| Abstract: | The effect of melting behaviour on upward flame spread of thermoplastic materials when subjected to small ignition sources and considered to suffer no external flux was studied using large-scale tests. For moderate fire conditions the cone calorimeter was utilized, with the sample set in a vertical orientation to study the melting behaviour of the specimens. Under these conditions the results indicate that the melting behaviour significantly affects upward flame spread behaviour. A pool of the melt which formed at the base of the vertically oriented sample tested creates a pool fire which then controls the fire growth and flame spread. In contrast, it was found that some thermoplastic materials which have higher glass transition temperatures or undergo a special pyrolysis process such as depolymerization, intumescing or charring do not experience significant melting behaviour when exposed to the same thermal insult. As a result, they behave very differently in terms of upward flame spread. The study also indicates that the melting behaviour of thermoplastic materials is an important characteristic in fires which should be taken into account in the development of modelling, in particular for upward flame spread models. © 1997 by John Wiley & Sons, Ltd. |
