PHYSICAL BEHAVIOR AND CONTAINER PRESSURIZATION DURING THERMAL DECOMPOSITION OF POLYURETHANE FOAMS

摘要

Polymer foam encapsulants provide mechanical, electrical, and thermal isolation in engineered systems. In fire environments, gas pressure from thermal decomposition of polymers can cause mechanical failure of sealed systems. Systems safety analyses use numerical simulations to predict heat transfer and container pressurization. In previous experiments, liquefaction and flow of decomposing polyurethane foam and erosive channeling by hot gases in the foam's cell structure greatly influenced container pressurization rates. To obtain further data for developing and evaluating models, recent experiments examined how foam density (160 to 720 kg/m~3) and composition (TDI-based versus PMDI-based) influence foam liquefaction and flow, penetration and erosive channeling by hot gases, and container pressurization rates. As foam density increased, penetration and erosive channeling by hot gases were increasingly inhibited, and effects of liquefaction and flow on container pressurization rates were diminished. Implications that the experimental results have for modeling are illustrated by comparing them to numerical results.