FIRE PERFORMANCE OF COMPOSITE LAMINATES COATED WITH HYBRID CARBON NANOFIBER PAPER

摘要

Exfoliated graphite nanoplatelets (xGnP) were used to improve the flame resistant performanceof glass fiber reinforced polyester composites. Along with xGnP, traditional intumescent fireretardant, APP was added into the polymer matrix as a dominant additive in order to reduce theheat release rate (HRR) and total heat released (THR) of the composites. The cone calorimetertests results indicate that the optimum concentration of xGnP and APP is 3 wt% and 17 wt%,respectively. Associated with the optimum weight ratio, a synergistic effect between xGnP andAPP is demonstrated. The flame resistant performance of the nanocomposites was furtherimproved by coating xGnP dominant carbon nanofiber (CNF)/xGnP hybrid nanopaper onto thesurface of the samples. Comparing to the control sample, the integration of the HRR (THR) from0 to 100s of the sample coated with the nanopaper of CNF/xGnP=1/3 shows more than 30%decrease in THR. Based on the results of mass loss, the coating also significantly enhances thestructural stability of the samples under fire condition, which is critical to the mechanicalproperties of composites. It is found that the thermal properties and permeability of compositesand char formation play important roles in determining the fire behavior of the composites.Furthermore, another type of hybrid nanopaper was evaluated in this paper where the presence ofAPP within paper would serve as blow agent to further improve the fire retardant effectivenessof hybrid paper, i.e. the pristine glass fiber reinforced polyester composites were coated withCarbon Nanofiber/Clay/APP (CCA) paper and Carbon Nanofiber/xGnP/APP (CXA) paper whenthey were exposed to heat flux during cone calorimeter test (the pristine group). The test resultsshow that both heat release rates and mass loss are significantly reduced. For the samples coatedwith CXA papers, their time to ignition (TTI) was prolonged by 45% compare to the sampleswithout the coating. After the samples were exposed to heat for various time periods, their postfire mechanical properties were determined by three-point bending tests. The results show thatthe samples coated with the hybrid nanopapers exhibit more than 20% improvement inmechanical resistance at the early stage of combustion. The mechanism of hybrid carbonnanofiber papers protecting the underlying composites structure is discussed in this study.