Bilayer coating strategy for glass fiber reinforced polymer composites toward superior fire safety and post-fire mechanical properties

The inherent heat and fire vulnerability from the polymer matrix of fiber-reinforced polymer composites (FRPs) contributes to fire propagation, matrix decomposition and especially loss of structural integrity during fire hazards. Applying surface fire protective coating is a popular approach without sacrificing mechanical properties. In this work, the influence of fire protective coating on the fire safety and post-fire mechanical properties of FRPs with an ingeniously designed coating bilayer composition. The combustion behavior study showed that the bilayer substantially postpones the decomposition of the polymer matrix through the thickness, showing a reduction of 50 % and 65 % for peak heat release rate and total smoke production respectively. Fire insulation tests showed good thermal insulation capabilities with no burn-through. Furthermore, the tensile strength of protected composite coupons was screened and showed a retention of 79 % original tensile strength after suffering 120s of heat/fire attack. This investigation resulted in a proposed protective strategy and mechanism offering a meaningful approach to enhancing the fire safety and fire structural integrity of polymer composites.