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.
An electrostatically enhanced aramid fiber/polytetrafluoroethylene emulsion/tourmaline particle (AF/PTFE/TM) composite filter media was successfully designed and fabricated by impregnation technology, especially for harsh industrial environment with high temperature. The AF/PTFE/TM composite filter media exhibited the optimum quality factor when the concentration of PTFE emulsion was 10% and the content of TM particles was 12.5 g/cm2. The collection efficiency, pressure drop characteristic, thermal decomposition behavior and kinetics, and tensile strength in machine and cross directions of the composite filter media have been systematically evaluated. Benefiting from the pyroelectricity and piezoelectricity of TM particles, the composite filter media has better collection efficiency with the increase of incoming air temperature. With the increase of flow velocity, the decrease of collection efficiency is smaller than the filter media without TM particles. Meanwhile, the pressure drop across the composite filter media is a little higher than that across the raw filter media. Additionally, it was found PTFE emulsion coating can improve the thermal stability and tensile strength of the composite filter media. TM particles have no negative impact on the thermal behavior of the composite filter media, but slightly attenuates the enhancement in tensile strength. This study provides new insight into the application of TM particles as well as other pyroelectric and piezoelectric materials in industrial filtration.
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