Modeling decomposition of unconfined rigid polyurethane foam

The decomposition of unconfined rigid polyurethane foam has been modeled by a kinetic bond-breaking scheme describing degradation of a primary polymer and formation of a thermally stable secondary polymer. The bond-breaking s cheme is resolved using percolation theory to describe evolving polymer fra gments. The polymer fragments vaporize according to individual vapor pressu res. Kinetic parameters for the model were obtained from thermal gravimetri c analysis (TGA). The chemical structure of the foam was determined from th e preparation techniques and ingredients used to synthesize the foam. Scale -up effects were investigated by simulating the response of an incident hea t flux of 25 W/cm(2) on a partially confined 8.8-cm diameter by 15-cm long right circular cylinder of foam that contained an encapsulated component. P redictions of internal foam and component temperatures, as well as regressi on of the foam surface, were in agreement with measurements using thermocou ples and X-ray imaging. (C) 2000 Elsevier Science Ltd. AU rights reserved.