Flame retardancy in polyethylene/CNT and polyethylene/silica nanocomposites

Introduction. The properties of a composite material depend not only upon the properties of the individual component phases (matrix, filler, interface), but also upon their interaction. An improvement in flammability properties of polymers using the unique interface that can be developed with layered silicates, has been demonstrated for clay nanocomposites [1,2]. Nanoscale silica particles also can have a large interfacial area as long as the diameter of the particles is in the range of nanometers and they are well dispersed in the polymer. Although they do not have the structure of a layered clay, the improvement in physical properties and also some improvement in thermal stability by the addition of nanoscale silica particles to polymers were reported [3]. Carbon nanotubes provide another candidate as a flame retardant additive because of their highly elongated shape. Recent papers demonstrates the flame retardant effectiveness of nanocomposites made with several polymer resins [4,5]. These papers demonstrate that flame retardant effectiveness of those fillers is in someway similar to that verified for clay nanocomposites. The objective of this paper is to understand the flame retardant mechanism of polyethylene/carbon nanotubes or fumed silica nanocomposites by measuring certain thermal characteristics.