Abstract
In fires, polymeric materials are consumed by flaming combustion which is a gas phase process. Thus the polymer must degrade to yield volatile combustible species to fuel the conflagration. To begin, this chapter first considers the various processes by which pure polymer systems degrade. Then any influence by which the presence of oxygen can affect these processes is discussed. The different structures of the various polymer types influence the end consequence of any decomposition and this will affect the resistance, if any, to combustion. At this point the polymer combustion cycle will be described.