Mechanical properties of fire-damaged glass-reinforced phenolic composites

Changes to the mechanical and physical properties of a glass-reinforced resole phenolic composite due to intense radiant heat and fire are investigated. Fire testing was performed using a cone calorimeter, with the composite exposed to incident heat fluxes of 25, 50, 75 or 100 kW/m(2) for 325 s and to a constant flux of 50 kW/m(2) for different times up to 1800 s, The post-fire tensile and flexural properties were determined at room temperature, and these decreased rapidly with increasing heat flux and heat exposure time due mainly to the chemical degradation of the phenolic resin matrix. The intense radiant heat did not cause any physical damage to the composite until burning began on exposure to a high heat flux. The damage consisted of cracking and combustion of the phenolic matrix at the heat-exposed surface, hut this only caused a small reduction to the mechanical properties. The implication of the findings for the use of glass-reinforced resole phenolic composites in load-bearing structures for marine craft and naval ships, where fire is a potential hazard, is discussed. Copyright (C) 2000 John Wiley & Sons, Ltd.