Complex Char Formation in Flame-retarded Fibre-intumescent Combinations — Ⅳ. Mass Loss and Thermal Barrier Properties

摘要

Previously reported fibre/intumescent composite textile systems are leading to the development of a range of high performance thermal barrier fabrics. These systems comprise nonwoven cores of flame retardant cellulose/regenerated cellulose throughout which fibre-interactive intumescent chemicals (melamine and phosphate based) are dispersed. When heated, both components decompose by compatible physical and chemical mechanisms leading to a complex carbonaceous 'char-bonded structure'. Mass loss studies of these samples indicate that decomposition takes place in three stages, an initial volatilization, char formation (both occurring during the first 3.5 min exposure period) and a char oxidative stage continuing over a much longer period. Kinetic analysis of mass loss curves gives insight into their thermal behaviour. Thermal insulative properties of these samples have been observed by embedding thermocouples within layers of fabrics and measuring their temperatures as functions of time. Using this technique, a measure of the time dependence of the thermal barrier properties has been gained at heat fluxes in the range 25-75 kW m~(-2). Derived thermal resistivity values illustrate the superior barrier properties afforded by the complex chars formed.