Flame Retardancy of Laponite- and Montmorillonite-Based Nylon 6 Nanocomposites
- PDF / 841,991 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 36 Downloads / 245 Views
L8.46.1
Flame Retardancy of Laponite- and Montmorillonite-Based Nylon 6 Nanocomposites Gunes Inan, Prabir K. Patra, Yong K. Kim, and Steven B. Warner University of Massachusetts - Dartmouth, Department of Textile Sciences 285 Old Westport Road, North Dartmouth, MA 02747 ABSTRACT The flame retardancy of nylon 6/laponite and nylon 6/montmorillonite nanocomposites was investigated. The pronounced effect of layered silicates on heat release and mass loss rates of nylon 6 was examined. We found that nylon 6/laponite has 46 % and nylon 6/montmorillonite has 52.5 % lower peak heat release rates than that of neat nylon 6. The 6.5 % difference between the peak heat release rates of laponite- and montmorillonite-based nanocomposites was attributed to differences in aspect ratio and surface charge density of the nanoparticles. The barrier properties of nanocomposite chars was evaluated by examining the peak heat release and mass loss rate reductions of stacks of layers, with the bottom layer being neat nylon 6 polymer and the top layers being nanocomposites that formed chars during the experiments. We observed that the peak heat release rate of a 10×10×0.3 cm neat nylon 6 slab was reduced by about 45 % when protected with a char-forming nylon 6/montmorillonite slab of same dimensions. The dramatic reduction of the peak heat release rate of neat nylon 6 when covered with a nanocomposite char was consistent with the notion that the flame retardancy of polymer/clay nanocomposites is affected by the (thermal and/or mass) barrier properties of the char. In order to test the thermal insulation of the char, temperature profiles of the layered samples were measured during cone calorimeter experiments. We observed that the nanocomposite char that brought about a 44.5 % reduction in peak heat release and mass loss rates reduced the heating rate of the same neat nylon 6 by about 31.2 %. The reduction in the heating rate increased with the amount of nanocomposite char formed. INTRODUCTION Flame retardancy of polymer layered silicate nanocomposites has been extensively reported in the literature (1, 2). Since Gilman et al first reported a 63 % reduction in heat release rate of a nylon 6/montmorillonite nanocomposite with as little as 5 wt % montmorillonite, the flame retardancy of polymers filled with nanoparticles, such as clays, carbon nanotubes or silicas, has not further improved to achieve industrial acceptance. Because of the upcoming restrictions on some of today’s popular flame retardants (3), the flame retardancy of the nanoparticle-filled systems or any non-halogen alternatives need to be improved to meet the new standards. Introduction of layered silicates brings about substantial changes in the flame retardancy of polymers. In order to improve flame retardancy, the direct (or indirect) influence of nanoparticles on polymer pyrolysis should be well understood. Thermogravimetric analyses of nylon 6/montmorillonite conducted in inert or oxidizing atmospheres showed that montmorillonite neither increased the decomposition
L8.46.
Data Loading...
