residue after pyrolysis at different characteristic temperatures were further investigated using scanning electron microscopy. Additionally, thermogravimetric Fourier transform infrared spectroscopy was used to analyze the vapors and gases evolved during the thermal decomposition. It was determined that the pyrolysis reactions of carbon/epoxy laminates and foam‐core sandwich composites consist of three decomposition steps. Furthermore, an increase in the heating rate of each material results in higher initial and final temperatures for each thermal decomposition step. Kinetic parameters for the decomposition for carbon/epoxy composites were estimated using Kissinger, Flynn‐Wall‐Ozawa, and Starink methods, and the corresponding thermodynamic parameters were obtained. Through analysis of the reaction kinetics, it was determined that the pyrolysis reactions of carbon/epoxy composites are not easily activated, requiring significant activation energy, but the series of reactions take place easily once this energy barrier is overcome. [ABSTRACT FROM AUTHOR]

According to structural characteristics, composites are classified as laminated structure and sandwich structure. Carbon/epoxy laminate and foam core sandwich composite are the most commonly used laminate and sandwich structure material in the aircraft industry. The flammability of epoxy resins and foam core material is an inherent hazard. Many previous studies focused primarily on their mechanical properties, while the studies on the thermal and fire properties of carbon/epoxy laminate and its foam core sandwich composite have rarely conducted. Therefore, to characterize their thermal and fire properties, a comprehensive experimental investigation and theoretical analysis were carried out in this work using thermogravimetric analysis, cone calorimeter, vertical/horizontal burning tests, limiting oxygen index and scanning electron microscope tests. Several typical characteristic parameters were obtained and analyzed, such as pyrolysis temperature, heat release rate, mass loss, flaming spread rate and limiting oxygen index. These experimental data coupled with theoretical analysis can provide support for fire risk assessment and fire protection design in aircrafts. The carbon/epoxy laminate and foam core sandwich composite are both characterized as the thermally thick materials. The ignition models and mass loss rate models were obtained. Foam core material negatively affects most of the thermal and fire properties of sandwich composite, but the foam core sandwich composite has self-extinguishing behavior during horizontal burning tests, whose LOI is higher than that of carbon/epoxy laminate. Thus, an important conclusion was reached that the ignition position and flame spread direction have critical effect on the fire behavior of foam core material. [ABSTRACT FROM AUTHOR]