Thermal degradation and flammability properties of the two types of nanocomposites with nanosilica and carbon nanotubes were studied. PMMA, poly(metheyl methacrylate), nanocomposites were made by in situ radical polymerization of MMA, methylmethacrylate, with colloidal silica (ca. 12 nm) to study the effects of nanoscale silica particles on the physical properties and flammability properties of PMMA. Transparent samples resulted and the dispersity of the particles was examined by TEM and AFM. The addition of nanosilica particles (13 % by mass) did not significantly change the thermal stability, but it made a small improvement in modulus, and it reduced the peak heat release rate roughly 50 %. Nanocomposites based on polypropylene and multi-wall carbon nanotubes (up to 2 vol.-%) were melt blended, yielding a good dispersion of nanotubes without using any organic treatment or additional additives. Carbon nanotubes are found to significantly enhance the thermal stability of polypropylene in nitrogen at high temperatures. Specifically, the nanotube additive greatly reduced heat release rate of polypropylene. They are found to be at least as effective a flame-retardant as clay/polypropylene nanocomposites. The results show a great potential for the use of carbon nanotubes as a flame retardant additive for polymer materials, especially for the important case of polyolefins when environmentally friendly flame retardants are needed.
Pub Type: Journals
carbon nanotubes, flame retardant, nanocomposites, silica