HOW TO DESIGN POLYMER NANOCOMPOSITES WITH FLAME RETARDANTS?

摘要

Polymeric materials are commonly used in everyday life increasing fire hazards and so flame retardants are very often incorporated into them to limit their flammability [1]. Of particular interest is the developed nanocomposite technology consisting of a polymer and nanoparticles because they often exhibit remarkably improved mechanical properties and various other properties as compared with those of virgin polymer at loading as low as 3 to 5 wt.-% [2]. Numerous nanocomposites containing different nanoparticles including organomodified clays [3]- [5], nanoparticles of TiO_2 [6], nanoparticles of silica [7], layered double hydroxides (LDH) [8]-[9], carbon nanotubes (CNT) [10] or polyhedral silsesquioxanes (FOSS) [11] have been prepared and characterized. All those materials exhibit improved flame retardancy associated to other properties such as enhanced mechanical or electrical properties. Polymer nanocomposites usually provide large reduction of heat release rate in specific scenario but they are not able to pass fire tests such as LOI, UL-94, glow wire ... required by the legislation to qualify the materials. The incorporation of flame retardants (FR) in polymeric materials permits sometimes to create large -synergistic effects but also antagonistic effects. It is the purpose of this paper to discuss the benefit of combining nanoparticles with FR. We will focus our work on intumescent systems. Polyamide-6 (PA-6) and polyethyleneterephtalate (PET) will be used as typical examples with the intention to provide some 'clues' on how to design polymer nanocomposite with FR identifying key parameters.